System and method for detecting light radiation

Abstract

The invention relates to a system (100) for detecting light radiation, comprising a transmitter unit (30) for sending a light beam (26) onto an object (40), and an optical receiver unit (10) for receiving secondary radiation (24) induced by the light beam (26) in a region (62) of the object (40). The optical receiver unit (10) includes a photodetector (70), a mask unit (28) between the object (40) and the photodetector (70), which is switchable at least partially between an optically non-transmitting and an optically transmitting state, and an optical unit (16) arranged in the beam path between the object (40) and the at least one mask unit (28). An image (66, 68) of the light-emitting area (62) of the object (40) can be mapped onto at least one mask unit (28) and, in the at least partially transmitting state of the mask unit (28), can be directed to the photodetector (70).The invention further relates to a method for detecting light radiation with such a system.

Description

Prior ArtThe invention relates to a system for detecting light radiation and to a method for detecting light radiation with such a system and to a use of such a system for detecting light radiation.The detection of laser-optical radiation, such as, for example, a location-true detection of a plurality of optical measurement signals, is important in optical communication technology and in the detection of hazardous materials and in the execution of safety checks, for example at boundary transitions or at airports.In optical camera communication, optical data, for example from a modulated LED, is received directly with a camera chip. In order to achieve greater data rates, it is necessary to arrange a plurality of light emitters next to one another. In addition, many items of image information which do not contain any data streams must be evaluated. In an application for laser-based measurement techniques, optical measurements of laser-induced effects can be captured by means of a video camera.In the case of a rigid, in particular coaxial, beam guidance, the emitting measurement beam and the receiving measurement beam are placed one above the other. In order to achieve different measurement positions, both light beams must be moved simultaneously. This can be done either by the mechanical movement of the measurement setup or by the transmission of both measurement beams via a common optical scanner.DE 102016121517A1 discloses a laser spectroscopic device in which a laser beam is tracked over a moving object and this object is analyzed laser spectroscopically during the process. In this case, the laser beam and the detection optics are tracked. This can be achieved technically by means of a scanning mirror unit. In the case of three-dimensional objects, the depth position is additionally adjusted, which is effected via a mechanical displacement table. As a result, at least two mechanically movable parts are present in the system. A permanent use is possible to a limited extent by mechanical adaptation, taking account of cooling times or reaction times.DE 102018132033 A1 describes a method for detecting a hazardous substance, in particular an explosive, on a sample, in particular in a spatial detection region, in which a first optical spectrum of the sample is recorded during a first spectrum recording time window using a first optical spectroscopy method and a second optical spectrum of the sample is recorded during a second spectrum recording time window using a second optical spectroscopy method, wherein the first and the second optical spectroscopy methods differ. The first optical spectrum and the second optical spectrum are compared with provided reference spectra of the at least one hazardous substance for determining whether or not the at least one hazardous substance is present on the sample. The first spectrum recording time window and the second spectrum recording time window overlap at least partially in time.DE 102019124547 A1 discloses a detector apparatus for the remote analysis of substances, in particular hazardous substances, comprising at least one laser which is designed for radiating pulsed laser light onto a sample located at a detection distance, and a telescope which is designed for collecting and / or focusing laser light scattered on the sample and for forwarding the scattered laser light into an optical spectrometer. The optical spectrometer is designed for spectral analysis of the laser light scattered on the sample.In DE 102019124547 A1, the laser is followed by a first beam path with a first reference beam and a further beam path with a second reference beam for the laser light. A unit for determining a time difference between pulses of the first reference beam and pulses of the second reference beam is provided, wherein the detection distance is determined from the time difference.Disclosure of the InventionThe object of the invention is to provide an improved system for detecting light radiation.A further object of the invention is to specify an improved method for detecting light radiation.Another object of the invention is to provide a use for an improved system for detecting light radiation.The objects are achieved by the features of the independent claims. Advantageous embodiments and advantages of the invention are evident from the further claims, the description and the drawing.According to one aspect of the invention, a system for detecting light radiation is proposed, comprising at least one transmission unit for transmitting a light beam onto an object, at least one optical reception unit for receiving a secondary radiation induced by the light beam in at least one region of the object, wherein the optical reception unit comprises at least one photodetector, at least one mask unit which is arranged between the object and the at least one photodetector and which is designed to be switchable back and forth at least in regions between an at least partially optically non-transmissive and at least partially optically transmissive state, and an optical unit which is arranged in the beam path between the object and the at least one mask unit.In this case, an image of the at least one light-emitting region of the object can be imaged onto the at least one mask unit and can be directed to the photodetector in the at least partially forwarding state of the at least one mask unit.An object can be either a solid body or a volume spreader, such as a liquid, for example water, or a gaseous medium, for example air, smoke, mist, aerosols or the like.The system comprises a directed transmitting unit, typically a laser, which generates secondary radiation in a region of the object, which secondary radiation serves for measuring laser measurement-technical variables. For example, methods such as Raman spectroscopy, laser induced fluorescence (LIF), laser induced plasma spectroscopy (LIBS), laser scattering, tunable diode laser absorption spectroscopy (TDLAS), and others may be used. An example of a volume spreader is, for example, a so-called "wind LIDAR".In the case that the secondary radiation originates from the surface of the object, the region of the object can be registered as a light point which corresponds to the light point of the incident light beam. In the case of a volume spreader as object, the region from which the secondary radiation originates can be an extended region and in particular have a corresponding depth distribution in the direction of the incident light beam.The region of the object is then localized, optionally with the aid of a camera, and sighted by the directed receiving unit with the position information obtained in this way.The optical unit serves to image the light-emitting region onto the at least one mask unit, which can be designed as an at least partially relaying, spatially resolved addressable dynamic mask. Secondary radiation of selected light-emitting regions can thus be transmitted to the receiving unit in a targeted manner.The secondary radiation generated by the laser is imaged onto at least one first mask unit. The mask unit can be switched selectively in the region where the image of the region of the object from which the secondary radiation originates is projected at least partially in a forwarding manner, for example in a transparent or transmissive or reflective manner, such that the image of the region is guided to the receiving unit, where it can be received and forwarded to a data processing system.Optically propagating is intended to mean that the optical signal of the at least one light source can pass through the mask unit. Optically non-relaying is intended to mean that the optical signal cannot pass through the mask unit. The term propagating may be understood to mean that the light is transmitted through the mask or diffracted or reflected or absorbed. Thus, signals can be passed on as black and white signals or in grey levels.In this way, individual light beams can be transmitted or masked in a targeted manner via the mask unit.The light transmitted through the mask unit can now be recorded with a detector of the receiving unit, for example a photodiode, a photodiode array, a photomultiplier, a photomultiplier array, a CCD / CMOS chip, etc., and converted into electrical digital signals.The proposed system advantageously makes it possible to assign light beams, in particular laser-optical light beams, to individual points or lines on the object in a spatially resolved manner by means of the optical receiving unit and the mask unit.The system also enables multiple arbitrary light radiation spectral ranges to be simultaneously received and combined with conventional techniques supported by photodiodes or photomultipliers. Furthermore, a polarization-dependent separation of the light beams can also additionally take place. This allows, for example, direct referencing of the light radiation against a polarized background radiation.The technology also makes it possible to track and evaluate a plurality of independent optical measurement sources, for example laser spots, almost independently of one another. This is advantageous, for example, if the measurement method prohibits or impairs coaxial reading and the location of incidence of the light beam and thus the observed location in the detection channel of the receiving unit varies.Optionally, it is possible to use light-sensitive, in particular infrared light-sensitive row or matrix sensors, in order to identify and localize the light-emitting regions.Furthermore, dynamic shading / masking is used via a mask unit in order to improve the signal-to-noise ratio, in particular for specific angles of incidence of the light beams.This feature can be combined with an arrangement, in particular an array of photodetectors, for example photodiodes, in order to be able to receive a plurality of light sources simultaneously.The system thus permits some type of optical multiplexing. This makes it possible to suppress light beams which otherwise strike the same detector in a simple manner in a targeted manner without electrically complicated structuring of the detector.Advantageously, the proposed system makes it possible to utilize fast response times of the detector of the receiving unit or a high effective measurement rate.Because no rigid beam guidance of the light beams is required, high positioning speeds of the light beams can be achieved. Multiple simultaneous measurements of different light beams may thus be performed. Scanning surfaces, for example of a person in a security lock, can be carried out very quickly with the proposed system.According to a favorable embodiment of the system, at least one locating unit, in particular a camera, can be provided for locating the region of the object of the secondary radiation induced by the light beam. Advantageously, the receiving unit can thus be aligned specifically to the light-emitting region of the object. As a result, the system makes it possible to assign the light beams, in particular laser-optical light beams, to individual points or lines on the object in a spatially resolved manner by means of the directed receiving unit. The localization of the region of the object can be effected, for example, by means of conventional digital cameras which are sensitive enough in the wavelength range of the light beams. The mask unit can thus be controlled in a targeted manner with the location information of the light-emitting region and switched to at least partially forward.The system may optionally include a camera having a wide field of view for locating the light beams and having sensitivity in the infrared light spectrum.According to a favorable embodiment of the system, the at least one mask unit can have at least one spatially resolved addressable dynamic mask that can be switched at least in regions between states that are at least partially optically non-transmissive and at least partially optically transmissive. The dynamic mask can thus be switched selectively at least partially forward for the secondary radiation localized with the aid of the camera, so that the light signal data can be received.The dynamic mask can be designed, for example, as a liquid crystal (TFT) screen (TFT=thin film transistor). It is also possible, for example, to use a micromirror actuator or LCoS (LCoS= Li Crystal on Silicon) display, in particular in the form of a so-called DLP chip (DLP= Digital Light Processing). The dynamic mask can now be switched to at least partially forward in a targeted manner for the secondary radiation localized with the aid of the camera, such that the light beams can be received by the receiving unit.It is also possible for the dynamic mask to be designed as a light-diffracting component which can be switched between a transmissive state and a non-transmissive state by a switchable diffraction effect.Optionally, it is thus possible to use light-sensitive, in particular infrared light-sensitive row or matrix sensors, in order to identify and localize the light-emitting regions. Furthermore, dynamic shading / masking can be used via the mask unit in order to improve the signal-to-noise ratio, in particular for specific angles of incidence of the light beams.The use of a mask unit in the form of a transmissive mask offers substantial advantages with regard to a compact overall size of the system. Here, the transmission of partially or completely forwarding states is possible when selecting the mask. In particular, if the receiving unit is directly adjacent to the mask unit, a very compact overall size for the system can be achieved. Thus, a large angle of acceptance in the intermediate image of the light source onto the mask unit can also be granted, whereby more compact systems are possible.Advantageously, a light distance between the at least one mask unit and / or the imaging thereof onto the at least one receiving unit and an entry aperture of the at least one receiving unit can be at most so large that a light cone of the image of the at least one light-emitting region of the object forwarded by the mask unit corresponds at most to the entry aperture of the at least one photodetector of the receiving unit.The requirement for the clear distance preferably follows from the detector size and / or the sub-apertures of the individual photodetectors. Thus, crosstalk between different photodetectors can be advantageously reduced or even avoided.According to a favorable embodiment of the system, a polarization-separating optical element, in particular a birefringent optical element, can be arranged in the beam path between the optical unit and the at least one mask unit. In particular, a delay element can be arranged between the optical unit and the polarization-separating optical element. Polarization-separating elements can be, for example, birefringent optical elements, or polarizing beam splitter cubes, polarizing beam splitter plates, dielectric thin-film polarizers, various prisms such as Nomarski, Glan-Foucault, Glan-Thompson, Nicol, Rochon, Senarmont, Wollaston, Glan-Taylor.A birefringent optical element (DBE) can separate two states of polarization, namely a horizontal or vertical state of polarization. With the delay element, for example a lambda / 4 plate, it is possible to distinguish circularly polarized states, namely left / right circularly polarized. Up to two virtual light sources thus arise in the plane of the mask unit.In addition, a birefringent optical element may be installed before or after the mask unit to bypass blind spots on a photodetector array of the receiving unit. As a result, two or more optical images of the light-emitting region can be projected onto different regions of the detector array, with the result that at least one image illuminates a photodetector on its sensitive aperture.According to a favorable embodiment of the system, a polarization-separating optical element, in particular a birefringent optical element, followed by a polarization-rotating element, can be arranged in the beam path between the optical unit and the at least one mask unit. In particular, the mask unit may comprise at least one polarizer followed by a dynamic mask followed by an analyzer. In particular, a delay element can be arranged between the optical unit and the polarization-separating optical element. In particular, the polarization-rotating element can be integrated into the dynamic mask.The mask unit can advantageously first comprise a liquid crystal which is designed to rotate the phase of the light beams before the latter passes over into a customary LCD / TFT display consisting of polarizer, liquid crystal matrix and analyzer.Thus, the dynamic mask can be designed as a polarization-rotating component which can be switched between a transmissive state and a non-transmissive state by a switchable birefringence effect in combination with polarizer and analyzer.In order to maximize the signal transmission through the mask unit by means of an LCD unit, it is possible to combine a birefringent optical element with a polarization-rotating LCD element, in particular as a lambda / 2 delay element, which is designed analogously to the embodiment of a dynamic mask as a polarization-rotating component, which is switchable between a polarization-rotating state and a non-polarization-rotating state. Thus, both polarization components of the transmitted light beams can be separated and components that are mismatched for the mask unit can be controlled separately in terms of polarization, so that a large part of the light impinges on the photodetectors.According to a favorable embodiment of the system, the at least one mask unit can have at least two dynamic masks. In particular, the at least one mask unit can have at least two dynamic masks that can be controlled separately from one another. If the position of the light-emitting regions is not known, it is also possible to confine relevant signal sources by means of mask units which are switched in a skillful manner at least partially iteratively, alternately at least partially in a forwarding manner, and thus to track them. This allows the light-emitting regions to be localized even without a camera.Furthermore, the design of the mask unit has the advantage that a higher optical contrast for background suppression can be achieved and that a simple approach to a focusability of the mask unit can be achieved. As a result, the contrast at different distances of the light sources can be improved even when a plurality of light sources are detected simultaneously.According to a favorable embodiment of the system, at least one further optical unit can be arranged in the beam path between the at least one mask unit and the receiving unit.The light transmitted through the first mask unit can be imaged via a further imaging system, in particular with dispersive properties, similar to a spectrometer onto the receiving unit or a further mask unit of the receiving unit, which can now selectively transmit or block specific wavelengths.Advantageously, the distance between the at least one mask unit and / or its mapping onto the at least one receiving unit and the entry aperture of the at least one receiving unit corresponds at most to a quotient of a diameter of the entry aperture of at least one photodetector of the receiving unit and an F-number of the further optical unit in the beam path between the at least one light-emitting region and the at least one mask unit, in order to avoid crosstalk between different photodetectors.The smallest possible distance between the mask unit and the inlet aperture means that the mask or its optical imaging is not further away than a distance Δz from the inlet aperture with effective diameter D of an individual photodetector, wherein the distance Δz results from: wherein α is half the aperture angle of the imaged light source.For an objective with a focal length f, it holds true that 2sin(α) corresponds to the F-number, i.e. at aperture f / 2 the maximum distance corresponds to twice the diameter D of the entrance aperture of the photodetector. This makes it possible to avoid permanent crosstalk between adjacent photodetectors, which could result in a greater distance and which could thus impair the usability of the system.According to a favorable embodiment of the system, the further optical unit can be arranged in the beam path upstream of the at least one dynamic mask and / or downstream of the at least one dynamic mask or between the at least two dynamic masks. In particular, the optical unit can have at least one dispersive optical element between two diffractive or refractive or reflective optical elements or can be designed to be self-refractive, diffractive or reflective.In a further exemplary embodiment, the further optical unit can be supplemented by a dispersive optical element, for example a transmissive or reflective grating or a prism. This enables spectral splitting of the light beams onto a plurality of detectors of the receiving unit. Here, a linear arrangement of photodiodes with a high aspect ratio, i.e. an elongate configuration, may be expedient in order to minimize the spacing of the photodiodes. Depending on the position of the light source, all spectral channels can thus be received simultaneously by the photodetectors. This allows many monochromatic measurement channels or fewer polychromatic measurement channels with a higher bandwidth to be used in the same system architecture. In order to address individual "subchannels" only in a targeted manner, it is also possible to install a further shading mask in front of the photodetectors and to block undesired channels. In this way, the signal-to-noise ratio can also be further optimized in bright environments without being fixed to a specific wavelength.According to a favorable embodiment of the system, the optical receiving unit can have an arrangement of photodetectors, in particular an array of photodiodes. By means of an arrangement of a plurality of photodetectors, in particular a rectangular array of photodetectors, secondary radiation from a plurality of light-emitting regions can be received simultaneously. In addition, it is possible to sequentially drive secondary radiation from light-emitting regions lying close to one another and nevertheless to separate it cleanly.According to a favorable embodiment of the system, the at least one mask unit can have at least one liquid crystal screen as a dynamic mask. This type of screen can be easily switched to at least partially forward in a spatially resolved addressable manner. They also represent conventional screens.According to a favorable embodiment of the system, the transmitting unit can be designed to illuminate the object with the light beam in a point-shaped manner in a predetermined temporal and / or local grid. Thus, for example, in the case of a security check, a person can be scanned by raster scan, the mask being continuously followed at the receiving end.According to a favorable embodiment of the system, the transmitting unit can be designed to expand the light beam linearly over a predetermined angular range and to illuminate the object with the linearly expanded light beam in a predetermined temporal and / or local grid. In particular, the transmitting unit can be designed to illuminate the object with the linearly expanded light beam in a direction perpendicular to the linearly expanded light beam in a predefined temporal and / or local grid. In such a so-called line detection, the first light beam can be widened and a person can be scanned from top to bottom with the strip-shaped light beam. The mask can be adapted according to the three-dimensional geometry, so that only the necessary measurement range is detected.According to a favorable embodiment of the system, at least one further transmitting unit can be provided for transmitting a further light beam, in particular coaxial to the light beam, onto the object. In particular, the further light beam can be provided for locating the at least one light-emitting region of the object. The further light beam, for example of a pilot laser, can be used coaxially to the directed light beam for locating the light-emitting region. In this case, invisible light radiation, for example infrared radiation, can be used advantageously. Thus, a laser visible to the digital camera can be superimposed coaxially with the laser of the transmitting unit in order to track the latter.According to a further aspect of the invention, a method for detecting light radiation is proposed with a system, wherein at least one transmission unit transmits a light beam to an object; and at least one optical reception unit receives secondary radiation induced by the light beam in at least one region of the object, wherein the optical reception unit comprises at least one photodetector, at least one mask unit which is arranged between the object and the at least one photodetector and which can be switched back and forth at least in regions between an at least partially optically non-relaying and at least partially optically relaying state, and an optical unit which is arranged in the beam path between the object and the at least one mask unit, wherein an image of the at least one light-emitting region of the object is imaged on the at least one mask unit and is conducted to the photodetector in the at least partially relaying state of the at least one mask unit.An object can be either a solid body or a volume spreader, such as a liquid, such as water, or a gaseous medium, such as air, smoke, mist, aerosols or the like.The system comprises a directed transmitting unit, typically a laser, which generates secondary radiation or scattered radiation in a region of the object, which serves for measuring laser measurement-technical variables. For example, methods such as Raman spectroscopy, laser induced fluorescence (LIF), laser induced plasma spectroscopy (LIBS), laser scattering, tunable diode laser absorption spectroscopy (TDLAS), and others may be used. An example of a volume spreader is a so-called "wind LIDAR".According to the proposed method, the region of the object from which the secondary radiation originates is then localized, optionally with the aid of a camera, and sighted by the directed receiving unit with the position information obtained in this way.The secondary radiation generated by the laser is imaged onto at least one first mask unit. The mask unit can be switched selectively in the region where the image of the region of the object from which the secondary radiation originates is projected at least partially in a forwarding manner, for example in a transparent or transmissive or reflective manner, such that the image of the region is guided to the receiving unit, where it can be received and forwarded to a data processing system.Optically propagating is intended to mean that the optical signal of the at least one light source can pass through the mask unit. Optically non-relaying is intended to mean that the optical signal cannot pass through the mask unit. The term propagating may be understood to mean that the light is transmitted through the mask or diffracted or reflected or absorbed. Thus, signals can be passed on as black and white signals or in grey levels.In this way, individual light beams can be transmitted or masked in a targeted manner via the mask unit.The light transmitted through the mask unit can now be recorded with a detector of the receiving unit, for example a photodiode, a photodiode array, a photomultiplier, a photomultiplier array, a CCD / CMOS chip, etc., and converted into electrical digital signals.The proposed method advantageously makes it possible to assign light beams, in particular laser-optical light beams, to individual points or lines on the object in a spatially resolved manner by means of the optical receiving unit and the mask unit.The method also makes it possible to receive a plurality of freely selectable spectral ranges of the light radiation simultaneously and to combine this reception with conventional techniques which are supported by photodiodes or photomultipliers. Furthermore, a polarization-dependent separation of the light beams can also additionally take place. This allows, for example, direct referencing of the light radiation against a polarized background radiation.The method also makes it possible to track and evaluate a plurality of independent optical measurement sources, for example laser spots, almost independently of one another. This is advantageous, for example, if the measurement method prohibits or impairs coaxial reading and the location of incidence of the light beam and thus the observed location in the detection channel of the receiving unit varies.The requirement for the clear distance preferably follows from the detector size and / or the sub-apertures of the individual photodetectors. Thus, crosstalk between different photodetectors can be advantageously reduced or even avoided.Optionally, it is possible to use light-sensitive, in particular infrared light-sensitive row or matrix sensors, in order to identify and localize the light-emitting regions.Furthermore, dynamic shading / masking is used via a mask unit in order to improve the signal-to-noise ratio, in particular for specific angles of incidence of the light beams.This feature can be combined with an arrangement, in particular an array of photodetectors, for example photodiodes, in order to be able to receive a plurality of light sources simultaneously.The method thus allows some type of optical multiplexing. This makes it possible to suppress light beams which otherwise strike the same detector in a simple manner in a targeted manner without electrically complicated structuring of the detector.Advantageously, the proposed method makes it possible to utilize fast reaction times of the detector of the receiving unit or a high effective measurement rate.Because no rigid beam guidance of the light beams is required, high positioning speeds of the light beams can be achieved. Multiple simultaneous measurements of different light beams may thus be performed. Scanning surfaces, for example of a person in a security lock, can be carried out very quickly with the proposed system.According to a favorable embodiment of the method, the region of the object of the secondary radiation induced by the light beam can be localized by a localization unit, in particular a camera. Advantageously, the receiving unit can thus be aligned specifically to the light-emitting region of the object. As a result, the method makes it possible to assign light beams, in particular laser-optical light beams, to individual points or lines on the object in a spatially resolved manner by means of the directed receiving unit. The localization of the secondary radiation can be effected, for example, by means of conventional digital cameras which are sensitive enough in the wavelength range of the secondary beams. The mask unit can thus be controlled in a targeted manner with the location information of the light-emitting region and switched to at least partially forward.According to a favorable embodiment of the method, the at least one light-emitting region of the object can be imaged via at least one optical unit onto at least one dynamic mask of the at least one mask unit, and the dynamic mask can be switched to the at least partially transmissive state at a section at which the secondary radiation impinges on the at least one dynamic mask.The optical unit can serve to image a light-emitting region onto the at least one mask unit, which can be designed as an at least partially relaying, spatially resolved addressable dynamic mask. Light beams of selected light-emitting regions can thus be transmitted to the receiving unit in a targeted manner.According to a favorable embodiment of the method, the light-emitting region of the object can be imaged as separate images on different sections of the mask unit via a polarization-separating optical element, in particular a birefringent element, in the beam path between the optical unit and the at least one mask unit. In particular, the light-emitting region of the object can be imaged via a delay element arranged between the optical unit and the polarization-separating optical element.A polarization-separating element, for example a birefringent optical element (DBE), can separate two polarization states, namely a horizontal or vertical polarization state, from one another. With the delay element, for example a lambda / 4 plate, it is possible to distinguish circularly polarized states, namely left / right circularly polarized. Up to two virtual light sources thus arise in the plane of the mask unit.In addition, a birefringent optical element may be installed before or after the mask unit to bypass blind spots on a photodetector array of the receiving unit. As a result, two or more optical images of the light-emitting region can be projected onto different regions of the detector array, with the result that at least one image illuminates a photodetector on its sensitive aperture.According to a favorable embodiment of the method, images of the light-emitting region of the object that are polarization-deficient for the mask unit can be optically forwarded separately to the mask unit via a polarization-separating optical element followed by a polarization-rotating element in the beam path between the optical unit and the at least one mask unit.The mask unit has at least one polarizer followed by a dynamic mask followed by an analyzer. In particular, a delay element can be arranged between the optical unit and the polarization-separating optical element.The mask unit can advantageously first comprise a liquid crystal which is designed to rotate the phase of the light beams before the latter passes over into a customary LCD / TFT display consisting of polarizer, liquid crystal matrix and analyzer.Thus, the dynamic mask can be designed as a polarization-rotating component which can be switched between a transmissive state and a non-transmissive state by a switchable birefringence effect in combination with polarizer and analyzer.In order to maximize the signal transmission through the mask unit by means of an LCD unit, it is possible to combine a birefringent optical element with a polarization-rotating LCD element, in particular as a lambda / 2 delay element, which is designed analogously to the embodiment of a dynamic mask as a polarization-rotating component, which is switchable between a polarization-rotating state and a non-polarization-rotating state. Thus, both polarization components of the transmitted light beams can be separated and components that are mismatched for the mask unit can be controlled separately in terms of polarization, so that a large part of the light impinges on the photodetectors.According to a favorable embodiment of the method, images of the light-emitting region of the object that are circularly polarized in different ways can be optically forwarded separately to the mask unit via a delay element arranged between the optical unit and the polarization-separating optical element. Advantageously, with correct installation, left and right circularly polarized light can thus be converted into vertically and horizontally polarized light beams suitably oriented with respect to the polarization-separating element. These can be read out separately with sufficiently great spatial separation.According to a favorable embodiment of the method, at least two dynamic masks of the at least one mask unit for secondary radiation from at least two light-emitting regions of the object can be switched separately into the at least partially transmissive state. In particular, the secondary radiation of at least two light-emitting regions of the object can be driven sequentially. If the position of the light-emitting regions is not known, it is also possible to confine relevant signal sources by means of mask units which are switched in a skillful manner at least partially iteratively, alternately at least partially in a forwarding manner, and thus to track them. This allows the light-emitting regions to be localized even without a camera.Furthermore, the design of the mask unit has the advantage that a higher optical contrast for background suppression can be achieved and that a simple approach to a focusability of the mask unit can be achieved. As a result, the contrast at different distances of the light sources can be improved even when a plurality of light sources are detected simultaneously.According to a favorable embodiment of the method, at least two light-emitting regions of the object can be localized simultaneously with the localization unit, in particular a camera. In this way, it is possible to simultaneously locate light emitting regions. In the case of closely adjacent light-emitting regions as light sources, these can be interrogated sequentially.According to a favorable embodiment of the method, a spectral splitting of the secondary radiation of the at least one light-emitting region of the object can take place via at least one further optical unit in the beam path upstream of the at least one dynamic mask and / or downstream of the at least one dynamic mask or between at least two dynamic masks.In particular, a spectral splitting of the secondary radiation of the at least one light-emitting region of the object can be effected via at least one dispersive optical element between two diffractive or refractive or reflective optical elements of the optical unit or via the optical unit itself, which is embodied as refractive, diffractive or reflective. In this case, the light-emitting region of the object can be imaged onto the second dynamic mask in a spectrally resolved manner.Here, a linear arrangement of photodiodes with a high aspect ratio, i.e. an elongated configuration, may be expedient in order to minimize the spacing of the photodiodes. Depending on the position of the light source, all spectral channels can thus be received simultaneously by the photodetectors. This allows many monochromatic measurement channels or fewer polychromatic measurement channels with a higher bandwidth to be used in the same system architecture. In order to address individual "subchannels" only in a targeted manner, it is also possible to install a further shading mask in front of the photodetectors and to block undesired channels. In this way, the signal-to-noise ratio can also be further optimized in bright environments without being fixed to a specific wavelength.According to a favorable embodiment of the method, the secondary radiation of the at least one light-emitting region of the object can be evaluated in a data processing system. In particular, the secondary radiation can be processed in a system for virtual and / or augmented reality and / or data processing. In this way, true-to-location virtual representations of measurements of a wide variety of measurement methods in connection with VR / AR applications can be realized.According to a further aspect of the invention, a use of a system for detecting light radiation is proposed, wherein an, in particular moving, object is detected within a defined measurement range with a light beam of at least one transmission unit. A secondary radiation induced by the light beam in at least one region of the object is received by at least one optical receiving unit.In this case, the secondary radiation of the at least one light-emitting region of the object is evaluated in a data processing system, and in particular processed in a system for virtual and / or augmented reality and / or data storage.The proposed system can advantageously be used in a multiplicity of laser-optical stand-off detection applications. In particular, use is possible for security checks of persons when accessing sensitive areas or at security locks, for example at airports. Implementation of specialized LIDAR applications may also be advantageous with the system.The transmitting unit and the receiving unit need not be installed on the same platform. The transmitting unit can be installed on a moving or portable platform, for example, while the receiving unit is installed on a flying platform, for example a drone. This is to be understood as an example; it could also be, for example, two moving systems. Thus, a plurality of receiving units can receive and analyze secondary radiation induced by a light beam of a transmitting unit.DRAWINGFurther advantages are evident from the following description of the drawings. Exemplary embodiments of the invention are illustrated in the drawings. The drawings, specification and claims contain numerous features in combination. The skilled person will expediently also consider the features individually and summarize them to form meaningful further combinations.The following are shown by way of example: FIG. 1 is a schematic illustration of a system for detecting light radiation according to an exemplary embodiment of the invention; FIG. 2 is a schematic illustration of a process of detecting light beams with a receiving unit having a mask unit having a dynamic mask according to an exemplary embodiment of the invention; FIG. 3 is a schematic illustration of a process of detecting light beams with a receiving unit having a mask unit having a dynamic mask according to a further exemplary embodiment of the invention; FIG. 4 is a schematic illustration of a process of detecting light beams with a receiving unit having a mask unit having two dynamic masks according to a further exemplary embodiment of the invention; FIG. 5 is a schematic illustration of a process of detecting light beams with a receiving unit having a mask unit having two dynamic masks according to a further exemplary embodiment of the invention; FIG. 6 is a schematic illustration of a system for detecting light radiation according to a further exemplary embodiment of the invention; FIG. 7 shows a scanning process on a person with a system for detecting light radiation according to an exemplary embodiment of the invention with a punctiform light beam; FIG. 8 shows measurement results of the scanning process on the person according to FIG. 7 for two measurement points; FIG. 9 shows a scanning process on a person with a system for detecting light radiation according to a further exemplary embodiment of the invention with a linearly expanded light beam; FIG. 10 shows measurement results of the scanning process on the person according to FIG. 9 for line detection; FIG. 11 shows a flow chart of the method for detecting light radiation in a scanning process according to FIG. 7 ; FIG. 12 shows a flow chart of the method for detecting light radiation in a scanning process according to FIG. 9 ; FIG. 13 is a system diagram of a light radiation detection system according to an embodiment of the present invention; FIG. 14 shows an exemplary embodiment of a use of a system for detecting light radiation when entering a portal; and FIG. 15 shows a further exemplary embodiment of a use of the system for detecting light radiation in a safety lock.Embodiments of the InventionIn the figures, components of the same type or having the same effect are denoted by the same reference numerals. The figures merely show examples and should not be understood as limiting.Before describing the invention in detail, it should be understood that it is not limited to the particular components of the apparatus, as well as the particular method steps, as these components and methods may vary. The terms used herein are intended to describe particular embodiments only and are not used in a limiting sense. Moreover, when the singular or indefinite articles are used in the specification or claims, this also refers to the plurality of these elements unless the overall context clearly indicates otherwise.Directional terminology used in the following with terms such as "left", "right", "top", "bottom", "front", "behind", "after" and the like is merely used for better understanding of the figures and is in no case intended to represent a limitation of generality. The components and elements illustrated, their design and use can vary within the meaning of the considerations of a person skilled in the art and be adapted to the respective applications.FIG. 1 shows a schematic representation of a system 100 for detecting light radiation according to an exemplary embodiment of the invention. FIG. 2 shows a schematic illustration of a process of detecting light beams with a receiving unit 10 having a mask unit 28 having a dynamic mask 12 according to an exemplary embodiment of the invention.The system 100 comprises a directed transmitting unit 30, typically a laser, which transmits a light beam 26 onto an object 40 and generates secondary radiation 24 in at least one region 62 of the object 40, which secondary radiation serves for measuring laser measurement technical variables. For example, methods such as Raman spectroscopy, laser induced fluorescence (LIF), laser induced plasma spectroscopy (LIBS), laser scattering, tunable diode laser absorption spectroscopy (TDLAS), and others may be used.The region 62 of the object 40 is then localized, optionally with the aid of a camera ( 22), and sighted by the directed receiving unit 10 with the position information obtained in this way.The system 100 thus comprises the transmission unit 30 for transmitting the light beam 26 onto the object 40, and the optical reception unit 10 for receiving the secondary radiation 24 induced by the light beam 26 in the region 62 of the object 40.The transmitting unit 30 is designed to illuminate the object 40 with the light beam 26 in a predefined temporal and / or local grid point-like manner or, in the case of a volume spreader, in the form of a beam.The receiving unit 10 further comprises a mask unit 28, which is arranged between the object 40 and the optical receiving unit 10 and which is designed to be switchable back and forth at least in regions between an at least partially optically non-relaying and at least partially optically relaying state.An optical unit 16, for example an objective 16, is arranged in the beam path between the object 40 and the at least one mask unit 28, which images an image 66, 68 of the light-emitting region 62 of the object 40 onto the mask unit 28, as schematically illustrated in FIG. 2. In the at least partially transmissive state of the mask unit 28, this image 66, 68 is then transmissive to the photodetector 70.The light-emitting region 62 of the object 40 is imaged onto a dynamic mask 12 of the mask unit 28 via the optical unit 16, and the dynamic mask 12 is switched to the at least partially transmissive state at a section 46, 47 at which the secondary radiation 24 impinges on the at least one dynamic mask 12.The mask unit 28 has at least one dynamic mask 12 which can be addressed in a spatially resolved manner and which can be switched at least in regions between states which are at least partially optically non-transmissive and at least partially optically transmissive.The mask unit 28 as a dynamic mask 12 may include, for example, at least one liquid crystal screen.As can be seen in FIG. 2, a polarization-separating element 78, for example a birefringent optical element 78, can be arranged in the beam path between the optical unit 16 and the at least one mask unit 28. The two or more images 66, 68 of the light-emitting region 62 of the object 40 can thus be imaged via the birefringent optical element 78 in the beam path between the optical unit 16 and the at least one mask unit 28 as separate images 66, 68 onto different sections 46, 47 of the mask unit 28. The two images of the light-emitting region 62 of the object 40 are thus imaged onto the mask unit 28 with different polarization, for example horizontally and vertically polarized.In the optical path, a polarization-rotating element 52 can furthermore be arranged behind the birefringent optical element 78, as shown.The polarization-rotating element 52 can also be integrated into the dynamic mask 12.Images 66, 68 of the light-emitting region 62 of the object 40 that are polarization-mismatched for the mask unit 28 can advantageously be optically passed separately to the mask unit 28 via the birefringent optical element 78 followed by the polarization-rotating element 52 in the beam path between the optical unit 16 and the at least one mask unit 28.For this purpose, the mask unit 28 has at least one polarizer 56 followed by a dynamic mask 12 followed by an analyzer 58.The optical receiving unit 10 can advantageously have an arrangement of photodetectors 70, in particular an array of photodiodes 70.The secondary radiation 24 caused by the light beam 26 in the region 62 of the object 40 is imaged with the optical unit 16 through the birefringent element 78 onto the first dynamic mask 12 of the mask unit 28. Two states of polarization, for example horizontally polarized or vertically polarized, can be separated from one another by the birefringent element 78.Thus, up to two virtual light sources 66, 68 are produced in the plane of the mask unit 28, which has a liquid crystal as polarization-rotating element 52, which is designed to rotate the phase of the secondary radiation 24 before it passes into a conventional LCD / TFT display consisting of polarizer 56, liquid crystal matrix 12 and analyzer 58.The light transmitted in this way can be directed via an imaging system 18, optionally with dispersive properties, similar to a spectrometer, onto the photodetector 70 of the receiving unit 10.The transmitted light can be recorded with the detector 70 of the receiving unit, for example a photodiode, a photodiode array, a photomultiplier, a photomultiplier array, a CCD / CMOS chip, etc., and converted into electrical digital signals.It can be advantageous if a light distance 84 between the at least one mask unit 28 and / or the imaging thereof onto the at least one receiving unit 10 and an entry aperture of the at least one receiving unit 10 is at most so large that a light cone of the image 66, 68 of the at least one light-emitting region 62 of the object 40 forwarded by the mask unit 28 corresponds at most to the entry aperture of the at least one photodetector 70 of the receiving unit 10.FIG. 3 shows a receiving unit 10 according to a further exemplary embodiment, in which a further optical unit 18 is arranged in the beam path between the at least one mask unit 28 and the receiving unit 10.The further optical unit 18 can be arranged in the beam path after the at least one dynamic mask 12. In particular, as can be seen, the optical unit 18 can have at least one dispersive optical element 86 between two diffractive or refractive or reflective optical elements 82, for example lenses or concave mirrors. In general, all optical systems suitable for spectrometers or monochromators can be used as further optical unit 18.FIG. 4 shows a schematic illustration of a process of detecting light beams with a receiving unit 10 having a mask unit 28 having two dynamic masks 12, 14 according to a further exemplary embodiment of the invention.The at least one mask unit 28 has two dynamic masks 12, 14, which can be controlled in particular separately from one another.A delay element 54 is arranged between the optical unit 16 and the birefringent optical element 78 as polarization-separating element 78. As a result, in particular the two or more images 66, 68 of the light-emitting region 62 of the object 40 can be imaged via the delay element 54 arranged between the optical unit 16 and the birefringent optical element 78.The images of the light-emitting region 62 of the object 40 which are circularly polarized differently in front of the delay element 54 can be optically passed on further via the delay element 54 as images 66 and 68 which are linearly polarized again, separately to the mask unit 28.The further optical unit 18 can be arranged in the beam path after the at least one dynamic mask 12 or, as illustrated in FIG. 3, between the at least two dynamic masks 12, 14.By means of the further optical unit 18, spectral splitting of the secondary radiation of the at least one light-emitting region 62 of the object 40 can take place. The spectral splitting can be effected, for example, via at least one dispersive optical element 86 between two diffractive or refractive or reflective optical elements 82, for example lenses or concave mirrors, of the optical unit 18. In this case, the image 66, 68 of the light-emitting region 62 of the object 40 can be imaged onto the second dynamic mask 14 in a spectrally resolved manner. Optionally, an element can also be used as further optical element 18 which combines dispersive, diffractive and refractive properties in one element.The at least two dynamic masks 12, 14 of the at least one mask unit 28 can be switched separately into the at least partially transmissive state for secondary radiation from at least two light-emitting regions 62 of the object 40. In particular, the secondary radiation of at least two light-emitting regions 62 of the object 40 can thus be driven sequentially.In the exemplary embodiment illustrated in FIG. 4, the secondary radiation 24 caused by the light beam 26 in the region 62 of the object 40 is imaged with the optical unit 16 by the delay element 54, for example a lambda / 4 plate, and the birefringent element 78 onto the first dynamic mask 12 of the mask unit 28. Two states of polarization, for example horizontally polarized or vertically polarized, can be separated from one another by the birefringent element 78. With the lambda / 4 plate 54, it is possible to distinguish circularly polarized states of the secondary radiation 24, for example circularly polarized to the left or to the right.The light transmitted in this way is imaged via the imaging system 18 with dispersive properties, similar to a spectrometer, onto the further mask 14, which can selectively transmit or block specific wavelengths.The light transmitted in this way can be recorded by the detector 70 of the receiving unit 10 and converted into electrical digital signals.FIG. 5 shows a further exemplary embodiment of a receiving unit 10 in a minimum configuration. The receiving unit 10 has only one optical unit 16. The mask unit 28 comprises a dynamic mask which is disposed in front of the photodetector 70 in an undermitable manner.The light-emitting region 62 of the object 40 is imaged via the optical unit 16 as images 66, 68 with different polarization onto the dynamic mask 14 of the mask unit 28, and the dynamic mask 14 is switched to the at least partially transmissive state at a section 46, 47 at which the secondary radiation impinges on the at least one dynamic mask 14, such that the secondary radiation can be received by means of the photodetector 70.FIG. 6 shows a schematic illustration of a system 100 for detecting light radiation according to a further exemplary embodiment of the invention.In this exemplary embodiment, a localization unit 20, for example a camera 22, is provided for localization of the region 62 of the object 40 from which the secondary radiation 24 originates. In this way, for example, at least two regions 62 of the object 40 can be localized simultaneously with the localization unit 20, in particular a camera 22, preferably a 3D camera.Furthermore, in the exemplary embodiment shown in FIG. 6, a further transmitting unit 31 is provided for transmitting a further light beam 27, in particular coaxial to the light beam 26, onto the object 40. The further light beam 27 can advantageously be used, in particular if it is emitted coaxially with respect to the light beam 26, for locating the at least one light-emitting region 62 of the object 40.FIG. 7 shows a scanning process on a person 41 with a system 100 for detecting light radiation according to an exemplary embodiment of the invention with a punctiform light beam 26.Advantageously, the system 100 can be used for detecting light radiation. A moving person 41 can be detected as object 40, for example within a defined measurement range 42, with the light beam 26 of the transmission unit 30. A secondary radiation 24 induced by the light beam 26 in at least one region 62 of the object 40 can then in turn be received and analyzed by the optical receiving unit 10.The measuring range 42 is scanned by the transmission unit 30 with the light beam 26. A secondary radiation 24 can then be emitted from a light-emitting region 62 of a measurement point 64, 65, which secondary radiation can be received by the optical receiving unit 10.FIG. 8 illustrates, by way of example, mask configurations in the scanning process on the person 41 according to FIG. 7 for the two measurement points 64, 65.The mask configurations corresponding to the two-dimensional measurement region 42 are shown in the two measurement windows 43 for the two measurement points 64, 65. During the measurement, the dynamic masks 12, 14 of the mask unit 28 are continuously adapted to the received light beams 24 of the individual measurement points 64, 65. In the measurement windows 43, the sections 46, 47 of the light-emitting regions 62 of the individual measurement points 64, 65, which sections are respectively imaged on the dynamic mask 12, 14, can be seen as extended white areas with a clear center.Depth information can arise if the transmitting unit 30 and the receiving unit 10 are at a sufficiently large distance from one another. Since the light-emitting regions 62 can be localized with a camera 22 of the system 100, it is thus possible to also capture different distances of the light-emitting region 62 to the receiving unit 10.FIG. 9 shows a scanning process on a person 41 with a system 100 for detecting light radiation according to a further exemplary embodiment of the invention with a linearly widened light beam 34.In this exemplary embodiment, the transmitting unit 30 is designed to expand the light beam 26 linearly over a predefined angular range 32 and to illuminate the object 40 with the linearly expanded light beam 34 in a predefined temporal and / or local grid. In particular, the object 40 can thus be illuminated with the linearly expanded light beam 34 in a direction 36 perpendicular to the linearly expanded light beam 34 in a predefined temporal and / or local grid.In this case, the emanating first light beam 26 can already be widened in a fan shape in the transmission unit 30, such that the light beam 26 covers the entire desired measurement range 42, for example. For a safety check, it is sufficient to scan the object 40 in a scanning direction 36 transversely to the linearly widened light beam 34. The person 41 can thus be scanned, for example, from top to bottom with the expanded light beam 34.Light emitting regions 62 can be detected in the line of the irradiated light beam 26 simultaneously. The secondary radiation 24 emanating from the light-emitting regions 62 of such a line can also be simultaneously detected and analyzed by the receiving unit 10.FIG. 10 illustrates, by way of example, a mask configuration in the scanning process on the person 41 according to FIG. 7 for line detection.The mask configuration of a snapshot of the scanning process is shown in the measurement window 43. The dynamic masks 12, 14 of the mask unit 28 can advantageously be adapted according to the three-dimensional geometry of the object 40, so that only the necessary measurement range 42 is detected.The section 46 shown in light in the measurement window 43 thus represents a projection of a section of the line plane with the object surface into the view of the receiving unit 10.Both for the detection with a punctiform light beam shown in FIG. 7 and for the line detection in FIG. 9, a reduction of the ambient light can be achieved with the proposed system 100 by adapting the masks 12, 14 of the mask unit 28 to the respective light point or the line of the light beam 34.FIG. 11 shows a flow chart of the method for detecting light radiation in a scanning process according to FIG. 7.The raster scan for a detection process with a punctiform light beam 26 of the transmission unit 30 starts with step S 100. In the next step S 102, a region 62 is captured and localized as the location of incidence of the light beam 26 on the object 40 using the camera 22, preferably a 3D camera, so that the position information can be evaluated in the next step S 104.The dynamic mask 12, 14 is then adapted accordingly to the mask unit 28 in step S 106, such that the detection and evaluation of the induced secondary radiation 24 can take place in step S 108.FIG. 12 correspondingly shows a flow chart of the method for detecting light radiation in a scanning process according to FIG. 9.The method essentially proceeds as the method described in FIG. 9. The difference is that no raster scan is carried out with the light beam 26, but rather a line scan is carried out with the expanded light beam 34 in step S 200, for example by scanning the person 41 in the vertical direction from top to bottom with the expanded light beam 34.Here, in step S 202, a location, more precisely a line, of the expanded light beam 34 is localized on the object 40 using the camera 22, and the position information is evaluated in step S 204.For the actual detection of the secondary radiation 24 induced by light-emitting regions 62, the dynamic mask 12, 14 is adapted to the mask unit 28 in step S 206, with the result that the detection and evaluation of the secondary radiation 24 can take place in step S 208.FIG. 13 illustrates a system diagram of a light radiation detection system 100 according to an embodiment of the invention.A central data processing system 50 receives data of the secondary radiation 24 induced by the light beam 26 on a light-emitting region 62 of the object 40 from photodetectors 70 of the receiving unit 30. In addition, the data processing system 50 receives information from the localization unit 20 regarding the location of the area 62 on the object 40 from which the secondary radiation 24 originates. As a result, the data processing system 50 is able to control the mask unit 28 in a suitable manner.The secondary radiation 24 emanating from the light-emitting region 62 of the object 40 is imaged via the first optical unit 16 onto at least one mask 12 of the at least one mask unit 28. The optical information of the mask unit 28 is in turn imaged by the second optical unit 18 onto the photodetector 70 of the receiving unit 10Results of the evaluation of the secondary radiation 24 can be presented in particular on a virtual and / or augmented reality system 60 or can be stored for documentation purposes.FIG. 14 shows an exemplary embodiment of a use of a system 100 for detecting light radiation when entering a portal.Laser spectroscopic scanning of a moving person 41 within a defined measurement range 42 can thus advantageously take place without moving components.The person 41 enters a portal, for example. A laser of a transmitting unit 30 transmits a light beam 26 into a measuring region 42 as soon as the person 41 enters the measuring region 42. Secondary radiation 24 is emitted by light-emitting regions 62 of person 41, which is registered by a receiving unit 10. The system 100 adjusts a mask unit 28 such that the light emanating from the light emitting regions 62 can be suitably detected and evaluated. The system 100 may be operated and controlled via an operating unit 88.In this way, for example, a safety check for contamination of the person with specific substances can take place.FIG. 15 shows a further exemplary embodiment of a use of the system 100 for detecting light radiation in a safety lock 200.Such a system 100 can also be used, for example, in a security lock 200, for example in an airport.By means of the proposed system 100, persons 41 can thus be checked for contamination or the entrainment and / or adhesion of certain substances.Specialized LIDAR applications can also be implemented using such a system 100.Reference numerals denote reference numerals10 Receiving unit 12 Dynamic mask 14 Dynamic mask 16 Optical unit 18 Further optical unit 20 Localization unit 22 Camera 24 Secondary radiation 26 Light beam 27 Further light beam 28 Mask unit 30 Transmitting unit 31 Transmitting unit 32 Angle range 34 Expanded light beam 36 Scanning direction 40 Object 41 Person 42 Measuring range 43 Measuring window 46 Section 47 Section 50 Data processing system 52 Polarization-rotating element 54 Delay element 56 Polarizer 58 Analyzer 60 VR / AR system 62 Light-emitting region 64 Measuring point 65 Measuring point 66 Imaging light-emitting region 68 Imaging light-emitting region 70 Photodetector 78 Polarization-separating optical element 82 Lens / concave mirror 84 Distance 86 Dispersive optical element 88 Operating unit 100 System 200 Security lockReferences 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 102016121517A1

[0005] DE 102018132033 A1

[0006] DE 102019124547 A1 [0007, 0008]

Claims

System (100) for detecting light radiation, comprising at least one transmission unit (30) for transmitting a light beam (26) onto an object (40), at least one optical reception unit (10) for receiving a secondary radiation (24) induced by the light beam (26) in at least one region (62) of the object (40), wherein the optical reception unit (10) comprises at least one photodetector (70), at least one mask unit (28), which is arranged between the object (40) and the at least one photodetector (70) and which is designed to be switchable back and forth at least in regions between an at least partially optically non-transmissive and at least partially optically transmissive state, and an optical unit (16), which is arranged in the beam path between the object (40) and the at least one mask unit (28), wherein an image (66, 66, onto the at least one mask unit (28), 68) of the at least one light-emitting region (62) of the object (40) can be imaged and conducted to the photodetector (70) in the at least partially conducting state of the at least one mask unit (28).The system according to claim 1, wherein at least one locating unit (20), in particular a camera (22), is provided for locating the region (62) of the object (40) of the secondary radiation (24) induced by the light beam (26).The system according to claim 1 or 2, wherein the at least one mask unit (28) has at least one spatially resolved addressable dynamic mask (12, 14), which can be switched at least in regions between states that are at least partially optically non-relaying and at least partially optically relaying.The system according to any one of the preceding claims, wherein a polarization-separating optical element (78), in particular a birefringent optical element, is arranged in the beam path between the optical unit (16) and the at least one mask unit (28), in particular wherein a delay element (54) is arranged between the optical unit (16) and the polarization-separating optical element (78).The system according to any one of the preceding claims, wherein a polarization-separating optical element (78), in particular a birefringent optical element, followed by a polarization-rotating element (52), is arranged in the beam path between the optical unit (16) and the at least one mask unit (28), in particular wherein the mask unit (28) has at least one polarizer (56) followed by a dynamic mask (12) followed by an analyzer (58), in particular wherein a delay element (54) is arranged between the optical unit (16) and the polarization-separating optical element (78), in particular wherein the polarization-rotating element (52) is integrated into the dynamic mask (12).The system according to any one of the preceding claims, wherein the at least one mask unit (28) has at least two dynamic masks (12, 14), in particular at least two dynamic masks (12, 14) which can be controlled separately from one another.The system according to any one of the preceding claims, wherein at least one further optical unit (18) is arranged in the beam path between the at least one mask unit (28) and the receiving unit (10).The system according to claim 7, wherein the further optical unit (18) is arranged in the beam path before the at least one dynamic mask (14) and / or after the at least one dynamic mask (12) or between the at least two dynamic masks (12, 14), in particular wherein the optical unit (18) has at least one dispersive optical element (86) between two diffractive or refractive or reflective optical elements (82) or wherein the optical unit (18) is formed to be self-refractive, diffractive or reflective.The system according to any one of the preceding claims, wherein the optical receiving unit (10) comprises an array of photodetectors (70), in particular an array of photodiodes (70).The system according to any one of the preceding claims, wherein the at least one mask unit (28) comprises at least one liquid crystal screen as a dynamic mask (12, 14).System according to one of the preceding claims, wherein the transmitting unit (30) is designed to illuminate the object (40) with the light beam (26) in a point-shaped manner in a predetermined temporal and / or local grid.The system according to any one of the preceding claims, wherein the transmitting unit (30) is configured to expand the light beam (26) linearly over a predetermined angular range (32) and to illuminate the object (40) with the linearly expanded light beam (34) in a predetermined temporal and / or local grid, in particular wherein the transmitting unit (30) is configured to illuminate the object (40) with the linearly expanded light beam (34) in a direction (36) perpendicular to the linearly expanded light beam (34) in a predetermined temporal and / or local grid.The system according to any one of the preceding claims, wherein at least one further transmitting unit (31) is provided for transmitting a further light beam (27), in particular coaxial to the light beam (26), onto the object (40), in particular wherein the further light beam (27) is provided for locating the at least one light-emitting region (62) of the object (40).Method for detecting light radiation with a system (100) according to one of the preceding claims, wherein at least one transmission unit (30) transmits a light beam (26) onto an object (40); at least one optical reception unit (10) receives a secondary radiation (24) induced by the light beam (26) in at least one region (62) of the object (40), wherein the optical reception unit (10) comprises at least one photodetector (70), at least one mask unit (28) which is arranged between the object (40) and the at least one photodetector (70) and which can be switched back and forth at least in regions between an at least partially optically non-transmissive and at least partially optically transmissive state, and an optical unit (16) which is arranged in the beam path between the object (40) and the at least one mask unit (28); wherein an image (66, 68) of the at least one light-emitting region (62) of the object (40) is imaged onto the at least one mask unit (28) and is conducted to the photodetector (70) in the at least partially conducting state of the at least one mask unit (28).Method according to claim 14, wherein the region (62) of the object (40) of the secondary radiation (24) induced by the light beam (26) is localized by a localization unit (20), in particular a camera (22).Method according to Claim 14 or 15, wherein the at least one light-emitting region (62) of the object (40) is imaged via at least one optical unit (16) onto at least one dynamic mask (12, 14) of the at least one mask unit (28), and the dynamic mask (12, 14) is switched to the at least partially transmissive state at a section (46, 47) at which the secondary radiation (24) impinges on the at least one dynamic mask (12, 14).Method according to claim 16, wherein the light-emitting region (62) of the object (40) is imaged via a polarization-separating optical element (78), in particular a birefringent element, in the beam path between the optical unit (16) and the at least one mask unit (28) as separate images (66, 68) on different sections (46, 47) of the mask unit (28), in particular wherein the light-emitting region (62) of the object (40) is imaged via a retardation element (54) arranged between the optical unit (16) and the polarization-separating optical element (78).Method according to Claim 16 or 17, wherein images (66, 68) of the light-emitting region (62) of the object (40) that are mismatched in polarization are optically passed separately to the mask unit (28) for the mask unit (28) via a polarization-separating optical element (78) followed by a polarization-rotating element (52) in the beam path between the optical unit (16) and the at least one mask unit (28), wherein the mask unit (28) has at least one polarizer (56) followed by a dynamic mask (12) followed by an analyzer (58), in particular wherein a delay element (54) is arranged between the optical unit (16) and the polarization-separating optical element (78).Method according to Claim 17 or 18, wherein images (66, 68) of the light-emitting region (62) of the object (40) which are circularly polarized differently are optically passed separately to the mask unit (28) via a delay element (54) arranged between the optical unit (16) and the polarization-separating optical element (78).Method according to one of Claims 14 to 19, wherein at least two dynamic masks (12, 14) of the at least one mask unit (28) for secondary radiation (24) of at least two light-emitting regions (62) of the object (40) are switched separately into the at least partially transmissive state, in particular wherein the secondary radiation (24) of at least two light-emitting regions (62) of the object (40) is driven sequentially.Method according to claim 20, wherein at least two light emitting regions (62) of the object (40) are localized simultaneously with the localization unit (20), in particular a camera (22).Method according to Claim 20 or 21, wherein a spectral splitting of the secondary radiation (24) of the at least one light-emitting region (62) of the object (40) takes place via at least one further optical unit (18) in the beam path upstream of the at least one dynamic mask (12) and / or downstream of the at least one dynamic mask (12) or between at least two dynamic masks (12, 14), in particular wherein a spectral splitting of the secondary radiation (24) of the at least one light-emitting region (62) of the object (40) takes place via at least one dispersive optical element (86) between two diffractive or refractive or reflective optical elements (82) of the optical unit (18) or via the optical unit (18) itself, which is designed to be refractive, diffractive or reflective, wherein the light-emitting region (62) of the object (40) is imaged onto the second dynamic mask (14) in a spectrally resolved manner.Method according to one of Claims 14 to 22, wherein the secondary radiation (24) of the at least one light-emitting region (62) of the object (40) is evaluated in a data processing system (50), in particular is processed in a virtual and / or augmented reality system (60) and / or data storage.Use of a system (100) for detecting light radiation according to one of claims 1 to 13, wherein an, in particular moving, object (40) is detected within a defined measurement range (42) with a light beam (26) of at least one transmission unit (30), wherein a secondary radiation (24) induced by the light beam (26) in at least one region (62) of the object (40) is received by at least one optical receiving unit (10), wherein the secondary radiation (24) of the at least one light-emitting region (62) of the object (40) is evaluated in a data processing system (50), in particular is processed in a virtual and / or augmented reality system (60) and / or data storage.

Images