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

Abstract

The invention relates to a laser protection device (8) with a planar 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 back. The laser protection device (8) also has at least one detector (17) for detecting the laser radiation (19), which can reach the detector (17) through selective destruction of the absorber material (13) and subsequent guidance in the waveguide element (14). The laser protection device (8) is designed to output a signal for causing a source (2) of laser radiation (19) to be switched off upon its detection by the detector (17). The invention also relates to a laser optics assembly (4) equipped with the laser protection device (8), as well as to a laser system (1) comprising the same, and to a method for operating such a laser system (1).

Description

The present invention relates to a laser protection device, i.e. a protection device for protecting against unintentionally emerging laser radiation, and to a laser optics assembly and laser system equipped therewith. The invention further relates to a method for operating such a laser system.Lasers can be usefully employed for a variety of different applications, for example for material processing or for generating UV radiation, for example for EUV lithography. In many cases, increasingly higher power or intensity of the laser radiation is required. This can lead to problems and even to safety risks. Thus, with increasing system power, for example, thermal and mechanical loads in a laser system may increase, which may negatively influence the positional stability of components and the robustness or reliability of the laser system. In addition, scattered light or reflections or, for example, due to misalignment or destruction of beam-guiding components in the laser system, components surrounding uncontrolled or unintentionally emerging laser radiation or persons in the environment can then be damaged.As an approach to counter these challenges, DE 10 2006 053 579 A1 describes a laser protection device with a passive laser protection wall, which deposits radiation energy of a laser. There, a laser protection device is provided upstream in the direction of the laser radiation, which brings about a change detectable when laser radiation impinges. A sensor is connected to a corresponding laser via a threshold value switch in order to switch off the laser when a received detector signal exceeds or falls below a threshold value.It is an object of the present invention to enable reliable operation of a powerful laser system.The object is achieved by the subject matters of the independent claims. Further possible embodiments of the invention are specified in the dependent claims, the description and the drawing. Features, advantages and possible configurations which are set forth in the context of the description for one of the subject matters of the independent claims are to be regarded at least analogously as features, advantages and possible configurations of the respective subject matter of the other independent claims and of each possible combination of the subject matters of the independent claims, optionally in conjunction with one or more of the dependent claims.The laser protection device according to the invention is configured to protect, for example, an environment or surrounding persons from uncontrolled emerging laser radiation or laser radiation which propagates unintentionally. Since the laser protection device according to the invention is not a simple passive barrier that is opaque to the laser radiation, it can also be referred to as an active laser protection device. The laser protection device has a waveguide element which extends in a planar manner for guiding or guiding laser radiation entering therein at least in a main direction of extent or dimension or a main surface of extent or main plane of extent 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 thus be thin in comparison 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 a 100 μm, but can extend over many centimeters or decimeters or meters in the two directions or dimensions perpendicular thereto. The waveguide element is configured or configured to guide laser radiation at least substantially perpendicular to its thickness or parallel to or in its main direction or main area of extent.The laser radiation can be guided in the waveguide element, for example, by internal total reflection and / or scattering at inner front and rear sides. The waveguide element can thus be at least substantially transparent here for the respective 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 a material composition of the waveguide element can be selected accordingly. If a plurality of laser beams having different wavelengths are used, the waveguide element can be made transparent only to the laser radiation to be detected ultimately. In such a case, it is advantageous if the waveguide element is not transparent to the laser radiation of the remaining laser beams. This can be realized, for example, via corresponding filters.The laser protection device also has an absorber material or absorber element which covers a front side of the waveguide element, that is to say is arranged or fastened on the front side of the waveguide element and, just like this, is extended in a planar manner. The absorber material can thus completely or almost completely cover one of those two sides of the waveguide element which are 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 to be destroyed thereby at a respective point of impingement of the laser radiation, i.e. in particular only in corresponding points or regions. The absorber material can be thermally destroyed, for example, by the energy deposited therein by the laser radiation, that is to say, for example, vaporising or melting or carbonizing and / or shrinking and thereby tearing or rolling in regions or the like. This can be set or ensured by material selection and / or thickness of the absorber material that is suitable for the respective application, i.e. the wavelengths of the laser radiation used in each case, perpendicularly to its main plane or surface of extent, i.e. perpendicularly to the front side. The absorber material can be a coating here, for example a paint or lacquer layer or the like on the waveguide element. Likewise, the absorber material can be an independent component which is arranged on the front side of the waveguide element. The absorber material can then be held on the waveguide element, for example, by an adhesive or electrostatically or on account of the surrounding air pressure.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 part of the laser radiation that has entered the waveguide element in a direction that enables the laser radiation to be propagated in the at least one main direction of extension or dimension of the waveguide element. The scattering structure thus serves, for example in the case of a planar shape of the waveguide element, to scatter at least a part of the laser radiation which has entered therein parallel to its front and rear side and / or at an angle at which the laser radiation fulfills a condition for total reflection on the inner sides or the front and rear side of the waveguide element. The scattering structure can be designed or configured in particular to enable this at least substantially independently of the direction of incidence or impingement of the laser radiation on the absorber material or the scattering structure. For this purpose, the scattering structure can therefore be configured or configured to scatter laser radiation impinging thereon in a multiplicity 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 may be formed in the material of the waveguide element itself. The scattering structure can likewise be an independent component which is arranged or fastened on the rear side of the waveguide element, that is to say opposite the absorber material, for example analogously to the absorber material.The laser protection device according to the invention also has at least one detector, which is arranged on the waveguide element and is different from or separate from the absorber material, for detecting the laser radiation guided in the waveguide element or emerging therefrom into or onto the detector. The at least one detector is covered or shielded from the laser radiation or also from other light or ambient brightness at least in terms of potential directions of incidence of the laser radiation on the front side of the absorber material at least prior to the partial destruction of the absorber material by the laser radiation. The detector can be covered or shielded, for example, by the absorber material, which is initially opaque to the laser radiation. As long as, in the intended use of the laser protection device, for example in a laser system or along an intended beam path or beam path of a laser beam, the absorber material is not yet destroyed by laser radiation impinging thereon, the detector would accordingly not detect laser radiation, in particular also not scattered radiation which, although it impinges on the laser protection device, is not intense or not powerful enough to destroy the absorber material at points. If, on the other hand, laser radiation enters the waveguide element, this laser radiation can also be detected by means of the at least one detector if it is arranged spatially spaced apart from an incidence or entry location of the laser radiation, since at least a part of the laser radiation is guided within the waveguide element as far as the detector. Thus, a correspondingly large-area region on incident laser radiation can be monitored by means of a significantly smaller detector area. This can enable a comparatively simple and cost-effective construction of the laser protection device, since detectors are relatively cost-intensive and can require significant outlay, for example for their electrical supply, a signal tap and a signal evaluation.According to the invention, the laser protection device is configured to automatically output a corresponding electrical electronic signal upon detection of laser radiation by means of the at least one detector in order to cause or to cause a source of the 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 thereto. Such a signal processing device can, for example, detect and evaluate a sensor or detector signal of the at least one detector and, if appropriate, generate and output a control signal or switch-off signal in order to switch off the laser radiation source or to cause or to cause the latter to switch off.The laser protection device proposed here may have substantially a multilayer structure or a multilayer structure. This makes it possible to create a simple possibility which can be integrated comparatively easily into laser systems or laser application areas, and which can also be retrofitted in a relatively simple manner if appropriate, in order to ensure laser protection in systems, machines, beam guiding optics and corresponding working areas. Since the different layers of the laser protection device according to the invention can be relatively thin, use or installation is also possible in restricted installation situations in which only little installation space is available for the laser protection device. Advantageously, in the laser protection device according to the invention, an at least substantially complete shielding of the at least one detector from ambient light, low-intensity scattered radiation and the like is possible, so that detection only occurs in the event of an actual partial destruction of the front-side absorber material by correspondingly intensive laser radiation impinging thereon. The laser protection device according to the invention can thus be used as a particularly robust and reliable fault sensor for detecting and intercepting severe safety incidents in which significant deviations from an intended beam path or an intended beam guidance occur, in order to prevent or limit uncontrolled escape of laser radiation into the environment. The laser protection device according to the invention can use an optical detection principle, i.e. a direct detection of the laser radiation by means of the at least one detector. This can be particularly robust, for example with respect to electromagnetic, thermal and electrical influences, and enable a particularly rapid and precise response, for example in comparison with thermal sensors. The waveguide element and the absorber material or also the scattering structure can be produced as large-area mass-produced goods, for example as a film web, and can therefore be produced particularly cost-effectively and in a practicable manner.The laser protection device according to the invention can be used as a fixed protection and detector, i.e. permanently arranged at a respective location of use and remaining, and can therefore also particularly easily fulfil the described detection and protection task permanently without further outlay.The laser protection device according to the invention can be adapted to various requirements or application cases by its construction. Since, for example, the absorber material, i.e. a corresponding absorber layer, must first be destroyed locally in order to subsequently enable detection of the corresponding laser radiation, a response behavior or response level of the laser protection device can be set via the thickness and / or material selection of the absorber material. In particular, comparatively easy fault cases can thus be delimited from more severe faults or problems and correspondingly intercepted. In the event of a slight fault, there may be, for example, a slight or slight misalignment, as a result of which only a very small proportion of the laser radiation used in the respective application case impinges on the laser protection device. This proportion can then not have enough intensity or power, for example, to destroy the absorber material. In the case of such a slight fault event, there is typically no significant risk of laser radiation exiting or resulting in damage or risk in the case of an exiting. In the case of a more severe fault, however, such a severe misalignment or such damage may be present, for example, that at least a large part of the laser radiation impinges on the laser protection device. If this major part of the laser radiation or the complete laser beam were to exit into the environment in such a case, this could lead to significant damage or risk. In such a case, however, the absorber material can be destroyed at least locally on account of the corresponding intensity or power of the laser radiation and the laser radiation can be detected by means of the at least one detector of the laser protection device and the laser radiation source can then be automatically switched off. This can not only avoid or minimize damage or corresponding risk, but also already indicate in itself that a correspondingly severe fault case is present and thus a corresponding repair or new adjustment is necessary.It is also advantageous that, due to the configuration or design of the absorber material absorbing the laser radiation, a reflection of laser radiation impinging on the absorber material from the absorber material can be limited or minimized. This may possibly prevent damage being caused by corresponding reflections within the laser system or a beam guiding device or the like. In the present case, therefore, material is used as the absorber material that does not reflect the laser radiation, or does so significantly, or reflects it only as weakly as possible.In one possible configuration of the present invention, the waveguide element and / or the absorber material is or are configured 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 a surface-oxidized aluminum foil, or an anodizing layer or the like. The waveguide element and / or the absorber material or element can have a thickness in the range of 100 μm, for example. The embodiment proposed here as a film or films makes it possible to use cost-effective and established production processes and to enable large-area production. This also allows simple cutting to size or shapes required in the respective application. In addition, the film-like and thus flexible configuration of the laser protection device or at least of the layer structure composed of the absorber material and the waveguide element or else of the scattering structure makes it possible to provide covering over a large area of potentially endangered regions and also covering complex shapes in a particularly simple, low-complexity 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 likewise be configured as a film.In another possible embodiment of the present invention, the waveguide element is designed as a plate component. Such a plate component may 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 here, that is to say can independently retain its plate-shaped planar shape or be flexurally rigid. For example, the waveguide element can be designed here as a glass plate, in particular as a float glass plate or quartz glass plate or sapphire glass plate. The waveguide element can be coated with the absorber material as described here or coated with a film serving as absorber material. The embodiment proposed here can make it possible to use the laser protection device for particularly high laser powers. Laser radiation with higher power and / or higher intensity can thus be guided in the waveguide element in a non-destructive manner here, that is to say would be possible, for example, if the waveguide element were designed as a plastic film.In a further possible embodiment of the present invention, the scattering structure is equipped as structuring of the rear side of the waveguide element itself, which rear side is remote from the absorber material or opposite the absorber material. In other words, the scattering structure here is therefore not an independent component or material. For example, the rear side of the waveguide element can be structured or roughened by shot blasting or by mechanical or laser-based characterization or by other processing methods, for example, and thereby have the described functionality for scattering laser radiation impinging thereon on the inside. By means of the embodiment of the present invention proposed here, a corresponding further component for the scattering structure can therefore be saved. As a result, the laser protection device can be constructed in a particularly simple and compact manner.In another possible embodiment of the present invention, the scattering structure is designed as a separate component which is applied to the rear side of the waveguide element, i.e. is attached or arranged on the rear side and extends in a planar manner just like the waveguide element, or as a coating of the rear side 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 adjustable or predeterminable in a particularly flexible and precise manner, in particular independently of the thickness or the material of the waveguide element. This can be useful, for example, if the waveguide element is so thin that direct processing or roughening of its rear side for producing the scattering structure would be too complicated or would entail the risk of destruction or unintentional perforation of the waveguide element during production, for example. By means of the embodiment of the present invention proposed here, the laser protection device can thus be produced as required and particularly reliably and easily.In a further possible embodiment of the present invention, the laser protection device has a plurality or a plurality of detectors for detecting the laser radiation which may be guided in the waveguide element or emerging therefrom into or onto the detector. These multiple detectors are arranged spaced apart spatially over the rear side of the waveguide element. The detectors can be arranged, for example, 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 a plurality of detectors proposed here can enable particularly rapid 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. The laser radiation cannot be guided without losses within the waveguide element, for example, and can therefore be detected only up to a limited distance from the point of incidence or impingement of the laser radiation on the absorber material or into the waveguide element. Due to the distributed arrangement of the multiple detectors at corresponding distances proposed here, reliable detection of the laser radiation can thus be realized with limited effort even in the case of a large-area configuration or application of the laser protection device.In a possible development of the present invention, collective connection elements or collective contact elements or collective bridges are arranged on two end sides or edges of the waveguide element, to each of which collective connection elements or collective bridges an electrical contact of all detectors distributed over the rear side of the waveguide element is electrically connected. One side or one pole of the detectors can thus 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 possibility for picking up the signals of 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 individually connected to each individual detector separately. This can enable a simplified construction and simplified handling of the laser protection device. The detectors can be connected to the collective connection elements, for example, via flexible conductor tracks or conductor foils. This allows the flexibility of the layer structure of the laser protection device to be maintained, for example in the case of the configuration of at least the waveguide element as a film described elsewhere. Corresponding connection lines or connecting lines from the detectors to the collective connection elements can be arranged, for example, on the rear side of the scattering structure, that is to say on a rear side of the scattering structure or scattering layer facing away from the waveguide element. There, they can be glued on or let into a further layer or integrated, for example into a shield 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, a plurality of detectors can be connected by means of the same line or connected to one of the collecting connection elements. For example, in a regular arrangement of the detectors, all detectors in a column can be connected to one line and all detectors in a line can be connected to another line. In this way, a relatively simple contacting or wiring of the detectors can be realized and at the same time it can be respectively determined which of the detectors detects the laser radiation or, for example, the greatest intensity of the laser radiation. For this purpose, it is possible to determine in which of the lines for the different columns of detectors and in which of the lines for the different 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 interconnections of the detectors may likewise be possible. For example, a plurality or all of the detectors can be connected or connected in series or in parallel or in a combination, that is to say in a plurality of groups of detectors respectively connected in series or in parallel.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 therefrom into or onto the detector is arranged on an end face of the waveguide element. By means of such an arrangement, on the one hand, the laser protection device can be designed to be particularly thin and simple at least over the major part of its surface. On the other hand, laser radiation can be detected, if necessary, by means of an end-face arrangement of at least one detector, which laser radiation propagates within the waveguide element exactly parallel to its front side and rear side and thus ultimately then impinges on the corresponding end side or the detector arranged there. The end face can thus be a narrow side of the waveguide element which is at least substantially perpendicular to the front side and rear side. In the case of an arrangement of the detector or of a detector there, the latter is therefore located at the edge of the waveguide element and can therefore be contacted particularly easily. This makes it possible, for example, to save corresponding production costs for arranging and wiring a detector on the rear side of the waveguide element. Likewise, however, one detector or a plurality of detectors can be arranged on the end face or a plurality of end faces and additionally on the rear side of the waveguide element. This allows a particularly reliable detection of laser radiation that has entered the waveguide element.In a further possible embodiment of the present invention, a shielding which is impermeable to the laser radiation and is stable or insensitive - or at least more stable or insensitive - than the absorber material - is arranged on the rear side of the scattering structure facing away from the waveguide element or the absorber material, as is the waveguide element, which shielding extends in a planar manner. Such a shielding can firstly prevent laser radiation from emerging from the waveguide element toward the rear side thereof and then entering the environment. Thus, the safety or protective effect of the laser protection device can be further improved. On the other hand, the shielding can prevent light or radiation from the environment from entering the waveguide element through the rear side of the latter and reaching the detector. This makes it possible to avoid the risk of erroneous detections. The shield can be designed, for example, such that it can withstand the laser radiation at least for a predefined time period which is greater than the time which passes from the first-time entry of the laser radiation into the waveguide element until the source of the laser radiation is ultimately switched off as a result. This can enable a corresponding improved safety and reliability of the laser protection device, but its flexibility can nevertheless be ensured if appropriate. For example, a metal foil or an arrangement of multiple layers of a metal foil can be used as the shield. In particular in the case of a configuration of the waveguide element as a plate, the shield can likewise be configured as a plate and thus offer a correspondingly increased robustness. If at least one detector is arranged on the rear side of the waveguide element, it can be embedded in the shield or corresponding recesses of the shield or be surrounded by the shield, for example. The shield can likewise also cover the detector itself on the rear side and thus offer additional protection against undesired detection of radiation or light from the environment and / or hold or fix the at least one detector.In a further possible embodiment of the present invention, the laser protection device is configured to output the signal only if or if the detected laser radiation meets a predefined criterion. As such a criterion, it can be specified in particular that the intensity of the laser radiation and / or the increase in the intensity of the laser radiation within a specified time period, i.e. the gradient of a corresponding intensity signal, corresponds to at least one specified threshold value. Thus, it can be set according to requirements in each case such that, for example, the laser radiation source is only caused to be switched off in the case of potentially critical problems and not, for example, in the case of scattered radiation arriving at the detector in a manner that is not critical from safety aspects or functional aspects. In particular, by detecting a rise, i.e. a signal edge, as a criterion, it is also possible, for example, to take account of a residual or background intensity arriving at the detector that is given in safe operation. Thus, for example, the laser protection device does not have to be replaced or repaired after a preceding point destruction of the absorber material, even if radiation or light still enters the waveguide element as a result of this damage during safe operation, for example after a misalignment or the like responsible for this has been eliminated.The present invention also relates to a laser optical assembly for guiding a laser beam along an intended predefined beam path or beam path. The laser optical assembly has a housing, on the sides of which the laser protection device or a laser protection device according to the invention is arranged, so that its absorber material faces the intended beam path or beam path. The laser protection device can be arranged in particular on the inside of the housing. Depending on the application or situation, however, an arrangement of the laser protection device on an outer side of the housing or an arrangement of the laser protection device integrated in its housing walls may likewise be possible. A corresponding laser optics assembly can be, for example, a beam guide tube or channel or a beam guide optics or device or a beam shaping optics or device or a deflection or scanner mirror or modulator or phase shifter or the like arranged in a housing in each case. With such laser optics assemblies, at least a part of a laser system can be constructed in modular fashion, wherein the integrated laser protection devices then automatically result in a correspondingly high level of protection or safety of the laser system, for example without the latter having to be additionally packaged in a housing or a surrounding laser protection device overall. This allows a simple construction of such a laser system and good accessibility to its components from the outside.The present invention also relates to a laser system which has at least one laser radiation source. Along an intended beam path of a laser beam in the laser system, the laser protection device according to the invention and / or the laser optics assembly according to the invention is arranged. The laser system according to the invention is configured for automatically switching off the laser radiation source in response to the signal or a signal of the at least one laser protection device. For this purpose, the laser system can comprise, for example, a corresponding signal processing and switch-off device, which can be connected, on the one hand, to the laser protection device and, on the other hand, 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 can correspond to this.The present invention also relates to a method for operating the laser system according to the invention. Therein, after the laser system including the at least one laser protection device has been put into operation, a corresponding signal is generated by the at least one laser protection device upon detection of laser radiation by means of the at least one detector of the at least one laser protection device and the laser radiation source is automatically switched off upon detection of this signal or by this signal.Switching off the laser radiation source in the present sense can mean that the generation of laser radiation by means of the laser radiation source is ended or the laser radiation that continues to be generated is no longer output from the laser radiation source. The latter can be achieved, for example, by deflecting 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 optical assembly and / or laser system according to the invention can form further, optionally optional method steps of the method according to the invention.Further features of the invention can be derived from the following description of the figures and from the drawing. The features and combinations of features mentioned above in the description and 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 respectively specified combination but also in other combinations or alone without departing from the scope of the invention.The drawing shows in: FIG. 1 shows a schematic illustration of a laser system with an integrated protective device against unintentionally emerging laser radiation; FIG. 2 is a schematic sectional view showing a structure of the protector; FIG. 3 is a schematic sectional view for further illustrating a structure of the protection device; and FIG. 4 shows a schematic sectional illustration for illustrating a detector contact in the protective device.Identical or functionally identical elements are provided with the same reference numerals in the figures. Of the same or similar elements that are present multiple times, only a representative selection is optionally explicitly identified at least in part in the figures for the sake of clarity.FIG. 1 shows a schematic illustration of a portion of a laser system 1 having a laser radiation source 2, which laser radiation source 2 can emit a laser beam 3. By way of example, the laser system 1 here also comprises an optical assembly 4. this optical assembly 4 here comprises, purely by way of example, a housing 5 with a deflection mirror 6 arranged therein for deflecting the laser beam 3.In the present case, however, misalignment may have occurred, so that the deflection mirror 6 is no longer in its desired position 7. As a result, the laser beam 3 is deflected here in a manner not provided, so that it would strike an inner side of the housing 5, for example. The laser beam 3 could then possibly damage or even bore through the housing 5 and emerge into the environment, or reflections of the laser beam 3 could occur within the housing 5, which could lead to laser radiation emerging into the environment through an inlet or at an unintentional angle through the outlet of the housing 5.Likewise, for example, the laser radiation source 2 could be deadjusted, so that the laser beam 3 would not first enter the optical assembly 4.In order to avoid or limit risks or safety risks associated therewith, the laser system 1 comprises a plurality of laser protection devices 8, which are arranged here, by way of example, along an intended beam path or beam path from the laser radiation source 2 to the optical assembly 4 and on inner sides of the housing 5. The laser protection devices 8 are coupled to a data or signal processing device 9 of the laser system 1. For this purpose, the signal processing device 9 has an interface 10 by way of example and is configured for processing signals of the laser protection devices 8. For this purpose, the signal processing device 9 has, for example, a corresponding circuit or, as indicated schematically here, a processor 11, that is to say, for example, a microchip or microprocessor or microcontroller or the like, and a computer-readable data memory 12 coupled thereto. The signal processing device 9 is also configured to switch off 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 transmitted from at least one of the laser protection devices 8. For this purpose, the signal processing device 9 is likewise connected here to the laser radiation source 2. Likewise, the signal processing device 9 could be integrated, for example, completely or partially into the laser protection devices 8 and / or the laser radiation source 2.The laser protection devices 8 here comprise a layer of an absorber material 13 on their side facing the intended beam path or beam path of the laser beam 3. Arranged on the rear side thereof is in each case a waveguide element 14, in which a portion of the laser beam 3 entering therein after point-wise 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 of the waveguide element 14. Arranged on the rear side of the waveguide element 14 is a scattering layer or scattering structure 15 for scattering the laser radiation 19. This scattering structure 15 is in turn covered on the rear side by an opaque shield 16.The laser protection devices 8 also each comprise a plurality of detectors 17 for detecting the laser radiation 19. The detectors 17 can be connected, for example, to connection elements 18 via which the respective laser protection device 8 can be connected to the signal processing device 9.To illustrate in more detail the structure and the mode of operation of the laser protection devices 8, FIG. 2 shows a schematic illustration, in sections, of a part of a laser protection device 8 and indicates the signal processing device 9. the laser protection device 8 comprises a layer structure composed of the absorber material 13, the waveguide element 14, the scattering structure 15 and the shield 16. For forming 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 the rear side thereof from the inside, that is to say an inner side or front side of the scattering structure 15, is scattered in various directions, as is schematically indicated here. For this purpose, the rear side of the waveguide element 14 can be structured, for example, by means of shot blasting or sandblasting or can be provided with a microstructure, such as micro cones or micro pyramid or the like. The waveguide element 14 can likewise be coated with a film or a coating which forms the scattering structure 15. Instead of a film, for example made of a plastic material such as PMMA or the like, the waveguide element 14 can likewise be formed as a plate-shaped component, for example made of float glass or quartz glass or sapphire or the like. The back shield 16 may be opaque and prevent ambient light from entering the waveguide element 14.In the section shown here, one of the detectors 17 is also indicated. This is arranged directly on the waveguide element 14. In particular, no scattering structure 15 can be present 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 therefore be arranged in corresponding recesses or holes of 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 lying between the detectors 17 or surrounding 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 adhesively bonded or adhesively fastened. As a result, laser radiation 19 striking the inner rear side of the waveguide element 14 can be detected particularly effectively in or by the detector 17 in the region of a detector 17.As can also be seen in FIG. 1, in normal operation of the laser system 1 which is free from errors or adjusted as intended, the laser beam 3 does not strike one of the laser protection devices 8. At least almost no light or no laser radiation 19 is then guided in the waveguide element 14. If, in the event of a fault, for example in the event of a misalignment of the deflecting mirror 6 or of the laser radiation source 2 or in the event of a failure of a corresponding control or the like, the laser beam 3 impinges on a laser protection device 8 or the absorber material 13 thereof, as indicated here, the absorber material 13 can be destroyed at least at points by the impinging laser beam 3. In this case, therefore, from a certain point in time onwards, the laser beam 3 enters the waveguide element 14 which has not been led, or does not have been led significantly, at all up to then. The laser beam 3 then passes through the waveguide element 14 in the form of the laser radiation 19 indicated here and impinges on the scattering structure 15 or the front side thereof. There, the laser radiation 19 is at least partially scattered such that a specific proportion of the laser radiation 19 satisfies the angular condition for total internal reflection within the waveguide element 14. Thus, the corresponding portion of the scattered laser radiation 19 within the waveguide element 14 runs in at least one of its main extension directions or in the transverse direction. After a certain time, the scattered laser radiation 19 thus 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 predefined threshold value or a corresponding signal edge, i.e. an increasing detected laser radiation intensity, is detected, the signal processing device 9 can send a switch-off signal, i.e. a signal for switching off the laser radiation source 2 or for switching off the output of the laser beam 3, to the laser radiation source 2, for example via the interface 10.In particular, the laser protection device 8 and the signal processing device 9 can be configured to effect this switching off of the laser radiation source 2 or of the laser beam 3 so quickly that, until the laser beam 3 has been switched off at its point of incidence on the absorber material 13, the latter has not yet destroyed over the entire cross section or diameter of the laser beam 3 or the laser radiation 19 has not yet emerged over the rear side or an end side of the waveguide element 14 or has not yet penetrated the shield 16.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 and indicates the detected laser radiation 19 and generates or outputs a corresponding error signal or the switch-off signal, for example, starting from a specific threshold value, and as a safety device which optionally switches off the laser radiation source 2 or the laser beam 3 when the corresponding error signal has been generated, or generates the switch-off signal and transmits it to the laser radiation source 2.In other words, a laser protection device 8 is thus 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 there is a potential risk, possibly in combination with the signal processing device 9, generates a corresponding fault or switch-off signal which can be read out, for example, by a corresponding safety device or safety circuit and brings about a switch-off of the laser radiation source 2 or of the laser beam 3.As a result of the scattering structure 15, it is also possible, if appropriate, for perpendicularly 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 as far as the closest detector 17. The detectors 17 can be integrated firmly into the respective laser protection device 8 at a corresponding distance, for example in a regular pattern.For further illustration, FIGS. 3 and 4 show schematic representations, in sections, of one of the laser protection devices 8 from different viewing directions. The individual detectors 17 can be electrically connected, connected or contacted by means of corresponding lines or flexible conductor foils, for example connected in parallel and / or in series. 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 connection lines 20 running at least substantially in a first main extension direction of the waveguide element 14 and, for example, second connection lines 21 running 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.In FIG. 4, the matrix-like arrangement and contacting of the detectors 17 can be seen even more clearly. The first connection lines 20 and the second connection lines 21 can connect the detectors 17 to the connection elements 18 arranged laterally or at the edge of the waveguide element 14. There, the connecting lines 20, 21 can, for example, pierce or extend through the shield 16 as far as the respective connecting element 18. The arrangement shown here can enable a flexible design and adaptation of the laser protection devices 8 to spatial conditions or to different sizes of the different laser protection devices 8. For example, its layer structure can first be manufactured as an endless web. This can then be cut to size according to requirements and the blanks can then be provided with the connection elements 18.Overall, the examples described show how an active laser protection device can be constructed and used.LIST OF REFERENCE CHARACTERS1 Laser system 2 Laser radiation source 3 Laser beam 4 Optical assembly 5 Housing 6 Deflection mirror 7 Setpoint position 8 Laser protection device 9 Signal processing device 10 Interface 11 Processor 12 Data memory 13 Absorber material 14 Waveguide element 15 Scattering structure 16 Shield 17 Detector 18 Connection element 19 Laser radiation 20 First connection lines 21 Second connection linesReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2006 053 579 A1

[0003]

Claims

Laser protection device (8) for protection against laser radiation (3, 19), comprising - a planarly extending waveguide element (14) for guiding laser radiation (19) entering therein at least in a main extension direction, - an absorber material (13) covering a front side of the waveguide element (14), which 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 impingement location of the laser radiation (3), - a scattering structure (15) arranged at a rear side of the waveguide element (14) for scattering at least a part of laser radiation (3, 19) entering the waveguide element (14) in a direction which enables a 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), which is arranged on the waveguide element (14) and is different from the absorber material (13), for detecting the laser radiation (3, 19) and is covered at least before the partial destruction of the absorber material (13) at least in potential directions of incidence of the laser radiation (3) on 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 on by means of the at least one detector (17).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.Laser protection device (8) according to claim 1, characterised in that the waveguide element (14) is designed as a plate component.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).Laser protection device (8) according to one of Claims 1 to 3, characterized in that the scattering structure (15) is designed as a component which extends in a planar manner and is applied to the rear side of the waveguide element (14), or as a coating of the rear side of the waveguide element (14).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 detectors are arranged, in particular in a matrix-like manner, spatially distributed over the rear side of the waveguide element (14).Laser protection device (8) according to claim 6, characterised in that a respective collective connection element (18) is arranged on two edges of the waveguide element (14), to which a respective electrical contact of all detectors (17) distributed over the rear side of the waveguide element (14) is electrically connected.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).Laser protection device (8) according to one of the preceding claims, characterized in that a shielding (16) which extends over a large area and is impermeable to the laser radiation (3, 19) and stable with respect to laser radiation (3, 19) impinging thereon is arranged on the rear side of the scattering structure (15) which faces away from the waveguide element (14).Laser protection device (8) according to one of the preceding claims, characterized in that the laser protection device (8) is configured to output the signal only if the detected laser radiation (19) meets a predefined criterion, in particular the intensity of the laser radiation (19) and / or the increase in the intensity of the laser radiation (19) within a predefined time period corresponds to at least one predefined threshold value.Laser optical assembly (4) for guiding a laser beam (3) along an intended predefined 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, such that the absorber material (13) faces the beam path.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 an intended beam path and the laser system (1) is configured for automatically switching off the laser radiation source in response to the signal of the laser protection device (8).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.

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