DE20120119U1 - Device for transmitting a laser beam from a laser source to an application - Google Patents

Description

Field of the invention

The present invention relates generally to transmission paths for guiding a laser beam from a laser source to an application. In particular, the present invention relates to a device for wall-enclosed laser beam transmission paths, which reduces contamination of the transmission paths and improves their cleaning. '

Background of the invention

Electromagnetic radiation of short wavelength, especially in the wavelength range below 250 nm, is strongly attenuated (absorbed) when passing through atmospheric air, especially by the components oxygen (O ₂ ) and water vapor (H ₂ O).

For example, in the case of VUV laser radiation with a wavelength of 157 nm, the high absorption cross section of oxygen (σ = 5.2 x λ ¹⁸ cm ² ) essentially prevents propagation in normal air. As can be seen from the table in Fig. 1 and the graphic representation in Fig. 2, a laser beam with a wavelength of 157 nm is almost completely absorbed over a propagation distance of a few micrometers.

Furthermore, atmospheric components such as oxygen and vapor contamination cause absorbing layers to build up on optical components, which can degrade the optical properties and lead to destruction.

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Accordingly, it is usual to guide laser radiation through a beam line surrounded by a wall that protects the laser radiation from atmospheric influences on its propagation path from a laser source to an application. Such beam lines generally comprise tubular components at the ends of which devices are provided, such as fastening flanges, in order to seal the beam line on the input side with a laser beam source and on the output side with an application device ("application").

The walls of the beam lines are essentially impermeable to gases, so that laser radiation can propagate in a beam line shielded from ambient air. In order to prevent absorption of laser radiation in a beam line or at least to reduce it so that the laser radiation supplied to an application has the desired properties, it is known to use evacuated beam lines. These have the disadvantage that they become contaminated relatively quickly with components that cause absorption and desorb from the walls of the beam line.

Therefore, beamlines are preferred which are cleaned or flushed using a cleaning or purging gas. Inert gases such as nitrogen (N ₂ ), helium (He), argon (Ar), neon (Ne) and the like are generally used for this purpose. The use of cleaning or purging gases also has the advantage that, in addition to removing substances in the beamline which cause absorption, optical components are also freed from layers which have accumulated on them. Examples of such optical components include windows, lenses, prisms, mirrors, optical shutters and the like.

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A disadvantage of known beam lines that are cleaned to reduce or prevent absorption is that the beam line can become contaminated during repair or maintenance work. This requires that it be cleaned or rinsed again when it is put back into operation. Furthermore, it has previously been necessary for such beam lines to be cleaned or rinsed in such a way that they meet the highest purity standards required for an application, even though these only have to be met for certain areas of the beam line. For example, higher purity requirements are often made on the application side due to the expensive and sensitive lighting and projection optics of the application than on the laser radiation source side.

Object of the invention

The object of the present invention is to improve a beam line for transmitting laser radiation from a laser source to an application in such a way that the aforementioned disadvantages of the prior art are avoided. In particular, the present invention should make it possible to clean or flush beam lines for laser radiation more easily and efficiently. Furthermore, the present invention should provide a solution that allows maintenance and repair measures to be carried out without having to completely clean or flush the entire beam line again.

Inventive solution

According to the invention, this is basically achieved by dividing a beam line arranged between a laser source and an application into at least two areas or volumes between which no exchange of substances or particles is possible.

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can take place, which leads to an absorption of the laser radiation

being able to lead.

The division of the beam line into at least two separate beam sub-lines leads to a clear separation of areas that are assigned to the devices connected by the beam line, for example the laser source on the one hand and the application on the other. This also ensures that contamination that occurs in a beam sub-line, for example due to faulty operating conditions, maintenance work or repair measures on the laser source or the application, does not contaminate the rest of the beam line. In addition, the invention makes it possible to meet different purity standards for a cleaning or purging gas in the beam sub-lines depending on the application and to use different cleaning or purging gases.

Furthermore, the beam sub-lines can be subjected to different cleaning or rinsing cycles or processes, which can also be started and/or ended at different times. In this way, for example, the cleaning or rinsing in the beam sub-lines assigned to the laser source and the beam sub-lines assigned to the application can be optimized, whereby the amount of cleaning or rinsing gases required can be reduced and the cleaning or rinsing of the beam sub-lines and the optical components assigned to them can be improved.

In addition, the separation of the beam line into at least two beam sub-lines simplifies the fault diagnosis, as contamination is easier to identify and localize. For example, if there is a fault in the area of the laser source that leads to contamination of the beam sub-line connected to it, the beam sub-line connected to the application is

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A beam line is not affected by this error and is therefore not contaminated.

Usually, the responsibilities for repair and maintenance measures for laser sources and applications are distributed differently, i.e. they are carried out by different service teams or companies. If the beam line assigned to an application is contaminated, the present invention only requires informing the departments responsible for the application so that they can carry out an inspection of the application.

The separation of a beam line for transmitting laser radiation according to the invention is particularly advantageous if it is designed in such a way that beam sub-lines can be separated from one another in such a way that they or the volumes defined by them for transmitting laser radiation remain closed in such a way that no impurities causing absorption can occur there.

Brief description of the invention

The present invention provides a device for transmitting laser radiation from a laser source to an application with a wall that encloses a volume for transmitting the laser radiation in its propagation direction and defines a transmission path for the laser radiation. The laser radiation is fed to the device at a receiving end, for example directly at the laser source, and after the laser radiation has propagated along the transmission path, it is emitted at an output end, for example directly at the application.

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In order to prevent the laser radiation propagating along the transmission path from being impaired by absorption, the wall is at least impermeable to the materials (e.g. gas-tight, air-tight, waterproof) that could lead to absorption of the laser radiation. For example, it is intended that the wall is impermeable to oxygen, water vapor, carbon dioxide, ozone and the like.

According to the invention, the device has a device arranged in the transmission path, which is impermeable to substances that cause absorption and allows laser radiation to pass through essentially unaffected. The device separates or divides the transmission path into two partial transmission paths or two transmission volumes, so that essentially no exchange of substances that cause absorption can take place between the partial transmission paths or partial volumes.

The wall of the device can be provided by a pipe or tube. The wall can be at least partially transparent to allow, for example, optical control of at least one transmission section. Alternatively, it is possible to make the wall opaque or opaque for certain wavelengths or wavelength ranges. For example, for safety reasons, the wall can be opaque in particular to laser radiation.

In order to supply cleaning or purge gases to the transfer sections or the corresponding partial volumes, according to a preferred embodiment, the wall has at least one supply connection and one discharge connection assigned to the transfer sections.

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Preferably, the device separating the transmission path comprises optical components such as windows, prisms, lenses, beam splitters, beam deflectors and the like, which are permeable to light of the wavelength of the laser radiation.

In order to reduce or prevent reflection losses of the laser radiation, in particular in the case of polarized laser radiation, it is preferable that optical components of the separating device are arranged at the Brewster angle relative to the propagation direction of the laser radiation K).

In the case of a one-piece wall of the device, the separating device can be integrated as a single unit. If the device comprises a multi-part wall, each part of which encloses a transmission section, the separating device can be integrated as a single unit in one of the wall parts and attached to the other using connecting devices formed there.

Furthermore, in the case of multi-part walls, it is possible for the separating device to be a separate component of the device and to be connected to the wall parts by means of connecting devices provided on the wall parts and/or as a separating device.

The separating device can also comprise two or more separating part devices which are arranged on the wall parts and have connecting devices in order to connect the separating part devices to one another and thus provide the separating device. In this embodiment of the separating device, the separating part devices can be designed in such a way that, when arranged on the wall parts, they seal them against substances causing absorption even when they are not connected to one another. This allows the device according to the invention to be dismantled in the area of the separating device without damaging the

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to contaminate the transfer volumes or transfer sections defined in the wall parts.

In order to connect the device to the laser source, it is provided that connecting devices or structures are arranged at the receiving end of the device, for example fastening flanges, bores, snap or locking devices and the like.

The same applies to the output end for connecting the transmission section assigned to it with the application.

Preferably, the device comprises a first closing device at its receiving end, which, like the separating device, is impermeable to substances causing absorption and is at least permeable to the laser radiation. In this way, sealing of the transmission section associated with the receiving end is ensured, regardless of a connection of the receiving end to an upstream device.

In a similar manner, a second closing device can be arranged at the discharge end, which ensures that the transfer section associated with the discharge end is closed off from substances that cause absorption.

The first and/or the second termination device can comprise optical components such as windows, prisms, lenses, beam splitters, beam deflectors and the like, which are permeable to light of the wavelength of the laser radiation. Reflection losses of the laser radiation, in particular in the case of polarized laser radiation, can be reduced or prevented by arranging the optical components of the first and/or the second termination device at the Brewster angle relative to the direction of propagation of the laser radiation.

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Furthermore, the device can have further output ends, e.g. 2, 3, 4 etc. output ends, in order to supply laser radiation to more than one application. For this purpose, the device according to the invention can, for example, comprise output devices provided in the wall, each of which provides an output end. Windows, lenses, prisms and the like can be used as output devices. Furthermore, it is provided that optical devices are arranged along the propagation path of the laser radiation so that they supply laser radiation to the output ends. Examples of such optical devices are beam splitters, semi-transparent mirrors, lens arrangements, etc. These optical components are preferably designed in such a way that they act as a separating device, i.e. define partial transmission paths which are assigned to the various output ends, preferably individually in each case.

Another possibility for providing additional output ends is that the device according to the invention comprises walls assigned to the individual output ends, which define transmission volumes for the laser radiation to the different output ends. Here, it is provided that the separating device distributes the laser radiation, which is supplied via the transmission section assigned to the laser source, into the transmission volumes assigned to the output ends.

In this case, the separation device may comprise, for example, semi-transparent mirrors, beam splitters, beam-splitting lens arrangements and the like.

The transfer volumes associated with the discharge ends can be in fluid and/or gas connection, which allows a simple construction of the device according to the invention, but has the disadvantage that substances causing absorption can be exchanged between the transfer volumes to the discharge ends. This can be avoided, if necessary, by positioning the separating device relative to the

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Transmission volumes are arranged in such a way that they are sealed against substances that cause absorption and thus define transmission sections for the transmission volumes.

In this case, the separating device can have corresponding connecting structures for fastening the wall enclosing the transfer volumes assigned to the delivery ends. Alternatively, it is provided that the separating device comprises several components which are arranged on the walls of the individual transfer sections and connecting structures in order to connect the individual components to one another and thus provide the separating device.

Alternatively or additionally, it is intended to use more than one separating device that defines partial transmission paths to the output ends.

Short description of the characters

In the following description of preferred embodiments, reference is made to the accompanying drawings, in which:

Fig.1

a table showing the absorption of gases and vapours at a wavelength of 157nm,

Fig. 2 Fig. 3

a graphical representation of the absorption by gases and vapours as a function of wavelength,

a schematic representation of a first embodiment of the device according to the invention,

Fig.4

a schematic representation of a second embodiment of the device according to the invention,

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Fig.5

a schematic representation of a third embodiment of the device according to the invention, and

Fig. 6a-6c

Schematic representations of a further embodiment of a separating device according to the invention.

Description of preferred embodiments

Fig. 3 shows a schematic representation of a device, designated as a whole by 6, arranged between a laser source 2 and an application 4 for transmitting laser radiation from the laser source 2 to the application 4.

The transmission device 6 comprises a wall 8 which is connected to the laser source 2 and the application 4 in such a way that laser radiation can pass from the laser source 2 to the application 4. In order to avoid contamination of the transmission device 6 at the connection points to the laser source 2 and the application 4, the wall 8 is connected to the laser source 2 or the application 4 in these areas, for example by flanges provided with seals.

25 connected.

A separating device 10 is arranged in the transmission device 6, which is impermeable to substances (gases, vapors, particles, etc.) that can cause absorption of the laser radiation. The separating device 10 divides the transmission path defined by the wall 8 from the laser source 2 to the application 4 into a first transmission path 12 and a second transmission path 14. >

For separate cleaning or rinsing of the transmission sections 12 and 14, an inlet is provided on the transmission section 12

·

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and an outlet 18 and an inlet 20 and an outlet 22 are provided on the transfer section 14. In order to prevent contamination of the transfer sections 12 and 14 via the inlets 16 and 20 and the outlets 18 and 22, these are closed by devices (not shown), such as valves, shut-off valves and the like, when they are not being used for cleaning or flushing.

In the embodiment shown in Fig. 4, a device generally designated 24 is used for transmitting laser radiation 26 from a laser source 28 to two applications 30 and 32.

The transmission device 24 comprises a wall 34 and separating devices 36, 38 and 40.

The transmission paths provided by the transmission device 24 from the laser source 28 to the applications 30 and 32 are divided by the separating devices 36, 38 and 40 into partial transmission paths 42, 44, 46, 48 and 50, wherein the separating devices 36, 38 and 40 prevent substances such as gases or vapors from passing from one partial transmission path to another.

In the illustrated transmission device 24, the separating device 36 comprises a mirror 52 which deflects the laser radiation 26 from the laser source 28 and directs it onto a semi-transparent mirror 54 of the separating device 38. A portion of the laser radiation 26 is fed to the application 30 from the semi-transparent mirror 54, while the other portion of the laser radiation 26 reaches the application 32 via a deflection mirror 56 of the separating device 40.

According to Fig. 5, a device designated as a whole by 58 for transmitting a laser radiation 60 from a laser

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source 62 to applications 64 and 66 a wall 66 and a separating device 68.

The separating device 68 divides the volume provided by the transfer device 58 into partial transfer sections 70, 72 and 74.

The separation device 68 has a beam splitter 76 which splits the laser radiation 60 coming from the laser source 62 and leads it to the applications 64 and 66.

Fig. 6a-6c show schematic representations of an embodiment of a device, designated as a whole by 100, for transmitting laser radiation from a laser source to at least one application. The transmission device 100 has supply and discharge connections 102 and 104, which are attached to a housing part 110, and supply and discharge connections 106 and 108, which are attached to a housing part 112. Substances, for example noble gases, can be supplied for flushing and cleaning to the transmission sections separated by the transmission device 100 for transmitting laser beams via the supply and discharge connections 102, 106 and 104 and 108.

The housing parts 110 and 112 are tightly connected to one another using fastening devices 114 and 116.

Furthermore, 4 openings are provided on the fastening devices 114 and 116, of which only the openings 118 to 128 are designated in Fig. 6a. The openings, which can also have an internal thread, serve to fasten the transmission device 100 to a transmission path coming from a laser source or to a transmission path leading to an application.

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The housing parts 110 and 112 and the fastening devices 114 and 116 are designed in such a way that no substances can penetrate that would result in absorption of the laser radiation. The same applies to the connections of the transmission device 100 with the transmission paths from the laser source and to the application.

As can be seen in Fig. 6c, the transfer device 100 comprises a separating device designed as a window 130, which divides the space enclosed by the housing parts 110 and 112 into sub-spaces 132 and 134. The window 130 prevents a transfer of absorption-causing substances between the sub-spaces 132 and 134 by means of a corresponding arrangement or fastening to the housing parts 110 and 112 or between them. The window 130 advantageously prevents any fluid or gas connection between the sub-spaces 132 and 134.

In order to transmit laser radiation transmitted via the transmission device 100 essentially unchanged, the window 130 is arranged at the Brewster angle.

Claims (9)

1. Device for transmitting laser radiation from a laser source ( 2 ) to an application ( 4 ), comprising: 1. a wall ( 8 ) which encloses a transmission path for laser radiation from the laser source ( 2 ) to the application ( 4 ), and - a separating device ( 10 ) which is impermeable to substances which can cause absorption of the laser radiation and divides the transmission path into partial transmission paths ( 12 , 14 ). 2. Device according to claim 1, wherein the separating device ( 10 ) comprises at least one optical component, such as a window, a prism, a lens, a beam splitter, a beam deflector and the like, which is transparent to the wavelength of the laser radiation. 3. Device according to claim 2, wherein the optical component is arranged at the Brewster angle relative to the propagation direction of the laser radiation. 4. Device according to one of the preceding claims, in which the separating device ( 10 ) is constructed as a unit on the wall ( 8 ). 5. Device according to one of claims 1 to 3, wherein the separating device ( 10 ) is fastened to the wall ( 8 ) using connecting devices, wherein the connecting devices are provided on the separating device ( 10 ) and/or the wall ( 8 ). 6. Device according to one of the preceding claims, in which the wall ( 8 ) has supply and discharge connections ( 16 , 18 ; 20 , 22 ) which are respectively assigned to the transmission sections ( 12 , 14 ). 7. Device according to one of the preceding claims, in which the wall ( 8 ) has a receiving end for receiving the laser radiation and an output end for emitting the laser radiation, the receiving end and the output end having connecting devices for connecting the wall ( 8 ) to the laser source ( 2 ) and the application ( 4 ) in such a way that no substances causing absorption can enter the transmission sections ( 12 , 14 ). 8. Device according to claim 7, in which termination devices comprising optical components are arranged at the receiving end and the output end of the wall ( 8 ), which termination devices are designed to prevent penetration of absorption-causing substances into the partial transmission paths ( 12 , 14 ). 9. Device according to one of the preceding claims, in which at least one further separating device is present which defines at least one further transmission section.