System and method for detecting light radiation

Abstract

The invention relates to a system (100) for detecting light radiation, comprising a sending unit (30) for sending a light beam (26) onto an object (40), and an optical receiving unit (10) for receiving secondary radiation (24) induced in a region (62) of the object (40) by the light beam (26). The optical receiving unit (10) comprises a photodetector (70), a mask unit (28) between the object (40) and the photodetector (70) which can be switched at least partially back and forth between an optically non-transmitting state and an optically transmitting, and an optical unit (16) which is 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 region (62) of the object (40) can be imaged onto the at least one mask unit (28) and can be transmitted to the photodetector (70) when the at least one mask unit (28) is in the at least partially transmitting state. The invention further relates to a method for for detecting light radiation by means of such a system.

Description

[0001] Description

[0002] title

[0003] System and method for detecting light radiation

[0004] State of the art

[0005] The invention relates to a system for detecting light radiation and a method for detecting light radiation with such a system and a use of such a system for detecting light radiation.

[0006] The detection of laser optical radiation, such as the location-accurate detection of multiple optical measurement signals, is important in optical communication technology as well as in the detection of hazardous substances and in the implementation of security checks, for example at border crossings or at airports.

[0007] In optical camera communication, optical data, for example, from a modulated LED, is received directly by a camera chip. To achieve higher data rates, multiple light emitters must be arranged side by side. Furthermore, a large amount of image information that does not contain data streams must be evaluated. In an application for laser-based measurement techniques, optical measurements of laser-induced effects can be captured using a video camera.

[0008] With a rigid, particularly coaxial, beam guide, the emitting measuring beam and the receiving measuring beam are superimposed. To achieve different measuring positions, both light beams must be moved simultaneously. This can be achieved either by mechanically moving the measuring setup or by transmitting both measuring 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 using laser spectroscopy during the process. The laser beam and the detection optics are tracked. This can be technically achieved using a scanning mirror unit. For three-dimensional objects, the depth position is also adjusted using a mechanical translation stage. This results in at least two mechanically moving parts in the system.Permanent use is possible to a limited extent, taking into account cooling times or reaction times, through mechanical adjustment.

[0009] DE 102018132033 A1 describes a method for detecting a hazardous substance, in particular an explosive, on a sample, in particular in a spatial detection area, 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 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 to determine whether or not the at least one hazardous substance is present in the sample. The first spectrum recording time window and the second spectrum recording time window overlap at least partially in time.

[0010] DE 102019124547 A1 discloses a detector device for the remote analysis of substances, in particular hazardous substances, comprising at least one laser designed to irradiate pulsed laser light onto a sample located at a detection distance, and a telescope designed to collect and / or focus laser light scattered by the sample and to transmit the scattered laser light into an optical spectrometer. The optical spectrometer is designed for the spectral analysis of the laser light scattered by 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 is provided for determining a time difference between pulses of the first reference beam and pulses of the second reference beam, wherein the detection distance is determined from the time difference.

[0011] Disclosure of the invention

[0012] The object of the invention is to create an improved system for detecting light radiation.

[0013] A further object of the invention is to provide an improved method for detecting light radiation.

[0014] A further object of the invention is to provide a use for an improved system for detecting light radiation.

[0015] The objects are achieved by the features of the independent claims. Advantageous embodiments and advantages of the invention emerge from the further claims, the description, and the drawings.

[0016] According to one aspect of the invention, a system for detecting light radiation is proposed, comprising at least one transmitting unit for transmitting a light beam onto an object, at least one optical receiving unit for receiving secondary radiation induced by the light beam in at least one region of the object, wherein the optical receiving 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 some regions between an at least partially optically non-transmitting and at least partially optically transmitting 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 guided to the photodetector in the at least partially transmitting state of the at least one mask unit.

[0017] An object can be either a solid body or a volume scatterer, such as a liquid, for example water, or a gaseous medium, for example air, smoke, fog, aerosols or the like.

[0018] The system comprises a directed transmitter unit, typically a laser, that generates secondary radiation in a region of the object, which is used to measure laser-measured quantities. 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 can be used. An example of a volume scatterer is a so-called "wind LIDAR."

[0019] Induced secondary radiation is understood to mean that at least one property, in particular a quantum-mechanical property, is influenced, apart from a change in propagation direction, along the light path and on or within the object. Examples of quantum-mechanical properties include, in particular, power density, photon flux and / or photon number, wavelength, optical path length / phase, and / or polarization.

[0020] If the secondary radiation emanates from the surface of the object, the area of ​​the object can be registered as a light point corresponding to the light point of the incident light beam. In the case of a volume scatterer as the object, the area from which the secondary radiation emanates can be an extended area and, in particular, exhibit a corresponding depth distribution in the direction of the incident light beam.

[0021] The area of ​​the object is then located, optionally with the help of a camera, and the position information thus obtained is used to target the directional receiver unit. The optical unit serves to image the light-emitting area onto the at least one mask unit, which can be designed as an at least partially forwarding, spatially addressable dynamic mask. This allows secondary radiation from selected light-emitting areas to be transmitted in a targeted manner to the receiver unit.

[0022] The secondary radiation generated by the laser is imaged onto at least one first mask unit. The mask unit can be selectively switched to at least partially transmitting, for example, transparent, transmissive, or reflective, in the area toward which the image of the area of ​​the object from which the secondary radiation emanates is projected, so that the image of the area is directed to the receiving unit, where it can be received and forwarded to a data processing system.

[0023] "Optically transmitting" means that the optical signal from at least one light source can pass through the mask unit. "Optically non-transmitting" means that the optical signal cannot pass through the mask unit. The term "transmitting" can be understood to mean that the light is transmitted through the mask, or is diffracted, reflected, or absorbed. Thus, signals can be transmitted as black-and-white signals or in grayscale.

[0024] In this way, individual light rays can be transmitted or blocked out via the mask unit.

[0025] The light transmitted through the mask unit can now be recorded by 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.

[0026] The proposed system advantageously enables the spatially resolved assignment of light beams, particularly laser-optical light beams, to individual points or lines on the object using the optical reception unit and the masking unit. The system also allows for the simultaneous reception of several freely selectable spectral ranges of light radiation and the combination of this reception with conventional techniques supported by photodiodes or photomultipliers. Furthermore, polarization-dependent separation of the light beams can also be performed. This allows, for example, direct referencing of the light radiation against a polarized background radiation.

[0027] The technology also allows multiple independent optical measurement sources, such as laser spots, to be tracked and evaluated virtually independently of one another. This is advantageous, for example, when the measurement method prohibits or discriminates against coaxial readout and the point of incidence of the light beam, and thus the observed location in the detection channel of the receiving unit, varies.

[0028] Optionally, it is possible to use light-sensitive, particularly infrared light-sensitive, line or matrix sensors to identify and localize the light-emitting areas.

[0029] Furthermore, dynamic shading / masking via a mask unit is used to improve the signal-to-noise ratio, especially for certain angles of incidence of the light rays.

[0030] This feature can be combined with an arrangement, in particular an array of photodetectors, for example photodiodes, in order to be able to receive several light sources simultaneously.

[0031] The system thus enables a type of optical multiplexing. This allows for the simple and targeted suppression of light beams that would otherwise hit the same detector, without requiring complex electrical structuring of the detector.

[0032] The proposed system advantageously utilizes fast response times of the detector of the receiving unit or a high effective measurement rate. Because no rigid beam guidance is required, high positioning speeds of the light beams can be achieved. This allows for multiple simultaneous measurements of different light beams. The scanning of surfaces, for example, a person in a security checkpoint, can be performed very quickly with the proposed system.

[0033] According to a favorable embodiment of the system, at least one localization unit, in particular a camera, can be provided for localizing the area of ​​the object where the secondary radiation is induced by the light beam. Advantageously, the receiving unit can thus be specifically aligned with the light-emitting area of ​​the object. This allows the system to assign the light beams, in particular laser-optical light beams, to individual points or lines on the object with spatial resolution using the directed receiving unit. The area of ​​the object can be localized, for example, using conventional digital cameras that are sensitive enough in the wavelength range of the light beams. This allows the mask unit to be specifically controlled using the location information of the light-emitting area and at least partially switched to forward it.

[0034] The system may optionally include a camera with a large field of view for localizing the light rays, which has a sensitivity in the infrared light spectrum.

[0035] According to a favorable embodiment of the system, the at least one mask unit can have at least one spatially addressable dynamic mask that can be switched, at least in part, between at least partially optically non-transmitting and at least partially optically transmitting states. The dynamic mask can thus be selectively switched to at least partially transmitting the secondary radiation localized with the aid of the camera, so that the light signal data can be received. The dynamic mask can, for example, be designed as a liquid crystal (TFT) screen (TFT = Thin Film Transistor). It is also possible, for example, to use a micromirror actuator or LCoS (LCoS = Liquid 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 transmit the secondary radiation located with the help of the camera, so that the light rays can be received by the receiving unit.

[0036] Furthermore, it is also possible for the dynamic mask to be designed as a light-diffracting component which can be switched between a transmitting state and a non-transmitting state by a switchable diffraction effect.

[0037] Optionally, it is possible to use light-sensitive, particularly infrared-sensitive, line or matrix sensors to identify and localize the light-emitting areas. Furthermore, dynamic shading / masking can be used via the mask unit to improve the signal-to-noise ratio, especially for certain angles of incidence of the light beams.

[0038] The use of a mask unit in the form of a transmitting mask offers significant advantages in terms of a compact system size. This allows for the transmission of both partially and fully transmitting states depending on the mask selected. Especially when the receiving unit is directly adjacent to the mask unit, a very compact system size can be achieved. This also allows for a large acceptance angle in the intermediate image of the light source onto the mask unit, thus enabling more compact systems.Advantageously, a clear distance between the at least one mask unit and / or its image onto the at least one receiving unit and an entrance 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 transmitted by the mask unit corresponds at most to the entrance aperture of the at least one photodetector of the receiving unit.

[0039] The required clearance preferably follows from the detector size and / or the subapertures of the individual photodetectors. This advantageously reduces or even eliminates crosstalk between different photodetectors.

[0040] 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, or various prisms such as Nomarski, Glan-Foucault, Glan-Thompson, Nicol, Rochon, Senarmont, Wollaston, or Glan-Taylor.

[0041] A birefringent optical element (DBE) can be used to separate two polarization states, namely horizontal or vertical polarization. A delay element, such as a quarter-wave plate, makes it possible to distinguish between circularly polarized states, namely left / right circular polarization. This creates up to two virtual light sources in the plane of the mask unit. Furthermore, a birefringent optical element can be installed before or after the mask unit to eliminate blind spots on a photodetector array of the receiving unit. This allows two or more optical images of the light-emitting region to be projected onto different areas of the detector array, so that at least one image always illuminates a photodetector at its sensitive aperture.

[0042] 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 can 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.

[0043] The mask unit can advantageously initially comprise a liquid crystal designed to rotate the phase of the light rays before it transitions into a conventional LCD / TFT display consisting of a polarizer, liquid crystal matrix and analyzer.

[0044] Thus, the dynamic mask can be designed as a polarization-rotating component, which can be switched between a transmitting state and a non-transmitting state by a switchable birefringence effect in combination with polarizer and analyzer.

[0045] To maximize signal transmission through the mask unit using an LCD unit, it is possible to combine a birefringent optical element with a polarization-rotating LCD element, particularly as a lambda / 2 delay element. This element, similar to the design of a dynamic mask, is designed as a polarization-rotating component that can be switched between a polarization-rotating state and a non-polarization-rotating state. This allows both polarization components of the transmitted light beams to be separated, and polarization-mismatched components for the mask unit can be controlled separately, ensuring that a large portion of the light reaches the photodetectors.

[0046] According to a favorable embodiment of the system, the at least one mask unit can comprise at least two dynamic masks. In particular, the at least one mask unit can comprise at least two separately controllable dynamic masks. If the position of the light-emitting regions is unknown, it is also possible to narrow down and thus track relevant signal sources by cleverly switching mask units, at least partially iteratively and alternately, at least partially forwarding. This allows the light-emitting regions to be localized even without a camera.

[0047] Furthermore, the design of the mask unit has the advantage of allowing for higher optical contrast for background suppression and allowing for easy adjustment of the mask unit's focus. This allows for improved contrast at different light source distances, even when multiple light sources are simultaneously detected.

[0048] 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.

[0049] The light transmitted through the first mask unit can be imaged onto the receiving unit or onto a further mask unit of the receiving unit via a further imaging system, in particular with dispersive properties, similar to a spectrometer, which can then selectively transmit or block certain wavelengths. Advantageously, the distance between the at least one mask unit and / or its image onto the at least one receiving unit and the entrance aperture of the at least one receiving unit corresponds at most to a quotient of a diameter of the entrance 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.

[0050] The smallest possible distance between the mask unit and the entrance aperture means that the mask or its optical image is not further than a distance Az from the entrance aperture with effective diameter D of a single photodetector, where the distance Az is given by:

[0051] Az < 0 / (2 sin(a)) where a is half the aperture angle of the imaged light source.

[0052] For a lens with a focal length f, 2sin(a) corresponds to the f-number, so at an aperture of f / 2, the maximum separation corresponds to twice the diameter D of the photodetector's entrance aperture. This prevents permanent crosstalk between neighboring photodetectors, which could occur with a larger separation and thus impair the usability of the system.

[0053] According to a favorable embodiment of the system, the additional 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 comprise at least one dispersive optical element between two diffractive, refractive, or reflective optical elements, or can itself be refractive, diffractive, or reflective.

[0054] In a further embodiment, the additional optical unit can be supplemented with a dispersive optical element, for example, a transmissive or reflective grating or a prism. This enables spectral splitting of the light beams across multiple detectors of the receiving unit. A linear arrangement of photodiodes with a high aspect ratio, i.e., an elongated configuration, can be useful here to minimize the spacing between the photodiodes. Depending on the position of the light source, all spectral channels can be received simultaneously by the photodetectors. This allows the use of many monochromatic measurement channels or fewer polychromatic measurement channels with higher bandwidth in the same system architecture. To specifically address only individual "subchannels," it is also possible to install an additional shading mask in front of the photodetectors to block unwanted channels.In this way, the signal-to-noise ratio can be further optimized in bright environments without being restricted to a specific wavelength.

[0055] According to a favorable embodiment of the system, the optical receiving unit can comprise an array of photodetectors, in particular an array of photodiodes. An array of multiple photodetectors, in particular a rectangular array of photodetectors, allows secondary radiation from multiple light-emitting regions to be received simultaneously. Furthermore, it is possible to sequentially control secondary radiation from closely spaced light-emitting regions while still maintaining a clean separation.

[0056] According to a favorable embodiment of the system, the at least one mask unit can comprise at least one liquid crystal screen as a dynamic mask. These types of screens can be easily switched to be at least partially forwarded in a spatially resolved manner. Furthermore, they represent conventional screens.

[0057] According to a favorable embodiment of the system, the transmitting unit can be designed to point-illuminate the object with the light beam in a predetermined temporal and / or spatial grid. For example, during a security check, a person can be scanned using a raster scan, with the mask on the receiving side being continuously tracked. According to a favorable embodiment of the system, the transmitting unit can be designed to linearly expand the light beam over a predetermined angular range and to illuminate the object with the linearly expanded light beam in a predetermined temporal and / or spatial 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 predetermined temporal and / or spatial grid.With this type of line detection, the first light beam can be expanded and a person can be scanned from top to bottom with the striped light beam. The mask can be adjusted according to the three-dimensional geometry so that only the necessary measurement area is captured.

[0058] According to a favorable embodiment of the system, at least one additional transmitting unit can be provided for transmitting an additional light beam, in particular coaxial with the light beam, onto the object. In particular, the additional light beam can be provided for locating the at least one light-emitting region of the object. The additional light beam, for example from a pilot laser, can be used coaxially with the directed light beam to locate the light-emitting region. Invisible light radiation, for example infrared radiation, can advantageously be used. Thus, a laser visible to the digital camera can be coaxially superimposed with the laser of the transmitting unit in order to track it.

[0059] According to a further aspect of the invention, a method for detecting light radiation using a system is proposed, wherein at least one transmitting unit transmits a light beam onto an object; and at least one optical receiving unit receives secondary radiation induced by the light beam in at least one region of the object, wherein the optical receiving 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 some regions between an at least partially optically non-transmitting and at least partially optically transmitting 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 is projected onto the at least one mask unit and is guided to the photodetector in the at least partially transmitting state of the at least one mask unit.

[0060] An object can be either a solid body or a volume scatterer, such as a liquid such as water or a gaseous medium such as air, smoke, fog, aerosols or the like.

[0061] The system comprises a directed emitter, typically a laser, that generates secondary or scattered radiation in a region of the object, which is used to measure laser-measured quantities. 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 can be used. An example of a volume scatterer is a so-called "wind LIDAR."

[0062] According to the proposed method, the area of ​​the object from which the secondary radiation emanates is then localized, optionally with the help of a camera, and targeted by the directional receiving unit using the position information thus obtained.

[0063] The secondary radiation generated by the laser is imaged onto at least one first mask unit. The mask unit can be selectively switched to at least partially transmitting, for example, transparent, transmissive, or reflective, in the area toward which the image of the area of ​​the object from which the secondary radiation emanates is projected, so that the image of the area is directed to the receiving unit, where it can be received and forwarded to a data processing system.

[0064] "Optically transmitting" means that the optical signal from at least one light source can pass through the mask unit. "Optically non-transmitting" means that the optical signal cannot pass through the mask unit. The term "transmitting" can be understood to mean that the light is transmitted through the mask, or is diffracted, reflected, or absorbed. Thus, signals can be transmitted as black-and-white signals or in grayscale.

[0065] In this way, individual light rays can be transmitted or blocked out via the mask unit.

[0066] The light transmitted through the mask unit can now be recorded by 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.

[0067] Advantageously, the proposed method enables light beams, in particular laser-optical light beams, to be assigned to individual points or lines on the object in a spatially resolved manner by means of the optical receiving unit and the mask unit.

[0068] The method also allows for the simultaneous reception of several freely selectable spectral ranges of light radiation and the combination of this reception with conventional techniques supported by photodiodes or photomultipliers. Furthermore, polarization-dependent separation of the light beams can also be performed. This allows, for example, direct referencing of the light radiation against a polarized background radiation.

[0069] The method also allows multiple independent optical measurement sources, such as laser spots, to be tracked and evaluated virtually independently of one another. This is advantageous, for example, when the measurement method prohibits or discriminates against coaxial readout and the point of incidence of the light beam, and thus the observed location in the detection channel of the receiving unit, varies.

[0070] The requirement for the clearance preferably follows from the detector size and / or the subapertures of the individual photodetectors. This advantageously reduces or even eliminates crosstalk between different photodetectors. Optionally, it is possible to use light-sensitive, particularly infrared-sensitive, line or matrix sensors to identify and localize the light-emitting areas.

[0071] Furthermore, dynamic shading / masking via a mask unit is used to improve the signal-to-noise ratio, especially for certain angles of incidence of the light rays.

[0072] This feature can be combined with an arrangement, in particular an array of photodetectors, for example photodiodes, in order to be able to receive several light sources simultaneously.

[0073] The process thus enables a type of optical multiplexing. This allows for the simple and targeted suppression of light beams that would otherwise hit the same detector, without requiring complex electrical structuring of the detector.

[0074] The proposed method can advantageously utilize fast response times of the detector of the receiving unit or a high effective measurement rate.

[0075] Because no rigid beam guidance is required, high positioning speeds of the light beams can be achieved. Multiple simultaneous measurements of different light beams can thus be performed. The proposed system can be used to scan surfaces, such as a person in a security checkpoint, very quickly.

[0076] According to a favorable embodiment of the method, the area of ​​the object where the secondary radiation is induced by the light beam can be localized by a localization unit, in particular a camera. Advantageously, the receiving unit can thus be specifically aligned with the light-emitting area of ​​the object. The method thus enables the directed receiving unit to assign light beams, in particular laser-optical light beams, to individual points or lines on the object with spatial resolution. The secondary radiation can be localized, for example, using conventional digital cameras that are sensitive enough in the wavelength range of the secondary beams. This allows the mask unit to be specifically controlled using the location information of the light-emitting area and at least partially switched to forward it.

[0077] 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 forwarding state at a section at which the secondary radiation impinges on the at least one dynamic mask.

[0078] The optical unit can be used to image a light-emitting region onto the at least one mask unit, which can be configured as an at least partially forwarding, spatially addressable dynamic mask. This allows light beams from selected light-emitting regions to be transmitted in a targeted manner to the receiving unit.

[0079] According to a favorable embodiment of the method, the light-emitting region of the object can be imaged as separate images onto 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.

[0080] A polarization-separating element, such as a birefringent optical element (DBE), can separate two polarization states, namely horizontal or vertical. A delay element, such as a quarter-wave plate, can distinguish between circularly polarized states, namely left / right circular polarization. This creates up to two virtual light sources in the plane of the mask unit. Furthermore, a birefringent optical element can be installed before or after the mask unit to eliminate blind spots on a photodetector array of the receiving unit. This allows two or more optical images of the light-emitting region to be projected onto different areas of the detector array, so that at least one image always illuminates a photodetector at its sensitive aperture.

[0081] According to a favorable embodiment of the method, images of the light-emitting region of the object that are mismatched in polarization for the mask unit can be optically transmitted 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.

[0082] The mask unit comprises at least one polarizer, followed by a dynamic mask, and then an analyzer. In particular, a delay element can be arranged between the optical unit and the polarization-separating optical element.

[0083] The mask unit can advantageously initially comprise a liquid crystal designed to rotate the phase of the light rays before it transitions into a conventional LCD / TFT display consisting of a polarizer, liquid crystal matrix and analyzer.

[0084] Thus, the dynamic mask can be designed as a polarization-rotating component, which can be switched between a transmitting state and a non-transmitting state by a switchable birefringence effect in combination with polarizer and analyzer.

[0085] To maximize signal transmission through the mask unit using an LCD unit, it is possible to combine a birefringent optical element with a polarization-rotating LCD element, particularly as a lambda / 2 delay element. This element, similar to the design of a dynamic mask, is designed as a polarization-rotating component that can be switched between a polarization-rotating state and a non-polarization-rotating state. This allows both polarization components of the transmitted light beams to be separated, and polarization-mismatched components for the mask unit can be controlled separately, ensuring that a large portion of the light reaches the photodetectors.

[0086] According to a favorable embodiment of the method, differently circularly polarized images of the light-emitting region of the object can be optically transmitted separately to the mask unit via a delay element arranged between the optical unit and the polarization-separating optical element. With correct installation, left and right circularly polarized light can advantageously be converted into vertically and horizontally polarized light beams aligned to match the polarization-separating element. These can be read out separately with sufficient spatial separation.

[0087] According to a favorable embodiment of the method, at least two dynamic masks of the at least one mask unit can be separately switched to the at least partially transmitting state for secondary radiation from at least two light-emitting regions of the object. In particular, the secondary radiation from at least two light-emitting regions of the object can be controlled sequentially. If the position of the light-emitting regions is unknown, it is also possible to narrow down and thus track relevant signal sources by cleverly switching mask units at least partially iteratively, alternately, to at least partially transmitting. This allows the light-emitting regions to be localized even without a camera.

[0088] Furthermore, the design of the mask unit has the advantage that a higher optical contrast can be achieved for background suppression, and that a simple approximation of the focusability of the mask unit can be achieved. This allows the contrast to be improved at different distances between the light sources, even with simultaneous detection of multiple light sources. According to a favorable embodiment of the method, at least two light-emitting regions of the object can be located simultaneously with the localization unit, in particular a camera. In this way, it is possible to locate light-emitting regions simultaneously. If the light sources are located close to one another, they can be interrogated sequentially.

[0089] 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 be carried out via at least one further optical unit in the beam path in front of the at least one dynamic mask and / or after the at least one dynamic mask or between at least two dynamic masks.

[0090] In particular, a spectral splitting of the secondary radiation of the at least one light-emitting region of the object can be achieved via at least one dispersive optical element between two diffractive, refractive, or reflective optical elements of the optical unit, or via the optical unit itself, which is designed to be refractive, diffractive, or reflective. The light-emitting region of the object can be imaged onto the second dynamic mask in a spectrally resolved manner.

[0091] Here, a linear arrangement of photodiodes with a high aspect ratio, i.e., an elongated design, can be useful to minimize the spacing between the photodiodes. Depending on the position of the light source, all spectral channels can be received simultaneously by the photodetectors. This allows the use of many monochromatic measurement channels or fewer polychromatic measurement channels with a higher bandwidth in the same system architecture. To specifically address only individual "subchannels," it is also possible to install an additional shading mask in front of the photodetectors to block unwanted channels. In this way, the signal-to-noise ratio can be further optimized in bright environments without being restricted to a specific wavelength. According to a favorable embodiment of the method, the secondary radiation of 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. This allows for the creation of accurate, virtual representations of measurements using a wide variety of measurement methods in connection with VR / AR applications.

[0092] According to a further aspect of the invention, the use of a system for detecting light radiation is proposed, wherein an object, in particular a moving one, is detected within a defined measuring range with a light beam from at least one transmitting unit. Secondary radiation induced by the light beam in at least one region of the object is received by at least one optical receiving unit.

[0093] The secondary radiation of 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.

[0094] The proposed system can be advantageously used in a variety of laser-optical stand-off detection applications. In particular, it can be used for security screening of persons entering sensitive areas or at security gates, for example, at airports. The system can also be advantageous for implementing specialized LIDAR applications.

[0095] The transmitting unit and the receiving unit do not have to be installed on the same platform. The transmitting unit can be installed, for example, on a mobile or portable platform, while the receiving unit is installed on a flying platform, such as a drone. This is to be understood as an example; there could also be two mobile systems, for example. In this way, multiple receiving units can receive and analyze secondary radiation induced by a light beam from a transmitting unit. Drawing

[0096] Further advantages will become apparent from the following description of the drawings. The drawings illustrate exemplary embodiments of the invention. The drawings, the description, and the claims contain numerous features in combination. Those skilled in the art will also expediently consider the features individually and combine them into useful further combinations.

[0097] Examples include:

[0098] Fig. 1 is a schematic representation of a system for detecting light radiation according to an embodiment of the invention;

[0099] Fig. 2 is a schematic representation of a detection process of light rays with a receiving unit with a mask unit with a dynamic mask according to an embodiment of the invention;

[0100] Fig. 3 is a schematic representation of a detection process of light rays with a receiving unit with a mask unit with a dynamic mask according to a further embodiment of the invention;

[0101] Fig. 4 is a schematic representation of a detection process of light rays with a receiving unit with a mask unit with two dynamic masks according to a further embodiment of the invention;

[0102] Fig. 5 is a schematic representation of a detection process of light rays with a receiving unit with a mask unit with two dynamic masks according to a further embodiment of the invention;

[0103] Fig. 6 is a schematic representation of a system for detecting light radiation according to a further embodiment of the invention;

[0104] Fig. 7 shows a scanning process on a person using a system for detecting light radiation according to an embodiment of the invention with a point-shaped light beam; Fig. 8 shows measurement results of the scanning process on the person according to Fig. 7 for two measurement points;

[0105] Fig. 9 shows a scanning process on a person with a system for detecting light radiation according to a further embodiment of the invention with a linearly expanded light beam;

[0106] Fig. 10 Measurement results of the scanning process on the person according to Figure 9 for a line detection;

[0107] Fig. 11 is a flowchart of the method for detecting light radiation in a scanning process according to Fig. 7;

[0108] Fig. 12 is a flowchart of the method for detecting light radiation in a scanning process according to Fig. 9;

[0109] Fig. 13 is a system diagram of a system for detecting light radiation according to an embodiment of the invention;

[0110] Fig. 14 shows an embodiment of a use of a system for detecting light radiation when entering a portal; and

[0111] Fig. 15 shows a further embodiment of a use of the system for detecting light radiation in a security gate.

[0112] Embodiments of the invention

[0113] In the figures, components of the same type or function similarly are designated by the same reference numerals. The figures are merely examples and are not to be construed as limiting.

[0114] Before the invention is described in detail, it should be pointed out that it is not limited to the specific components of the device or the specific method steps, since these components and methods can vary. The terms used herein are intended solely to describe particular embodiments and are not used in a limiting sense. Furthermore, when the singular or indefinite article is used in the description or claims, this also refers to the plural of these elements, unless the overall context clearly indicates otherwise. Directional terminology used below with terms such as "left", "right", "top", "bottom", "before", "behind", "after" and the like is intended solely to improve understanding of the figures and is in no way intended to limit the generality.The components and elements shown, their design and use may vary according to the considerations of a specialist and may be adapted to the respective applications.

[0115] Figure 1 shows a schematic representation of a system 100 for detecting light radiation according to an embodiment of the invention. Figure 2 shows a schematic representation of a light beam detection process using a receiving unit 10 with a mask unit 28 with a dynamic mask 12 according to an embodiment of the invention.

[0116] The system 100 comprises a directed transmission 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 to measure laser-measured quantities. 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 can be used.

[0117] The area 62 of the object 40 is then located, optionally with the aid of a camera (22), and targeted by the directional receiving unit 10 using the position information thus obtained.

[0118] The system 100 thus comprises the transmitting unit 30 for transmitting the light beam 26 onto the object 40, and the optical receiving unit 10 for receiving the secondary radiation 24 induced by the light beam 26 in the region 62 of the object 40. For this purpose, the optical receiving unit 10 has, as shown in Figures 2 to 5, at least one photodetector 70. In the induced secondary radiation, at least one property, in particular a quantum-mechanical property, has been influenced, apart from a change in propagation direction, along the light path and on or in the object. Examples of quantum-mechanical properties include, in particular, power density, photon flux and / or photon number, wavelength, optical path length / phase, and / or polarization.

[0119] The transmitting unit 30 is designed to illuminate the object 40 with the light beam 26 in a predetermined temporal and / or spatial pattern in a point-like manner, or, in the case of a volume scatterer, in a beam-like manner.

[0120] 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 some regions, between an at least partially optically non-transmitting and at least partially optically transmitting state.

[0121] An optical unit 16, for example, a lens 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 shown in Figure 2. In the at least partially transmitting state of the mask unit 28, this image 66, 68 is then transmitted to the photodetector 70.

[0122] The light-emitting region 62 of the object 40 is imaged via the optical unit 16 onto a dynamic mask 12 of the mask unit 28, and the dynamic mask 12 is switched to the at least partially transmitting state at a section 46, 47 at which the secondary radiation 24 impinges on the at least one dynamic mask 12.

[0123] The mask unit 28 has at least one spatially addressable dynamic mask 12 that can be switched, at least in certain regions, between at least partially optically non-transmitting and at least partially optically transmitting states. The mask unit 28, as a dynamic mask 12, can, for example, have at least one liquid crystal screen.

[0124] As can be seen in Figure 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 as separate images 66, 68 onto different sections 46, 47 of the mask unit 28 via the birefringent optical element 78 in the beam path between the optical unit 16 and the at least one mask unit 28.

[0125] 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.

[0126] Furthermore, as shown, a polarization-rotating element 52 can be arranged behind the birefringent optical element 78 in the beam path.

[0127] The polarization-rotating element 52 can also be integrated into the dynamic mask 12.

[0128] Images 66, 68 of the light-emitting region 62 of the object 40 which are mismatched in polarization for the mask unit 28 can advantageously be optically transmitted 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.

[0129] The mask unit 28 has at least one polarizer 56 followed by a dynamic mask 12, followed by an analyzer 58.

[0130] The optical receiving unit 10 can advantageously comprise an array 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 by the optical unit 16 through the birefringent element 78 onto the first dynamic mask 12 of the mask unit 28. The birefringent element 78 can separate two polarization states, for example, horizontally polarized or vertically polarized.

[0131] This creates up to two virtual light sources 66, 68 in the plane of the mask unit 28. This has a liquid crystal as a polarization-rotating element 52, which is designed to rotate the phase of the secondary radiation 24 before it merges into a conventional LCD / TFT display consisting of polarizer 56, liquid crystal matrix 12 and analyzer 58.

[0132] The light thus transmitted can be guided to the photodetector 70 of the receiving unit 10 via an imaging system 18, optionally with dispersive properties, similar to a spectrometer.

[0133] The transmitted light can be recorded by 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.

[0134] It may be advantageous if a clear distance 84 between the at least one mask unit 28 and / or its image onto the at least one receiving unit 10 and an entrance 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 entrance aperture of the at least one photodetector 70 of the receiving unit 10.

[0135] Figure 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, refractive, or reflective optical elements 82, for example, lenses or concave mirrors. In general, any optical system suitable for spectrometers or monochromators can be used as the further optical unit 18.

[0136] Figure 4 shows a schematic representation of a detection process of light rays with a receiving unit 10 with a mask unit 28 with two dynamic masks 12, 14 according to a further embodiment of the invention.

[0137] The at least one mask unit 28 has two dynamic masks 12, 14, which can in particular be controlled separately from one another.

[0138] A delay element 54 is arranged between the optical unit 16 and the birefringent optical element 78 as a polarization-separating element 78. This allows, in particular, the two or more images 66, 68 of the light-emitting region 62 of the object 40 to be imaged via the delay element 54 arranged between the optical unit 16 and the birefringent optical element 78.

[0139] The differently circularly polarized images of the light-emitting region 62 of the object 40 in front of the delay element 54 can be optically forwarded separately to the mask unit 28 via the delay element 54 as linearly polarized images 66 and 68.

[0140] The further optical unit 18 can be arranged in the beam path downstream of the at least one dynamic mask 12 or, as shown in Figure 3, between the at least two dynamic masks 12, 14. Spectral splitting of the secondary radiation of the at least one light-emitting region 62 of the object 40 can be achieved via the further optical unit 18. The spectral splitting can be achieved, for example, via at least one dispersive optical element 86 between two diffractive, refractive, or reflective optical elements 82, for example lenses or concave mirrors, of the optical unit 18. The image 66, 68 of the light-emitting region 62 of the object 40 can be imaged in a spectrally resolved manner onto the second dynamic mask 14. Optionally, an element that combines dispersive, diffractive, and refractive properties in one element can also be used as the further optical element 18.

[0141] The at least two dynamic masks 12, 14 of the at least one mask unit 28 can be separately switched to the at least partially transmitting state for secondary radiation from at least two light-emitting regions 62 of the object 40. In particular, the secondary radiation from at least two light-emitting regions 62 of the object 40 can thus be controlled sequentially.

[0142] In the embodiment illustrated in Figure 4, the secondary radiation 24 caused by the light beam 26 in the region 62 of the object 40 is imaged by the optical unit 16 through the delay element 54, for example, a quarter-wave plate, and the birefringent element 78 onto the first dynamic mask 12 of the mask unit 28. The birefringent element 78 allows two polarization states, for example, horizontally polarized or vertically polarized, to be separated from one another. The quarter-wave plate 54 makes it possible to distinguish between circularly polarized states of the secondary radiation 24, for example, left or right circularly polarized.

[0143] The light thus transmitted 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 certain wavelengths.

[0144] The light thus transmitted can be recorded by the detector 70 of the receiving unit 10 and converted into electrical digital signals. Figure 5 shows another embodiment of a receiving unit 10 in a minimal configuration. The receiving unit 10 has only one optical unit 16. The mask unit 28 has a dynamic mask, which is arranged directly in front of the photodetector 70.

[0145] 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 transmitting state at a section 46, 47 at which the secondary radiation impinges on the at least one dynamic mask 14, so that the secondary radiation can be received by means of the photodetector 70.

[0146] Figure 6 shows a schematic representation of a system 100 for detecting light radiation according to a further embodiment of the invention.

[0147] In this embodiment, a localization unit 20, for example, a camera 22, is provided for localizing the area 62 of the object 40 from which the secondary radiation 24 emanates. In this way, for example, at least two areas 62 of the object 40 can be localized simultaneously with the localization unit 20, in particular a camera 22, preferably a 3D camera.

[0148] Furthermore, in the embodiment illustrated in Figure 6, a further transmitting unit 31 is provided for transmitting a further light beam 27, in particular coaxial with the light beam 26, onto the object 40. The further light beam 27 can advantageously be used, in particular when emitted coaxially with the light beam 26, to localize the at least one light-emitting region 62 of the object 40.

[0149] Figure 7 shows a scanning process on a person 41 using a system 100 for detecting light radiation according to an embodiment of the invention with a point-shaped light beam 26. The system 100 can advantageously be used for detecting light radiation. A moving person 41 can be detected as an object 40, for example, within a defined measuring range 42 with the light beam 26 of the transmitting 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.

[0150] The measuring area 42 is scanned by the transmitting unit 30 with the light beam 26. A secondary radiation 24 can then be emitted from a light-emitting area 62 of a measuring point 64, 65, which can be received by the optical receiving unit 10.

[0151] Figure 8 shows exemplary mask configurations for the scanning process on the person 41 according to Figure 7 for the two measuring points 64, 65.

[0152] The mask configurations corresponding to the two-dimensional measurement area 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 adjusted 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, each imaged onto the dynamic mask 12, 14, can be seen as extended white areas with a distinct center.

[0153] Depth information can be obtained if the transmitting unit 30 and the receiving unit 10 are sufficiently far apart. Since the light-emitting areas 62 can be localized with a camera 22 of the system 100, it is also possible to detect different distances between the light-emitting area 62 and the receiving unit 10.

[0154] Figure 9 shows a scanning process on a person 41 using a system 100 for detecting light radiation according to a further exemplary embodiment of the invention with a linearly expanded light beam 34. In this exemplary embodiment, the transmitting unit 30 is designed to linearly expand the light beam 26 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 spatial pattern. 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 predetermined temporal and / or spatial pattern.

[0155] The outgoing first light beam 26 can be expanded into a fan shape already in the transmitting unit 30, so that the light beam 26, for example, covers the entire desired measuring area 42. For a security check, it is thus sufficient to scan the object 40 in a scanning direction 36 perpendicular to the linearly expanded light beam 34. The person 41 can thus be scanned, for example, from top to bottom with the expanded light beam 34.

[0156] Light-emitting regions 62 can be simultaneously detected in the line of the incident light beam 26. 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.

[0157] Figure 10 shows an example of a mask configuration for the scanning process on the person 41 according to Figure 7 for line detection.

[0158] The mask configuration of a snapshot of the scanning process is displayed in the measurement window 43. The dynamic masks 12, 14 of the mask unit 28 can advantageously be adjusted according to the three-dimensional geometry of the object 40, so that only the necessary measurement area 42 is captured.

[0159] The section 46 shown brightly in the measuring window 43 thus represents a projection of an intersection of the line plane with the object surface into the view of the receiving unit 10. Both for the detection with a point-shaped light beam shown in Figure ? and the line detection in Figure 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.

[0160] Figure 11 shows a flowchart of the method for detecting light radiation in a scanning process according to Figure 7.

[0161] The raster scan for a detection process with a point-shaped light beam 26 from the transmitting unit 30 starts with step S100. In the next step S102, the camera 22, preferably a 3D camera, captures and localizes an area 62 as the point of impact of the light beam 26 on the object 40, so that the position information can be evaluated in the next step S104.

[0162] Thereafter, the dynamic mask 12, 14 of the mask unit 28 is adjusted accordingly in step S106 so that the detection and evaluation of the induced secondary radiation 24 can take place in step S108.

[0163] Figure 12 shows a flow chart of the method for detecting light radiation in a scanning process according to Figure 9.

[0164] The method proceeds essentially like the method described in Figure 9. The difference is that no raster scan is performed with the light beam 26, but rather a line scan is performed with the expanded light beam 34 in step S200, for example, by scanning the person 41 in the vertical direction from top to bottom with the expanded light beam 34.

[0165] Here, in step S202, the camera 22 locates a location, more precisely a line, of the expanded light beam 34 on the object 40, and the position information is evaluated in step S204. For the actual detection of the secondary radiation 24 induced by the light-emitting regions 62, the dynamic mask 12, 14 of the mask unit 28 is adjusted in step S206, so that the detection and evaluation of the secondary radiation 24 can take place in step S208.

[0166] Figure 13 illustrates a system diagram of a system 100 for detecting light radiation according to an embodiment of the invention.

[0167] A central data processing system 50 receives data from photodetectors 70 of the receiving unit 30 regarding the secondary radiation 24 induced by the light beam 26 on a light-emitting region 62 of the object 40. Furthermore, the data processing system 50 receives information from the localization unit 20 regarding the location of the region 62 on the object 40 from which the secondary radiation 24 emanates. This enables the data processing system 50 to appropriately control the mask unit 28.

[0168] 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 10.

[0169] Results of the evaluation of the secondary radiation 24 can be displayed in particular on a system for virtual and / or augmented reality 60 or stored for documentation purposes.

[0170] Figure 14 shows an embodiment of a use of a system 100 for detecting light radiation when entering a portal.

[0171] Advantageously, a laser spectroscopic scanning of a moving person 41 within a defined measuring area 42 can take place without moving components. For example, the person 41 enters a portal. A laser of a transmitting unit 30 sends a light beam 26 into a measuring area 42 as soon as the person 41 enters the measuring area 42. Secondary radiation 24 is emitted by light-emitting areas 62 of the person 41, which is registered by a receiving unit 10. The system 100 adjusts a mask unit 28 so that the light emitted by the light-emitting areas 62 can be suitably detected and evaluated. The system 100 can be operated and controlled via an operating unit 88.

[0172] In this way, for example, a security check can be carried out to determine whether the person is contaminated with certain substances.

[0173] Figure 15 shows a further embodiment of a use of the system 100 for detecting light radiation in a security gate 200.

[0174] Such a system 100 can also be used, for example, in a security gate 200, for example in an airport.

[0175] By means of the proposed system 100, persons 41 can be checked for contamination or the carrying and / or adhesion of certain substances.

[0176] Specialized LIDAR applications can also be implemented with such a system 100.

[0177] Reference symbol

[0178] 10 Receiving unit

[0179] 12 dynamic mask

[0180] 14 dynamic mask

[0181] 16 Optical unit

[0182] 18 additional optical units

[0183] 20 localization unit

[0184] 22 Camera

[0185] 24 Secondary radiation

[0186] 26 light beam

[0187] 27 further ray of light

[0188] 28 Mask unit

[0189] 30 transmitter unit

[0190] 31 Transmitter unit

[0191] 32 angle range

[0192] 34 expanded light beam

[0193] 36 Scan direction

[0194] 40 objects

[0195] 41 people

[0196] 42 measuring range

[0197] 43 measuring windows

[0198] Section 46

[0199] Section 47

[0200] 50 Data processing system

[0201] 52 polarization-rotating element

[0202] 54 Delay element

[0203] 56 Polarizer

[0204] 58 Analyzer

[0205] 60 VR / AR systems

[0206] 62 light-emitting area

[0207] 64 measuring points

[0208] 65 measuring points

[0209] 66 Figure light-emitting area

[0210] 68 Figure light-emitting area

[0211] 70 Photodetector polarization-separating optical element Lens / concave mirror distance dispersive optical element Control unit System Security gate

Claims

Claims 1. A system (100) for detecting light radiation, comprising at least one transmitting unit (30) for transmitting a light beam (26) onto an object (40), at least one optical receiving 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 receiving 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 some regions, between an at least partially optically non-transmitting and at least partially optically transmitting 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) and can be guided to the photodetector (70) in the at least partially transmitting state of the at least one mask unit (28).

2. System according to claim 1, wherein at least one localization unit (20), in particular a camera (22), is provided for localizing the area (62) of the object (40) of the secondary radiation (24) induced by the light beam (26).

3. System according to claim 1 or 2, wherein the at least one mask unit (28) has at least one spatially addressable dynamic mask (12, 14) which can be switched at least regionally between at least partially optically non-transmitting and at least partially optically transmitting states.

4. System according to 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).

5. System according to 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).

6. System according to 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) that can be controlled separately from one another.

7. System according to 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).

8. System according to claim 7, wherein the further optical unit (18) is arranged in the beam path in front of 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) itself is designed to be refractive, diffractive or reflective.

9. System according to one of the preceding claims, wherein the optical receiving unit (10) comprises an array of photodetectors (70), in particular an array of photodiodes (70).

10. System according to one of the preceding claims, wherein the at least one mask unit (28) has at least one liquid crystal screen as a dynamic mask (12, 14).

11. 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-like manner in a predetermined temporal and / or spatial grid.

12. System according to one of the preceding claims, wherein the transmitting unit (30) is designed 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 spatial grid, in particular wherein the transmitting unit (30) is designed 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 spatial grid.

13. System according to 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 with 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).

14. A method for detecting light radiation using a system (100) according to any one of the preceding claims, wherein at least one transmitting unit (30) transmits a light beam (26) onto an object (40); at least one optical receiving unit (10) receives secondary radiation (24) induced by the light beam (26) in at least one region (62) of the object (40), wherein the optical receiving unit (10) comprises at least one photodetector (70), at least one mask unit (28) arranged between the object (40) and the at least one photodetector (70), and which can be switched back and forth, at least in some regions, between an at least partially optically non-transmitting and at least partially 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);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 guided to the photodetector (70) in the at least partially transmitting state of the at least one mask unit (28); 15. The 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).

16. The 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 forwarding state at a section (46, 47) at which the secondary radiation (24) impinges on the at least one dynamic mask (12, 14).

17. The 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) onto 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 delay element (54) arranged between the optical unit (16) and the polarization-separating optical element (78).

18. The method according to claim 16 or 17, wherein images (66, 68) of the light-emitting region (62) of the object (40) which are mismatched in polarization for the mask unit (28) are optically forwarded separately to 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).

19. The method according to claim 17 or 18, wherein differently circularly polarized images (66, 68) of the light-emitting region (62) of the object (40) are optically transmitted separately to the mask unit (28) via a delay element (54) arranged between the optical unit (16) and the polarization-separating optical element (78).

20. 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) from at least two light-emitting regions (62) of the object (40) are separately switched to the at least partially forwarding state, in particular wherein the secondary radiation (24) from at least two light-emitting regions (62) of the object (40) is controlled sequentially.

21. The method according to claim 20, wherein at least two light-emitting regions (62) of the object (40) are located simultaneously with the localization unit (20), in particular a camera (22).

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 in front of the at least one dynamic mask (12) and / or after 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 spectrally resolved to the second dynamic mask (14) is depicted.

23. 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 in a system for virtual and / or augmented reality (60) and / or data storage.

24. Use of a system (100) for detecting light radiation according to one of claims 1 to 13, wherein an object (40), in particular a moving object, is detected within a defined measuring range (42) with a light beam (26) of at least one transmitting 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 processed in a system for virtual and / or augmented reality (60) and / or data storage.

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