WO2025068383A1 - Device and method for the laser-supported machining of a workpiece made of glass-based material and use of same - Google Patents

Abstract

The invention relates to a device (100) and method (100) for the laser-supported machining of a workpiece (2) made of glass-based material, in particular for introducing damage into the workpiece (2), said device being configured to arrange the workpiece in the machining plane (W), with an ultra-short pulse laser (3), the focus region (1) of which lies at least partially within the workpiece and in which the irradiation intensity is so great that in the operating state, x-ray radiation is emitted from the focus region (1) in an energy range EM which is dependent on the composition of the workpiece. The focus region (1) is surrounded, at least in regions, by at least one shielding element (300, 310) for x-ray radiation, and thus provides a machining space (302). The shielding element (300, 310) comprises a material which has an x-ray absorption which is adapted to the energy range EM, in particular the material of the shielding element has a particularly high x-ray absorption in the energy range EM.

Description

Device and method for laser-assisted processing of a workpiece made of glass-based material and their use

The invention relates to a device and a method for laser-assisted processing of a workpiece made of glass-based material. The invention also covers their application.

For the purposes of the invention, glass-based materials are all materials that have a glass-like network at least in some areas and/or are derived from a glass material. Glass-based materials include, in particular, glasses as such, but also glass ceramics obtained by at least partial crystallization of elements made of glass material.

Laser-assisted machining is based on the introduction of damage into the glass-based material using ultrashort pulse lasers that emit ultrashort laser pulses. One well-known application is laser cutting. This typically involves introducing filament-shaped damage into the workpiece, generally running perpendicularly through its thickness. If several damages are then placed side by side, a parting line is created, along or at which the workpiece can be cut.

The often-described mechanism is that microcracks originating from the damage weaken the material of the workpiece. In adjacent damage areas, the cracks connect, allowing separation along this connecting line.

WO 2012/006736 A2 describes a laser cutting process based on the nonlinear optical Kerr effect. This is based on two nonlinear effects: the self-focusing of the pulse due to the optical Kerr effect and its defocusing due to the plasma generated by the laser in the material. It is stated that the self-focusing occurs over a focal length of approximately 500 up to 1000 m, and then spatially dispersed when the pulse energy is not sufficient to refocus itself and create a plasma channel again.

EP 3169635 A1 uses a Bessel beam with an axicon optic to extend the laser focal line during laser cutting. The inventors of this document argue that the difference from a method based on the Kerr effect, such as WO 2012/006736 A2, is that refocusing the laser beam according to WO 2012/006736 A2 requires a modification of the refractive index of the workpiece material, in this case glass. This inevitably results in a different damage pattern, which can be undesirable.

DE 102018200033 A1 describes a laser processing head with an integrated X-ray sensor that detects the process-related X-ray radiation, and the machine control adjusts the process parameters based on the sensor signals. In particular, processing is interrupted if a predetermined X-ray dose is exceeded. This does not allow for rational manufacturing processes, for example, in industrial series production. DE 102020127575 A1 follows a similar approach.

DE 102018200030 B3 describes the influencing of X-ray emission during material processing with ultrashort laser pulses by suitably arranged particle streams.

DE 102018120022 A1 describes the metrological monitoring of a workpiece machining process using an X-ray sensor that detects radiation with a photon energy of more than 0.5 keV and analyzes it, particularly with regard to radiation energy distribution and dose rate. DE 102018120019 A1 describes the associated detector module, and DE 102019000143 A1 extends the sensor functionality with regard to different radiation types and evaluation variants. DE 102019000144 A1 describes the testing of a housing for leaks using an X-ray sensitive sensor that is held at a predefined distance from the housing wall by means of a spacer.

What the aforementioned documents have in common is that they do not enable efficient machining of workpieces, such as those required for industrial series production of workpieces made of glass-based materials, for example the cutting of glass panes and/or glass ribbons, in particular ribbons made of ultra-thin glass.

The inventors have recognized that when processing glass-based workpieces with ultrashort pulse lasers, especially when inducing filament-shaped damage, X-rays with a characteristic spectrum can be generated. Part of the finding is that this occurs particularly when the irradiated laser energy is high and/or a burst of laser pulses is used.

The object of the invention is to provide a device and method that enables the efficient processing of workpieces made of glass-based material. The invention is based on the principle of limiting the propagation of the resulting X-ray radiation and thus providing an efficient production environment and/or an efficient method for the processing and/or production of elements made of glass-based workpieces, in particular those made of glass and/or glass-ceramic.

This object is achieved by the subject matter of the independent claims and the content of the present description. Preferred embodiments are set forth in the dependent claims.

The invention comprises a device for laser-assisted machining of a workpiece made of glass-based material, in particular for introducing damage into the workpiece, which is designed to arrange the workpiece in the machining plane W. The device further comprises a Ultrashort pulse laser for emitting ultrashort laser pulses with a wavelength A and a single pulse energy Ep and a laser beam direction z, wherein the laser and/or the laser pulses are configured such that the workpiece is at least substantially transparent to the wavelength A, and a beam-shaping optics configured to form a focus region of the laser beam which, in the operating state, lies at least partially within the workpiece and in which the irradiance Ef is so great that, in the operating state, X-ray radiation is emitted in an energy range EM that depends on the composition of the workpiece, and wherein at least the focus region is at least partially surrounded by at least one shielding element for X-ray radiation, thus providing a processing space, either alone or in combination with further shielding elements. The shielding element consists of or comprises a material which has an X-ray absorption that is adapted to the energy range EM.

The emission of X-rays occurs particularly from the focus area.

Particularly advantageously, the material of the shielding element has a particularly high X-ray absorption in the EM energy range.

For the purposes of the invention, the workpiece made of glass-based material is located in the focal area during processing. In other words, the glass-based material is processed using ultrashort laser pulses. Therefore, it is also within the scope of the invention that the workpiece may comprise additional materials, for example, in its edge region. For the purposes of the invention, the region containing the glass-based material is processed using the ultrashort laser radiation.

Damage within the meaning of the inventions is generally any form of material modification and/or material removal resulting from the interaction of the ultrashort laser pulses with the material of the workpiece. This may include refractive index changes, material discoloration, weaknesses of the Material structure, in particular through cracks, local melting, ablation, introduction of hollow channels and/or blind holes, etc. The introduction of filament-shaped damage is particularly advantageous.

A filament is generally understood to be an elongated, thread-like structure whose diameter is significantly smaller than its length. Particularly advantageously, the device is configured and/or the method is designed such that hollow-channel-shaped filaments are introduced into the workpiece. Such a hollow-channel-shaped filament is characterized by the hollow space extending along the filament axis. Such a hollow channel goes beyond mere material damage and/or refractive index changes and enables efficient further processing of the workpiece, for example, the separation or further expansion of the filaments.

The device further comprises an ultrashort pulse laser configured to emit ultrashort laser pulses. In an ultrashort pulse laser, the pulse width of a laser pulse is very short, i.e., in the range of less than 1 ns, in particular in the range of a few ps to fs, in particular in the range of 40 fs to 20 ps. Particularly advantageous lower limits are 100 fs or 200 fs, and advantageous upper limits are 10 ps, 3 ps, or 1 ps. The upper and lower limits can be combined with one another as desired. In particular, this results in an advantageous range of 100 fs to 10 ps, or 200 fs to 10 ps, or 100 fs to 3 ps.

For the pulse durations mentioned, average laser powers in the range of 1 W to 10 kW or more are commercially available.

The irradiance Ef represents the incident laser power per unit area, i.e., the beam cross-sectional area, measured at the point of interaction with the workpiece. With oblique incidence onto the workpiece surface, the area illuminated by the laser beam becomes larger, and thus the irradiance decreases. The maximum achievable power density corresponds to the intensity of the laser beam at the focus. The laser powers are emitted as individual pulses or as burst pulse groups, also referred to herein as burst packets, with the repetition frequency f _re p, which in particular, it can be in the range from 10 kHz to 100 MHz. Preferred ranges are 25 kHz to 50 MHz, 50 kHz to 20 MHz, and/or repetition frequencies less than 50 MHz, 20 MHz, 10 MHz, 8 MHz, 4 MHz, 2 MHz, or 1 MHz.

If the energy provided by individual pulses is not yet sufficient, the irradiation of at least one burst packet of laser pulses can be provided. A burst packet consists of a group or sequence of ultrashort laser pulses, also referred to below as individual burst pulses. A burst packet therefore has at least two individual burst pulses. As a rule, however, around 2 to 20 individual burst pulses are used, advantageously 3 to 10, although upper limits of around 100 individual burst pulses are also possible. The burst packet advantageously has a pulse energy Ep of 100 pJ to 1 J. Equally advantageous ranges are from 100 pJ to 50 mJ or from 100 pJ to 10 mJ. As already described, Ep here refers to the accumulated energy of the burst packet. The use of a single pulse is also possible.

The pulse duration of a single pulse and/or burst pulse corresponds to the pulse duration of the laser, the duration of the burst packet, called burst duration Tb, depends on the pulse duration of the burst pulse, the number of burst pulses in the corresponding burst packet and the time interval between the burst pulses, called intra-burst delay Ti, measured in each case at the time of the maximum intensity of a burst pulse.

The individual burst pulses of a burst pulse group advantageously have a time interval in the range of a few nanoseconds, e.g., 15 ns, and thus their own burst pulse frequency, which is typically in the megahertz range between 30 MHz and 60 MHz, preferably 50 MHz. In special cases, burst pulse groups themselves can consist of additional subpulses, so-called burst-in-burst or biburst modes, whose time intervals are in the range of ps and the frequency base is accordingly in the gigahertz range. For the purposes of this description, the laser emits laser radiation of wavelength A. This wavelength is selected to be suitable for the desired material processing, particularly for the introduction of damage. This generally means that the laser wavelength A is selected according to the desired interaction mechanism with the workpiece material.

For the purposes of this description, UKP is short for ultrashort pulse. In general, U KP laser systems can currently provide laser wavelengths in the range 350 nm to 2700 nm. Typical emission wavelengths are in the range 350 nm to 1400 nm, advantageously 400 nm to 1100 nm. Examples include ultrashort pulse laser systems with an emission wavelength of 800 nm, 1030 nm, or 1064 nm, and the corresponding frequency-doubled versions at 532 nm and 515 nm, respectively. The wavelengths of higher harmonic excitation are also possible. Advantageously, the wavelength A is selected so that the workpiece is transparent to the laser wavelength A used, at least in the laser beam impact area. This means that the transmission of the workpiece at this point is greater than 50% or greater than 85%, advantageously greater than 90%, and particularly advantageously greater than 95% at wavelength A. In this way, filament-shaped damage can be introduced into the workpiece, in particular hollow channels and/or blind holes.

The laser radiation is emitted in the direction of the laser beam, e.g.

The device further comprises beam-shaping optics designed to focus the laser beam in a focal region, wherein the irradiance Ef in the focal region is so high that X-rays are emitted from the focal region during operation. This can occur, in particular, through interaction of the high-energy laser radiation in the focal region with the material of the workpiece or even with the surrounding medium, for example, the atmosphere in the focal region—in the simplest case, air. The decisive factor here is the achieved irradiance Ef, which is generally calculated as the quotient of laser power and beam diameter. The maximum irradiance is calculated for a spatially and temporally normally distributed pulse shape (Gaussian beam) as

Where Q is the pulse energy, TH is the pulse duration, d _n o is the beam diameter, which comprises 86% of the laser power, and d o, 63 is the diameter corresponding to 63% of the total power. In order to modify the surface of a substrate, an irradiance of at least 10 ¹² W/cm ² must be achieved, and preferably 10 ¹³ W/cm ² . At these values, a plasma forms on the substrate surface, and the workpiece can be modified, i.e., ablated. Due to braking and absorption processes in the plasma, the released energy is emitted in the form of continuously distributed or discrete X-rays.

The workpiece is arranged in a processing plane (W). The position of the processing plane and the position of the focus area are advantageously coordinated. This can be achieved by adjusting the processing plane and/or, individually or in combination, by adjusting the position of the laser, in particular its height, and/or the beam-shaping optics.

Advantageously, the device is configured such that the focal region lies at least partially within the workpiece. Particularly advantageously, the beam-shaping optics are configured such that the focal region is represented by an elongated focal line directed toward the workpiece at an angle α, α advantageously 90°, and the focal line lies at least partially within the workpiece. Typically, the focal line penetrates the surface of the workpiece on at least one side, and in particular on both sides. As previously described, the laser radiation in the described device and the method described below generates X-rays. The inventors have determined that these X-rays are emitted in an energy range (EM) typical for a glass-based material.

According to the invention, the emitted X-ray radiation is shielded by at least one shielding element. For this purpose, the shielding element is arranged alone or in combination with other shielding elements such that at least the focal area is at least partially surrounded by the shielding element(s), thus providing a processing space. The shielding element consists of or comprises a material that has an X-ray absorption that is adapted to the EM energy range of the X-ray emission. In particular, the material of the shielding element has a particularly high X-ray absorption in the EM energy range.

The shielding element works by efficiently absorbing the generated X-rays. This effectively keeps the generated X-rays within the processing area and/or reduces the radiation intensity outside the processing area than inside.

The decisive factor for the protective effect of the shielding element is the absorbed dose E behind the shielding element and/or the corresponding equivalent dose H as a measure of biological effectiveness. This is calculated by multiplying the absorbed dose by a weighting factor and takes into account that different types of radiation have different effects on biological tissue. For X-rays, this weighting factor is 1. The following applies: [H] = 1 Sv = 1 J/kg.

Because X-ray radiation has different effects on biological tissue, a distinction is made between the directional equivalent dose H'(0.07,Q) at 0.07 mm (penetration) depth for skin, the directional equivalent dose H'(3,Q) at 3 mm Penetration depth for the eye and the ambient equivalent dose H*(10) at 10 mm tissue depth for the body. Each is referred to as an equivalent dose for the purposes of this description. The equivalent dose rate is the respective equivalent dose per unit of time. For the purposes of this description, it is measured at a distance of 10 cm from the outer wall of the shielding element.

A shielding element is considered advantageous within the meaning of the invention if all three equivalent dose rates do not exceed 10 pSv/h. A shielding element is particularly advantageous if all three equivalent dose rates do not exceed 1 pSv/h at a distance of 10 cm from its outer wall.

The protective effect of a shielding element is particularly high if an irradiance of greater than 10 ¹³ W/cm ² , more than 10 14 W/cm ² , preferably more than 10 ¹⁵ W/cm ² or particularly preferably more than ^{10 16 W} /cm ² is generated in the focus on the laser side of the wall by the laser process and its focusing optics and the equivalent dose rates on the side of the shielding element facing away from the laser remain below 10 pSv/h or 1 pSv/h, thus in the range from 0.1 to 10 pSv/h and/or from 0.1 to 1 pSv/h.

The lower limit of 0.1 pSv/h is usually determined by the natural X-ray radiation in the environment.

Or in other words, an advantageous embodiment is a device in which, in the operating state, the equivalent dose rates outside the processing chamber, measured at a distance of 10 cm from its outer wall, are less than 10 pSv/h, preferably less than 1 pSv/h.

As already described, the equivalent dose rates are the dose rates of the directional equivalent dose at 0.07 mm (penetration) depth for skin, the directional equivalent dose at 3 mm penetration depth for the eye and the ambient equivalent dose at 10 mm tissue depth for the body. Equally advantageous are embodiments in which an irradiance of more than 10 ¹³ W/cm ² , more than 10 ^{14 W/cm 2 , more than 10 15} W/cm ² or particularly advantageously more than ^{10 16} W/cm ² is generated in the focus area on the laser side of the wall by the laser process and ^its focusing optics and the generated X-ray radiation has photons with an energy of more than 7 keV, more than 10 keV, more than 12 keV, 15 keV or more than 20 keV and on the side of the shielding element facing away from the laser the equivalent dose rates remain below 10 pSv/h or below 1 pSv/h.

It is easy for the reader to see that the specific arrangement of the shielding elements is such that the X-rays emitted from the focal area can be absorbed by them.

The device is particularly advantageously designed so that the X-ray radiation has an energy of 2 keV to 40 keV, in particular of 3 keV to 30 keV or of 4 keV to 40 keV.

In glass-based materials, the emitted X-rays exhibit maxima in the range of 6 keV to 10 keV.

In accordance with the invention, the material of the shielding element is advantageously selected such that it has a high X-ray absorption in the region in which the maxima of the emitted X-ray radiation of the workpiece made of glass-based materials lie.

A device is particularly advantageous in which the material of the shielding element has a maximum of X-ray absorption in the energy range from 6 keV to 10 keV.

A maximum in the sense of the above description can also be understood as a local maximum. An advantageous device is designed such that the shielding element consists of a material or comprises a material selected from the group of metals, in particular comprising iron, steel, stainless steel, tungsten, glass, or selected from the group of plastic composites, in particular comprising plastic composite filled with tungsten or glass.

In general, the shielding element aims for the highest possible shielding efficiency. However, it should also be efficient to manufacture and operate. The shielding behavior correlates fundamentally with the atomic number of the atoms in the material comprising the shielding element. The interaction with the thickness of the shielding element then determines the overall ability of the shielding element to at least reduce and/or shield X-ray radiation.

Metals fulfill this compromise particularly well. For example, lead is known to be a good X-ray absorber. However, in operation it is not the most advantageous material. For the purposes of the invention, ferrous materials are advantageously used, in particular steel and/or stainless steel, particularly in accordance with EN 10020:2000, issue date 07/2000, including unalloyed stainless steels and alloyed stainless steels. Tungsten has also proven advantageous. Likewise possible are metal-filled plastic composites, in particular tungsten-filled plastic composites. Also possible and encompassed by the invention are radiation protection glasses and/or glass-filled plastic composites, in particular glasses that have high X-ray absorption. Such glasses are also used as dental glasses and can contain barium, for example. Such glasses can have aluminum equivalent thicknesses, abbreviated ALET, of over 100%, sometimes even over 200%.

In an advantageous embodiment, the device is designed such that the shielding element for X-ray radiation at least partially encloses the workpiece. This means that it can be advantageous if the shielding elements not only enclose the focus area, but also if the workpiece is located within the processing space. As described later, this can be an entire workpiece, such as a glass pane, in a single processing operation, or a section of a continuous workpiece strip, such as a glass ribbon.

A device is advantageous which is designed to generate a plasma in the focus area of the laser beam which emits X-rays.

Particularly at high laser powers, a plasma can be generated and/or ignited, particularly in the focal area and/or in the workpiece. The inventors have recognized that this plasma, in particular, can emit X-rays. At the same time, the plasma can be used particularly advantageously to introduce filamentary hollow-channel-shaped damage into the workpiece. It is assumed that the effect of the plasma creates a micro-explosion that pushes material into the workpiece perpendicular to the filament axis, thus creating the hollow channel and/or blind hole as a cavity.

In a further advantageous device, the laser is configured to emit at least one burst packet of laser pulses consisting of a sequence of ultrashort burst pulses with the repetition frequency f _rep . Particularly advantageously, the first burst pulse of the burst packet generates an initial plasma, which is supplied with energy and thus maintained by the following burst pulses of the burst packet.

The individual burst pulses following the first individual burst pulse of the burst packet essentially feed the initial plasma and keep it burning. It has been found that particularly good material processing is possible in burst mode, but also generates a particularly high level of X-ray radiation. The present invention makes it possible to utilize the advantage of good processability and compensate for the disadvantages of the higher X-ray radiation. The total pulse energy can be distributed evenly across the pulses of the burst packet, or with decreasing or increasing energy content throughout the burst packet. It has also been observed that, particularly in the latter case, a particularly high dose rate can occur. Therefore, it may be advantageous to adjust the energy of the individual burst pulses in the burst packet so that it remains constant and/or decreases advantageously.

A further advantageous embodiment of a device is set up such that the laser emits a laser wavelength A in which the workpiece is at least substantially transparent to the laser wavelength A. Particularly advantageously, the laser wavelength A is from 500 nm to 1100 nm and/or the pulse duration of an individual pulse is from 200 fs to 11 ps and/or the burst duration is from 1 ps to 500 ns and/or the accumulated energy of a burst packet is from 100 pJ to 10000 pJ and/or the repetition frequency f _rep is from 10 kHz to 100 MHz and/or the workpiece consists of or comprises glass and/or glass ceramics.

The aforementioned transparency means that the transmission of the workpiece at the point of laser irradiation is greater than 85%, advantageously greater than 90%, particularly advantageously greater than 95% at wavelength A.

To still achieve interaction of the laser beam with the workpiece material, an ultrashort pulse laser is used according to the invention. As described, the pulse width of such a laser is very short, i.e., in the range of less than 1 ns, in particular in the range of a few ps to fs, in particular in the range of 100 ps or 10 ps to 100 fs or 10 fs. The range of 10 ps to 200 fs is particularly advantageous.

Particularly advantageously, the workpiece comprises glass and/or glass ceramics, at least in the processing area and/or focus area. It is particularly advantageous if it is made of these materials, at least there. In a further advantageous embodiment, it is provided that the focus area is arranged such that the workpiece itself at least partially absorbs the emitted X-ray radiation.

This is based on the finding that the glass-based material itself absorbs X-rays, at least partially in the spectral range in which the X-rays generated by the laser irradiation are emitted. For example, if the laser's focal line is positioned so that it penetrates the surface of only one side of the workpiece, the resulting X-rays are absorbed by the glass-based material on the other surface.

In general, it can be stated that when one of the two workpiece surfaces is penetrated by the focal line, X-rays and thus a dose rate are generated, depending on the energy distribution along the focal line. If a purely internal modification is performed without penetrating the workpiece surfaces, the resulting dose rate is absorbed by the surrounding glass-based material. If both surfaces are penetrated, two plasma flares are created, which emit X-rays as described above.

This shows that the direction of emission can also be influenced by the arrangement of the focal line and the workpiece.

A further advantageous device comprises a workpiece support on which the workpiece rests during processing, wherein the workpiece support consists, at least in the region of the focus area in the z-direction, of a material which absorbs X-radiation, in particular glass and/or glass ceramic and/or X-ray protective glass or plastic composite filled with glass, or there is a free space, in particular an air gap, below the workpiece as viewed in the laser beam direction, wherein the free space is delimited downwards, in continuation of the z-direction, at least in regions by an element which absorbs X-radiation, in particular an element made of glass and/or glass ceramic and/or X-ray protective glass and/or glass-filled plastic composite.

Below means, in the sense of the invention, viewed in the laser beam direction, below the workpiece and/or below the processing plane (W) on the side of the workpiece facing away from the laser, i.e. in other words further away from the laser and in the z-direction.

These two embodiments allow emitted X-rays to be absorbed even below the workpiece. They are particularly advantageous when the focal region is located at least partially below the workpiece, or in other words, partially penetrates the workpiece with a significant energy component below the workpiece plane.

Particularly advantageously, said element comprises a material beneath the workpiece or consists of a non-metal material, at least in the projection line of the focal area. This material is particularly advantageously glass and/or glass-ceramic or glass-filled plastic composite.

This is based on the inventors' finding that the impact of a focused ultrashort laser pulse on a metal surface also generates a significant amount of X-ray radiation. Accordingly, the invention seeks to prevent such a focused ultrashort laser pulse from striking a metal surface, for example, a previously known standard workpiece support or a standard workpiece holder. This is all the more important because the workpiece, as described, is essentially transparent to the incident laser radiation, and thus high-energy laser radiation can penetrate the workpiece. If the non-metal material mentioned is located directly beneath the workpiece, in particular in contact with the workpiece, the unwanted X-ray radiation is not generated or is generated only to a (significantly) reduced extent. The workpiece to be machined, made of glass-based material, also has a shielding effect on the X-ray radiation generated on the workpiece support, which depends on the workpiece thickness. The thinner the The larger the workpiece to be processed, the greater the probability that X-rays generated on the workpiece surface will pass through the substrate to be processed into free space.

The aforementioned alternative solution and/or embodiment provides for a free space beneath the workpiece. The focus area of the laser is configured such that, when it penetrates the workpiece, it is also located within this free space. In this way, impact with metal is avoided. The empty space can be filled with a fluid, in particular a gas, in the simplest case with the surrounding atmosphere and thus air. The free space can then be understood as an air gap. Particularly advantageously, the free space is delimited downwards in the direction of the laser beam, i.e., below the processing plane (W), by at least one element that absorbs X-rays, in particular an element made of glass and/or glass-ceramic or a glass-filled plastic composite. A coating of a substrate with the aforementioned materials is also to be understood as an aforementioned element.

A particularly advantageous embodiment provides that the workpiece is fed into the machining space on a feed plane (B) which differs from the machining plane (W), in particular the feed plane lies below or above the machining plane (W) when viewed in the z-direction.

In other words, this means that the plane on which the workpiece is guided to the processing location and/or processing space is offset from the plane of workpiece processing, specifically offset relative to the laser beam direction z. In particular, the plane of feed lies above or below the plane of laser processing and thus the location where the X-ray radiation is generated. This allows, in particular, for areas of the shielding element to be located in the area between the planes.

This principle of plane offset is generally applicable to all types of workpieces within the meaning of this description. For individual workpieces, for example For example, in the case of sheets made of glass-based material, the workpiece can be discretely moved from the feed plane (B) to the processing plane (W), for example by means of a lift and/or a conveyor belt. However, this principle is particularly advantageous for continuous processing and thus feeding of the workpiece, for example when the workpiece is in the form of a strip made of glass-based material. The strip is then moved from the feed plane (B) to the processing plane (W), in particular while bending it. As is generally known, such glass strips can have a thickness of a few mm, but can in particular be very thin or ultra-thin glasses with thickness ranges as described herein.

An advantageous device is designed such that the shielding element has a feed opening through which the workpiece can be introduced into the processing space.

This can be applied in the sequential processing of glass panes, for example, but also in the continuous processing of a glass ribbon, especially one made of ultra-thin glass. In sequential processing, the feed opening can also be identical to the removal opening.

For the purposes of this description, an ultra-thin glass is a glass with a thickness of at most 400 pm, in particular at most 30 pm. The lower limit at the time of the invention is approximately 5 pm, although even lower thicknesses are to be expected in future developments. Lower limits of 2 pm or 3 pm appear possible or even foreseeable. Advantageous thickness ranges for ultra-thin glasses, in the form of discs or strips and all other possible shapes, are thus from 5 pm to 400 pm or from 5 pm to 200 pm or from 5 pm to 100 pm or from 5 pm to 50 pm or from 5 pm to 30 pm, in particular from 7 pm to 40 pm.

Particularly advantageously, the feed opening can be closed by at least one closure device which comprises a material which absorbs the X-ray radiation emitted in the operating state, in particular the closure device is selected from the group of shutter curtain, roller and/or water curtain or combinations thereof.

In particular, a shutter curtain and/or a roller can be in contact with the workpiece as it is fed into the processing chamber. If the device is integrated into the manufacturing process in which the workpiece is produced by hot forming, it is particularly advantageous if the feed takes place at a point where the workpiece has cooled sufficiently and/or has such a high viscosity that the shutter device creates as few indentations and/or scratches on the workpiece as possible.

Particularly advantageously, the selected closure device comprises a material that absorbs X-rays. For example, a corresponding roller can have a metal axle on which a cylindrical body made of absorbent plastic, in particular the previously mentioned filled plastics, is arranged. In the simplest case, the feed opening is located on a feed plane (B) that lies on or near the processing plane (W).

Alternatively or additionally, the feed opening can advantageously be arranged in a plane (B) which, viewed perpendicular to the z-direction, is located above or below the processing plane (W). Particularly advantageously, a region of the shielding element is located in the processing plane (W), in particular between the feed plane (B) and the processing plane (W).

This arrangement is based on the aforementioned principle that the workpiece is fed to the processing on an offset plane. The X-ray emission occurs at least primarily from the focus area of the laser and thus the processing plane (W). If the feed opening is arranged outside this plane (W), at least a portion of the shielding element is located in the processing plane (W), but in particular between the feed plane (B) and the processing plane (W). The X-ray radiation emitted during operation can thus be shielded and/or deflected by other elements, so that it does not enter the feed opening. These elements can be, for example, the workpiece support and/or a workpiece holder, but in particular also the workpiece itself. As described above, it has been found within the scope of the invention that workpieces comprising or consisting of glass-based material in particular absorb the X-ray radiation generated during the aforementioned laser processing. In an advantageous arrangement, a disk-shaped workpiece or workpiece element, for example a section of a glass ribbon, is located parallel to or on the processing plane (W). X-ray radiation emitted along this plane therefore interacts with the workpiece over a relatively long path, at least over a path that is greater, in particular significantly greater, than the thickness of the workpiece. This makes it possible, despite possibly low specific X-ray absorption properties of the workpiece material, to achieve good X-ray absorption in the direction, i.e. in particular parallel to the plane (W), due to the greater path. The workpiece itself then contributes, so to speak, to the X-ray absorption in an advantageous device.

Based on the explanations, it is easy to see that the feed opening can also be the edge region of a shielding element or of the shielding element itself, in particular if the shielding element extends beyond the processing plane (W) in the direction of the feed plane (B) and the planes (W) and (B) do not lie on top of one another.

In a particularly advantageous embodiment, the feed opening is located in the processing plane W at a distance of at most 200 cm from the focus area, in particular at most 150 cm or at most 100 cm or at most 50 cm; preferably in the range from 10 cm to 200 cm or 10 cm to 150 cm or from 10 cm to 100 cm or from 10 cm to 50 cm. Particularly advantageously, a region of the workpiece and an air space are located between the focus area and the feed opening. Both the workpiece made of glass-based material and the air space absorb at least partially emitted X-rays. This makes it possible to ensure that the feed opening does not have to be designed to be closable with closure means, but that in the simplest case it can be designed in particular as a gap in the shielding element.

This embodiment is particularly suitable for, but not limited to, workpieces in the form of continuous glass ribbons. A particularly advantageous embodiment of the device is therefore configured to feed the workpiece in the form of a ribbon of glass-based material, in particular a glass ribbon, in particular in the form of ultra-thin glass with a thickness of 5 pm to 400 pm or 5 pm to 200 pm or 5 pm to 100 pm or 5 pm to 50 pm or 5 pm to 30 pm, in particular 7 pm to 40 pm, which is fed into the processing space, in particular continuously.

Continuous, of course, in the context of this description, does not exclusively mean feeding over an infinitely long period of time, but rather the feeding of a workpiece that is significantly longer than it is wide and is generally fed into the processing area over a period longer than a few seconds. A common element is a glass ribbon, which can typically range in length from several to many meters.

Particularly advantageously, the device is designed to feed the glass ribbon into the processing space while bending the glass ribbon.

This utilizes the bendability of a strip made of glass-based material. If the feed level (B) is located below or above the processing level (W), a glass strip can be deflected, for example, using rollers, and thus fed into the processing area in the processing level (W).

The thickness of the glass-based material strip generally determines the possible bending radii. As described, a particularly advantageous application of the invention is the processing of ultra-thin glass strips. have very small bending radii, so that a compact arrangement of the device and its integration into production systems is particularly easy.

A further advantageous embodiment of the device provides that the shielding element has, in addition to the feed opening, a removal opening which in particular has the measures and/or properties described with regard to the feed opening, in particular its arrangement with respect to the processing plane W.

The removal opening can be provided in sequential operation as well as particularly advantageously in continuous operation for processing strips made of glass-based material,

Particularly advantageously, the device comprises feeding means which are designed to introduce the workpiece into the processing space, and particularly advantageously removal means which are designed to guide the workpiece out of the processing space and/or synonymously remove it.

In an advantageous development of the device, it comprises a sensor device, in particular a sensor device assigned to the processing space, which is configured to detect the emitted X-rays and thus provide sensor data. Preferably, the laser is configured to be controllable taking the sensor data into account. In particular, it can be provided that the laser is also switched off when maximum emission values of the X-rays are reached, thus enabling safety-related functions to be implemented.

The sensor device can, for example, be arranged in the processing area and detect light reflections of the incoming laser beam or, in particular, the emitted X-rays. Other measurement variables are also conceivable, particularly if they correlate with the energy of the incident laser power and/or the intensity of the generated X-rays. Advantageously, the energy of the emitted laser power can be used as a control variable for the laser and a Positioning device can be used. For this purpose, the sensor device can be connected to the control device. For example, the X-ray emission can be used as a measure of the incoming laser power and the laser can be controlled so that desired processing parameters are maintained using these measured variables. In this way, the amount of X-ray radiation generated can also be recorded and further safety measures can be initiated in a production environment. It is of course also possible to have a sensor device outside the processing area, which detects the residual X-ray radiation penetrating the shielding element and uses the obtained values, in particular, for further safety measures.

A particularly advantageous device is designed so that the laser and the beam-shaping optics produce a filament-shaped damage in the workpiece, in particular a filament-shaped hollow channel.

The hollow channel has already been described above. The term also includes a blind hole. A filamentary hollow channel can penetrate the workpiece as a through-hole, i.e., connecting one surface to another, or it can end within the volume of the workpiece, thus representing a blind hole.

In a particularly advantageous embodiment of the device, the beam-shaping optics are configured to provide a laser intensity distribution in the focus area that is constant in the laser beam direction in the range of ± 30%.

This is based on the realization that the emitted X-rays are lower when the intensity of the laser radiation is largely constant and/or remains within the specified range over the length of the focus area, i.e. generally in the z-direction, i.e. parallel to the optical axis and thus perpendicular to the processing plane (W). The alternative option of focusing the laser as tightly as possible on one point leads to higher X-ray emissions and is therefore less advantageous, but can be applied accordingly. The shielding elements must then be designed to absorb more X-rays.

The device according to the invention can be integrated, as described, into a production facility for workpieces made of glass-based material. A device as an element of a glass production facility, in particular a facility for producing ultra-thin glass, is particularly advantageous, in particular arranged on a continuous glass ribbon with a border, wherein the device is configured to produce the border and/or a cross-section.

The border is generally an area at the edges of a ribbon of glass-based material that extends longitudinally, i.e., in the transport direction of the glass ribbon. The border typically has a lower surface quality than the central region; in particular, it may exhibit greater thickness and/or waviness, and is therefore advantageously removed from the glass ribbon. The corresponding process is called border cutting or longitudinal cutting.

Alternatively or additionally, it is possible to perform a cross-section using the described device. This cross-section runs perpendicularly or at a specific angle to the longitudinal direction of the glass ribbon. It is also possible to arrange several of the described devices on a glass ribbon, for example, to use one for cutting the border and another for cross-section.

In particular, it is also possible to structure or even mark workpieces with the described device, e.g., to provide the individual workpiece produced after a cross-section with a unique identification number or 1D/2D barcode in order to obtain traceable products. The marking can, for example, be carried out ablatively by changing the workpiece surface or - preferably with an ultrashort pulse laser, since the material damage caused here is spatially very limited - by local modification of the material inside the substrate. Structuring naturally also includes the introduction of structures, in particular as Result of damage that allows subsequent separation of the workpiece made of glass-based material.

In addition to the device, the invention also encompasses a method for machining a brittle workpiece with an ultrashort pulse laser. The description given with regard to the device is also applicable to the method according to the invention. All features and/or embodiments relating to the device also apply to the method described below.

The invention comprises a method for machining a brittle workpiece with an ultrashort pulse laser, in particular for introducing damage into the workpiece, wherein the workpiece is arranged in the machining plane (W), wherein the laser emits ultrashort laser pulses with a wavelength A and a single pulse energy Ep, wherein the laser beam is focused in a focus area by means of beam-shaping optics, and wherein the single pulse energy Ep within the focus area is so large that X-ray radiation is emitted, and wherein at least the focus area is at least partially surrounded by at least one shielding element for X-ray radiation and thus, either alone or in combination with further shielding elements, a machining space is provided, so that outside the machining space there is a lower intensity of the X-ray radiation than inside the machining space.

Advantageously, it can be achieved that outside the processing space, measured at a distance of 10 cm from the outer wall of the shielding element (300), an X-ray dose of less than 10 pSv/h is present, particularly advantageously less than 1 pSv/h, in particular from 0.1 to 10 pSv/h or from 0.1 to 1 pSv/h.

The material of the shielding element and its design, in particular its thickness, are selected in such a way that the described X-ray absorption is present in the desired strength and in particular outside of the processing room only the mentioned proportion of the X-ray radiation occurring in the processing room is present.

In particular, the method can be designed such that the X-ray radiation within the processing space has an energy of more than 1 keV, preferably between 2 keV and 30 keV, in particular an energy between 3 and 20 keV.

Particularly advantageously, the method comprises the use of a shielding element which consists of a material or comprises a material as described above, which is in particular adapted to the typical emission of a glass-based material, thus selected from the group of metals, in particular comprising iron, lead or lead foil, steel, stainless steel, tungsten, glass, or selected from the group of plastic composites, in particular comprising plastic composite filled with tungsten or glass.

A method is advantageous in which a plasma is generated in the focus area of the laser beam, which plasma emits X-ray radiation; in particular, the laser emits at least one burst packet of laser pulses, which consists of a sequence of ultrashort burst pulses.

Particularly advantageously, the first single burst pulse of the burst packet generates an initial plasma, which is supplied with energy and thus maintained by the following single burst pulses of the burst packet.

The burst pulses following the first burst pulse of the burst packet essentially feed the plasma and keep it burning. However, because the pulses following the first burst pulse of the burst packet have lower burst energy, the plasma explosion appears to be controllable. This can be particularly advantageous when using the process for separating brittle workpieces, also known as cutting. Also advantageous is a method wherein the laser wavelength A is selected such that the workpiece (2) is at least substantially transparent to the laser wavelength A. Particularly advantageously, the laser wavelength A is from 350 nm to 1100 nm and/or the pulse duration of an individual pulse is from 200 fs to 11 ps and/or the burst duration is from 1 ps to 500 ns and/or the accumulated energy of a burst packet is from 100 pJ to 1 J and/or the repetition frequency f _rep is from 10 kHz to 100 MHz and/or the workpiece consists of or comprises glass and/or glass ceramics and/or silicon and/or ceramics. Equally advantageous ranges for the accumulated energy of a burst packet are from 100 pJ to 50 mJ or from 100 pJ to 10 mJ.

An advantageous development of the method provides that the workpiece rests on a workpiece support and wherein the workpiece support consists, at least in the region of the focus area, of a material which absorbs X-rays, in particular glass and/or glass ceramic or glass-filled plastic composite, or wherein (viewed in the laser beam direction) there is a free space below the workpiece, in particular an air gap, wherein the free space is delimited at least in regions at the bottom by an element which absorbs X-rays, in particular an element made of glass and/or glass ceramic or glass-filled plastic composite, and wherein the focus area of the laser is preferably arranged at least partially within the empty space.

As previously explained with regard to the device, the method advantageously also utilizes the principle of offsetting the feed plane (B) and the processing plane (W). A particularly advantageous embodiment of the method provides that the workpiece is fed into the processing space on a feed plane (B) that differs from the processing plane (W); in particular, the feed plane (B) lies below or above the processing plane (W) when viewed in the z-direction. Particularly advantageously, a region of the shielding element is located in the processing plane (W), in particular between the feed plane (B) and the processing plane (W). This principle and/or design have already been described in detail in connection with the device. This description also applies to the method.

A method is advantageous in which the shielding element has a feed opening through which the workpiece is introduced into the processing space.

Particularly advantageously, the feed opening is closed by at least one closure device which comprises a material which absorbs the emitted X-radiation, in particular the closure device is selected from the group consisting of a closure curtain, a roller and/or a water curtain or combinations thereof.

A method is particularly advantageous wherein the feed opening is arranged in a plane (B) that is located above or below the processing plane (Z). In particular, a region of the shielding element can be located in the processing plane (Z).

These designs have already been discussed in detail in connection with the device.

An advantageous method also provides that the workpiece is in the form of a glass ribbon, in particular an ultra-thin glass with a thickness of 5 pm to 100 pm, which is continuously fed into the processing space.

The previously mentioned thickness ranges for ultra-thin glass also apply here.

It is advantageous in a process if the glass ribbon is fed into the processing area while bending the glass ribbon.

It is also advantageous in a method if the generated X-ray radiation is detected by a sensor device, in particular the X-ray radiation generated in the processing space, and thus sensor data are provided which are preferably taken into account when controlling the laser. An advantageous method provides in particular that filament-shaped damage is produced in the workpiece, in particular filament-shaped hollow channels or filament-shaped blind holes.

A particularly advantageous method is one in which the laser intensity distribution in the focus area is constant within ± 30% in the direction of the laser beam. This has also been discussed in detail above.

A method for producing glass elements, in particular elements made of ultra-thin glass, comprising the above-mentioned method steps is particularly advantageous, wherein the supplied glass ribbon in particular has a border which is separated by means of the method, or wherein a cross-section is carried out by means of the method.

Accordingly, the invention also encompasses a glass element made of ultra-thin glass, which is or can be produced with the method described.

The invention thus also includes the use of a device according to the above description and/or the application of a method described above for producing glass elements, in particular ultra-thin glass.

The invention has the advantage of enabling the use of high-energy, ultrashort laser pulses without disrupting a production environment through the resulting X-rays. The influence of X-rays on sensitive electronics, particularly interference with them, can also be avoided. High-energy, ultrashort laser pulses enable rapid processing, which is particularly required in mass production. Overall, the invention thus enables the realization of efficient devices, methods, production systems, and/or production environments. The invention will be further explained below with reference to exemplary embodiments and the drawings. Comments on the drawings also represent exemplary embodiments.

As described, the invention is suitable for cutting workpieces made of glass-based materials. These materials are generally brittle.

According to an advantageous embodiment, micro-explosions of the plasma generate micro-cracks in the workpiece, which run from the hollow channel-shaped filament into the volume of the workpiece.

For this purpose, in one embodiment, a focused laser beam from a pulsed laser with a wavelength A was directed onto the workpiece made of glass-based material for processing, the workpiece being transparent to the wavelength A of the laser, the filament being produced by the irradiation of at least one burst packet of laser pulses, the at least one burst packet having a burst duration Tb and comprising a sequence of ultrashort individual burst pulses having an individual pulse energy Ep and an intra-burst delay Ti, the individual pulse energy of the individual burst pulse at the beginning of the burst duration Tb being greater than the individual burst pulse energy of the laser pulse at the end of the burst duration. A hollow channel-shaped filament can be produced by using a plurality of burst packets. It is advantageous if each hollow channel-shaped filament is produced by a single burst packet.

If a plurality of burst packets are used to produce a hollow-channel-shaped filament, it is sufficient for the purposes of this description if a single burst packet, in particular the first one, has the aforementioned property that the first burst pulse of the burst packet has a higher energy than the last. This particularly advantageously applies to all respective burst packets. Within a burst packet, it is especially advantageous that the individual pulse energy of each burst pulse is lower than that of the previous burst pulse. A workpiece made of glass-based material within the meaning of the description comprises, at least in the region of the filament, a material that consists of or comprises a glass-based material. A glass-based material is typically a brittle material that can only be plastically deformed to a limited extent. It is therefore characterized by low ductility. Brittle fracture occurs at low elongation and usually close to the yield point. A glass-based material and/or a glass-based material within the meaning of the invention comprises, in particular, glass and/or glass-ceramic, including green glass as a precursor product of a glass-ceramic.

To efficiently provide sufficient energy to produce the filament, even with industrially available laser sources, the filament is advantageously produced by irradiating at least one burst of laser pulses, the so-called single burst pulses. A burst packet consists of a sequence of ultrashort single burst pulses. A burst packet therefore contains at least two single burst pulses. Typically, however, approximately 2 to 20 single burst pulses are used, preferably 3 to 10, although upper limits of around 100 single burst pulses are also possible.

The pulse duration of a single burst pulse corresponds to the pulse duration of the laser. The duration of the burst packet, called burst duration Tb, depends on the pulse duration of the single burst pulse, the number of single burst pulses in the corresponding burst packet, and the time interval between the single burst pulses, called intra-burst delay Ti, measured at the time of the maximum intensity of a single burst pulse. The burst packet therefore has a repetition frequency, which is referred to as f _rep . Each single burst pulse has a single burst pulse energy Ep, which corresponds to the integral of the intensity curve of a single burst pulse over the single burst pulse duration and, with a constant burst pulse duration, correlates with the maximum intensity of a single pulse in the burst packet. It was found to be particularly suitable to set the burst single pulse energy of the burst single pulse at the beginning of the burst duration Tb to be greater than the burst single pulse energy of the burst single pulse at the end of the burst duration.

Until now, it was assumed that the individual burst pulses of the burst packet should accumulate as much energy as possible in the workpiece. The inventors recognized that it is not necessary to apply as much energy as possible, but that a temporally controlled amount of energy input can, on the one hand, efficiently produce a hollow channel-shaped filament and, on the other hand, control its mechanical interaction with the surrounding workpiece material.

An advantageous embodiment of the method provides that the burst packet has a burst degression of 40% to 90%, advantageously 50% to 70%, particularly advantageously 60% to 70%.

The burst degression BG considers the ratio of the burst single pulse energy Ep _x of the last burst single pulse of the burst packet at the end of the burst duration and the burst single pulse energy of the first burst single pulse Epo of the burst packet at the beginning of the burst duration in percent. The burst degression BG is therefore the quotient of Ep _x and Epo, preferably expressed as a percent. The formula applies accordingly:

For example, if Epo is 100 units and Ep _x 60 units, BG = 0.6 = 60%

The burst pulse energy is significantly reduced at the end of the burst duration compared to the first burst pulse. This makes it possible that fewer and/or shorter microcracks are formed around the filament, emanating from the filament into the workpiece. This helps to prevent unintentional weakening of the filamented workpiece.

In particular, it has been shown to be advantageous if the method is designed in such a way that, from the second single burst pulse of a burst packet onwards, the single burst pulse energy of a laser pulse is lower than the single burst pulse energy of the previous single burst pulse.

This, of course, applies from the second burst pulse onward. One can also formulate it equivalently by saying that the burst pulse energy of a laser pulse in the burst packet is greater than the burst pulse energy of the subsequent burst pulse.

In other words, this means that the energy of the individual burst pulses in the burst packet decreases over time. Although significantly less energy is deposited in the workpiece and/or filament by the burst packet of individual burst pulses, it is still possible to efficiently produce a hollow-channel filament. This is particularly surprising given that the goal is to apply as much energy as possible.

It has been shown that it is advantageous if the burst single pulse energy decreases linearly within the burst packet or particularly advantageous if the burst single pulse energy decreases exponentially during the burst duration.

It is particularly advantageous if the burst single pulse energy during the exponential decrease according to the formula

abnimmt. E(t) symbolisiert dabei die Intensität eines Bursteinzelpulses zum Zeitpunkt t eines Burstpakets, Eo die Bursteinzelpulsenergie des ersten Bursteinzelpulses des Burstpakets, und AF den Abnahmefaktor des gesamten Burstpakets, d.h. die Abnahme der Bursteinzelpulsenergie des letzten Pulses des Burstpakets gegenüber dem ersten Puls. In der vorgenannten vorteilhaften Ausführungsform, bei welcher der letzte Bursteinzelpuls beispielsweise 60% der Bursteinzelpulsenergie aufweist, beträgt die Abnahme 40%. E(t) = E

E(t) symbolizes the intensity of a single burst pulse at time t of a burst packet, Eo the burst single pulse energy of the first burst single pulse of the burst packet, and AF the decay factor of the entire burst packet, ie the decay of the burst single pulse energy of the last pulse of the Burst packet compared to the first pulse. In the aforementioned advantageous embodiment, in which the last burst pulse has, for example, 60% of the burst pulse energy, the decrease is 40%.

Tests have shown that it is particularly suitable if a filament-shaped initial channel is generated during the first single burst pulse of a burst packet, in particular an initial hollow channel which is widened by the following single burst pulses of the burst packet.

It is assumed that this describes the mechanism of action of the filamentation described herein. In the selected embodiment, the first single burst pulse already creates a filament-shaped initial channel. This can, in particular, already be a hollow channel. The subsequent single burst pulses of the laser in the burst packet then further expand this initial channel, which means at least essentially its diameter. The result is the hollow-channel-shaped filament in the workpiece.

Even though we're talking about the diameter of a hollow channel here, it should be noted that in reality, a laser-generated filament in a workpiece rarely corresponds to a uniform channel. This approach is an idealized, simplified description. Local variations in diameter are certainly possible along the filament axis, i.e., the axis in the longitudinal direction of the filament. It is also possible, and encompassed by the invention, for the filament to have a different diameter at the beginning and/or end than in between.

However, a considerable amount of X-ray radiation is generated, particularly when using burst packets as described above. Therefore, according to the invention, it is provided to control the energy distribution of the individual burst pulses within the burst packet. Alternatively, the invention encompasses the generation of a filament using a single laser pulse, i.e., without the use of burst packets. A further variation of the process involved creating a region of compressed workpiece material around the hollow channel-shaped filament, also called a compression zone or compression region, which has a higher density, particularly compared to the starting material.

The compaction of the surrounding material appears to be a result of the widening of the initial channel caused by the laser pulse. Simply put, a cylindrical region of compacted workpiece material is located around the hollow-channel-shaped filament, with the filament axis and the cylinder axis essentially overlapping. This region of compressed material has the advantage that the hollow-channel-shaped filament, particularly the filament wall, can be mechanically stabilized by this region. The filament wall is thus, in a sense, hardened.

It is astonishing that, firstly, the first burst pulse of the burst packet is sufficient to generate the initial channel without energy pooling being able to take place, and that, furthermore, the decrease of the burst pulse energies in the burst packet still leads to the compression of the surrounding workpiece material.

It was observed that the individual burst pulses of a burst packet can push material of the workpiece into the workpiece during the expansion of the initial channel, especially perpendicular to the channel axis.

The described compression also results in workpiece material not being removed from the workpiece by the interaction with the laser pulses, but being pressed into the filament wall and thus into the workpiece. One advantage of the described process is that, as a rule, significantly less material is removed by inserting the hollow channel-shaped filaments than is pressed into it. This is because removed material, which is ablated, is released as dust in the production facilities. This dust can not only contaminate the sensitive optics for steel forming, but, if it is floating in the beam path and/or even in the initial channel, absorbs the incoming laser radiation, especially since the ablated material is at least in the Essentially corresponds to the material being processed through interaction with the laser radiation. Such parasitic absorptions negatively impact the efficiency of the process.

In particular, it is assumed that the described reduction of the burst single pulse energy in the burst packet contributes to reducing the proportion of ablated material in favor of compressed material.

The finding that the aforementioned compression occurs with the process described here was based on measurement tests, according to which a workpiece to be filamented was first weighed. The workpiece was then filamented using the described process, i.e. the hollow channel-shaped filaments were introduced into the workpiece as described. The diameter and length of the hollow channels were measured and their volume determined from this. By correlating this measured volume of the hollow channels with the specific gravity of the workpiece material, it was found that significantly less weight and therefore material was removed from the workpiece by filamentation than would be expected from the inserted hollow channel volume. The material must therefore still be present in the workpiece, plausibly as compressed material as previously described.

In the described process, the relative weight loss per filament is less than 10%.

The relative weight loss per hollow-channel filament was determined to be less than 10% as follows (here, as an example, for a 2 mm thick soda-lime glass, which was cut to a size of 150 x 250 ^mm² by manual scoring and breaking with a standard glass cutter): Particles, fingerprints, and other contaminants were removed by cleaning both sides with glass cleaner, ethanol, and compressed air, either manually or in an automated cleaning process (washing machine). The prepared sample was then weighed on a precision balance. The entire setup was enclosed in a transparent plastic box to protect the To increase measurement accuracy, the sample was then mounted on the holder of an XY-axis system. It was aligned using two stops and secured against slipping. Laser processing was performed as described above using an ultrashort pulse laser with a pulse width of 10 ps, a wavelength of 1064 nm, and an energy of 400 pJ in a burst packet, specifically with 3 to 7 individual pulses. A two-dimensional grid of hollow-channel filaments measuring 90 x 160 ^mm² was created. The sample was then weighed again. To rule out any falsification of the measurement results that could be caused by particle deposition during the laser process, the previously mentioned cleaning steps (glass cleaner, ethanol, compressed air) or automated cleaning procedures were performed one more time, and the sample was weighed again. The following calculation procedure was used to calculate the relative weight loss per filament.

The theoretical weight loss mtheo per hollow channel-shaped filament, if the complete material of the hollow channel were removed from the sample, is calculated as:

Where d: diameter of the hollow cylindrical filament, determined from SEM images of fracture edges along the filamentation h: glass thickness p: density of the sample, from material data sheet The actual weight loss m _actual per pre-damage is calculated by dividing the measured weight loss m _mess by the number of pre-damages N:

The relative mass loss is determined by forming the quotient:

Here, as an example, for a 2 mm thick glass: With a sample thickness of h = 2 mm and a density of p = 2.5 g/cm ³ as well as a determined filament diameter of d = 600 ± 60 nm, this results in a theoretical mass loss of rritheo = 1413 ± 60 pg per filament.

The actual (mean) weight loss at mmess = 6 ± 1 mg and N = 5.8 ■ 10 ⁷ is mactuai = 104 ± 17 pg per filament. The relative weight loss is calculated from this to be 7.4 ± 2.7%. All calculations are made taking error propagation into account.

The relative weight loss m _fe / per hollow channel filament can be less than 10%, measured by

IDrel ⁼ actual / mtheo and/or particularly advantageous, the workpiece has a material densification of at least 1% compared to the actual material density, measured at a radius of 3 pm around the longitudinal axis of the respective hollow channel-shaped filament.

The fact that the glass or glass ceramic has a material compaction of at least 1% compared to the actual material density in the radius of 3 pm around the longitudinal axis of the respective cylindrically symmetric pre-damage was determined by means of determined using the following measurement method: Lena Bressel, Dominique de Ligny, Camille Sonneville, et al. “Femtosecond laser induced density changes in GeO2 and SiO2 glasses: Fictive temperature effect [Invited]”, Optical Materials Express, Vol. 1 , No.

4, 605 613 (1 August 2011 ) DOI: 10.1364/OME.1 .000605. The evidence of material densification was demonstrated indirectly via a spectral shift of the Nd peak in the Raman spectrum. For this purpose, the Raman microscope had to have a spectral range of 10,000 cm ^-1 so that the Nd luminescence at approximately 890 nm can be measured upon excitation at 488 nm, and it had to be equipped with suitable motorized XYZ stepper motor axes and a suitable microscope objective (NA > 0.7) in order to achieve a spatial resolution of better than one micrometer. The components according to the invention were scanned in the area to be measured using the stepper motors. A Raman spectrum of the Nd peak was recorded at each point. Its spectral position is recorded, and pressures and densities were calculated using standard spectra. These standard spectra were recorded from glass or glass-ceramic specimens that had been compacted using belt presses. Further verification was performed using spatially resolved Brillouin spectra. The radius of 3 pm around the longitudinal axis or filament axis represents the measurement location of the compression or compaction and is also referred to below as the compression measurement line. The compression zone can extend even further around the filament into the material of the workpiece.

The diameter of the hollow channel-shaped filament, as used in this description, refers to the distance from one channel wall to the other, perpendicular to the filament axis. In a cylindrical channel, the diameter is essentially the same throughout. However, it is possible for the hollow channel-shaped filament to taper or, depending on the viewpoint, widen towards one of the surfaces of the workpiece. In this case, we speak of V-shaped filaments. It is also possible for the hollow channel-shaped filament to have a local constriction, thus creating an hourglass or X-shape, so to speak. The shape of the filament can be influenced by the formation of the focal line and its position. An advantageous method provides for the hollow-channel-shaped filament to have a diameter of 100 nm to 3 pm. Ranges from 250 nm to 1.5 pm or from 500 nm to 1 pm are particularly advantageous. The pitch between individual filaments can, in particular, be from 3 pm to 50 pm.

If the filament is not formed as a hollow cylinder, or as a hollow cylinder with significant local deviations, but rather in a V-shape or X-shape, the aforementioned diameter refers to the diameter at the location with the maximum value, or, in other words, at the widest point. In this description, the diameter of the filament is measured at the surface of the workpiece, specifically at the surface that is and/or was facing the laser. This side can also be clearly determined on the workpiece being processed.

As already described, the invention balances the need for efficient production by producing the largest possible filaments, especially filaments with the largest diameters, which can, however, adversely weaken the workpiece due to unwanted cracking around the filament, with the control of energy input and thus crack formation. As described, the workpiece material is particularly advantageously compacted around the filament axis.

This is particularly advantageously done according to a process in which the focused laser beam generates a plasma in the workpiece, which forms the hollow channel-shaped filament.

It is assumed that the burst packet of ultrashort laser pulses ignites a plasma in the workpiece, particularly within the elongated laser focus line. As described, the plasma explosion can push material into the workpiece perpendicular to the filament axis, thus creating the hollow channel and/or the hollow channel-shaped filament with the previously described geometries. According to one embodiment of the method, the plasma creates microcracks in the workpiece, which run from the hollow channel-shaped filament into the volume of the workpiece.

Such crack formation is particularly important when applying the method to separate the workpiece. In principle, crack formation occurs perpendicular to the filament axis and runs from the filament into the volume of the workpiece. The cracks are usually evenly distributed around the filament axis. This means that, when viewed from above, the filament and/or the filament axis exhibit essentially the same crack density within a 360° area around the filament. It has been shown that the method according to the invention reduces the number of cracks and thus the crack density as well as the average crack length compared to a method in which the individual pulse energy within the burst packet is not reduced.

A particularly advantageous embodiment of the method provides that at least 90% of the microcracks end within the aforementioned compression zone, particularly advantageously within a radius of 3 pm around the longitudinal axis of the hollow channel-shaped filament.

This is a statistical analysis. The number of microcracks and their length are observed, and it is evaluated how many of the microcracks end within the compression range and how many extend beyond it. It is advantageous if at least 10% of the microcracks end within the compression range. As described, the degree of compression is measured within a radius of 3 pm around the longitudinal axis of the hollow-channel filament. This means that, particularly advantageously, 90% of the microcracks end within this 3 pm radius. The compression range thus advantageously limits the vast majority of microcracks.

In order to provide a particularly efficient separation process, a further advantageous embodiment of the method provides that the elongated focus line is widened in a direction perpendicular to the axis of the filament and the length and/or number of microcracks in the direction of the widening of the focal line is greater than in the direction perpendicular to the widening.

The direction of the focal line expansion perpendicular to the filament axis is also referred to below as the preferred direction. The expansion of the focal line in one direction also causes the plasma to expand in that direction. The plasma explosion is presumably stronger in the direction of expansion. In any case, the number of microcracks in the preferred direction is greater than perpendicular to the preferred direction and/or the average length of the microcracks is greater in the preferred direction than perpendicular to the preferred direction. In other words: the stress distribution in the narrow tips of the ellipse is significantly higher than along the wide side, meaning that microcracks preferentially propagate from the tips.

In particular, the preferred direction can be selected to lie in the direction of and/or at least substantially congruent with a provided dividing line of the workpiece. This means that the widening of the laser focus relative to the workpiece is controlled accordingly. This can be achieved by movable optical devices and/or movable workpiece holders, which are controlled in particular by microcontrollers and/or data processing devices. This and the meaning of the invention also encompasses the possibility of the preferred direction being individually adjustable at any point on the workpiece, i.e., the preferred direction can be variable and, in particular, adjustable depending on the position of the focus line on the workpiece.

The shape of the focal line expansion can be chosen arbitrarily within the meaning of the invention. A laser focus in the shape of an oval is particularly common. The main axis of the oval then corresponds to the preferred direction. Linear, asymmetrical, and any other suitable form of expansion are also conceivable and encompassed by the invention. The described method can be designed such that the plasma emits X-ray radiation which is attenuated and/or shielded by at least one shielding element.

In proven embodiments, the plasma explosion described above causes the emission of X-rays. In particular, this can be at least in the range of 2 keV to 20 keV and is thus surprisingly intense. This can also be used specifically, for example, to examine materials and/or workpieces and/or the workpiece to be processed, especially simultaneously with its laser processing. It has also been shown that the reduction of the individual burst pulse energies in the burst packet can contribute to a reduction in the emitted X-ray radiation.

With regard to the lowest possible X-ray emission beyond (on the side facing away from the laser process) the shielding element, and thus outside the processing area, the use of a laser beam with a preferred direction can have two advantageous effects:

First, structuring the workpiece with a preferred direction allows for the use of larger shot-to-shot spacing (pitches). This means that the number of laser shots and thus the X-ray dose per cutting length is reduced. For a given throughput in the cutting process, this reduces the dose rate of the generated X-ray radiation.

Secondly, the ablation cloud, i.e., the cloud above the workpiece, consisting of material vaporized and/or ejected by the micro-explosion, interacts with the X-ray radiation and, in addition to technical devices such as the shielding element mentioned above, can significantly contribute to X-ray attenuation. If the ablation cloud is also expanded in one direction by using a beam expanded in that direction, this can lead to a beneficial attenuation of the X-ray radiation in that direction. This represents a particular advantage for devices designed for cutting a continuous strip. are designed because the X-ray radiation is then attenuated more strongly in the direction of the openings in the housing, i.e. the feed and/or removal opening, in cuts which are parallel to the transport direction of the belt, than in the direction perpendicular to this, in which effective shielding can be ensured by the housing being closed in this direction.

Regardless of the lateral shape of the laser focus, the ablation cloud can be influenced by other means, particularly by suction or compressed air. The flow profile at the laser process site should be adjusted so that as few ablation products as possible are present in the volume swept by the laser beam. This reduces the absorption of laser radiation, which firstly leads to a more efficient and stable structuring process of the workpiece and secondly reduces the generation of X-rays in the ablation cloud. It is assumed that this prevents previously ablated and/or removed material from being excited again.

Furthermore, the shielding effect of the ablation cloud can be advantageously used by means of a suitable flow profile, as previously demonstrated using the structuring method using a laser beam with a preferred direction.

As previously described, it is advantageous to direct the laser beam onto the workpiece in the form of an elongated focal line. Accordingly, an advantageous method comprises directing the focused laser beam onto the workpiece in an elongated focal line. Particularly advantageously, the elongated focal line is generated by beam-shaping optics comprising optical elements selected from the group consisting of SLM (Spacial Light Modulator), axicon, truncated cone axicon, double axicon, spherically aberrant lens, and/or chromatically aberrant lens.

To achieve a spatial limitation of the laser radiation across the focus line, so-called Bessel beams are ideally used. These consist of a central, bright beam surrounded by weaker rings. Maximum and, unlike the Gaussian beams emitted by lasers, have the property that their radius remains constant in the direction of propagation. They enable both machining over a greater depth range and greater tolerance in workpiece alignment. Furthermore, they are virtually diffraction-free.

The generation of Bessel beams and a long, extended line focus is achieved, among other things, with so-called axicons as beam-shaping lenses. The axicon as an optical element was described by McLeod in 1954 (John H. McLeod: The Axicon: A New Type of Optical Element. J. Opt. Soc. Am. / Vol. 44, No. 8, August 1954). According to this, an axicon is an optical element that images the light from small point sources onto a straight, continuous focal line. McLeod describes various forms of axicons, but emphasizes the glass cone as the most important axicon.

The truncated cone axicon has a flattened surface at the apex of the axicon cone, in the laser beam axis. The center beam is not refracted by the truncated cone axicon. This facilitates the adjustability of the optical system, as it is usually very difficult to align the center beam precisely with the axicon apex. Likewise, tilting of the axicon and/or its manufacturing precision, i.e., the sharpness and symmetry, especially of the cone apex, are less critical.

The double axicon has an entrance surface designed to form a ring beam within the double axicon. The advantage of the double axicon is that by selecting the laser energy, the refractive index of the double axicon, and the axicon angle of the entrance surface, the intensity of the laser beam within the double axicon can be set lower than the threshold intensity of the material of the double axicon, so that the material of the double axicon is not destroyed during the beam's passage.

It may also be advantageous to create the elongated laser focus and/or the line focus using Gaussian optics. The beam extension can then be achieved through the spherical aberration of a Gaussian lens. Spherical lenses and/or cylindrical lenses, each with aspherical components, are particularly suitable for this purpose.

When exploiting spherical aberration, it can be provided, in particular, that the laser beam is not aligned with the geometric center of the lens and/or that the lens is tilted. This can also be implemented dynamically, i.e., that the lens alignment relative to the laser beam can be controlled by actuators and microcontrollers and/or data processing devices.

Instead of a monochromatic laser, a pulsed, polychromatic laser beam with a specific pulse duration and specific wavelengths can also be used. Using an optical arrangement with chromatic aberration for wavelength-dependent focusing of the laser beam and advantageously with at least one filter for wavelength-dependent filtering of the laser beam, this can generate a focal line along the beam direction of the laser beam, allowing the machining depth of the workpiece to be selectively and precisely adjusted. In particular, the length of the focal line can be adjusted by creating different focal points.

In some cases, the presence of an elongated laser focus is not important. In these cases, conventional Gaussian optics are usually sufficient. These cases are, of course, also covered by the invention.

As described, the shape of the created hollow channel or blind hole can be cylindrical, V-shaped, and/or X-shaped. This can be adjusted, in particular, by adjusting the focus position of the line focus relative to the workpiece in the beam direction and the intensity profile of the focus line perpendicular to the beam direction.

In an advantageous method, the laser wavelength is from 350 nm to 1100 nm, advantageously 1020 nm to 1080 nm, and/or the pulse duration of a single pulse is from 40 fs to 20 ps and/or the burst duration is from 1 ps to 500 ns and/or the single pulse energy of the first single pulse at the beginning of the burst duration is from 100 pJ to 1 pJ, advantageously from 200 pJ to 500 pJ, and/or the workpiece consists of or comprises glass and/or glass ceramics and/or silicon and/or ceramics.

In the previous paragraphs, it was explained that the microcrack density and/or microcrack length around the hollow channel-shaped element can be controlled by reducing the single pulse energy in the burst packet.

To enable efficient separation of the workpiece by filamentation, the spacing between two adjacent filaments must be adjusted accordingly. When using burst packs, the spacing between two adjacent filaments is advantageously between 3 pm and 20 pm, particularly between 3 pm and 10 pm or between 4 pm and 8 pm. For glasses with a thickness of over 0.5 mm, the empirical formula for the spacing between the filaments is particularly advantageous:

Distance in mm = thickness of the workpiece ■ Z where the factor Z can assume values from 3 to 7. This empirical formula for selecting the distance has proven particularly applicable for workpieces made of glass and/or glass ceramic with a thickness or material strength in the range of 0.5 mm to 30 mm. For example, applying this formula for a workpiece with a thickness of 1 mm results in an advantageous distance between the filaments of 3 pm to 7 pm.

A burst degression of 90% to 70% is particularly advantageous, in particular with burst packets with 2 to 7 single burst pulses, in particular 3 to 5 single burst pulses.

The above parameters apply in particular to glasses containing silicon and boron. The combination of the above-mentioned parameters enables a particularly efficient process for machining the workpieces.

The invention is explained in more detail below with reference to the figures. The figures are schematic and not necessarily to scale. The figures also represent exemplary embodiments. The same reference numerals in different figures have the same meaning. They show:

Fig. 1 : Spectral energy distribution of the emitted X-rays during burst processing of stainless steel

Fig. 2: Spectral energy distribution during burst processing of glass, measured simultaneously at different distances from the focal point

Fig. 3: Mass attenuation of iron

Fig. 4: Transmission of air as a function of the energy of the X-ray photon, measured at different distances from the radiation source

Fig. 5: A schematically illustrated device

Fig. 6: Another schematically illustrated device

Fig. 7: Another schematically illustrated device

Fig. 8: Another schematically illustrated device

Fig. 9: Another schematically illustrated device

Fig. 10: Another schematically illustrated device

Fig. 11 : Another schematically illustrated device

Fig. 12: Schematic representation of the self-absorption of the workpiece

Fig. 13: Another schematically illustrated device Fig. 14: Another schematically illustrated device

Fig. 15: A schematically illustrated device for producing glass ribbons with device

Fig. 16: Burst packets of laser pulses

Fig. 17a to 17d: Examples of energy profiles of the laser pulses within a burst packet

Fig. 18a to 18c: Examples of machined workpieces

Fig. 19: Top view of a machined workpiece

Fig. 20: Filaments with microcracks in the workpiece

Fig. 21 : Filaments with microcracks in the compression area

Fig. 22: Filaments with shortened microcracks in top view

Fig. 23: Filaments with microcracks in the preferred direction in plan view

Fig. 24: Dependence of the microcrack length on the preferred direction

Fig. 25: Examples of focus areas with preferred direction in plan view

Fig. 1 shows the spectral energy distribution of the emitted X-rays produced when stainless steel is irradiated with a burst of ultrashort laser pulses. The diagram is based on the processing of stainless steel with a laser wavelength of 1030 nm, repetition frequency of 100 kHz, pulse duration of 1 ps, average laser power of 80 W, two individual burst pulses, and an irradiance at the focus of approximately 1.2 * 10 ¹⁶ W/cm ² . The intensity of the emitted photons is plotted as emission in work units (AU) against the energy of the emitted photons EPh in keV, which are generated during laser processing of the laser beam. As can be seen, a very strong emission occurs at approximately 7 keV. From this, it can be deduced within the scope of the invention that when processing glass-based materials in corresponding systems, the ultrashort laser beam should advantageously not impinge on metal components, especially those made of stainless steel.

Fig. 2 shows the spectral energy distribution of the emission of emitted radiation during the processing of glass-based material, in this case glass, using ultrashort laser radiation, here using a burst packet. The intensity of the emitted photons is plotted as in Fig. 1 as emission in work units (AU) against the energy of the emitted photons EPh in keV. The solid line S11 represents the measurement with a sensor mounted at a distance of 38 cm from the processing site, i.e., the area where the glass was processed with the ultrashort laser pulses. The dashed line S3 represents the measurement with a sensor mounted 106 cm from the processing site. The following parameters were used for the laser processing underlying this figure: average laser power 200 W at an emission wavelength of 1030 nm, pulse repetition frequency 50 kHz, 2 single burst pulses, pulse duration of a single burst pulse 1 ps.

The inventors have thus determined that the aforementioned laser processing of glass generates a significant amount of X-ray radiation in an energy range of 4 to 10 keV. A maximum is found in the range of approximately 6 keV to 9 keV. It is also evident that there is a difference between the measurements taken with sensors mounted at different distances. This results, on the one hand, from the inverse square law and the absorption properties of air. Higher-energy radiation is absorbed less strongly by air than lower-energy, i.e., softer radiation.

Fig. 3 shows the mass attenuation of iron. This means that the energy Ephoton of the photons incident on an iron element in MeV is the absorption capacity ('Absorption' in Fig. 3) of the iron in work units (Mass Attenuation Coefficient). A logarithmic scale was chosen to represent the photon energy. It can be seen that the absorption capacity of iron is highest in the range from 1 keV to 100 keV, with a maximum at approximately 6 to 12 keV. This maximum absorption lies surprisingly in the range of the emission of X-rays that arise during laser processing of glass-based materials, especially glass, with ultrashort laser pulses. In other words, if an iron-containing material is used as a material for or in the shielding element, it exhibits particularly good X-ray absorption for the X-rays generated during the processing of glass-based materials. By matching the glass-based material to be processed and the material of the shielding element, the process can be carried out particularly efficiently.

Fig. 4 shows the transmission of air as a function of the energy of the X-ray photon, measured at different distances from the radiation source. It can be seen that the transmission of air is clearly energy-dependent. For low-energy photons with an energy of 2.5 keV at a distance of 10 mm, air has a transmission of approximately 75%, while at a distance of 100 mm its transmittance is less than 10%. In contrast, at a distance of 1 m, photons with an energy of up to 5 keV are almost completely absorbed, while photons with an energy of 10 keV are still registered at the detector at 50%. Since typical dimensions of a laser processing device are in the range of approximately 1 m (distance between the laser impact point and the inner wall), it is to be expected that a shielding element will be exposed primarily to X-ray radiation with an energy greater than 5 keV, in particular 7.5 keV or more than 10 keV. The shielding of the housing is therefore particularly effective if the material of the shielding element has a particularly good absorption capacity between 5 keV and 10 keV.

As previously described, this is advantageous for shielding elements consisting of or comprising a ferrous material. Accordingly, steel and/or stainless steel are particularly advantageous materials. Fig. 5 schematically shows the principle of a device according to the present description. In particular, the device (100) is suitable for applying the described method. With the device (100), in particular, a hollow channel-shaped filament (180) is inserted into the workpiece (2). The device comprises an ultrashort pulse laser (3) with beam-shaping optics (30). This focuses the laser beam (4) with the wavelength A as an elongated focal line in the focus region (1) into the workpiece (2). At least part of this focal line lies within the workpiece, where the filament (180) is produced by interaction with the ultrashort individual pulses or burst individual pulses of the burst packet.

The workpiece (2) is arranged on a workpiece holder (303). The positioning device (200) can be used to position the point of incidence of the laser beam (4) of the ultrashort pulse laser (3) on the surface of the workpiece (2) laterally and/or transversely. As described, the workpiece (2) is a workpiece comprising a glass-based material, in particular glass and/or glass ceramic. The wavelength A of the laser (3) is selected, as already described, such that the workpiece (2) is transparent to this wavelength.

As described, the beam-shaping optics (30) can also be designed such that the focal line is widened perpendicular to the filament axis to provide a preferred direction (DR). It is also possible to incorporate apertures into the beam path to create a correspondingly shaped focus.

In the example shown, the positioning device (200) comprises an xy table on which the workpiece (2) rests on its underside. Alternatively or additionally, it is also possible to design the laser (3) and/or the beam-shaping optics (30) to be movable in order to move the laser beam (4) so that the point of impact of the laser beam 4 can be moved even when the glass element (2) is held stationary. A combination of the two methods is also possible. The ultrashort pulse laser (3), the positioning device (200) and/or the beam-shaping optics (30) are connected to a control device (210), for example a microcontroller and/or a data processing device.

As described above, the interaction of the ultrashort laser pulses and the workpiece (2), particularly when using a burst packet, generates a plasma, resulting in the filament forming in the workpiece (2). X-ray radiation is released in the process. The shielding element (300) serves to protect the surroundings from this radiation. The shielding element (300) is configured to form a processing space (302). Outside the processing space, the surroundings are protected from the X-ray radiation, particularly by the shielding element (300).

The shielding element (300) comprises a printed material of a suitable thickness, which at least partially absorbs the X-ray radiation. In the illustrated case, the shielding element (300) is made of stainless steel sheet, which encloses at least the area of the laser focus. The sensor device (400) is provided as an optional element, which can, for example, detect light reflections of the incoming laser beam or, in particular, the emitted X-ray radiation. Other measured variables are also conceivable, particularly if they correlate with the energy of the irradiated laser power. In the present case, the energy of the emitted laser power can be used as a control variable for the laser (3) and/or the positioning device (200). For this purpose, it is connected to the control device (210). In this way, high process stability can be achieved, for example, by using the X-ray emission as a measure of the incoming laser power and controlling the laser (3) such that desired processing parameters are maintained using these measured variables.

The workpiece (2) in this embodiment is mounted on the workpiece holder (310). Its surface defines the machining plane W, which extends in the xy direction within the scope of this description. The machining of the The workpiece (2) is processed in this plane and/or in its immediate vicinity. The shielding element extends in the direction of the laser beam (4) in the z-direction beyond the processing plane W to plane B, through which the workpiece (2) can be fed in and/or removed.

The edge and/or the region in the z-direction below the edge of the shielding element (300) represents, so to speak, the feed and/or removal opening. In other words, the feed opening is arranged here in a plane (B) which is perpendicular to the z-direction below the processing plane (W). In particular, a region of the shielding element (300) is located in the processing plane (W). Due to the geometric arrangement, the feed or removal plane (B) is shaded from the resulting X-ray radiation both by the workpiece support (303) and by the workpiece (2) itself.

The workpiece (2) is inserted into the machining space (302) by means of a lifting device (201), which can generally be raised and lowered in the z-direction.

In this embodiment, the workpiece (2) can be fed sequentially into the processing chamber (302); it is therefore particularly suitable for disc-shaped workpieces, in particular glass panes.

The workpiece support (303) consists, at least in the region and/or in the extension of the laser beam (4) in the z-direction, of a material that absorbs X-rays. As described, this includes, in particular, glass and/or glass-ceramic or a glass-filled plastic composite. This takes into account the previously described finding that when the laser radiation strikes metal, in particular ferrous metal, a significant amount of X-rays is generated. The illustrated embodiment avoids this problem by making the workpiece support (303) of a different material. In the example embodiment shown in Fig. 5, it should be noted that the shielding element (300) naturally includes an opening for the laser beam (4) through which the processing is to take place. Any X-rays generated can escape into the environment through this opening. This can be reduced by the optical element (30) itself absorbing X-rays emitted in the z-direction, particularly since it is usually made of glass. Another effect is that during laser processing, the plasma can create a cloud of particles of the workpiece material, which are knocked out of the workpiece, particularly in the z-direction. This cloud itself absorbs any X-rays generated.

It will be readily apparent to those skilled in the art that the principle of the invention is applicable to variations and variants of the illustrated device. In particular, it is also possible to provide a closed device, in particular a closed processing chamber (302). This chamber is opened, in particular, for the insertion and/or removal of a workpiece and closed for processing. Such a chamber is primarily suitable for the sequential processing of workpieces.

Fig. 6 shows a device (100) in which, in particular, a workpiece (2) can be processed as strip material, thus enabling a continuous process. For example, a strip of glass. In the present example, this is, in particular, ultra-thin glass that is obtained from a drawing tank (250) by means of a downdraw process (cf. Fig. 15). A corresponding application of the invention is also possible with alternative ultra-thin glass production processes such as the overflow fusion process. The ultra-thin glass here has a material thickness of approximately at most 100 pm; in particular, the material thickness in this example is from 20 pm to 50 pm.

These (and other devices shown here) make use of the aforementioned principle that the machining plane (W) is different from the Feed plane (B) differs. In particular, the feed plane (B) can be located below the machining plane (W) in the z-direction. As shown in the following figures, it is also possible to arrange the feed plane (B) above the machining plane (W). This

By means of at least one deflection device (203), the strip material is deflected in the direction of the laser processing device with the laser (3) and brought into the processing plane (W). This configuration takes advantage of the bendability of the workpiece (2) made of glass-based material, which is particularly present in thin glasses and/or glass ceramics, especially ultra-thin glasses.

Due to the distance from the drawing tank, laser processing takes place in the cold section of the system. However, it is also possible for laser processing to take place in the hot section (220) closer to the drawing tank (250). The strip material can be picked up and/or stored, for example, on a drum in the form of a roll, in this case a glass roll (221). For this purpose, the drum rotates according to the draw-off speed of the glass strip (see Fig. 15).

Also provided is a shielding element (300), which at least partially surrounds the laser processing area (1), forms a processing space (302), and, as described, shields the surroundings from the emitted X-ray radiation. As explained with reference to the previous Fig. 5, in this example, the feed and/or removal plane (B) is located in the z-direction below the processing plane (W). A region of the shielding element (300) is located in the area between these planes.

An air gap (305) is located below the processing plane (W) (viewed in the z-direction). Therefore, when passing through the workpiece (2), the laser beam (4), i.e., its focus area (1) and/or a region of the laser beam with high energy density, does not encounter any other material that could, in turn, generate X-rays when irradiated with a focused laser beam. In the present case, an optional shielding element (310) is also provided beneath the workpiece. This can be made of the materials mentioned, in particular glass and/or the aforementioned plastic composites. However, metal-based materials are also possible, because, as mentioned above, the focused laser beam in this arrangement does not reach the shielding element (310) with a high energy density.

As can easily be seen, the area between the additional shielding element (310) and the area of the shielding element (300) facing the feed and/or removal plane B forms the feed and/or removal opening (320).

At this point, it should be noted again that the drawings are purely schematic in nature. In particular, the depiction of radii of curvature and/or deflection radii is not to scale. Those skilled in the art will be aware that these must be adapted to the workpiece in particular.

Fig. 7 shows an embodiment analogous to the principle of Fig. 6. However, the feed and/or removal plane (B) is arranged here in the z-direction above the processing plane (W). This can be achieved in particular by the arrangement of the deflection devices (203). Here, too, the air gap (305) is provided below the workpiece (2), as is the optional shielding element (310). It should be noted at this point that the deflection devices (203) can also consist of or comprise a material that itself absorbs X-ray radiation. For example, in the design of a roller made of metal and/or plastics, in particular the filled plastics mentioned above. This naturally applies to all embodiments in which deflection devices (203) are present.

The embodiment according to Fig. 7 shows a particularly compact shielding element (300) with small dimensions. Here, the deflection of the feed plane (B) to the processing plane (W) takes place outside the processing space (302). Just as in the embodiment according to Fig. 6 (and In all other corresponding embodiments), the workpiece (2) itself absorbs X-rays generated in the direction of the plane (W). The laser (3) is arranged in an opening of the shielding element (300) and thus, in this embodiment, contributes to shielding the resulting X-rays. This is an optional arrangement principle that is applicable to all embodiments. The same applies, of course, to the alternative arrangement possibilities described above.

Fig. 8 shows a further variant of an embodiment similar to those in Fig. 6 and Fig. 7, in which the shielding element (300) can also be present below the processing plane W. In particular, it forms a box as a closed processing space (302). The feed and/or removal opening (320) can in particular be designed as a slot in the shielding element (300). The deflection of the belt of the workpiece (2) from the feed plane (B) into the processing plane (W) takes place here within the processing space (302). It is of course also possible for this deflection to take place outside the processing space, similar to Fig. 7.

Fig. 9 shows a further variant and/or embodiment. In this variant, the workpiece (2), in particular a strip of glass-based material, in particular a strip of glass, in particular ultra-thin glass, is deflected multiple times. The feed plane (B) is crossed multiple times on the side of the feed and/or removal opening (320). Accordingly, a plurality of deflection devices (203) are provided. Since, as described, the glass-based material itself absorbs the X-radiation generated during its processing, the X-radiation in this embodiment must pass through the glass-based material multiple times if it is to escape from the feed or removal opening (320). This is prevented by self-absorption and/or the escaping X-ray dose is at least significantly reduced. Also shown are optional apertures (312) made of the material of the shielding element (300), which can be attached in the region of the feed and/or removal opening (320) and are intended to shield the X-ray radiation in this region. The apertures (312) can be formed as part of the shielding element (300). In particular, it can be provided that these apertures (312) and/or the additional shielding element below the processing plane (W) are designed such that they follow the course of the workpiece, in particular the workpiece (2) fed in strip form. In this exemplary embodiment, this course is represented by the bent shielding element (310) below the feed plane (B).

A further embodiment is shown in Fig. 10. Here, a deflection device is further developed such that it simultaneously forms the workpiece support (208). This can be achieved, for example, by designing it as a roller, in particular a rotatable roller, via which the workpiece (2), in particular a belt-shaped one, is fed to the processing space (302). This deflection device and workpiece support (208), as in the previous embodiments, causes the workpiece (2) to be brought from the feed and/or removal plane (B) into the processing plane (W). The deflection device and workpiece support (208) are here mounted at least in regions within the processing space (302). The deflection device and workpiece support (208) can in particular consist of a material, or at least comprise this on its surface, which absorbs X-rays. Glass-based materials or plastics, in particular glass-filled plastics, are particularly suitable.

Fig. 11 shows a further embodiment in which the feed and/or removal opening (320) is spaced at a distance A from the location of the laser processing (1 ) and/or the laser focus (1 ). A is measured from the laser focus (1 ), more precisely from the center line of the laser focus, to the inner wall of the shielding element (300) at the location where the feed and/or removal opening (320) is present. The distance A is selected so that the resulting X-radiation must pass through a sufficiently long air gap, in which it is absorbed by the air as described above, before it can escape the feed and/or removal opening (320) with an undesirably high dose rate. Since, as described, X-radiation in the energy range around 8 keV and/or higher occurs during the aforementioned processing of glass-based materials, A is advantageously selected in the range 10 mm to 1000 mm. Because in this embodiment the processing plane (W) lies in the plane of the feed and/or removal opening (320), this embodiment is suitable both for workpieces (2) which are not flexible enough for deflection, and for environments in which sufficient installation space is available and this simplest embodiment to implement is preferred.

When designing the distance A, it must also be taken into account that the material of the workpiece 2 itself absorbs the resulting X-radiation, and more efficiently than in air. Typically, the z-direction is considered, i.e., the X-radiation is mainly absorbed in the volume and/or depth of the workpiece (2). Since self-absorption of the glass-based material occurs, the majority of the resulting X-radiation, in particular the portion with the highest dose rate, escapes at an angle α from the processing location, where α is measured from the surface of the workpiece (2). At a suitable distance A, this (more precisely the majority of it) does not pass through the feed and/or removal opening (320), in particular because α > 1° or 1° < α < 90°.

At this point it should be mentioned that the further shielding elements (310, 300) can optionally also be present in this embodiment, individually or in combination.

The principle of direction-dependent emission of X-rays XEm during the processing of glass-based materials with ultrashort laser pulses is explained in more detail in Fig. 12. The figure shows the processing location (1) of the laser beam in the workpiece (2). This is the location where the interaction takes place, ie where the plasma is generated as described, especially in the Laser focus area. Stronger absorption occurs within the workpiece (2) made of glass-based material. Outside the workpiece, absorption in air occurs, although this is weaker than that by the workpiece material itself. Because the majority of the emitted X-rays originate in the volume of the workpiece (2) and thus in the z-direction below the workpiece surface, the majority of the X-rays XEm exit the workpiece surface at an angle α. α is measured from the plane of the workpiece surface and thus in the xy-direction. α is greater than 0°, in particular greater than 1°. In particular, α lies in the range from 1° to 90°, with the majority XEm indicating the arithmetic mean of the angle-dependent emission intensity averaged over all emission angles. It is thus evident that a geometric design of the processing space (302) and/or a geometrically suitable arrangement of the feed and/or removal opening (320), in particular with regard to distance A and/or arrangement to the processing plane W in the z-direction, can be used to reduce the escaping X-radiation.

Fig. 13 shows a further embodiment in which the supply and/or removal opening (320) is, so to speak, closed by at least one deflection device and/or supply and/or removal means (203). This advantageously consists of or comprises a material that absorbs X-ray radiation, in particular the materials described with regard to the shielding element (300) and/or the aforementioned plastics and/or filled plastics. These supply and/or removal means (203) can in particular be designed as a roller. A suitable combination and/or arrangement of these supply and/or removal means (203) can close the supply and/or removal opening (320) for the X-ray radiation, as shown, for example, in Fig. 13.

An alternative possibility for closing the supply and/or removal opening (320) is shown in Fig. 14. Here, it is closed by a curtain (326) of X-ray absorbing media, in particular fluids. The fluids can be introduced, for example, through fluid nozzles (325) in the area of the supply and/or removal opening. The removal opening (320) can be applied. These include, for example, a gas curtain and/or a water curtain.

At this point, it is emphasized again that all elements shown and/or described with respect to one embodiment can be combined with other embodiments. Using the teachings provided herein, a person skilled in the art can create a device that meets individual requirements and can provide effective X-ray protection.

Fig. 15 shows an embodiment in which the device (100) described herein is used in a production environment for glass-based workpieces (2) as strip material. In the present example, the workpiece (2) is, in particular, ultra-thin glass obtained from a drawing tank (250) by means of a downdraw process. A corresponding application of the method according to the invention is also possible with alternative ultra-thin glass production processes such as the overflow fusion process. The ultra-thin glass here has a material thickness in the aforementioned range, advantageously of approximately at most 400 pm or 100 pm; in particular, the material thickness in this example is from 20 pm to 50 pm. By means of a deflection device (203), the strip material is deflected in the direction of the device (100) with the laser (3) and the shielding elements (300, 310). Due to the distance from the drawing tank, the laser processing takes place in the cold area of the system. However, it is also possible for the laser processing to take place in the hot area closer to the drawing tank (250). The strip material can, for example, be picked up and/or stored on a drum in the form of a roll, here a glass roll (221). For this purpose, the drum is rotated according to the draw-off speed of the glass strip. The device (100) described herein can be used in particular for edge cutting and/or cross-cutting the glass strip (2).

In Fig. 16, three burst packets of laser pulses are shown as a plot of the intensity I of the laser pulse over time t. Since the energy of a single laser pulse corresponds to the integral of the laser power over time, the energy E of a laser pulse correlates with its intensity in a considered standard area. Accordingly, the representation also corresponds to a schematic plot of the laser pulse energy over time. Shown are three burst packets of four laser pulses each, here single burst pulses, with the burst duration being Tb. Tb is determined from the time of the highest intensity of the first laser pulse (41 ) of the burst packet to the time of the highest intensity of the last pulse of a burst packet.

In the given example, the number of individual burst pulses in a burst packet is four. Advantageous, for example, are from two to 20 individual burst pulses and/or from 2 to 10 individual burst pulses in the burst packet. The individual pulse width is advantageously from 300 fs to 11 ps. Tb is advantageously in the range from 1 ps to 500 ns and Ti from 400 fs to 400 ns. To produce a hollow channel-shaped filament in a glass-based workpiece, irradiation of the workpiece with a single burst packet may advantageously be sufficient. However, the use of two to 10 burst packets, in particular from 2 to 5 burst packets, is equally possible and advantageous. The time interval between the individual burst packets is referred to as the inter-burst delay Td. 1/Td can advantageously be from 1 to 1000 kHz.

These aforementioned parameters are selected in particular depending on the specific composition of the glass-based material of the workpiece and the desired geometries of the filament and distances between filaments.

The energy Epo of the first individual pulse (41) of a burst can advantageously be set such that it is greater than the energy Ep _x of the last individual pulse (42) of the same burst. The inventors have found that this reduces the emitted X-ray radiation.

Figures 17a to 17d show exemplary advantageous curves of the energies of the individual burst pulses over time t in a single burst packet. For simplicity For clarity, the curves are shown rather than discrete value points. The number of individual pulses in the burst packet is arbitrary, but preferably within the ranges mentioned above. The simplest energy curve is a linear curve as shown in Fig. 17a. In this case, the individual pulse energies within the burst packet decrease by at least essentially the same amount. It is also possible for the first individual pulse(s) of the burst packet to have at least essentially the same energy, and for the following pulses to have a lower, in particular equally constant, energy. This corresponds to a two-stage energy curve, as shown in Fig. 17b.

Nonlinear curves are also possible, for example, an exponential decrease in the individual pulse energies in the burst packet as shown in Fig. 17c. It can also be provided that the individual pulse energy in the burst packet initially increases and then decreases again, with the first individual pulse advantageously having a higher energy than the last. The laser pulse(s) following the first individual pulse then have a higher energy, which then decreases towards the last individual pulse. Such a curve is shown in Fig. 17d.

18a to 18c show cross sections through filamented workpieces (2) made of glass-based material that can be produced using the device according to the invention and the described method, in order to schematically illustrate possible shapes of hollow channel-shaped filaments. Fig. 18a shows the simplest case when cylindrical hollow channels are introduced into the workpiece (2) as filaments (180). The filaments lie essentially in the area of the laser focus (1). The filament axis A passes through the center of the filament. The filament walls are axially symmetrical. In the example shown, the filaments (180) connect the top side (O) of the workpiece (2) with its bottom side (U). The hollow channel-shaped filament (180) thus represents a through-channel or a through-opening. As previously described, it is also possible for the filament to end in the workpiece. In this case, not shown, it represents a blind hole. The workpiece has the workpiece thickness (s). The workpiece thickness (s) covers the range of ultra-thin glass or very thin glass with a few micrometers Thicknesses up to normal glass with thicknesses of several centimeters. Particularly used are the range from 10 μm to 200 μm, i.e. the range of very thin glasses including ultra-thin glasses, as well as the range from 0.5 mm to 3 mm, i.e. the range of substrate or flat glasses.

Figure 18a also shows the compression region (22) surrounding the filament. The compression region, also called the compression zone, and its formation have been described in detail above. It extends essentially perpendicular to the filament axis into the material of the workpiece.

According to Fig. 18b, a truncated cone-shaped filament (180) can also be provided, which is synonymously referred to as a V-shaped filament. This can also be described as having a hollow channel. The truncated cone-shaped filament is, in particular, also axisymmetric to the filament axis (A). In the present illustration, the filament opens towards the underside of the workpiece. This means that the diameter (dU) of the filament (180) on the underside of the workpiece (2) is larger than the diameter (dO) on the top. Not shown but again possible is a design as a blind hole. The expansion of the filament towards one side of the workpiece can be achieved in particular by adjusting the focus position of the beam-shaping optics, in particular by adjusting the convergence of the laser beam and the distance from the workpiece. Typical channel angles ß are approximately 0.05 to 0.1°. This channel angle is measured between the perpendicular through the workpiece and the inner wall of the filament and thus corresponds to half the opening angle.

Fig. 18c shows hourglass-shaped or synonymously x-shaped filaments (180), again designed as continuous hollow channels. This embodiment can be produced in particular by placing the area of the narrowest focus of the laser within the volume of the workpiece. The same ranges as mentioned for the v-shaped filaments are advantageous for the channel and/or opening angles ß. The x-shaped filaments (180) are characterized by a Constriction of the filament diameter in a region along the filament axis (A). In the example shown, the constriction is located in the center of the workpiece (2), i.e., at the same distance from its surfaces. There are also embodiments in which the constriction is located closer to one surface of the workpiece than to the opposite one.

For clarity, the compression region (22) is not shown in Figs. 18b and 18c. However, it can of course also be present in the case of V- and/or X-shaped filaments (180). In this case, it follows the respective channel wall.

Fig. 19 shows a top view of a filamented workpiece (2). The hollow channel-shaped filaments (180) are arranged in a predetermined pattern in the workpiece (2). This is also referred to as a structured workpiece (2). The filaments (180) are surrounded by the compression region (22), in which, as described above, the material of the workpiece is compacted by the effect of irradiation with the ultrashort laser pulses. As also described above, a compression of at least 1% is present in a radius of 3 pm, the so-called compression measurement line (23), around the filament axis. This means that the degree of compaction, synonymously referred to as compression, is determined at this compression measurement line (23).

Fig. 20 schematically shows the general mechanism by which glass-based workpieces are to be separated using laser filamentation. It shows a top view of a workpiece. The filaments (180) are surrounded by microcracks (50) of length RL. According to common explanations, the microcracks are caused by the shock wave generated by the plasma explosion in the focal region of the ultrashort laser pulse in the material of the workpiece (2), which can generate X-rays. If microcracks (50) combine to form a connected microcracks (51) in a neighboring filament, these connected microcracks (51) can form a continuous crack line along which the workpiece can be separated. Fig. 21 shows a schematic top view of another workpiece (2) that was filamented with decreasing individual pulse energy in the burst packet. Because the energy of the last individual pulse of a burst packet is smaller than the energy of the first individual pulse of a burst packet used to create a filament (180), the crack length RL is shorter than in the prior art and less X-ray radiation is generated and/or emitted. It is assumed that reducing the laser pulse energies in the burst packet at least reduces uncontrolled energy input into the material of the workpiece (2). The energy input into the plasma is, so to speak, better controlled. This also results in less X-ray radiation. This is surprising because it is usually assumed that it is more advantageous to deposit as much laser energy as possible in the material of the workpiece during filamentation.

When viewed from above, the microcracks (50) generally radiate from the filament (180) as the center into the workpiece material. Here, too, the microcracks of neighboring filaments can combine to form one or more connected microcracks (51), thus forming a dividing line.

The shortened crack length RL does have the disadvantage that the filaments (1) have to be arranged closer together in order to form connected filaments (51) and thus a parting line. However, this is balanced out by the advantage that shorter and/or fewer microcracks continue away from the parting line into the material of the workpiece (2). Otherwise, these weaken the edge of the workpiece that is created after parting, which manifests itself in reduced edge strength. However, high edge strength is advantageous because it allows further processing and/or application of the filamented workpiece to be carried out more efficiently and, in particular, results in less waste. This potential disadvantage is also offset by the reduction in X-ray radiation. Fig. 22 explains an advantageous embodiment in a representation analogous to Figs. 20 to 21 . According to this embodiment, the microcracks (50) run within the compression region (22). The crack length RL is thus less than the width of the compression ring around the filaments (180). In order to form a continuous parting line with connected microcracks (51), the compression regions (22) must at least be adjacent to one another and/or overlap. This applies in particular to the compression measuring line. If the filaments (180) are too far apart, no microcracks (52) form and thus a parting line is interrupted at this point. This can be particularly advantageous for setting the breaking force necessary for the actual separation of the parts of the workpiece along the parting line. In many cases, it is advantageous if the filamented workpiece does not separate or detach on its own, but rather an additional mechanical force, the separation force, is required. This can facilitate further processing, especially transport, of filamented workpieces.

In the present example of Fig. 22, a decrease in the individual pulse energy in the burst packet is also applied, thus causing the microcracks (50) in the compression region (22) to essentially die out. Crack propagation is apparently inhibited in the compacted material, so that the decreasing individual pulse energies in the burst packet, as described, can be particularly well adjusted so that the microcracks (50) terminate within the compression region (22), in particular within the compression measurement line, while simultaneously minimizing the resulting X-ray radiation. The compression measurement line is not shown here for clarity.

A particularly advantageous embodiment is represented by Fig. 23. The representation is analogous to Figs. 20 to 22; controlling the energy of the individual pulses in the burst packet is optional, but not necessary. In the top view, the laser focus is widened in the direction of the dividing line, in particular the intended dividing line. Thus, as described above, a Preferred direction. This has the consequence that the crack length RL of microcracks (50) in the preferred direction (VR) is greater than the crack length of microcracks (50) that do not run in the preferred direction. This makes it possible to arrange the filaments (180) further apart from one another in the preferred direction, microcracks in the preferred direction form connected microcracks (51) and thus create a dividing line, but only fewer and/or shorter microcracks propagate into the material of the workpiece (2) and thus less weaken the edge. Due to the described decrease in the individual pulse energies in the burst packet, it is particularly advantageously possible to confine the microcracks outside the preferred direction in the compression region (22), in particular within the compression measurement line, while microcracks (50) propagate in the direction of the preferred direction outside the compression region.

As previously described, the ablation cloud, i.e., the cloud above the workpiece (2), consisting of material vaporized and/or ejected by the micro-explosion, interacts with the generated X-ray radiation and, in addition to technical devices such as the aforementioned shielding element, can significantly contribute to X-ray attenuation. If the ablation cloud is also expanded in the preferred direction VR by using a laser beam (4) expanded in this direction, this can lead to a beneficial attenuation of the X-ray radiation in the preferred direction (VR). Because this direction can point in particular toward the feed and/or removal opening (320) and/or this is usually the case, the X-ray radiation arriving there can also be advantageously reduced in this direction.

This achieves a particularly good compromise between processing efficiency, edge stability and X-ray protection.

The relationship between the crack length RL of an individual microcrack and the angle Q of its course to the preferred direction is shown schematically in Fig. 24 The information derived from Fig. 24 is qualitative. It shows the average crack length RL versus angle Q. As mentioned, angle Q indicates the angle of the propagation direction of a microcrack to the axis of the preferred direction, here using the example of an elliptical focus expansion with the main axis of the ellipse in the preferred direction.

There is a highly nonlinear relationship between RL and Q. Perpendicular to the preferred direction, at a value of 90° for Q, the crack length is shortest and RL has the lowest value. In contrast, in the direction of the preferred direction, at a value of 0° for Q, the crack length is longest. This demonstrates that the efficient alignment of the preferred direction toward the parting lines has a disproportionate advantage for the effectiveness of the process and edge strength.

The shape of the focus widened in the preferred direction is not limited to the previously described elliptical shape in plan view. In principle, all applicable shapes are encompassed by the invention. Fig. 25 shows some examples of possible plan views of foci widened in the preferred direction. VR denotes the preferred direction as a vector. This lies on the intended dividing line (53). The first example is the elliptical widening with the main axis on the dividing line (53). Also possible are a drop-shaped widening, a heart-shaped widening, a triangular widening, and/or a two- or multi-part widening with the axis of symmetry on the dividing line (53).

As shown, the invention has the overall advantage of providing a device and method that enables efficient processing of glass-based materials while protecting the environment from emitted X-rays. The means and measures used for this purpose are suitable for use in production environments. List of reference symbols

1 Focus area 2 Workpiece

3 Laser 4 Laser beam 22 Compression region 23 Compression measurement line 30 Beam-forming optics 41 First pulse of a burst packet 42 Last pulse of a burst packet 50 Microcrack 51 Connected microcrack 52 No microcrack 53 Separation line

100 Device 180 Filament 200 Positioning device 201 Lifting device 203 Deflection device, feeding and/or removal means 208 Deflection device and workpiece support 210 Control device 221 Roller 250 Drawing tank 300 Shielding element 302 Processing space 303 Workpiece support 305 Free space 312 Aperture 320 Feed opening, removal opening 400 Sensor device

W Processing plane B Feed plane, removal plane Tb Burst duration Ti Intra burst delay Td Inter burst delay Epo Pulse energy of the first pulse of a burst packet Ep _x Pulse energy of the last pulse of a burst packet A Filament axis O Top side U Bottom side dO Filament diameter at the top side dll Filament diameter at the bottom s Workpiece thickness a Angle of XEm ß Channel angle

RL crack length

VR preferred direction

Q Angle to the preferred direction

XEm emitted X-rays

Claims

Patent claims 1. A device (100) for laser-assisted processing of a workpiece (2) made of glass-based material, in particular for introducing damage into the workpiece (2), which device is configured to arrange the workpiece in the processing plane (W), comprising an ultrashort pulse laser (3) for emitting ultrashort laser pulses having a wavelength A and a single pulse energy Ep and a laser beam direction with at least one component in the direction z that is perpendicular to the processing plane (W), wherein the laser and/or the laser pulses are configured such that the workpiece is at least substantially transparent to the wavelength A, and a beam-shaping optics (30) configured to form a focus region (1) of the laser beam, which, in the operating state, lies at least partially within the workpiece and in which the irradiance Ef is so great that, in the operating state, X-ray radiation is emitted in at least one energy range EM, and wherein at least the focus region (1) is at least partially surrounded by at least one shielding element for X-ray radiation (300). and thus, either alone or in combination with further shielding elements (310), a processing space (302) is provided, wherein the shielding element (300, 310) consists of or comprises a material which has an X-ray absorption which is adapted to the energy range EM; preferably, the material of the shielding element (300, 310) has a particularly high X-ray absorption in the energy range EM. 2. Device (100) according to claim 1, wherein the X-ray radiation is present at least in the energy range from 4 keV to 20 keV, preferably with maxima in the range from 6 keV to 10 keV. 3. Device (100) according to at least one of the preceding claims, wherein the material of the shielding element (300, 310) has a maximum of X-ray absorption in the energy range from 5 keV to 8 keV. 4. Device (100) according to at least one of the preceding claims, wherein in the operating state the equivalent dose rates outside the processing chamber (302), measured at a distance of 10 cm from its outer wall, are less than 10 pSv/h, preferably less than 1 pSv/h, in particular from 0.1 to 10 pSv/h or from 0.1 to 1 pSv/h. 5. Device (100) according to at least one of the preceding claims, wherein the shielding element (300, 310) consists of or comprises a material selected from the group of metals, in particular comprising iron, lead or lead foil, steel, stainless steel, tungsten, glass, or selected from the group of plastic composites, in particular comprising plastic composite filled with tungsten or glass. 6. Device (100) according to at least one of the preceding claims, wherein the shielding element (300, 310) for X-ray radiation at least partially encloses the workpiece (2). 7. Device (100) according to at least one of the preceding claims, which is arranged to generate a plasma in the focus area of the laser beam (1) which emits X-ray radiation. 8. Device (100) according to at least one of the preceding claims, wherein the laser (3) is configured to emit at least one burst packet of laser pulses consisting of a sequence of ultrashort burst pulses with the repetition frequency f _rep ; preferably, the first burst pulse (41) of the burst packet generates an initial plasma, which is supplied with energy and thus maintained and/or amplified by the following pulses of the burst packet. 9. Device (100) according to at least one of the preceding claims, which is set up such that the laser wavelength A is from 350 nm to 1100 nm and/or the pulse duration of a single pulse, in particular a burst single pulse, is from 40 fs to 20 ps and/or the burst duration Tb is from 1 ps to 500 ns and/or the accumulated energy of a burst packet is from 100 pJ to 1 J and/or the repetition frequency frep is from 10 kHz to 100 MHz and/or the workpiece consists of or comprises glass and/or glass ceramics. 10. Device (100) according to at least one of the preceding claims, wherein the focus region (1) is arranged such that the workpiece (2) itself at least partially absorbs the emitted X-radiation. 11. Device (100) according to at least one of the preceding claims, with a workpiece support (303) on which the workpiece (2) rests during processing, wherein the workpiece support (303) consists at least in the region and/or in the extension of the focus area (1) of a material which absorbs X-radiation, in particular glass and/or glass ceramic or glass-filled plastic composite, or wherein there is a free space (305) in the z-direction below the workpiece (2), in particular an air gap, wherein the free space (305) is delimited downwards in the z-direction at least in regions by an element (310), that absorbs X-rays, in particular an element made of glass and/or glass-ceramic or glass-filled plastic composite. 12. Device (100) according to at least one of the preceding claims, wherein the workpiece (2) is fed to the processing space on a feed plane (B) which differs from the processing plane (W), in particular the feed plane lies below or above the processing plane (W) when viewed in the z-direction. 13. Device (100) according to at least one of the preceding claims, wherein the shielding element (300) has a feed opening (320) through which the workpiece can be introduced into the processing space (302). 14. Device (100) according to claim 13, wherein the workpiece (2) itself absorbs X-ray radiation in the direction of the feed opening (320). 15. The device (100) according to at least one of claims 13 to 14, wherein the feed opening (320) is closable by at least one closure device (203, 326) comprising a material that absorbs the X-ray radiation emitted in the operating state. In particular, the closure device is selected from the group consisting of a closure curtain, a roller, and/or a water curtain, or combinations thereof. Particularly preferably, the closure device comprises a material according to claims 1 to 4. 16. Device (100) according to at least one of claims 13 to 15, wherein the feed opening (320) is arranged in a feed plane (B); preferably, the feed plane (B) differs from the processing plane (W); particularly preferably, a region of the shielding element is located in the processing plane (W), in particular between the feed plane (B) and the processing plane (W). 17. Device (100) according to at least one of claims 13 to 16, wherein the feed opening (320) is located in the processing plane (W) at a distance A of at most 200 cm from the focus area (1), in particular at most 150 cm or at most 100 cm or at most 50 cm; preferably in the range from 10 cm to 200 cm or 10 cm to 150 cm or from 10 cm to 100 cm or from 10 cm to 50 cm; particularly preferably, there is a region of the workpiece and an air space between the focus area and the feed opening, which at least partially absorbs emitted X-radiation. 18. Device (100) according to at least one of the preceding claims, which is designed to feed the workpiece (2) in the form of a strip of glass-based material, in particular in the form of an ultra-thin glass or ultra-thin glass with a thickness of from 5 pm to 400 pm or from 5 pm to 200 pm or from 5 pm to 100 pm or from 5 pm to 50 pm or from 5 pm to 30 pm, in particular from 7 pm to 40 pm, which is fed to the processing space (302) in particular continuously. 19. Device (100) according to claim 18, which is arranged to feed the strip of glass-based material (2) to the processing space (302) while bending the strip (2). 20. Device (100) according to at least one of claims 13 to 19, wherein the shielding element (300) has, in addition to the feed opening (320), a removal opening (320) which in particular has the measures and/or properties described with regard to the feed opening. 21. Device (100) according to at least one of the preceding claims, with feeding means (203) which are designed to introduce the workpiece (2) into the processing space (302) and preferably with removal means (203) which are designed to guide the workpiece out of the machining space (302). 22. Device (100) according to at least one of the preceding claims, wherein the device comprises a sensor device (400), in particular a sensor device (400) assigned to the processing space (302), which is configured to detect the emitted X-radiation and thus provide sensor data, wherein preferably the laser (3) is configured such that it can be controlled taking into account the sensor data. 23. Device (100) according to at least one of the preceding claims, wherein the laser (3) and the beam-shaping optics (30) are configured to produce a filament-shaped damage (180) in the workpiece (2), in particular a filament-shaped hollow channel or a filament-shaped blind hole. 24. Device (100) according to at least one of the preceding claims, wherein the beam-shaping optics (30) are configured to provide a laser intensity distribution in the focus region which is constant in the laser beam direction z in the range of ± 30%. 25. Device (100) according to at least one of the preceding claims as an element of a glass production device, in particular a device for producing ultra-thin glass, in particular arranged on a continuous glass ribbon with a border, wherein the device is designed to produce the border and/or a cross-section. 26. Method for machining a glass-based workpiece (2) with an ultrashort pulse laser (3), in particular for introducing damage into the workpiece (2), wherein the workpiece in the machining plane (W) is arranged, wherein the laser (3) emits ultrashort laser pulses with a wavelength A and a single pulse energy Ep in a laser beam direction z, wherein the laser wavelength A is selected such that the workpiece (2) is at least substantially transparent to the laser wavelength A, wherein the laser beam is focused in a focus area (1) by means of a beam-shaping optics (30), and wherein the single pulse energy Ep within the focus area is so large that X-ray radiation is emitted, and wherein at least the focus area (1) is at least partially surrounded by at least one shielding element for X-ray radiation (300) and thus, either alone or in combination with further shielding elements (310), a processing space (302) is provided, in particular such that outside the processing space, measured at a distance of 10 cm from the outer wall of the shielding element (300), there is an X-ray dose of less than 10 pSv/h, preferably less than 1 pSv/h, in particular of 0.1 to 10 pSv/h or from 0.1 to 1 pSv/h. 27. The method according to claim 26, wherein the workpiece (2) comprises a glass-based material at least in the focus region (1), and the X-ray radiation is generated within the processing space (302) at least in the energy range EM of 4 keV to 20 keV, in particular with maxima in the range of 6 keV to 10 keV; preferably, the material of the shielding element has a maximum of X-ray absorption in the energy range of 6 keV to 10 keV. 28. Method according to at least one of claims 26 to 27, wherein the shielding element (300, 310) consists of a material or comprises a material selected from the group of metals, in particular comprising iron, steel, stainless steel, tungsten, glass, or selected from the Group of plastic composites, in particular comprising plastic composite filled with tungsten or glass. 29. The method according to at least one of the preceding claims 26 to 28, wherein a plasma is generated in the focus region of the laser beam (1), which plasma emits X-ray radiation; preferably, the laser (3) emits at least one burst packet of laser pulses, which consists of a sequence of ultrashort individual pulses; particularly preferably, the first individual pulse of the burst packet generates an initial plasma, which is supplied with energy by the following individual pulses of the burst packet and is thus maintained and/or amplified. 30. Method according to at least one of the preceding claims 26 to 29, wherein the laser wavelength A is from 350 nm to 1100 nm and/or the pulse duration of a single pulse, in particular of a burst single pulse, is from 40 fs to 20 ps and/or the burst duration Tb is from 1 ps to 500 ns and/or the accumulated energy of a burst packet is from 100 pJ to 1 J and/or the repetition frequency f _rep is from 10 kHz to 100 MHz and/or the workpiece consists of or comprises glass and/or glass ceramics. 31 . Method according to at least one of the preceding claims 26 to 30, wherein the workpiece (2) rests on a workpiece support (303) and wherein the workpiece support (303) consists at least in the region and/or in the extension of the focus area (1) in the z-direction of a material which absorbs X-radiation, in particular glass and/or glass ceramic or glass-filled plastic composite, or wherein a free space (305) is located below the workpiece in the z-direction, in particular an air gap, wherein the free space (305) is delimited in the z-direction at least in regions by an element (300, 310) which absorbs X-radiation, in particular an element made of glass and/or Glass ceramic or glass-filled plastic composite, and wherein the focus area (1) of the laser is preferably arranged at least partially within the free space (305). 32. Method according to at least one of the preceding claims 26 to 31, wherein the workpiece (2) is fed to the processing space (302) on a feed plane (B) which differs from the processing plane (W), in particular the feed plane (B) lies below or above the processing plane (W) when viewed in the z-direction; preferably, a region of the shielding element (300) is located in the processing plane (W), in particular between the feed plane (B) and the processing plane (W). 33. Method according to at least one of the preceding claims 25 to 31, wherein the shielding element (300) has a feed opening (320) through which the workpiece is introduced into the processing space (305). 34. The method according to claim 33, wherein the feed opening (320) is closed by at least one closure device (203, 326) comprising a material that absorbs the emitted X-ray radiation. In particular, the closure device (203, 326) is selected from the group consisting of a closure curtain, a roller, and/or a water curtain, or combinations thereof. Preferably, the closure device comprises a material according to claims 26 to 27. 35. Method according to at least one of claims 33 to 34, wherein the feed opening (320) is arranged in the feed plane (B) which, viewed in the z-direction, is located above or below the processing plane (W). 36. Method according to at least one of claims 26 to 35, wherein the workpiece (2) is in the form of a strip of glass-based material, in particular as a strip of very thin glass or ultra-thin glass with a thickness of 5 pm to 400 pm or of 5 pm to 200 pm or of 5 pm to 100 pm or of 5 pm to 50 pm or of 5 pm to 30 pm, in particular of 7 pm to 40 pm, which is fed to the processing space (302) in particular continuously. 37. The method according to claim 35, wherein the glass ribbon is fed to the processing space (302) while bending the glass ribbon. 38. Method according to at least one of claims 26 to 37, wherein the shielding element (300) has, in addition to the feed opening (320), a removal opening (320) which in particular has the measures and/or properties described with regard to the feed opening. 39. Method according to at least one of claims 26 to 38, wherein the workpiece (2) is transported into the processing space (302) by means of feeding means (201, 203) and/or is transported out of the processing space (302) by means of removal means (201, 203). 40. Method according to at least one of claims 26 to 39, wherein the generated X-radiation is detected by a sensor device (400), in particular the X-radiation generated in the processing space (302), and thus sensor data are provided which are preferably taken into account in the control of the laser (3). 41. Method according to at least one of claims 26 to 40, wherein filament-shaped damages (180) are produced in the workpiece (2), in particular filament-shaped hollow channels or filament-shaped blind holes. 42. Method according to at least one of claims 26 to 41, wherein the laser intensity distribution in the focus region (1) in the laser beam direction z is constant in the range of ± 30%. 43. A method for producing glass elements, in particular elements made of ultra-thin glass, comprising method steps according to at least one of claims 26 to 42, wherein the supplied glass ribbon (2) has in particular a border which is severed by means of the method according to one of claims 26 to 42 and/or wherein a cross-section is carried out by means of the method according to one of claims 26 to 42. 44. Glass element, in particular glass element made of ultra-thin glass, manufactured according to one of claims 26 to 43. 45. Use of a device (100) according to at least one of the preceding device claims or of a method according to at least one of the preceding method claims for processing and/or producing glass elements (2), in particular ultra-thin glass.