Active partially destructible laser protection device, and assembly and laser system with the former, and method for operation thereof

Abstract

The invention relates to a laser protection device (8) with a flatly extending waveguide element (14) which is covered on the front side by an absorber material (13), and on which a scattering structure (15) for scattering laser radiation (19) is arranged on the rear side. The laser protection device (8) also comprises at least one detector (17) for detecting the laser radiation (19) which can arrive at the detector (17) by punctiform destruction of the absorber material (13) and subsequent guiding in the waveguide element (14). The laser protection device (8) is designed to output a signal to cause a source (2) of the laser radiation (19) to be switched off when it is detected by means of the detector (17). The invention also relates to a laser optics assembly (4) equipped with the laser protection device (8), and to a laser system (1) with the former, and to a method for operating a laser system (1) of this type.

Description

[0001] Active partially destructible laser protection device, assembly and laser system therewith, and method for operating the same

[0002] The present invention relates to a laser protection device, i.e., a protective device for protecting against unintentionally emitted laser radiation, as well as a laser optics assembly and laser system equipped therewith. The invention further relates to a method for operating such a laser system.

[0003] Lasers can be used beneficially for a wide variety of applications, for example, in material processing or for generating UV radiation, for example in EUV lithography. In many cases, increasingly higher power or intensity of the laser radiation is required. This can lead to problems and even safety risks. For example, with increasing system power, thermal and mechanical loads in a laser system can increase, which can negatively impact the positional stability of components and the robustness or reliability of the laser system. In addition, stray light or reflections, or, for example, due to misalignment or destruction of beam-guiding components in the laser system, can cause damage to surrounding components or people in the vicinity due to uncontrolled or unintentional laser radiation escaping.

[0004] As one approach to addressing these challenges, DE 10 2006 053 579 A1 describes a laser safety device with a passive laser protection wall that deposits laser radiation energy. This device includes a laser protection device positioned upstream of the laser radiation, which causes a detectable change upon impact of the laser radiation. A sensor is connected to a corresponding laser via a threshold switch to trigger a warning signal when the threshold is exceeded or undershot.

[0005] If a received detector signal falls below a threshold, the laser is switched off.

[0006] The object of the present invention is to enable the safe operation of a high-performance laser system. This object is achieved by the subject matter of the independent claims. Further possible embodiments of the invention are specified in the subclaims, the description, and the drawings. Features, advantages, and possible embodiments presented in the description for one of the subject matter of the independent claims are to be regarded at least analogously as features, advantages, and possible embodiments of the respective subject matter of the other independent claims, as well as any possible combination of the subject matter of the independent claims, optionally in conjunction with one or more of the subclaims.

[0007] The laser protection device according to the invention is designed to protect, for example, an environment or surrounding persons from uncontrolled laser radiation escaping or unintentionally propagating. Since the laser protection device according to the invention is not a simple passive barrier impermeable to laser radiation, it can also be referred to as an active laser protection device. The laser protection device has a planar waveguide element for guiding or directing laser radiation entering it at least in one main extension direction or dimension or a main extension surface or main extension plane of the waveguide element. The waveguide element can be plate- or film-shaped, i.e., much larger in two directions or dimensions than in the third direction or dimension.The waveguide element can therefore be thin compared to its size, for example, have a thickness in the range of less than 1 cm, in particular in the range of 1 mm or 100 pm, but extend over many centimeters, decimeters, or meters in the two perpendicular directions or dimensions. The waveguide element is configured or designed to guide laser radiation at least substantially perpendicular to its thickness or parallel to or in its main extension direction or area.

[0008] The laser radiation can be guided in the waveguide element, for example, by total internal reflection and / or scattering on the inner front and back surfaces. The waveguide element can therefore be at least essentially transparent to the laser radiation to be guided or ultimately detected. Depending on the application, i.e. depending on the wavelength of the laser radiation used, a material or material composition of the waveguide element can be selected accordingly. If multiple laser beams with different wavelengths are used, the waveguide element can be designed to be transparent only to the laser radiation to be ultimately detected. In such a case, it is advantageous if the waveguide element is not transparent to the laser radiation of the other laser beams. This can be achieved, for example, using appropriate filters.

[0009] The laser protection device also comprises an absorber material or absorber element that covers a front side of the waveguide element, i.e., is arranged or attached to the front side of the waveguide element and extends flatly just like the waveguide element. The absorber material can thus completely or almost completely cover one of the two sides of the waveguide element spanned by its two main extension directions or dimensions. The absorber material or absorber element is designed to absorb laser radiation impinging on its side facing away from the waveguide element, i.e., on the front side of the absorber material, and thus to be destroyed at the respective point of impact of the laser radiation, i.e., in particular, only at a specific point or in certain regions.The absorber material can be thermally destroyed by the energy deposited therein by the laser radiation, for example, i.e., it can evaporate, melt, carbonize, and / or shrink, thereby cracking or curling in some areas, or the like. This can be adjusted or ensured by selecting a material suitable for the respective application, i.e., the wavelengths of laser radiation used, and / or by selecting a thickness of the absorber material perpendicular to its main plane or surface, i.e., perpendicular to the front side. The absorber material can be a coating, for example, a paint or varnish layer or the like, on the waveguide element. Likewise, the absorber material can be a separate component arranged on the front side of the waveguide element.The absorber material can then be held to the waveguide element, for example, by an adhesive or electrostatically or due to the ambient air pressure.

[0010] The laser protection device according to the invention also has a scattering structure or scattering layer arranged on the rear side of the waveguide element opposite the front side, for scattering at least a portion of the laser radiation entering the waveguide element in a direction that enables propagation of the laser radiation in the at least one main extension direction or dimension of the waveguide element. The scattering structure therefore serves, for example, to scatter at least a portion of the laser radiation entering it parallel to the front and rear sides of the waveguide element and / or at an angle thereto at which the laser radiation fulfills a condition for total reflection on the inner sides or the front and rear sides of the waveguide element. The scattering structure can in particular be designed orbe designed to enable this at least substantially independently of the direction of incidence or impact of the laser radiation on the absorber material or the scattering structure. For this purpose, the scattering structure can therefore be set up or designed to scatter laser radiation impinging on it in a multitude of different directions or angles. For this purpose, the scattering structure can be or comprise, for example, a predefined regular structure or, for example, a random or stochastic roughening or the like. The scattering structure can be formed in the material of the waveguide element itself. Likewise, the scattering structure can be an independent component that is arranged or attached to the back of the waveguide element, i.e. opposite the absorber material, for example analogously to the absorber material.

[0011] The laser protection device according to the invention also has at least one detector arranged on the waveguide element and different from or separate from the absorber material for detecting the laser radiation guided in the waveguide element or emerging from it into or onto the detector. The at least one detector is covered or shielded against the laser radiation or other light or ambient brightness, at least before the absorber material is partially destroyed by the laser radiation, at least in potential directions of incidence of the laser radiation onto the front side of the absorber material. The detector can be covered or shielded, for example, by the absorber material, which is initially opaque to the laser radiation.As long as the absorber material has not yet been destroyed by laser radiation impinging on it during the intended use of the laser protection device, for example in a laser system or along a designated beam path or beam route of a laser beam, the detector would not detect any laser radiation, in particular not even scattered radiation that strikes the laser protection device but is not intense or powerful enough to destroy the absorber material at a specific point. However, if laser radiation enters the waveguide element, this laser radiation can be detected by the at least one detector even if the detector is arranged at a spatial distance from the point of impact or entry of the laser radiation, since at least a portion of the laser radiation is guided within the waveguide element to the detector.This allows a correspondingly large area to be monitored for incident laser radiation using a significantly smaller detector surface. This can enable a comparatively simple and cost-effective design of the laser protection device, since detectors can be relatively expensive and require significant effort, for example, for their electrical supply, signal acquisition, and signal evaluation.

[0012] According to the invention, the laser protection device is configured to automatically output a corresponding electrical / electronic signal upon detection of laser radiation by the at least one detector in order to effect or cause a source of laser radiation to be switched off. Such a signal can be generated and output, for example, by the detector itself or by a signal processing device coupled to it. Such a signal processing device can, for example, detect and evaluate a sensor or detector signal from the at least one detector and, if necessary, generate and output a control signal or switch-off signal to switch off the laser radiation source or to effect or cause its switch-off.

[0013] The laser protection device proposed here can essentially have a multi-layer design or a multi-layer structure. This provides a simple solution that can be integrated relatively easily into laser systems or laser application areas, and possibly also retrofitted relatively easily, to ensure laser protection in systems, machines, beam guidance optics, and corresponding work areas. Since the various layers of the laser protection device according to the invention can be relatively thin, it can be used or installed even in confined installation situations where limited space is available for the laser protection device.Advantageously, the laser protection device according to the invention enables at least one detector to be at least substantially completely shielded from ambient light, low-intensity scattered radiation, and the like, so that detection only occurs in the event of actual partial destruction of the front-side absorber material by correspondingly intense laser radiation impinging upon it. Thus, the laser protection device according to the invention can be used as a particularly robust and reliable error sensor for detecting and intercepting serious safety incidents in which significant deviations from a proper beam path or beam guidance occur, in order to prevent or limit the uncontrolled escape of laser radiation into the environment.The laser protection device according to the invention can employ an optical detection principle, i.e., direct detection of the laser radiation by means of at least one detector. This can be particularly robust against electromagnetic, thermal, and electrical influences, for example, and enable a particularly fast and precise response, for example, compared to thermal sensors. The waveguide element and the absorber material or the scattering structure can be manufactured as a large-area mass product, for example, as a film web, and can thus be produced particularly cost-effectively and practically.

[0014] The laser protection device according to the invention can be used as a fixed protection and detector, i.e. one that is permanently arranged and remains at a particular location, and can thus fulfill the described detection and protection task particularly easily and permanently without any additional effort.

[0015] The laser protection device according to the invention can be adapted to various requirements or applications thanks to its design. Since, for example, the absorber material, i.e. a corresponding absorber layer, must first be locally destroyed in order to then enable detection of the corresponding laser radiation, the response behavior or response level of the laser protection device can be adjusted via the thickness and / or material selection of the absorber material. In particular, this makes it possible to differentiate relatively minor errors from more serious errors or problems and to intercept them accordingly. In a minor error, for example, there may be a slight or weak misalignment, whereby only a very small proportion of the laser radiation used in the respective application hits the laser protection device. This proportion may then, for example, not have sufficient intensity or power to destroy the absorber material.In such a minor fault, there is typically no significant risk of laser radiation escaping or, if it does escape, leading to damage or danger. In a more serious fault, however, there may be such severe misalignment or damage that at least a large portion of the laser radiation hits the laser protection device. If, in such a case, this large portion of the laser radiation or the entire laser beam were to escape into the environment, this could lead to significant damage or danger. In such a case, however, due to the corresponding intensity or power of the laser radiation, the absorber material can be at least locally destroyed and the laser radiation can be detected by at least one detector of the laser protection device, and the laser radiation source can then be automatically switched off.This can not only prevent or minimize damage or corresponding danger, but can also indicate that a corresponding serious error has occurred and that appropriate repair or readjustment is necessary.

[0016] Another advantage is that, due to the absorbing design or configuration of the absorber material for laser radiation, reflection of laser radiation incident on the absorber material can be limited or minimized. This can potentially prevent damage within the laser system or a beam guidance device, or the like, caused by such reflections. In this case, the absorber material used is material that does not reflect laser radiation, or reflects it only slightly, or only reflects it at a minimal level.

[0017] In one possible embodiment of the present invention, the waveguide element and / or the absorber material is / are designed as a film. For example, the waveguide element here can be a PMMA film (polymethyl methacrylate) or a PC film (polycarbonate). The absorber material or absorber element can be or comprise, for example, an aluminum foil, in particular one with superficial oxidation, or an anodized layer or the like. The waveguide element and / or the absorber material or element can, for example, have a thickness in the range of 100 μm. The design as a film or films proposed here allows the use of cost-effective and established production processes and enables large-scale production. It also enables simple cutting to the sizes or shapes required for the respective application.In addition, the film-like and thus flexible design of the laser protection device or at least of the layer structure comprising the absorber material and the waveguide element or the scattering structure enables large-area coverage of potentially endangered areas as well as coverage of complex shapes in a particularly simple, low-effort, and cost-effective manner. If the scattering structure is not realized by an inherent structuring of the waveguide element itself, the scattering structure or scattering layer can also be designed as a film. In another possible embodiment of the present invention, the waveguide element is designed as a plate component. Such a plate component can be thicker than a film, for example, have a thickness in the range of 1 mm or several millimeters. In particular, the waveguide element can be intrinsically stable, i.e., can independently maintain its plate-like, flat shape or be rigid.For example, the waveguide element can be designed as a glass plate, in particular as a float glass plate, quartz glass plate, or sapphire glass plate. The waveguide element can be coated with the absorber material as described or covered with a film serving as the absorber material. The design proposed here can enable the laser protection device to be used for particularly high laser powers. Thus, laser radiation with higher power and / or higher intensity can be guided non-destructively in the waveguide element, as would be possible, for example, if the waveguide element were designed as a plastic film.

[0018] In a further possible embodiment of the present invention, the scattering structure is provided as a structuring of the rear side of the waveguide element itself, facing away from or opposite the absorber material. In other words, the scattering structure is not an independent component or material. For example, the rear side of the waveguide element can be structured or roughened by shot peening or sandblasting, or by mechanical or laser-based microstructuring, for example, or by other processing methods, and thus exhibit the described functionality for scattering laser radiation impinging on it from the inside. The embodiment of the present invention proposed here therefore makes it possible to eliminate the need for a corresponding additional component for the scattering structure. This allows the laser protection device to be constructed in a particularly simple and compact manner.

[0019] In another possible embodiment of the present invention, the scattering structure is designed as a separate component applied to the back of the waveguide element, i.e., attached or arranged on the back, extending flatly like the waveguide element, or as a coating of the back of the waveguide element with an additional light-scattering material. As a result, the scattering properties of the scattering structure or scattering layer can be adjusted or specified particularly flexibly and precisely, in particular independently of the thickness or material of the waveguide element. This can be useful, for example, if the waveguide element is so thin that direct machining or roughening of its back to create the scattering structure would be too complex or, for example, would entail the risk of destruction or unintentional perforation of the waveguide element during production.The embodiment of the present invention proposed here enables the laser protection device to be manufactured in a particularly reliable and simple manner, in line with requirements.

[0020] In a further possible embodiment of the present invention, the laser protection device has several or a plurality of detectors for detecting the laser radiation that may be guided in the waveguide element or emerging from it into or onto the detector. These several detectors are arranged spatially spaced from one another across the rear side of the waveguide element. The detectors can, for example, be arranged in a matrix-like manner, i.e., in a regular grid or checkerboard pattern or in regular rows and columns or the like. The use of several detectors proposed here can enable particularly fast and reliable detection of the laser radiation, but without, for example, equipping or covering the entire rear side or surface of the waveguide element with detector elements.For example, the laser radiation cannot be guided completely losslessly within the waveguide element and can therefore only be detected up to a limited distance from the point of incidence or impact of the laser radiation on the absorber material or into the waveguide element. The distributed arrangement of the multiple detectors at appropriate intervals proposed here allows for reliable detection of the laser radiation with limited effort, even with a large-area design or application of the laser protection device.

[0021] In a possible development of the present invention, collective connection elements or collective contact elements or collective bridges are arranged on two end faces or edges of the waveguide element, to each of which an electrical contact of all detectors distributed across the rear side of the waveguide element is electrically connected. Thus, one side or one pole of the detectors can be connected to one collective connection element and the other side or the other pole of the detectors can be connected to the other collective connection element. The collective connection elements can, in turn, offer a simple and bundled connection or contacting option for tapping the signals from the detectors. For example, a data or signal processing device can then be connected to the collective connection elements and thus does not have to be connected individually to each detector.This can enable a simplified design and handling of the laser protection device. The detectors can, for example, be connected to the collective connection elements via flexible conductor tracks or conductor foils. This allows the flexibility of the layered structure of the laser protection device to be maintained, for example in the embodiment described elsewhere in which at least the waveguide element is designed as a foil. Corresponding connection or connecting lines from the detectors to the collective connection elements can, for example, be arranged on the rear side of the scattering structure, i.e. on a rear side of the scattering structure or scattering layer facing away from the waveguide element. There they can, for example, be adhesively bonded or embedded or integrated into another layer, for example in a shielding or the like described elsewhere.Some or all of the detectors can be connected via individual lines or connected to the collective connection elements. Likewise, several detectors can be connected via the same line or connected to one of the collective connection elements. For example, with a regular arrangement of the detectors, all detectors in a column can be connected to one line and all detectors in a row can be connected to a different line. In this way, contacting or wiring of the detectors can be realized relatively easily and at the same time it can be determined which of the detectors is detecting the laser radiation or, for example, the greatest intensity of the laser radiation. To do this, it can be determined in which of the lines for the various columns of detectors and in which of the lines for the various rows of detectors a detector signal or the largest detector signal is present or detected.The combination of the corresponding row and column then indicates the corresponding detector. Other contacting or interconnection of the detectors is also possible. For example, several or all detectors can be connected in series or parallel, or in a combination, i.e., in several groups of detectors connected in series or parallel.

[0022] In a further possible embodiment of the present invention, the or at least one detector for detecting the laser radiation guided in the waveguide element or emerging from it into or onto the detector is arranged on an end face of the waveguide element. Such an arrangement allows, on the one hand, the laser protection device to be designed to be particularly thin and simple, at least over most of its surface. On the other hand, by means of an end-face arrangement of at least one detector, laser radiation can be detected if necessary, which propagates within the waveguide element exactly parallel to its front and rear sides and thus ultimately strikes the corresponding end face or the detector arranged there. The end face can therefore be a narrow side of the waveguide element that is at least substantially perpendicular to the front and rear sides.If the detector(s) are arranged there, they are located at the edge of the waveguide element and can thus be contacted particularly easily. This can, for example, save the corresponding manufacturing effort for arranging and wiring a detector on the back of the waveguide element. However, one or more detectors can also be arranged on the front side or several front sides and additionally on the back of the waveguide element. This can enable particularly reliable detection of laser radiation entering the waveguide element.

[0023] In a further possible embodiment of the present invention, a shield is arranged on the rear side of the scattering structure facing away from the waveguide element or the absorber material. This shield is opaque to laser radiation and stable or insensitive to laser radiation impinging on it—or at least more stable or less sensitive than the absorber material—and extends over a surface just like the waveguide element. Such a shield can, on the one hand, prevent laser radiation from escaping from the waveguide element through its rear side and then entering the environment. This can further improve the safety and protective effect of the laser protection device. On the other hand, the shield can prevent light or radiation from the environment from entering the waveguide element through the rear side and reaching the detector. This can avoid the risk of false detections.The shielding can, for example, be designed such that it can withstand the laser radiation at least for a predetermined period of time that is longer than the time that elapses from the time the laser radiation first enters the waveguide element until the source of the laser radiation is ultimately switched off. This can enable a correspondingly improved safety and reliability of the laser protection device, while, if necessary, its flexibility can still be maintained. For example, a metal foil or an arrangement of several layers of metal foil can be used as the shielding. In particular, if the waveguide element is designed as a plate, the shielding can also be designed as a plate and thus offer correspondingly increased robustness. If at least one detector is arranged on the back of the waveguide element, this can, for example, be integrated into the shielding orThe shielding can be embedded in corresponding recesses or surrounded by the shielding. The shielding can also cover the back of the detector itself, thus providing additional protection against unwanted detection of radiation or light from the environment and / or holding or fixing at least one detector.

[0024] In a further possible embodiment of the present invention, the laser protection device is configured to output the signal only if or when the detected laser radiation meets a predefined criterion. Such a criterion can, in particular, be that the intensity of the laser radiation and / or the increase in the intensity of the laser radiation within a predefined period of time, i.e., the gradient of a corresponding intensity signal, corresponds to at least a predefined threshold value. This allows for adjustment as needed, for example, to trigger shutdown of the laser radiation source only in the event of potentially critical problems and not, for example, in the event of scattered radiation reaching the detector that is uncritical from a safety or functional perspective.In particular, by detecting a rise, i.e., a signal edge, as a criterion, it is also possible to take into account, for example, a residual or background intensity arriving at the detector during safe operation. This eliminates the need to replace or repair the laser protection device after a prior localized destruction of the absorber material, even if this damage still causes radiation or light to enter the waveguide element during safe operation, for example, after correcting a misalignment or similar that caused it.

[0025] The present invention also relates to a laser optics assembly for guiding a laser beam along a predetermined, intended beam path. The laser optics assembly has a housing, on the sides of which the laser protection device or a laser protection device according to the invention is arranged, such that its absorber material faces the intended beam path. The laser protection device can, in particular, be arranged on the inside of the housing. Depending on the application or situation, however, it may also be possible to arrange the laser protection device on an outside of the housing or to integrate the laser protection device into its housing walls. A corresponding laser optics assembly can, for example, be a beam guiding tube or channel, or a beam guiding optics system or device, or a beam shaping optics system or- device or a deflection or scanning mirror, modulator, phase shifter, or the like, each arranged in a housing. With such laser optics assemblies, at least part of a laser system can be constructed modularly, with the integrated laser protection devices then automatically resulting in a correspondingly high level of protection or safety for the laser system, for example, without the entire system having to be additionally encased in a housing or a comprehensive laser protection device. This enables a simple construction of such a laser system and good accessibility to its components from the outside.

[0026] The present invention also relates to a laser system having at least one laser radiation source. The laser protection device(s) according to the invention and / or the laser optics assembly(s) according to the invention are arranged along a designated beam path of a laser beam in the laser system. The laser system according to the invention is configured to automatically shut off the laser radiation source in response to the signal(s) from the at least one laser protection device. For this purpose, the laser system can, for example, comprise a corresponding signal processing and shutdown device, which can be connected to the laser protection device and to the laser radiation source.Likewise, the at least one laser protection device can be directly connected to the laser radiation source, which can then be configured to automatically stop the generation or output of laser radiation in response to a signal sent by the laser protection device. The laser system according to the invention can, in particular, be the laser system mentioned in connection with the laser protection device according to the invention and / or the laser optics assembly according to the invention, or correspond thereto.

[0027] The present invention also relates to a method for operating the laser system according to the invention. In this method, after commissioning of the laser system including the at least one laser protection device, a corresponding signal is generated by the at least one laser protection device upon detection of laser radiation by the at least one detector, and the laser radiation source is automatically shut down upon detection of this signal or due to this signal.

[0028] Switching off the laser radiation source in the present sense can mean that the generation of laser radiation by the laser radiation source is terminated or that the laser radiation still being generated is no longer output from the laser radiation source. The latter can be achieved, for example, by redirecting the laser radiation within the laser radiation source into a beam trap or an absorber or dump output of the laser beam source. Further measures, sequences, or processes mentioned in connection with the laser protection device and / or laser optics assembly and / or laser system according to the invention can constitute further, possibly optional, method steps of the method according to the invention.

[0029] Further features of the invention can be derived from the following description of the figures and from the drawings. The features and combinations of features mentioned above in the description, as well as the features and combinations of features shown below in the description of the figures and / or in the figures alone, can be used not only in the respective combinations specified, but also in other combinations or on their own, without departing from the scope of the invention.

[0030] The drawing shows:

[0031] Fig. 1 is a schematic representation of a laser system with integrated protection device against unintentional laser radiation;

[0032] Fig. 2 is a schematic sectional view illustrating a structure of the protective device;

[0033] Fig. 3 is a schematic sectional view to further illustrate a structure of the protective device; and

[0034] Fig. 4 is a schematic sectional view illustrating a detector contact in the protective device. Identical or functionally identical elements are provided with the same reference numerals in the figures. For the sake of clarity, only a representative selection of identical or similar elements may be explicitly identified in the figures.

[0035] Fig. 1 shows a partial schematic representation of a laser system 1 with a laser radiation source 2. This laser radiation source 2 can output a laser beam 3. By way of example, the laser system 1 here also comprises an optical assembly 4. This optical assembly 4 here purely by way of example comprises a housing 5 with a deflecting mirror 6 arranged therein for deflecting the laser beam 3. In a correctly adjusted target position 7 of the deflecting mirror 6, indicated here by a dashed line, the laser beam 3 would exit through a provided outlet of the housing 5, which is also indicated here by a dashed line.

[0036] In this case, however, a misalignment may have occurred, so that the deflecting mirror 6 is no longer in its target position 7. As a result, the laser beam 3 is deflected in an unintended manner, so that it would, for example, strike the inside of the housing 5. The laser beam 3 could then potentially damage the housing 5 or even pierce it and escape into the environment, or reflections of the laser beam 3 could occur within the housing 5, which could lead to laser radiation escaping into the environment through an entrance or at an unintended angle through the exit of the housing 5.

[0037] Likewise, for example, the laser radiation source 2 could be misaligned so that the laser beam 3 would not enter the optical assembly 4 at all.

[0038] In order to avoid or limit associated dangers or safety risks, the laser system 1 comprises several laser protection devices 8. These are arranged here, for example, along a designated beam path from the laser radiation source 2 to the optics assembly 4 and on the inside of the housing 5. The laser protection devices 8 are equipped with a data or

[0039] Signal processing device 9 of the laser system 1 is coupled. For this purpose, the signal processing device 9 has, for example, an interface 10 and is configured to process signals from the laser protection devices 8. For this purpose, the signal processing device 9 has, for example, a corresponding circuit or, as schematically indicated here, a processor 11, such as a microchip, microprocessor, microcontroller, or the like, and a computer-readable data memory 12 coupled thereto. The signal processing device 9 is also configured to deactivate the laser radiation source 2 or the output of the laser beam 3 by means of the laser radiation source 2 in response to a signal sent by at least one of the laser protection devices 8. For this purpose, the signal processing device 9 is also connected to the laser radiation source 2 here.Likewise, the signal processing device 9 could, for example, be fully or partially integrated into the laser protection devices 8 and / or the laser radiation source 2.

[0040] The laser protection devices 8 comprise, on their side facing the intended beam path of the laser beam 3, a layer of absorber material 13. This absorber material 13 can absorb the laser beam 3 impinging upon it and thereby be destroyed at specific points, for example, by evaporation or melting. A waveguide element 14 is arranged at the rear thereof, in which a portion of the laser beam 3 entering therein after the specific destruction of the absorber material 13 can be guided or transported as laser radiation 19 (see Fig. 2) perpendicular to the thickness direction of the absorber material 13 and the waveguide element 14. A scattering layer or scattering structure 15 for scattering the laser radiation 19 is arranged at the rear of the waveguide element 14. This scattering structure 15, in turn, is covered at the rear by an opaque shield 16.

[0041] The laser protection devices 8 also each comprise a plurality of detectors 17 for detecting the laser radiation 19. These can be, for example, photodiodes or the like. The detectors 17 can, for example, be connected to connection elements 18, via which the respective laser protection device 8 can be connected to the signal processing device 9.

[0042] For a more detailed illustration of the structure and mode of operation of the laser protection devices 8, Fig. 2 shows a partial schematic representation of a part of a laser protection device 8 and indicated the signal processing device 9. The laser protection device 8 comprises a layer structure made up of the absorber material 13, the waveguide element 14, the scattering structure 15, and the shield 16. For example, the waveguide element 14 can be designed here as a waveguide and scattering foil, to which the absorber material 13 is attached as an absorber foil on the front side. To form the scattering structure 15, the waveguide element 14 can be structured on its rear side such that laser radiation 19 entering the waveguide element 14 and striking its rear side from the inside, i.e., an inner side or front side of the scattering structure 15, is scattered in different directions, as indicated schematically here.For this purpose, the rear side of the waveguide element 14 can be structured, for example, by shot or sand blasting, or provided with a microstructure, such as microcones or micropyramids or the like. Likewise, the waveguide element 14 can be coated with a foil or a coating that forms the scattering structure 15. Instead of a foil, for example made of a plastic material such as PMMA or the like, the waveguide element 14 can also be formed as a plate-shaped component, for example made of float glass, quartz glass, sapphire, or the like. The shield 16 arranged on the rear side can be opaque and prevent ambient light from entering the waveguide element 14.

[0043] In the section shown here, one of the detectors 17 is also indicated. This is arranged directly on the waveguide element 14. In particular, there can be no scattering structure 15 on a front side of the detector 17 or of all detectors 17 facing the waveguide element 14. In other words, the detectors 17 can be arranged in corresponding recesses or holes in the scattering structure 15, or the scattering structure 15 can be arranged or formed only in the regions of the rear side of the waveguide element 14 that lie between the detectors 17 or that surround the detectors 17. The detectors 17 for detecting the laser radiation 19 can therefore be arranged or fastened directly on the rear side of the waveguide element 14, for example, glued or adhesively fastened. As a result, laser radiation 19 striking the inner rear side of the waveguide element 14 can be particularly effectively detected in or on the rear side of a detector 17.be detected by the detector 17.

[0044] As can also be seen in Fig. 1, in error-free or properly adjusted normal operation of the laser system 1, the laser beam 3 does not strike one of the laser protection devices 8. Any scattered light that may nevertheless strike the laser protection devices 8 or their absorber material 13, which may have a much lower intensity or power than the laser beam 3, can be completely or almost completely absorbed in the absorber material 13 without destroying or penetrating it. Thus, at least almost no light or laser radiation 19 is guided in the waveguide element 14. If, in the event of a fault, for example, in the event of a misalignment of the deflection mirror 6 or the laser radiation source

[0045] 2 or in the event of a failure of a corresponding control system or the like, the laser beam 3 strikes a laser protection device 8 or its absorber material 13, as indicated here, the absorber material 13 can be destroyed at least locally by the impinging laser beam 3. In this case, from a certain point in time, the laser beam 3 enters the waveguide element 14, which until then did not or did not significantly conduct light or radiation. The laser beam 3 then passes through the waveguide element 14 in the form of the laser radiation 19 indicated here and strikes the scattering structure 15 or its front side. There, the laser radiation 19 is at least partially scattered in such a way that a certain proportion of the laser radiation 19 fulfills the angle condition for total internal reflection within the waveguide element 14.The corresponding portion of the scattered laser radiation 19 thus travels within the waveguide element 14 in at least one of its main directions of extension or in the transverse direction. Thus, after a certain time, the scattered laser radiation 19 reaches one of the detectors 17, where it is detected. The corresponding detector 17 can output a corresponding detector signal to the signal processing device 9. There, the detector signals of the detector 17 or of all detectors 17 can be processed or evaluated. If it is detected that the detected laser radiation 19 reaches or exceeds a predetermined threshold value, or if a corresponding signal edge, i.e. an increasing detected laser radiation intensity, is detected, the signal processing device 9 can output a shutdown signal, i.e. a signal for switching off the laser radiation source 2 or the laser radiation source 17, for example via the interface 10.to switch off the output of the laser beam 3 to the laser radiation source 2.

[0046] In particular, the laser protection device 8 and the signal processing device 9 can be configured to switch off the laser radiation source 2 or the laser beam

[0047] 3 so quickly that, until the laser beam 3 is switched off at the point of impact on the absorber material 13, it has not yet destroyed the absorber material 13 over the entire cross section or diameter of the laser beam 3 or the laser radiation 19 has not yet escaped via the rear side or an end face of the waveguide element 14 or has not yet penetrated the shielding 16.

[0048] The signal processing device 9 can therefore be used here as a combined evaluation unit, which evaluates a detector signal generated by one of the detectors 17, which indicates detected laser radiation 19, and, for example, generates or outputs a corresponding error signal or the shutdown signal from a certain threshold value, and a safety device, which, if necessary, switches off the laser radiation source 2 or the laser beam 3 when the corresponding error signal has been generated, or generates the shutdown signal and sends it to the laser radiation source 2.

[0049] In other words, a laser protection device 8 is proposed here which, for example in the event of a fault, i.e. if the laser beam 3 unexpectedly deviates from its intended beam path or beam path and thus a potential hazard exists, - optionally in combination with the signal processing device 9 - generates a corresponding fault or shutdown signal which can be read out, for example, by a corresponding safety device or safety circuit and causes the laser radiation source 2 or the laser beam 3 to be switched off.

[0050] The scattering structure 15 also allows any vertically incident laser radiation 19 to be coupled at least partially into the waveguide element 14 in such a way that it can propagate at least to the nearest detector 17. The detectors 17 can be permanently integrated into the respective laser protection device 8 at a corresponding distance, for example, in a regular pattern.

[0051] For further illustration, Fig. 3 and Fig. 4 show partial schematic representations of one of the laser protection devices 8 from different viewing directions. The individual detectors 17 can be electrically connected, for example in parallel and / or in series, or connected or contacted by means of corresponding lines or flexible conductor foils. By way of example, a matrix-like arrangement and contacting of the detectors 17 is provided here. For this purpose, the detectors 17 are provided via first connecting lines 20 running at least substantially in a first main extension direction of the waveguide element 14 and second connecting lines 21 running, for example perpendicular thereto in the second main extension direction of the waveguide element 14. In Fig. 3, the second connecting lines 21 can run at least substantially perpendicular to the plane of the drawing.

[0052] In Fig. 4, the matrix-like arrangement and contacting of the detectors 17 can be seen even more clearly. The first connecting lines 20 and the second connecting lines 21 can connect the detectors 17 to the connecting elements 18 arranged laterally or at the edge of the waveguide element 14. There, the connecting lines 20, 21 can, for example, pierce or protrude through the shielding 16 up to the respective connecting element 18. The arrangement shown here can enable flexible design and adaptation of the laser protection devices 8 to spatial conditions or different sizes of the various laser protection devices 8. For example, their layer structure can initially be manufactured as a continuous web. This can then be cut to size as required, and the cut pieces can then be provided with the connecting elements 18.Overall, the examples described show how an active laser protection device can be constructed and used.

[0053] LIST OF REFERENCE SYMBOLS

[0054] 1 laser system

[0055] 2 Laser radiation source

[0056] 3 laser beam

[0057] 4 Optical assembly

[0058] 5 housings

[0059] 6 deflecting mirrors

[0060] 7 Target position

[0061] 8 Laser protection device

[0062] 9 Signal processing device

[0063] 10 Interface

[0064] 11 processor

[0065] 12 data storage

[0066] 13 Absorber material

[0067] 14 Waveguide element

[0068] 15 Scattering structure

[0069] 16 Shielding

[0070] 17 Detector

[0071] 18 connecting element

[0072] 19 Laser radiation

[0073] 20 first connecting cables

[0074] 21 second connecting lines

Claims

PATENT CLAIMS 1. Laser protection device (8) for protection against laser radiation (3, 19), comprising - a planar waveguide element (14) for guiding laser radiation (19) entering therein at least in a main direction of extension, - an absorber material (13) covering a front side of the waveguide element (14), which absorber material is designed to absorb laser radiation (3) impinging on its side facing away from the waveguide element (14) and thereby to be destroyed at a respective point of incidence of the laser radiation (3), - a scattering structure (15) arranged on a rear side of the waveguide element (14) for scattering at least a portion of laser radiation (3, 19) entering the waveguide element (14) in a direction that enables propagation of the laser radiation (3, 19) in the at least one main extension direction of the waveguide element (14), - at least one detector (17) arranged on the waveguide element (14) and different from the absorber material (13) for detecting the laser radiation (3, 19), which detector is covered at least before the partial destruction of the absorber material (13) at least in respect of potential directions of incidence of the laser radiation (3) onto the absorber material (13), wherein the laser protection device (8) is configured to automatically output a corresponding signal for causing a source (2) of the laser radiation (3, 19) to be switched off upon detection of laser radiation (3, 19) by means of the at least one detector (17).

2. Laser protection device (8) according to claim 1, characterized in that the waveguide element (14) and / or the absorber material (13) is designed as a film.

3. Laser protection device (8) according to claim 1, characterized in that the waveguide element (14) is designed as a plate component.

4. Laser protection device (8) according to one of the preceding claims, characterized in that the scattering structure (15) is designed as a structuring of the rear side of the waveguide element (14).

5. Laser protection device (8) according to one of claims 1 to 3, characterized in that the scattering structure (15) is designed as a planar component applied to the back of the waveguide element (14) or as a coating of the back of the waveguide element (14).

6. Laser protection device (8) according to one of the preceding claims, characterized in that the laser protection device (8) has a plurality of detectors (17) for detecting the laser radiation (3, 19), which are arranged, in particular in a matrix-like manner, spatially distributed over the rear side of the waveguide element (14).

7. Laser protection device (8) according to claim 6, characterized in that a collective connection element (18) is arranged on each of two edges of the waveguide element (14), to which an electrical contact of all detectors (17) distributed over the rear side of the waveguide element (14) is electrically connected.

8. Laser protection device (8) according to one of the preceding claims, characterized in that at least one detector (17) for detecting the laser radiation (3, 19) is arranged on an end face of the waveguide element (14).

9. Laser protection device (8) according to one of the preceding claims, characterized in that on the rear side of the scattering structure (15) facing away from the waveguide element (14) there is arranged a flat shield (16) which is impermeable to the laser radiation (3, 19) and stable with respect to laser radiation (3, 19) impinging thereon.

10. Laser protection device (8) according to one of the preceding claims, characterized in that the laser protection device (8) is designed to output the signal only when the detected laser radiation (19) meets a predetermined criterion, in particular the intensity of the laser radiation (19) and / or the increase in the intensity of the laser radiation (19) within a predetermined period of time corresponds to at least one predetermined threshold value.

11. Laser optics assembly (4) for guiding a laser beam (3) along a predetermined beam path, comprising a housing (5), on the sides of which a laser protection device (8) according to one of the preceding claims is arranged, so that the absorber material (13) faces the beam path.

12. Laser system (1) comprising a laser radiation source (2), wherein a laser protection device (8) according to one of claims 1 to 10 and / or a laser optics assembly (4) is arranged along a designated beam path and the laser system (1) is configured to automatically switch off the laser radiation source in response to the signal from the laser protection device (8).

13. A method for operating a laser system (1) according to claim 12, wherein upon detection of laser radiation (3, 19) by means of the at least one detector (17) of the laser protection device (8), a corresponding signal is generated by the latter and upon detection of this signal or by this signal, the laser radiation source (2) is automatically switched off.

Images