DE102019124164A1 - Laser processing system and method for characterizing a laser beam from a laser processing system - Google Patents

Abstract

The present invention relates to a method for characterizing a laser beam (1002) of a laser processing system (1000). The method comprises determining an energy parameter of the laser beam (1002) and providing a calibration device (1014) in a working plane (2000) of the laser processing system (1000) and exposing the calibration device (1014) to the laser beam (1002) under the same conditions under which a use of the laser beam (1002) for processing a processing object is provided. The method further comprises determining a calibration parameter by means of the calibration device (1014) in the working plane (2000) and providing the calibration device (1014) in a control plane (2002) outside the working plane (2000) and deflecting the laser beam (1002) in this way that the calibration device (1014) in the control level (2000) is acted upon by the laser beam (1002). In addition, the method comprises determining a control parameter by means of the calibration device (1014) in the control level (2002), determining a deviation factor which characterizes a deviation between the calibration parameter and the control parameter and characterizing the laser beam (1002) by means of the calibration device (1002) in the control level (2002) using the deviation factor. The invention also relates to a laser processing system (1000).

Description

The present invention relates to a laser processing system and a method for characterizing a laser beam of a laser processing system, in particular for ophthalmic surgery of an eye. The invention is therefore in the field of laser processing systems for ophthalmic surgery.

Curvature of the cornea in the human eye is often the cause of ametropia. In many cases, these can be eliminated or reduced by means of ophthalmic surgery, in which refractive corneal correction can be carried out. To carry out such a refractive corneal correction, excimer lasers are mostly used, by means of which material is removed from the cornea to be corrected in order to provide the cornea with the desired refractive effect. It goes without saying that the correction of the refractive effect must be carried out very precisely in order to achieve a satisfactory treatment result in which the corrected cornea has the desired refractive effect.

In order to achieve the required precision when removing material from the cornea by means of a laser beam from an excimer laser, as well as for regulatory reasons, there is a need for regular characterization of the actual material removal that is effected with the laser beam. The laser beam should be calibrated and characterized in the working plane in which the laser processing system then also treats the eye to be treated, since the mostly focused laser beam has a different diameter due to the convergence or divergence in other planes along the optical axis of the laser beam and thus also has a different fluence. In addition, the characterization or calibration of the laser beam should take place as soon as possible before the laser processing system is used for a treatment of an eye, in order to minimize the risk of changes occurring due to drifts in one or more parameters. These two requirements cannot easily be implemented together, since the calibration of the laser beam or laser processing system in the working plane is no longer possible when a patient to be treated has taken up his treatment position and the eye to be treated is in the working plane. A characterization of the laser beam or the laser processing device at a point in time before the patient has taken the treatment place, in turn, does not allow a timely characterization before immediately before the start of treatment, since taking up the place and preparing the patient can require a considerable amount of time.

It is therefore the object of the present invention to enable reliable characterization and / or monitoring of the laser beam or the laser processing system in spite of the difficulties outlined above.

The laser beam is mostly in pulsed form, so that the material removal by the laser beam is typically determined as material removal per laser pulse or “shot” or for a predetermined pulse sequence or shot sequence (number of laser pulses). In the case of continuously working lasers, the material removal per irradiation time is determined.

Such a characterization of the material removal is often referred to as a "fluence test", since the "fluence" or fluence, as the ratio between laser pulse energy and the effective laser spot diameter, is usually the most important parameter for material removal when the material strongly absorbs the laser light, as is the case, for example, with the UV light of the excimer laser in plastics or biological tissues.

Various excimer laser systems for refractive corneal correction are known in the prior art, such as the applicant's systems referred to as MEL 80 and MEL 90. In these and also in other systems, the material removal can be checked regularly using so-called fluence papers, which typically consist of colored cardboard to which a metal-coated plastic film of known thickness is glued. To check the material removal, a predetermined shot pattern is applied to the fluence paper, with various test points on the fluence paper each being subjected to a certain number of pulses or shots, i.e. with certain ratios of the number of shots. The resulting material removal is then checked with the naked eye on the respective test points of the fluence paper, with the metal-coated plastic film still being retained for some predetermined shot sequences in or at the test points, while in test points of other shot sequences, for example with a higher number of shots, the one Flow of + 4%, has been partially removed. At those test points in which the metal-coated plastic film was at least partially removed, the colored cardboard arranged under the originally applied metallic plastic film is at least partially visible. The operator then checks with the naked eye.

An alternative method for characterizing the laser beam consists in working a lens profile into a substrate made of PMMA by means of the excimer laser corresponding material is removed from the PMMA substrate. This is followed by a complex measurement of the processed PMMA substrate, in which the actual refractive effect of the processed PMMA substrate or its lens shape is measured and compared with the corresponding, predetermined target value. On the basis of any deviations, conclusions can be drawn about the effect of the processing and the laser beam can be characterized. However, this method requires special measuring devices and a high degree of effort, so that a regular check of the laser beam with such a method on a daily basis is not economically sensible or possible. Carrying out such a method also requires a high level of technical expertise and for this reason is often left to specially trained personnel, such as a service technician, and cannot easily be carried out by a regular operator. Such a method is therefore typically only carried out during an initial calibration, for example during manufacture or when the system is first put into operation.

A method for determining the dimensions of a laser beam is also known in the prior art, in which the laser beam is scanned in a path over a reference edge, as for example in FIG US 6,559,934 B1 described. Furthermore describes the US 2002 / 0198515A1 a method in which, for the adjustment of a laser system, a structure is used in a treatment plane which has a slot or a reference edge for the purpose of adjustment or calibration. In addition, the WO 01/87199 A2 a device and a method for measuring the energy and / or position of a pulsed laser beam, in which the laser beam is temporarily directed onto a sensor.

The above-mentioned object is achieved by the invention. The invention relates to a method for characterizing a laser beam of a laser processing system and a laser processing system with the features of the respective independent claims. Preferred embodiments are specified in the dependent claims and in the description.

In a first aspect, the invention relates to a method for characterizing a laser beam of a laser processing system. The method includes determining an energy parameter of the laser beam. In addition, the method includes providing a calibration device in a working plane of the laser processing system and applying the calibration device with the laser beam under the same conditions under which the laser beam is intended to be used for processing a processing object, and determining a calibration parameter by means of the calibration device in the working plane. The method further includes providing the calibration device in a control plane outside the working plane and deflecting the laser beam in such a way that the calibration device is exposed to the laser beam in the control plane, and determining a control parameter by means of the calibration device in the control plane. In addition, the method includes determining a deviation factor which characterizes a deviation between the calibration parameter and the control parameter, and characterizing the laser beam by means of the calibration device in the control plane using the deviation factor.

In a further aspect, the invention relates to a laser processing system for processing a processing object by means of a laser beam. The laser processing system comprises an energy sensor which is designed to determine an energy parameter of the laser beam. Furthermore, the laser processing system comprises a calibration device, which can optionally be arranged in a working plane of the laser processing system and can be acted upon by the laser beam and can be arranged in a control plane outside the working plane and can be acted upon by the laser beam, and a deflection element which can be arranged in the beam path of the laser beam in such a way that the Deflection element deflects the laser beam directed onto the working plane into the control plane. The laser processing system is set up to arrange the calibration device in the working plane and to determine a calibration parameter, to arrange the calibration device in the control plane and to determine a control parameter, to determine a deviation factor that characterizes a deviation between the calibration parameter and the control parameter, and the laser beam to be characterized by means of the calibration device in the control level using the energy parameter and the deviation factor.

A laser beam is the radiation that is emitted by a laser, preferably an excimer laser. The laser beam does not necessarily have continuous wave radiation, but can also be pulsed. The laser beam can also be collimated and / or convergent and / or divergent for characterization. The laser beam preferably has electromagnetic radiation in the ultraviolet spectral range. The laser beam more preferably has a central wavelength of approximately 193 nm. The laser beam is preferably designed as a laser beam for refractive corneal correction and is preferably provided by an excimer laser. The laser beam is particularly preferably provided by an ArF excimer laser.

The characterization of the laser beam preferably includes the characterization of the beam profile of the laser and / or the characterization of a beam size. The characterization can preferably furthermore be a characterization of an energy, such as a pulse energy, and / or a peak power and / or an average power and / or the energy of a predetermined series or number of pulses and / or an intensity and / or a fluence (in particular in the working plane) and / or material removal that can be achieved thereby. The characterization can furthermore preferably include a characterization of a focus of the laser beam, such as a shape and / or a profile and / or an intensity of the focused laser beam.

The working plane is that plane in which the laser processing system acts on a processing object, for example an eye, with the laser beam in order to process the processing object. In other words, the laser processing system is designed to process a processing object with the laser beam in the working plane. For example, the laser beam can be focused into the working plane by the laser processing system.

An energy parameter that is determined in the context of the method is preferably a parameter that characterizes the energy and / or power of the laser beam. The intensity and / or fluence of the laser beam in the working plane can preferably be determined on the basis of the energy parameter together with the determined extent of the laser beam. The energy parameter preferably characterizes an energy of the laser beam and / or a power of the laser beam and / or an energy of a laser pulse and / or an energy of a series of laser pulses.

A calibration parameter that is determined within the scope of the method is a parameter on the basis of which material removal by the laser beam, in particular the cornea when applied to an eye to be treated, can be determined and / or anticipated. The calibration parameter can in particular include the fluence and / or intensity of the laser beam in the working plane or enable the fluence and / or intensity of the laser beam to be determined in the working plane. The control parameter preferably corresponds to the calibration parameter with the proviso that the control parameter characterizes the laser beam in the control plane. The calibration parameter and the control parameter are particularly preferably directly comparable with one another, so that the deviation factor preferably represents a dimensionless variable that quantifies a difference between the values or amounts or amplitudes of the calibration parameter on the one hand and the control parameter on the other. Determining a calibration parameter preferably comprises determining a fluence and / or an intensity of the laser beam in the working plane, wherein determining a control parameter comprises determining a fluence and / or an intensity of the laser beam in the control plane.

The control level is a level in which the control parameter is paid by means of the calibration device. The control parameter is preferably determined in the control plane in the same way as the calibration parameter is determined in the working plane. The control plane is arranged in such a way that the calibration device can also be arranged in the control plane when a patient has assumed the treatment position and one of the patient's eyes is arranged in the working plane. Accordingly, the control plane is preferably arranged and / or the calibration device is provided in the control plane in such a way that there is no spatial overlap between the calibration device provided in the control plane and a processing object arranged in the working plane. Particularly preferably, the control level is at least partially arranged within the laser processing system and / or the calibration device when provided in the control level is arranged within the laser processing system. This offers the advantage that the laser processing system can be designed to be particularly compact.

The length of the optical path of the laser beam up to the working plane is preferably essentially the same as the length of the optical path of the laser beam up to the control plane. The length of the optical path can be determined, for example, starting from the laser source or from the last optical element before the deflecting element. “Essentially the same” in this context means that any remaining difference has no influence on the characterization of the laser beam. For example, the difference can be so insignificant that the resulting changes in the beam size do not lead to any noticeable deviation in the fluence.

The invention offers the advantage that the laser beam can be characterized with only one calibration device, although several calibration devices can also be used in accordance with some embodiments. Because one calibration device is sufficient, deviations and Falsifications of the characterization of the laser beam due to differences between separate calibration devices can be avoided.

Furthermore, the invention offers the advantage that a proper calibration can first take place in the working plane and then, in particular during processing or treatment if it is not possible to arrange a calibration device in the working plane, a short-term characterization or monitoring of the laser beam using the control parameter and the energy parameter is possible by deflecting the laser beam into the control plane. Although the characterization in the control level may not allow calibration in the actual sense, because, for example, a calibration in the working level is mandatory, the characterization in the control level can still provide valuable additional information about whether one or more parameters of the laser beam have changed since have changed the last calibration or characterization and / or a new calibration appears advantageous or necessary. In this way, the interval of calibrations and / or characterizations in the working plane can preferably be lengthened and or a more regular characterization of the laser beam, in particular in time segments in which the patient is already or still in the working plane, can be made possible.

In addition, the invention offers the advantage that the characterization can be carried out particularly reliably, since the calibration device is preferably the last element in the beam path to the working plane or to the control plane, both in the working plane and in the control plane, and thus when the laser beam is applied to the processing object or the eye to be treated, no additional optical elements are arranged in the beam path that were not taken into account in the characterization of the laser beam.

In one embodiment, the calibration device provided in the control plane is a calibration device that is embodied separately from the calibration device provided in the working plane. In other words, according to a preferred embodiment, two separate calibration devices are used or provided in the control plane and in the working plane. This offers the advantage that the calibration device arranged in the control plane can preferably remain in position and only the calibration device provided in the work plane for treating an eye or machining a processing object has to be removed from the work plane. The calibration devices can preferably be designed in the same way or even identically. According to other embodiments, the calibration devices can also differ from one another, provided that the measurement results can be directly compared.

According to another preferred embodiment, the same calibration device is used both in the working plane and in the control plane. This offers the advantage that only one calibration device has to be provided. Furthermore, this offers the advantage that deviations between the calibration parameter and the control parameter due to deviations between the two separate calibration devices can be avoided.

The characterization of the laser beam by means of the calibration device in the control plane is preferably carried out in such a way that the energy parameter of the laser beam is also used. In other words, the laser beam is also characterized using the energy parameter. This offers the advantage that the cause of any changes in the fluence or other fluctuations resulting from a change in the energy and / or power of the laser can be reliably identified.

The control parameter is preferably determined immediately after the calibration parameter has been determined. This offers the advantage that deviations due to temporal fluctuations in the laser processing system can be minimized.

The energy parameter is preferably determined at least during the determination of the calibration parameter and during the determination of the control parameter. The energy parameter is particularly preferably determined continuously. This offers the advantage that changes resulting from a deviation in the energy of the laser beam can be recognized and can be taken into account when comparing the calibration parameter with the control parameter.

The laser beam is preferably deflected exclusively by means of precisely one optical deflecting element. In other words, the beam path of the laser beam for deflecting from the working plane into the control plane is changed exclusively by means of the deflecting element. This offers the advantage that disruptive influences on the laser beam, which can lead to a deviation between the laser beam provided in the working plane and the laser beam provided in the control plane, are reduced to a minimum. The deflecting element can particularly preferably be monitored and / or checked regularly, for example by determining a reflectivity and / or transmittance of the deflecting element. For example the laser beam and / or other optical radiation can be used for this purpose.

The laser processing system is preferably designed to automatically switch the arrangement of the calibration device between the working plane and the control plane and / or to automatically introduce the deflecting element into the beam path of the laser beam and / or remove it from the beam path. This offers the advantage that only one calibration device is required and calibration and / or characterization of the laser beam can preferably be carried out in a completely automated manner.

The calibration device is preferably designed to provide a measured value that scales linearly with the laser energy. For example, the calibration device can be set up to determine a material removal and / or a change in a thickness of a test object due to exposure to the laser beam, the material removal and / or the change in thickness preferably scaling linearly with the energy of the laser beam. Alternatively, the calibration device can have a diaphragm arrangement with a diaphragm and a photodetector, by means of which the fluence and / or the intensity of the laser beam can be determined by scanning the laser beam through one or more diaphragm openings of the diaphragm. It can be advantageous if the measurement signal of the photodetector is linear to the energy of the laser beam.

It goes without saying that the features and embodiments mentioned above and explained below are not only to be regarded as disclosed in the combinations explicitly mentioned in each case, but that other technically meaningful combinations and embodiments are also included in the disclosure content.

The laser beam is preferably deflected into the control plane by means of a deflection element which is introduced into the beam path for this purpose. For example, the deflecting element can be designed as a mirror. According to another embodiment, the deflecting element can also remain in the beam path and a deflection of the laser beam into the control plane can be achieved by changing its orientation.

The laser processing system is preferably designed to move the calibration device independently between the working plane and the control plane, for example with a corresponding translation and / or pivoting device. For example, this change in position takes place in such a way that the length of the optical path of the laser beam to the working plane and to the control plane is the same.

Further details and advantages of the invention will now be explained in more detail using the following examples and preferred embodiments with reference to the figures.

• 1A und 1B ein Laserbearbeitungssystem 1000 gemäß einer bevorzugten Ausführungsform in zwei verschiedenen Betriebsmodi zur Charakterisierung des Laserstrahls 1002.
• 2A und 2B in schematischen Darstellungen einen Bearbeitungskopf 1020 eines Laserbearbeitungssystems 1000 gemäß einer bevorzugten Ausführungsform.

Show it:

• 1A and 1B a laser processing system 1000 according to a preferred embodiment in two different operating modes for characterizing the laser beam 1002 .
• 2A and 2 B a machining head in schematic representations 1020 a laser processing system 1000 according to a preferred embodiment.

The 1A and 1B show a laser processing system in schematic representations 1000 according to a preferred embodiment in two different operating modes for characterizing the laser beam 1002 .

The laser processing system 1000 has a laser source 1004 on which the laser beam 1002 which is then initially emitted by a beam shaping device 1006 runs in which the laser beam 1002 is brought into the desired shape. After the beam shaping device 1006 the laser beam propagates through a deflection device 1008 or scanning device, by means of which the laser beam 1002 can be deflected in such a way that the laser beam 1002 in one working plane 2000 or in a control level 2002 is movable to perform the desired processing of a processing object, such as the treatment of an eye. The beam shaping device 1006 is preferably set up to use the laser beam 1002 into the working level 2000 or the control level 2002 to focus.

Between the beam shaping device 1006 and the deflector 1008 is a beam splitter 1010 in the beam path of the laser beam 1002 arranged, which a small part of the laser beam 1002 or the laser energy branches off and an internal energy sensor 1012 feeds. The beam splitter 1010 For example, it can be designed in such a way that it reflects around 10% of the energy of the laser beam and transmits the remaining energy, whereby beam splitters with a different ratio can also be used as long as enough energy is still transmitted for the treatment or processing in the working plane. The energy sensor 12 uses the supplied part of the laser beam to determine an energy parameter from which the energy and / or power of the entire laser beam can be derived. The laser processing system is preferably set up for this purpose by means of the energy sensor 1012 a continuous and / or regular determination of the energy parameter during the operation of the laser processing system 1000 perform.

1A shows the laser processing system in a first operating mode for characterizing the laser beam 1002 , in which a calibration device 1014 in the working level 2000 is arranged and for the characterization of the laser beam 1002 determines a calibration parameter. The calibration parameter enables the fluence of the laser beam 1002 in the working level 2000 to determine.

1 B shows the laser processing system 1000 in a second operating mode for characterizing the laser beam 1002 , in which the calibration facility 1014 in the control level 2002 is arranged. The control plane 2002 and also the calibration facility 1014 are located within the laser processing system 1000 . By means of the calibration device 1014 becomes a control parameter in the control level 2002 determined, which is preferably determined in an identical manner to the calibration parameter with the difference that the control parameter is not in the working plane 2000 but in the control level 2002 is determined. The control parameter enables the fluence of the laser beam 1002 in the control level 2002 to determine. The laser beam 1002 is done by a deflection element 1016 diverted so that it is not on the work plane 2000 but on the control level 2002 falls. The deflection element 1016 can be designed as a mirror, for example, and from the laser processing system 1000 into the beam path of the laser beam 1002 be moved. For example, the deflecting element can be arranged to be displaceable or pivotable in order to be able to be moved into and out of the beam path. After the determination of the control parameter has been completed, the deflecting element 1016 be removed from the beam path again, so that the laser beam 1002 can propagate back to the working level.

The determination of the control parameter is preferably carried out immediately after the determination of the calibration parameter in order to minimize the risk of changes in the meantime.

Using the calibration parameter and the control parameter, the laser processing system can 1000 then determine a deviation factor by means of which the two parameters or measured values based on them, such as the determined fluence values, can be related to one another.

Then the laser processing system 1000 a check of the laser beam 1002 perform by merely determining the control parameter, comparing it with a setpoint value and using the energy parameter to check whether the energy of the laser beam is also 1002 corresponds to the setpoint. This allows a check of the laser beam 1002 also take place when the working plane is not accessible for determining the calibration parameter.

The deflecting element is in a processing mode in which a processing object is processed by means of the laser beam 1016 also arranged outside the beam path, for example in FIG 1A shown, but in the edit mode the calibration device 1014 not in the working plane 2000 is arranged, but a processing object (not shown).

The 2A and 2 B show a machining head in schematic representations 1020 a laser processing system 1000 according to a preferred embodiment in two operating modes for characterizing the laser beam 1002 .

The processing head 1020 is designed to use the laser beam 1002 to emit so that this is along the optical axis A1 propagated and either in the working level 2000 or in the control level 2002 occurs.

Furthermore, the laser processing system 1000 on the processing head 1020 an arrangement to the calibration device 1014 optionally in the working level 2000 and in the control level 2002 to be able to arrange and the deflecting element 1016 optionally in or outside of the beam path or the optical axis A1 of the laser beam 1002 to be able to position. For this purpose, the arrangement has a drive 1022 and a guided tour 1024 on to the deflector 1016 from a position outside the beam path ( 2A) to a position in the beam path ( 2 B) to bring and vice versa.

Furthermore, the laser processing system 1000 a pivoting device to the calibration device 1014 from the work plane 2000 into the control level 2002 to pan and vice versa. For example, the calibration device 1014 over one arm 1024 on a swivel joint 1026 be attached about which the arm 2024 can be pivoted, as indicated by the curved arrow 2004 indexed. Of course, the arrangement is designed and / or arranged in such a way that the laser beam is not hindered or blocked by the arrangement or one of its components in any of the operating modes.

In an operating mode for processing a processing object or for treating an eye, for example, the calibration device 1014 be pivoted into the control plane and the deflecting element 1015 be arranged outside of the beam path.

• Insbesondere betrifft die folgende Erläuterung einer Verknüpfung der Kalibration mit der Kalibrationseinrichtung in der Arbeitsebene (externe Position) mit der Überpfügung mittels der Kalibrationseinrichtung in der Kontrollebene (interne Position):
  • Zunächst wird die Kalibration bzw. Charakterisierung des Laserstrahls mittels der Kalibrationseinrichtung in der Arbeitsebene (Ermitteln eines Kalibrierungsparameters) ohne ein zusätzliches optisches Element bzw. Umlenkelement durchgeführt. Hierbei wird außerdem ein Energieparameter als Referenzwert für den internen Energiesensor (Eint,0) gemäß Kalibrationsverfahren bestimmt und die Laserenergie wird so lange angepasst, bis die tatsächliche Fluenz F_{ist_extern} innerhalb der Toleranzen der Zielfluenz liegt (Ftarget, extern).
  • Unmittelbar daraufhin wird der Test auf der selben Kalibrationeinrichtung, jedoch in einer Kontrollebene innerhalb der Laserbearbeitungsvorrichtung durchgeführt, vorzugsweise in konstantem Arbeitsabstand bezogen auf die Apertur der Laserquelle, und ein Kontrollparameter ermittelt. Dies kann z.B. durch einen starren Schwenkmechanismus oder durch mechanische oder magnetische Anschläge realisiert werden. Hierbei kommt ein zusätzliches optisches Element als Umlenkekement zur Anwendung, um den Laserstrahl vollständig auf die interne Position der Kalibrationseinrichtung in der Kontrollebene zu lenken. Das zusätzlich eingebrachte Umlenkelement ist (in Strahlrichtung) hinter dem letzten optischen Element des Strahlengangs angeordnet.

The following is a calibration of the laser beam using an example 1002 a laser processing system 1000 described without the invention being limited to the following example:

• In particular, the following explanation relates to a link between the calibration and the calibration device in the working level (external position) and the transfer by means of the calibration device in the control level (internal position):
  • First, the calibration or characterization of the laser beam is carried out by means of the calibration device in the working plane (determination of a calibration parameter) without an additional optical element or deflection element. An energy parameter is also determined as a reference value for the internal energy sensor (Eint, 0) according to the calibration procedure and the laser energy is adjusted until the actual fluence F _{ist_extern is} within the tolerances of the target fluence (Ftarget, external).
  • Immediately thereafter, the test is carried out on the same calibration device, but in a control plane within the laser processing device, preferably at a constant working distance based on the aperture of the laser source, and a control parameter is determined. This can be achieved, for example, by a rigid swivel mechanism or by mechanical or magnetic stops. Here, an additional optical element is used as a deflection element in order to direct the laser beam completely onto the internal position of the calibration device in the control plane. The additionally introduced deflection element is arranged (in the beam direction) behind the last optical element of the beam path.

This determination of the control parameter with an internal fluence measurement (this measurement is explicitly not a calibration) is _{carried out internally with a fixed energy setting with regard to the energy found in step 1), i.e. at E int, 0} and provides a fluence value F act.

This value differs from the fixed value F _{target, externally} due to the properties of the additional deflecting element, such as the reflectivity of the deflecting element designed as a mirror. From this a deviation factor is determined with which these effects can be calculated: $$\text{R.}={\text{F.}}_{\text{is}\text{, internal}}{\text{/ F}}_{\text{target}\text{,external}}.$$

3) The characterization of the laser beam or the calibration of the laser system can then be carried out exclusively via the internal position (i.e. without the need to arrange the calibration device in the external position), i.e. via the control parameter, with the target value of the fluence using the range shown in FIG ) certain deviation factor R is calculated, $${\text{F.}}_{\text{target}\text{, internal}}=\text{R.}\ast {\text{F.}}_{\text{target}\text{,external}}.$$

4a) The calibration interval for determining the deviation factor R (steps 1 & 2) can be set in such a way that no degradation of the additional deflection element affects the calibration accuracy (e.g. by specifying adequate time intervals / number of tests).

4b) Ideally, any degradation of the deflection element, such as a decrease in reflectivity, can be checked by continuously monitoring the control parameter relative to that of the energy sensor in the laser arm, ie the energy parameter: This is preferably done by continuously comparing the measurement signals F act _{, internal} and E _{int, current} (cross calibration of the calibration device with the current measured value of the internal energy sensor in the case of a calibration device with a continuous measured value).

4c) Independently of this, any degradation of the deflecting element can be monitored in a different spectral range than that of the processing laser. For this purpose, a transmission or reflectivity measurement of the deflection element can be carried out regularly. Since degradation in an optical element at this position, i.e. as the last optical element in front of the working plane, can typically result from surface damage on the coated side (from the processing laser) or from contamination, for example from droplets of the rinsing fluid from the refractive operating room, a Degradation can also be determined in a different spectral range. For example, degradation can take place by means of a lighting device and a camera and / or by using the scanned aiming lasers that are typically present in such systems.

However, only a degradation can be determined in this way; a quantification can be achieved by means of the method presented in 4 b) or in steps 1) - 2). The finding alone can, however, serve to deactivate the laser processing system and / or to abort a treatment and / or to output a corresponding indication that a check is required.

List of reference symbols

1000

Laser processing system

1002

laser beam

1004

Laser source

1006

Beam shaping device

1008

Deflector

1010

Beam splitter

1012

Energy sensor

1014

Calibration facility

1016

Deflection element

1018

Arrangement for moving the deflection element

1020

Machining head

1022

drive

1024

guide

1026

Swivel joint

1028

poor

2000

Working level

2002

Control level

2004

Swivel direction

A1

optical axis / beam path of the laser beam

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• US 6559934 B1 [0009]
• US 2002/0198515 A1 [0009]
• WO 0187199 A2 [0009]

Claims (12)

Method for characterizing a laser beam (1002) of a laser processing system (1000), the method comprising the steps: - determining an energy parameter of the laser beam (1002); - Providing a calibration device (1014) in a working plane (2000) of the laser processing system (1000) and applying the calibration device (1014) with the laser beam (1002) under the same conditions under which the laser beam (1002) is to be used for processing a processing object ; - Determination of a calibration parameter by means of the calibration device (1014) in the working plane (2000); - Providing the calibration device (1014) in a control plane (2002) outside the working plane (2000) and deflecting the laser beam (1002) in such a way that the calibration device (1014) in the control plane (2000) is acted upon by the laser beam (1002); - Determination of a control parameter by means of the calibration device (1014) in the control level (2002); Determining a deviation factor which characterizes a deviation between the calibration parameter and the control parameter; Characterizing the laser beam (1002) by means of the calibration device (1002) in the control level (2002) using the deviation factor. Procedure according to Claim 1 , wherein the calibration device (1014) provided in the control plane (2002) is a calibration device (1014) formed separately from the calibration device (1014) provided in the working plane (2000), or the same calibration device (1014) for determining the calibration parameter in the Working level (2000) is provided and is provided for determining the control parameter in the control level. Procedure according to Claim 1 or 2 wherein the determination of the energy parameter takes place at least during the determination of the calibration parameter and during the determination of the control parameter and preferably takes place continuously. Method according to one of the preceding claims, wherein the deflection of the laser beam (1002) takes place exclusively by means of precisely one optical deflection element (1016). Method according to one of the preceding claims, wherein the control level (2002) is arranged in such a way and / or the provision of the calibration device (1014) in the control level (2002) takes place in such a way that between the calibration device (1014) and there is no spatial overlap of a processing object arranged in the working plane (2000). Method according to one of the preceding claims, wherein the control level (2002) is at least partially arranged within the laser processing system (1000) and / or the calibration device (1014) is arranged within the laser processing system (1000) when provided in the control level (2002). Method according to one of the preceding claims, wherein the energy parameter characterizes an energy of the laser beam (1002) and / or a power of the laser beam (1002) and / or an energy of a laser pulse and / or an energy of a series of laser pulses. Method according to one of the preceding claims, wherein determining a calibration parameter comprises determining a fluence and / or an intensity of the laser beam in the working plane (2000) and / or wherein determining a control parameter comprises determining a fluence and / or an intensity of the laser beam ( 1002) in the control level (2002). Method according to one of the preceding claims, wherein the length of the optical path of the laser beam (1002) up to the working plane (2000) is essentially equal to the length of the optical path of the laser beam (1002) up to the control plane. Laser processing system (1000) for processing a processing object by means of a laser beam (1002), comprising: - an energy sensor (1012) which is designed to determine an energy parameter of the laser beam (1002); - A calibration device (1014) which can be arranged optionally in a working plane (2000) of the laser processing system (1000) and can be acted upon by the laser beam (1002) and can be arranged in a control plane (2002) outside the working plane (2000) and with the laser beam (1002) can be acted upon; - A deflecting element (1016) which can be arranged in the beam path of the laser beam (1002) in such a way that the deflecting element (1016) deflects the laser beam directed onto the working plane (2000) into the control plane (2002); wherein the laser processing system (1000) is set up to arrange the calibration device (1014) in the working plane (2000) and to determine a calibration parameter, to arrange the calibration device (1014) in the control plane (2002) and to determine a control parameter, to determine a deviation factor showing a discrepancy between the Characterized calibration parameters and the control parameter, and characterize the laser beam (1002) by means of the calibration device (1014) in the control plane using the deviation factor. Laser processing system (1000) according to Claim 10 wherein the calibration device (1014) in the arrangement in the control plane (2002) is at least partially arranged within the laser processing device (1000). Laser processing device (1000) according to Claim 10 or 11 , wherein the laser processing system (1000) is designed to automatically switch the arrangement of the calibration device (1014) between the working level (2000) and the control level (2002) and / or the deflecting element (1016) automatically into the beam path of the laser beam (1002) to be introduced and / or removed from the beam path.

Images