Optical device and method for a lidar system, lidar system, computer program product, data processing system and signal processing unit

Abstract

The invention relates to an optical device (100) for a polarisation lidar system (200), to a method, to a polarisation lidar system (200), to a computer program product, and to a signal processing unit (70). The device comprises an optical transmitting unit (10) for emitting a pulsed, polarised light beam (14) for rasterised scanning of an environment (110) and an optical receiving unit (30) having photodetectors for receiving a backscattered light beam (36). The receiving unit (30) determines an intensity of the backscattered light beam (36) in two polarisation planes. A signal processing unit (70) processes signals from the photodetectors. The signal processing unit (70) is designed to simultaneously generate, from the same signals, both spatial information of the environment (110) from a temporal correlation of the pulsed light beam (14), and the backscattered light beam (36), and to determine a polarisation of the backscattered light beam (36) at least for localising and / or classifying an aerosol or a plurality of aerosols.

Description

[0001] Description

[0002] Optical device and method for a lidar system, lidar system, computer program product, data processing system and signal processing unit

[0003] State of the art

[0004] The invention relates to an optical device for a lidar system and a method for operating an optical device for a lidar system, a lidar system, as well as a computer program product for a lidar system, a data processing system and a signal processing unit for a lidar system.

[0005] Lidar (short for Light Detection and Ranging) is a method for optical distance and velocity measurement, as well as for remote sensing of atmospheric parameters. It is a form of three-dimensional scanning using laser beams. Lidar systems are used in many fields. A distinction can be made between airborne systems, which are used in aircraft or satellites to create, for example, elevation models of the Earth's surface, and terrestrial systems, which are installed in vehicles or stationary installations to create, for example, terrain maps or analyze the atmosphere.

[0006] The applications of lidar systems are diverse. They can be used in agriculture for soil monitoring, in aviation for measuring wind speeds, in bathymetry to create digital elevation models of shallow water reservoirs, rivers and the seabed along the coast, or in forestry for monitoring forests and as an early warning system for forest fires.

[0007] DLR-4354WO

[0008] 2025-12-17 Furthermore, high-resolution environmental maps can be created using lidar systems for mission planning.

[0009] US Patent 11,231,502 B2 describes a lidar system that measures distance through a semi-transparent medium by distinguishing the polarization state of the scattered signal. This system receives single or multiple scattered signals from the medium, allowing combined and overlapping single or multiple scattered light signals to be separated by exploiting their different polarization properties. This eliminates the conventional limitations of laser and detector pulse width, which define the system's operating bandwidth, and translates the measurement of relative depth into the conditions of two surface time measurements, achieving sub-pulse-width resolution.

[0010] Disclosure of the invention

[0011] The purpose of the invention is to create an improved optical device for a lidar system.

[0012] Another task is to specify an improved method for operating an optical device for a lidar system.

[0013] Another task is to create a lidar system with an optical device.

[0014] Another task is to create a computer program product for a lidar system with an improved optical device.

[0015] Another task is to create a data processing system for executing such an improved procedure.

[0016] DLR-4354WO

[0017] 2025-12-17 Another task is to create a signal processing unit for an optical device of a lidar system.

[0018] The problems are solved by the features of the independent claims. Favorable embodiments and advantages of the invention become apparent from the further claims, the description, and the drawings.

[0019] According to one aspect of the invention, an optical device for a polarization lidar system is proposed, comprising an optical transmitter unit with at least one laser source for emitting a pulsed, polarized light beam, wherein the light beam is configured for raster scanning of an environment, an optical receiver unit with at least two photodetectors for receiving a light beam backscattered from the environment, wherein the optical receiver unit is configured for determining an intensity of the backscattered light beam in at least two polarization planes, and a signal processing unit for processing, in particular electrical, signals from the at least two photodetectors of the optical receiver unit.The signal processing unit is designed to simultaneously generate spatial information of the environment from the same signals based on a temporal correlation of the pulsed light beam and the backscattered light beam, as well as to determine a polarization of the backscattered light beam, at least for the localization and / or classification of one or more aerosols.

[0020] The optical device can comprise at least two analog-to-digital converters for digitizing the electrical signals from the at least two photodetectors and for forwarding the digitized signals to the signal processing unit. In each such polarization channel from the photodetector to the signal processing unit, a limiter and a resistor can be arranged between the photodetector and each analog-to-digital converter.

[0021] DLR-4354WO

[0022] 2025-12-17 This allows overvoltages to be limited, the impedance to be adjusted and saturation to be avoided in the case of hard target backscattering, so that from the same pulse signals (i) the transit time for the measurement points, in particular point cloud, and (ii) the depolarization information of the aerosol or aerosols can be determined simultaneously.

[0023] The limiters allow the electrical signals to be conditioned in a suitable way for processing in the subsequent signal processing unit, and the resistors allow the impedance to be adjusted.

[0024] The analog-to-digital converters can, for example, have a resolution of 14 bits for the digitized signals.

[0025] The proposed optical device emits laser pulses and detects the light scattered back from the surroundings. The distance to the point of scattering is determined from the travel time of the light signals. This allows spatial information, such as a contour of the surroundings, to be derived. In this way, a mapping of the environment can be performed.

[0026] Clouds and dust particles in the air (aerosols) scatter the laser light, enabling high-resolution detection and distance measurement of clouds and aerosol layers. This allows atmospheric state parameters and the concentration of atmospheric trace gases to be determined.

[0027] Depending on the wavelength of the laser light used, lidar systems are more or less sensitive to molecular scattering or particle backscattering. The strength of backscattering at a given wavelength also depends on the particle size and concentration.

[0028] DLR-4354WO

[0029] 2025-12-17 Lidar systems, which use multiple wavelengths, can therefore determine the exact size distribution of atmospheric particles.

[0030] Lidar can be used to measure a wide range of atmospheric parameters: pressure, temperature, humidity, water vapor concentration, and the concentration of atmospheric trace gases (such as ozone, nitrogen oxides, sulfur dioxide, and methane). It can also be used to determine the optical properties of aerosols and cloud particles (extinction coefficient, backscattering coefficient, and depolarization).

[0031] In a polarization lidar configuration, the depolarizing properties of aerosols can be used in atmospheric measurements to determine the type of aerosol. This allows, for example, the determination of the state of matter (liquid or solid), such as whether cloud particles contain water or ice.

[0032] The shape of aerosol and cloud particles significantly influences the scattering of light. Therefore, it is important to know the shape of the particles in order to estimate their radiation effect. Furthermore, the effect of different particle shapes on the properties of scattered light can be used to estimate the particle shape and type. This effect is exploited in polarization lidar technology.

[0033] The proposed optical device of the polarization lidar system emits a linearly polarized beam of light into the surroundings and the atmosphere, which is scattered by objects in the environment, such as elevations, as well as by various atmospheric components. The shape of these objects influences the properties of the backscattered light beam. Spherical particles in the atmosphere maintain the polarization state, while non-spherical particles change the polarization state. This process is called depolarization.

[0034] DLR-4354WO

[0035] 2025-12-17 The optical device receives parallel-polarized light (with respect to the emitted light) and perpendicular-polarized light in two separate channels. The ratio of the backscattering coefficient (ratio of emitted to backscattered intensity) of the perpendicularly polarized light to that of the parallel-polarized light yields the depolarization ratio.

[0036] This requires knowledge of the polarization-dependent transmission and reflection of the optical elements. The depolarization ratio allows conclusions to be drawn about the aerosols present in the environment and enables their classification. Furthermore, the spatial information obtained allows the location and distribution of the aerosols to be determined.

[0037] The proposed optical device can advantageously be used to create environmental maps as well as to detect, locate and characterize aerosol clouds.

[0038] In a favorable design of the optical device, the optical transmitter unit can include a preamplifier and / or an amplifier for amplifying the light beam. This allows the light beam generated by the laser source to be amplified appropriately to achieve the necessary range for detecting the surroundings.

[0039] In a favorable embodiment of the optical device, the optical transmitter unit can have an exit optic with an aperture of at least one inch. Alternatively or additionally, the laser source can have a laser wavelength between at least 1400 nm and at most 2100 nm, preferably 1550 nm. In particular, the exit optic can have at least one converging lens, preferably at least one plano-convex lens.

[0040] DLR-4354WO

[0041] 2025-12-17 In this way, the emitted light beam can be designed to be sufficiently eye-safe, so that no danger to people is caused by the light beam. The light beam can also be appropriately collimated by the exit optics.

[0042] In a favorable embodiment of the optical device, the optical receiving unit can have a beam path with a telescope, in particular with at least two converging lenses, preferably at least two aspherical lenses, for receiving the backscattered light beam. A beam splitter can be arranged in the beam path for splitting the backscattered light beam between the at least two photodetectors. At least one bandpass filter and / or a delay plate, in particular a half-wave plate, can be arranged between the telescope and the beam splitter.

[0043] The telescope allows the desired sensitivity of the optical device to be achieved. The backscattered light beam can be appropriately conditioned so that the intensities of different polarizations of the backscattered light beam can be determined using at least two photodetectors. The retardation plate allows the polarization of the light beam to be corrected for detection. The beam splitter divides the received light beam into a beam polarized parallel to the emitted light beam and a beam polarized perpendicular to it. A photodiode, for example, can be used as the photodetector to convert the optical signals into electrical signals.

[0044] DLR-4354WO

[0045] 2025-12-17 According to a favorable embodiment, the optical device can comprise at least two analog-to-digital converters for digitizing the electrical signals from the at least two photodetectors and for forwarding the digitized signals to the signal processing unit. The analog-to-digital converters can, for example, have a resolution of 14 bits for the digitized signals.

[0046] According to a favorable embodiment of the optical device, at least one limiter and / or at least one resistor, in particular a 50-ohm resistor, can be arranged between the at least two photodetectors and the at least two analog-to-digital converters for conditioning the electrical signals. The limiters condition the electrical signals for processing in the subsequent signal processing unit, and the resistors allow the impedance to be adjusted.

[0047] According to a favorable embodiment of the optical device, the signal processing unit can comprise at least: at least two input buffers for receiving the digitized signals, at least two averaging units coupled to the at least two input buffers, a memory management unit coupled to the at least two averaging units, a memory unit, in particular a dynamic RAM memory, coupled to the memory management unit, a counter configured to count averaging cycles of the averaging units, a trigger unit coupled to the counter and the averaging units, and a data processing unit coupled to the memory unit. In particular, the data processing unit can comprise at least one arithmetic unit and one server.The trigger unit can be coupled with a control unit for the optical transmitter and the data processing unit.

[0048] DLR-4354WO

[0049] On December 17, 2025, a clock in the signal processing unit (SPU) triggered both the laser source and the SPU's counter with a delay between triggering and laser pulse output. The digitized electrical signals, processed by analog-to-digital converters, were written to the input buffers in a suitable format, for example, 6250 values ​​per cycle. The next 6250 values ​​were then written to the input buffer. After a number of cycles specified by the counter had been repeated, the values ​​stored in the current input buffer were sent to the memory management unit (MMU). The counter and clock were reset to restart the process. The MMU then transferred the values ​​to the storage unit, such as a dynamic RAM.The data processing unit can retrieve the stored values ​​from the storage unit for evaluation in the computing unit. The evaluated data can then be sent via the server to the output unit, such as a PC. The server can transmit the data at a high data rate, for example, via Ethernet.

[0050] Depending on the optical device's design, the signal processing unit can incorporate an FPGA (Field Programmable Gate Array) and / or an ASIC (Application Specific Integrated Circuit) for real-time digital signal processing, or be configured as both an FPGA and / or an ASIC. Advantageously, the FPGA can include individual logic blocks whose interconnections can be programmed by the user. This allows the signal processing unit to be compact and cost-effective. Furthermore, the signal processing unit can operate with low power consumption.

[0051] DLR-4354WO

[0052] 2025-12-17 According to a favorable embodiment of the optical device, the signal processing unit can be coupled with an output unit, in particular a computer. In this way, the spatial contour of the environment as well as the localized and classified aerosols can be displayed in real time.

[0053] With a favorable design of the optical device, the exit optics of the optical transmitter and the telescope of the optical receiver can be combined into a single transmitting / receiving optic. In a compact version of the optical device, the transmitted light beam and the backscattered light beam can be guided through a common optic.

[0054] According to a further aspect of the invention, a method for operating an optical device for a polarization lidar system is proposed, comprising: emitting a pulsed, polarized light beam, wherein the light beam scans an environment in a rasterized pattern; receiving the light beam backscattered from the environment; determining the intensity of the backscattered light beam in at least two polarization planes by at least two photodetectors; processing, in particular electrical, signals from the at least two photodetectors in a signal processing unit; and generating spatial information of the environment from a temporal correlation of the pulsed light beam and the backscattered light beam.Determining the polarization of the backscattered light beam using the signal processing unit and simultaneously locating and / or classifying one or more aerosols from the determined spatial information and the determined polarization of the backscattered light beam from the same detected pulses.

[0055] DLR-4354WO

[0056] 2025-12-17 Advantageously, a limiter and a resistor can be arranged in each polarization channel from the photodetector to the signal processing unit between the photodetector and an analog-to-digital converter. This allows overvoltages to be limited, the impedance to be matched, and saturation of the downstream electronics to be avoided in the case of backscattering from a hard target, so that (i) the transit time for the measurement points, in particular the point cloud, and (ii) the depolarization information of the aerosol(s) can be simultaneously acquired from the same pulse signals.

[0057] In a favorable embodiment of the method, the electrical signals from at least two photodetectors can be digitized in at least two analog-to-digital converters, and the digitized signals can be forwarded to the signal processing unit. The analog-to-digital converters can, for example, have a resolution of 14 bits for the digitized signals.

[0058] According to a favorable embodiment of the method, the electrical signals can be conditioned by at least one limiter and / or at least one resistor, in particular a 50 ohm resistor, which are arranged between the at least two photodetectors and the at least two analog-to-digital converters.

[0059] The limiters allow the electrical signals to be conditioned in a suitable way for processing in the subsequent signal processing unit, and the resistors allow the impedance to be adjusted.

[0060] DLR-4354WO

[0061] December 17, 2025: According to the proposed method, laser pulses are emitted and the light backscattered by the environment is detected. The distance to the point of scattering is determined from the travel time of the light signals. This allows spatial information, such as a contour of the environment, to be determined. In this way, a mapping of the environment can be carried out.

[0062] Clouds and dust particles in the air (aerosols) scatter the laser light, enabling high-resolution detection and distance measurement of clouds and aerosol layers. This allows atmospheric state parameters and the concentration of atmospheric trace gases to be determined.

[0063] Depending on the wavelength of the laser light used, lidar systems are more or less sensitive to molecular scattering or particle backscattering. The strength of backscattering at a given wavelength also depends on the respective particle size and concentration. Therefore, lidar systems that utilize multiple wavelengths can determine the precise size distribution of atmospheric particles.

[0064] Lidar can be used to measure a wide range of atmospheric parameters: pressure, temperature, humidity, water vapor concentration, and the concentration of atmospheric trace gases (such as ozone, nitrogen oxides, sulfur dioxide, and methane). It can also be used to determine the optical properties of aerosols and cloud particles (extinction coefficient, backscattering coefficient, and depolarization).

[0065] In a polarization lidar configuration, the depolarizing properties of aerosols can be used in atmospheric measurements to draw conclusions about the type of aerosol. This allows, for example, the determination of the state of matter (liquid or solid, i.e., in the case of cloud particles: whether water or ice is present).

[0066] DLR-4354WO

[0067] December 17, 2025: The shape of aerosol and cloud particles significantly influences the scattering of light. Therefore, it is important to know the shape of the particles in order to estimate their radiation effect. Furthermore, the effect of different particle shapes on the properties of scattered light can be used to estimate the particle shape and type. This effect is exploited in polarization lidar technology.

[0068] According to the proposed method, a linearly polarized light beam is emitted into the surroundings and the atmosphere, where it is scattered by objects in the environment, such as elevations, as well as by various atmospheric components. The shape of these objects influences the properties of the backscattered light beam. Spherical particles in the atmosphere maintain their polarization state, while non-spherical particles change their polarization state. This process is called depolarization.

[0069] In this method, parallel-polarized light (with respect to the emitted light) and perpendicular-polarized light are received in two separate channels. The depolarization ratio is obtained by calculating the ratio of the backscattering coefficient (ratio of emitted to backscattered intensity) of the perpendicularly polarized light to that of the parallel-polarized light. This requires knowledge of the polarization-dependent transmission and reflection of the optical elements.

[0070] The depolarization ratio allows conclusions to be drawn about the aerosols present in the environment and enables their classification. The specific spatial information further allows the location and distribution of the aerosols to be determined.

[0071] DLR-4354WO

[0072] 2025-12-17 Advantageously, the proposed method can be used to create environmental maps as well as to detect, locate and characterize aerosol clouds.

[0073] In a favorable embodiment of the method, the emitted light beam can be amplified by means of a preamplifier and / or an amplifier. This allows the light beam generated by the laser source to be amplified appropriately to achieve the necessary range for detecting the surroundings.

[0074] In a favorable embodiment of the method, an exit optic with an aperture of at least one inch, and / or a laser wavelength between at least 1400 nm and at most 2100 nm, preferably 1550 nm, can be used to emit the light beam. In particular, at least one converging lens, preferably at least one plano-convex lens, can be used as the exit optic. In this way, the emitted light beam can be designed to be sufficiently eye-safe, so that no danger to humans arises from the light beam. The light beam can also be suitably collimated by the exit optic.

[0075] In a favorable embodiment of the method, the backscattered light beam can be received with a telescope, in particular with at least two converging lenses, preferably at least two aspherical lenses. The received backscattered light beam can be split by a beam splitter to the at least two photodetectors. The received backscattered light beam can be guided between the telescope and the beam splitter through at least one bandpass filter and / or a delay plate, in particular a half-wave plate.

[0076] DLR-4354WO

[0077] December 17, 2025: The telescope allows the desired sensitivity of the optical device to be achieved. The backscattered light beam can be suitably conditioned so that the intensities of different polarizations of the backscattered light beam can be determined using at least two photodetectors. The retardation plate can be used to appropriately correct the polarization of the light beam for detection. The beam splitter divides the received light beam into a beam polarized parallel to the emitted light beam and a beam polarized perpendicular to it. A photodiode, for example, can be used as a photodetector to convert the optical signals into electrical signals.

[0078] In a favorable embodiment of the method, the electrical signals from at least two photodetectors can be digitized in at least two analog-to-digital converters, and the digitized signals can be forwarded to the signal processing unit. The analog-to-digital converters can, for example, have a resolution of 14 bits for the digitized signals.

[0079] In a favorable embodiment of the method, the electrical signals can be conditioned by at least one limiter and / or at least one resistor, in particular a 50-ohm resistor, which are arranged between the at least two photodetectors and the at least two analog-to-digital converters. The limiters condition the electrical signals for suitable processing in the subsequent signal processing unit, and the resistors adjust the impedance.

[0080] DLR-4354WO

[0081] 2025-12-17 According to a favorable embodiment, the method can further comprise: receiving the digitized signals in at least two input buffers of the signal processing unit; averaging the digitized signals by at least two averaging units coupled to the at least two input buffers; forwarding the averaged digitized signals by a memory management unit coupled to the at least two averaging units; storing the averaged digitized signals in a memory unit, in particular a dynamic RAM memory, coupled to the memory management unit; counting averaging cycles of the averaging units by a counter; triggering the storage operation of the averaged digitized signals by means of a trigger unit coupled to the counter and the averaging units;Processing the averaged digitized signals by a data processing unit coupled to the storage unit; correlating the averaged digitized signals with information from a controller of the optical transmitting unit.

[0082] A clock in the signal processing unit (CPU) can trigger both the laser source and the CPU counter with a delay between triggering and laser pulse output. The digitized electrical signals in the analog-to-digital converters are written to the input buffers in a suitable format, for example, 6250 values ​​per cycle. Then, the next 6250 values ​​are written to the input buffer. After a number of cycles specified by the counter has been repeated, the values ​​stored in the current input buffer are sent to the memory management unit. The counter and clock are then reset to restart the process.

[0083] DLR-4354WO

[0084] On December 17, 2025, the memory management unit (MMU) transferred values ​​to the storage unit, such as dynamic RAM. The data processing unit (DPU) retrieved the stored values ​​from the storage unit for evaluation in the computing unit (CPU). The server then sent the evaluated data to the output unit, such as a PC. The server can transmit the data at a high data rate, for example, via Ethernet.

[0085] With a favorable implementation of the method, the backscattered light beam can be processed in real time. This enables a real-time online display of the mapped environment of the optical device and the localization and classification of detected aerosols in the environment.

[0086] In a favorable embodiment of the method, the signals processed in the signal processing unit can be transmitted to an output unit, in particular a computer. In this way, the spatial contour of the environment as well as the localized and classified aerosols can be displayed in real time.

[0087] According to a further aspect of the invention, a polarization lidar system with an optical device is proposed, wherein the optical device is arranged on a mobile system carrier, which is designed to scan a vertical and / or horizontal extent of an environment with a light beam of the optical device and to simultaneously detect a spatial contour of the environment from the same signals as well as to locate and / or classify one or more aerosols in the environment.

[0088] DLR-4354WO

[0089] 2025-12-17 In each polarization channel between the photodetector and the signal processing unit, a limiter and a resistor can be placed between the photodetector and an analog-to-digital converter. This allows overvoltages to be limited, the impedance to be matched, and saturation of the downstream electronics to be avoided in the event of backscattering from a hard target, so that (i) the transit time for the measurement points, in particular the point cloud, and (ii) the depolarization information of the aerosol(s) can be simultaneously acquired from the same pulse signals.

[0090] The proposed polarization lidar system can perform 360° terrain mapping in an unknown environment, searching for aerosol clouds in the atmosphere and characterizing them with regard to their depolarizing properties. Based on these depolarizing properties, the aerosols can be classified and assessed for potential hazards.

[0091] The system can be advantageously used, for example, in crisis areas for creating environmental maps and for situational planning. Its capabilities for aerosol trooper detection, localization, and characterization also allow the system to be used for field security.

[0092] In a favorable system design, the mobile system carrier can be a vehicle, particularly one with a telescopic arm, at the free end of which the device is mounted. The vehicle is mobile and can be moved within its environment. The telescopic arm can be mounted on a system carrier and can be retracted for movement and extended for environmental mapping. The optical device is thus protected during transport. When the telescopic arm is extended, the optical device occupies an elevated position, thereby increasing the field of view.

[0093] DLR-4354WO

[0094] December 17, 2025: With a favorable system design, the mobile system carrier can be an aircraft. On an aircraft, the optical device has greater flexibility in terms of location and can be repositioned much more quickly. Furthermore, the field of view can be significantly increased due to the greater altitude.

[0095] According to a further aspect of the invention, a computer program product for a polarization lidar system with an optical device is proposed, wherein the computer program product comprises at least one computer-readable storage medium containing program instructions that are executable on a computer system and cause the computer system to execute a method as described above. Advantageously, the method can thus be executed essentially automatically, enabling automatic online mapping of the environment with corresponding localization and classification of aerosols.

[0096] According to a further aspect of the invention, a data processing system for executing a data processing program is proposed, which includes computer-readable program instructions for carrying out a method for operating an optical device. Advantageously, the method can thus be executed essentially automatically, enabling automatic online mapping of the environment with corresponding localization and classification of aerosols.

[0097] According to another aspect of the invention, a signal processing unit for an optical device of a polarization lidar system is proposed, which includes computer-readable program instructions to execute a method for operating the optical device.

[0098] DLR-4354WO

[0099] 2025-12-17 The signal processing unit can be used to efficiently acquire data from the optical device of the polarization lidar system and to evaluate the received light beams. The electrical signals can be processed to enable online mapping of the environment with corresponding localization and classification of aerosols.

[0100] With a favorable design, the signal processing unit can be implemented as an integrated microelectronic component for real-time digital signal processing, incorporating an FPGA and / or an ASIC, or configured as a combination of both. A signal processing unit in the form of an integrated microelectronic component enables the construction of a particularly compact, energy-efficient, and cost-effective polarization lidar system for online environmental mapping with corresponding localization and classification of aerosols.

[0101] drawing

[0102] Further advantages will become apparent from the following description of the drawings. The figures illustrate exemplary embodiments of the invention. The figures, the description, and the claims contain numerous features in combination. A person skilled in the art will expediently consider the features individually and combine them into meaningful further combinations.

[0103] They show, for example:

[0104] Fig. 1 shows an optical device for a polarization lidar system according to an embodiment of the invention;

[0105] DLR-4354WO

[0106] 2025-12-17 Fig. 2 a polarization lidar system with an optical device on a mobile system carrier according to an embodiment of the invention in the retracted state;

[0107] Fig. 3 shows the polarization lidar system with the optical device on the mobile system carrier in the extended state;

[0108] Fig. 4 shows an application of the polarization lidar system in an exemplary environmental situation;

[0109] Fig. 5 shows a vertical scan of the surroundings by the polarization lidar system; and

[0110] Fig. 6 shows a horizontal scan of the surroundings by the polarization lidar system.

[0111] Embodiments of the invention

[0112] In the figures, similar or equivalent components are numbered with the same reference symbols. The figures merely show examples and are not to be understood as limiting.

[0113] The directional terminology used below, including terms like "left," "right," "above," "below," "in front," "behind," "after," and the like, serves only to improve the understanding of the figures and is in no way intended to limit their generality. The components and elements depicted, their interpretation, and their use may vary according to the considerations of a person skilled in the art and be adapted to the specific applications.

[0114] Figure 1 shows an optical device 100 for a polarization lidar system 200 according to an embodiment of the invention.

[0115] The optical device 100 comprises an optical transmitter unit 10 with a laser source 12 for emitting a pulsed, polarized light beam 14. The light beam 14 is designed for raster scanning of an environment 110.

[0116] DLR-4354WO

[0117] 2025-12-17 The optical transmitter unit 10 has a preamplifier 16 and an amplifier 18 for amplifying the light beam 14. Corresponding beam profiles 28 of the generated light beam 14 are shown as examples.

[0118] The generated and amplified light beam 14 is guided through an optical fiber 22 and an exit aperture 24 into an exit optic 26. The exit optic 26 has, for example, an aperture of at least one inch. Together with the laser wavelength between at least 1400 nm and at most 2100 nm, preferably 1550 nm, it can be ensured that the optical transmitting unit 10 is eye-safe and poses no danger to people in the vicinity.

[0119] The exit optics 26 can, for example, comprise a converging lens 27, preferably at least one plano-convex lens.

[0120] Furthermore, the optical device 100 comprises an optical receiving unit 30 with two photodetectors 32, 34 for receiving a light beam 36 backscattered from the environment 110.

[0121] The optical receiving unit 30 is designed to determine the intensity of the backscattered light beam 36 in at least two polarization planes.

[0122] The optical receiving unit 30 has a beam path 31 with a telescope 38, in particular with at least two converging lenses 40, 42, preferably at least two aspherical lenses, for receiving the backscattered light beam 36.

[0123] DLR-4354WO

[0124] 2025-12-17 In the beam path 31, a beam splitter 48 is arranged to divide the backscattered light beam 36 onto the two photodetectors 32, 34. The light beams divided by the beam splitter 48 are focused onto the photodetectors 32, 34 via corresponding converging lenses 50, 52. Each of the photodetectors 32, 34 is arranged in a polarization channel that extends to a signal processing unit 70.

[0125] Between the telescope 38 and the beam splitter 48 a bandpass filter 44 and a delay plate 46, in particular a lambda half plate 46, are arranged.

[0126] The telescope 38 achieves the desired sensitivity of the optical device 100. The backscattered light beam 36 can be suitably conditioned so that the intensities of different polarizations of the backscattered light beam 36 can be determined using the two photodetectors 32, 34. The polarization of the light beam 36 can be appropriately corrected for detection using the delay plate 46. The beam splitter 48 divides the received light beam 36 into a light beam polarized parallel to the emitted light beam 14 and a light beam polarized perpendicular to it. A photodiode, for example, can be used as a photodetector 32, 34 to convert the optical signals into electrical signals.

[0127] The exit optics 26 of the optical transmitting unit 10 and the telescope 38 of the optical receiving unit 30 can also be designed as a common transmitting / receiving optics in order to realize a particularly compact optical device 100.

[0128] Two analog-to-digital converters 62, 64 are used to digitize the electrical signals of the two photodetectors 32, 34.

[0129] DLR-4354WO

[0130] 2025-12-17 The electrical signals are first limited in voltage to the subsequent electronics by a limiter 54, 56 between the two photodetectors 32, 34 and the two analog-to-digital converters 62, 64. The impedance is adjusted accordingly by a resistor 58, 60, in particular a 50-ohm resistor.

[0131] In one so-called polarization channel, the limiter 54 is arranged between the photodetector 32 and the analog-to-digital converter 62. In the other so-called polarization channel, the limiter 64 is arranged between the photodetector 34 and the analog-to-digital converter 64.

[0132] With the limiter 62, 64 and the resistor 58, 60, overvoltages can be limited, the impedance adjusted and saturation of the subsequent electronics avoided in the case of hard target backscattering, so that from the same pulse signals (i) the transit time for the measurement points, in particular point cloud, and (ii) the depolarization information of the aerosol or aerosols can be determined simultaneously.

[0133] The signal processing unit 70 of the optical device 100 serves to process the electrical signals of the two photodetectors 32, 34 of the optical receiving unit 30.

[0134] The signal processing unit 70 is designed both to generate spatial information of the environment 110 from a temporal correlation of the pulsed light beam 14 and the backscattered light beam 36 and to determine a polarization of the backscattered light beam 36 at least for the localization and / or classification of an aerosol or several aerosols.

[0135] DLR-4354WO

[0136] 2025-12-17 The signal processing unit 70 comprises two input buffers 72, 74, i.e., one for each polarization channel, for receiving the digitized signals; two averaging units 76, 78, which are coupled to the two input buffers 72, 74; a memory management unit 80, which is coupled to the at least two averaging units 76, 78; a memory unit 82, in particular a dynamic RAM memory, which is coupled to the memory management unit 80; a counter 84, which is configured for counting averaging cycles of the averaging units 76, 78; a trigger unit 86, which is coupled to the counter 84 and the averaging units 76, 78; and a

[0137] Data processing unit 88, which is coupled to storage unit 82. Data processing unit 88 includes a computing unit 90 and a server 92. A controller 20 of the optical transmitter unit 10 is further coupled to the trigger unit 86 and data processing unit 88.

[0138] In an advantageous embodiment, the signal processing unit 70 can include an FPGA and / or an ASIC for digital real-time signal processing or be configured as an FPGA and / or an ASIC.

[0139] The optical device 100 further comprises a power supply unit 68, which, for example, provides a 5V supply 96 for the signal processing unit 70 and a 12V supply 98 for the two photodetectors 32, 34. A 24V power supply 66 is also provided for the laser source 20. The power supply unit 68 can be switched off, for example, via an emergency switch 99.

[0140] The signal processing unit 70 is further coupled to an output unit 94, in particular a computer.

[0141] DLR-4354WO

[0142] 2025-12-17 The output unit 94 can be coupled with data processing system 300, for example via Ethernet, as shown in Figure 1.

[0143] The data processing system 300 can advantageously be configured to execute a data processing program which includes computer-readable program commands to perform the above-described method for operating an optical device 100.

[0144] A computer program product can be used for the polarization lidar system 200 with the optical device 100, which includes at least one computer-readable storage medium containing program instructions that are executable on the computer system 300 and cause the computer system 300 to execute the described method.

[0145] The optical device 100 shown in Figure 1 can be operated according to the method described above.

[0146] A pulsed, polarized light beam 14 is emitted, which scans the surroundings 110 in a raster pattern. The emitted light beam 14 can advantageously be amplified by means of a preamplifier 16 and / or an amplifier 18. To use an eye-safe laser system, an exit optic 26 with an aperture of at least one inch, and / or a laser wavelength between 1400 nm and 2100 nm, preferably 1550 nm, can be used to emit the light beam 14. The exit optic 26 can, for example, comprise at least one converging lens 27, preferably at least one plano-convex lens.

[0147] DLR-4354WO

[0148] 2025-12-17 A light beam 36 backscattered from the environment 110 is received. The backscattered light beam 36 is received with a telescope 38, which may in particular have at least two converging lenses 40, 42, preferably at least two aspherical lenses.

[0149] The intensity of the backscattered light beam 36 is determined in two polarization planes by two photodetectors 32, 34. For this purpose, the received backscattered light beam 36 is split between the at least two photodetectors 32, 34 by a beam splitter 48. Prior to this, the received backscattered light beam 36 can be passed between the telescope 38 and the beam splitter 48 through at least one bandpass filter 44 and / or a delay plate 46, in particular a half-wave plate 46, and accordingly selected and corrected.

[0150] Electrical signals from the two photodetectors 32, 34 are processed in the signal processing unit 70. For this purpose, the electrical signals from the two photodetectors 32, 34 are first digitized in two analog-to-digital converters 62, 64, and the digitized signals are then forwarded to the signal processing unit 70.

[0151] The electrical signals can be further conditioned by at least one limiter 54, 56 and / or at least one resistor 58, 60, in particular a 50 ohm resistor, which are arranged between the at least two photodetectors 32, 34 and the at least two analog-to-digital converters 62, 64. The respective limiter 54, 56 in the respective polarization channel prevents saturation of the subsequent electronics when backscatter signals are detected at a so-called hard target, thus enabling the simultaneous generation of spatial information and the determination of the polarization from the same pulse signals.

[0152] DLR-4354WO

[0153] 2025-12-17 In the signal processing unit 70, the digitized signals are received in two input buffers 72 and 74. The digitized signals are averaged by two averaging units 76 and 78, which are coupled to the two input buffers 72 and 74. The averaged digitized signals are forwarded by a memory management unit 80, which is coupled to the two averaging units 76 and 78, to a memory unit 82, for example, a dynamic RAM memory, which is coupled to the memory management unit 80.

[0154] The number of averaging cycles of the averaging units 76 and 78 is controlled by a counter 84. The storage of the averaged digitized signals can be triggered by the trigger unit 86, which is coupled to the counter 84 and the input buffers 72 and 74.

[0155] The averaged digitized signals are processed by a data processing unit 88, which is coupled to the storage unit 82. The averaged digitized signals are then correlated with information from a control unit 20 of the optical transmitter unit 10.

[0156] In this way, spatial information of the environment 110 can be created from the temporal correlation of the pulsed light beam 14 and the backscattered light beam 36.

[0157] The polarization of the backscattered light beam 36 is also determined by the signal processing unit 70.

[0158] This allows aerosols to be determined from the specific spatial information as well as from the specific polarization of the backscattered light beam 36.

[0159] DLR-4354WO

[0160] 2025-12-17 The signals processed in the signal processing unit 70 can, for example, be transmitted to an output unit 94, in particular a computer.

[0161] Advantageously, the backscattered light beam 36 can be processed in real time.

[0162] The signal processing unit 70 can advantageously include computer-readable program commands to execute the described method for operating the optical device 100.

[0163] Advantageously, the signal processing unit 70 can be designed as an integrated microelectronic component for digital real-time signal processing and may include an FPGA and / or an ASIC, or be designed as an FPGA and / or an ASIC.

[0164] Figure 2 shows a polarization lidar system 200 with an optical device 100 on a mobile system carrier 210 according to an embodiment of the invention in the retracted state.

[0165] In the illustrated embodiment, the mobile system carrier 210 is a vehicle 212 having a telescopic arm 214, at the free end of which the device 100 is arranged. The telescopic arm 214 can be retracted for movement and extended for mapping the environment. The optical device 100 is thus protected during transfer.

[0166] DLR-4354WO

[0167] 2025-12-17 With the optical device 100, which is arranged on the mobile system carrier 210, an environment 110 in a vertical and / or horizontal extent can be scanned with a light beam 14 of the optical device 100 and from this both a spatial contour 220 of the environment 110 can be detected as well as an aerosol cloud 120 in the environment 110 can be located and classified.

[0168] Alternatively, the mobile system carrier 210 can also be an aircraft, for example a drone, with which the surroundings 110 can be scanned.

[0169] Figure 3 shows the polarization lidar system 200 with the optical device 100 mounted on the mobile system carrier 210 with the telescopic arm 214 extended. With the telescopic arm 214 extended, the optical device 100 assumes an elevated position, thus increasing the field of view.

[0170] Figure 4 shows the use of the polarization lidar system 200 in an exemplary environmental situation. The envelope of the light beam 14 emitted by the optical device 100 and the backscattered light beam 36 is shown as a black line.

[0171] The system carrier 210 is located in a position protected from view and simultaneously creates a terrain map as an environment contour 220 of the environment 110, which is restricted by building 122, and a site plan from the depolarization measurement, in which aerosol clouds 120 (shown as black dots) are shown, using the polarization lidar system 200.

[0172] DLR-4354WO

[0173] 2025-12-17 Figure 5 shows a vertical scan of the environment 110 by the polarization lidar system 200. A possible vertical scan range 216 is indicated. The detected scan of the environment contour 220 is shown with a dotted line.

[0174] Figure 6 shows a horizontal scan of the environment 110 by the polarization lidar system 200. Possible horizontal swivel ranges 218 are indicated. The detected grid of the environment contours 220 in the form of the buildings 122 is shown with a dotted line.

[0175] A possible application of the polarization lidar system 200 is shown in Figures 2 to 6. With the telescopic arm 214 retracted and the optical device 100 mounted in its original position, the system carrier 210 moves into a position protected from view. In this position, the telescopic arm 214 is extended, and the system 200 is switched on, as shown in Figure 4. The system 200 begins scanning the surroundings 110 vertically, as shown in Figure 5, and horizontally, as shown in Figure 6.

[0176] In this process, maps of the visible terrain are created for site planning. Additionally, the system detects and locates 200 aerosol clouds (120) in the terrain and can precisely pinpoint their position on the terrain maps. To assess the hazard situation based on the detected aerosol clouds (120), the system's depolarization measurements allow conclusions to be drawn about the composition of the aerosol clouds (120).

[0177] DLR-4354WO

[0178] 2025-12-17 Reference number

[0179] 10 optical transmitter units

[0180] 12 Laser source

[0181] 14 Light beam

[0182] 16 preamplifiers

[0183] 18 amplifiers

[0184] 20 Control

[0185] 22 optical fibers

[0186] 24 Exit aperture

[0187] 26 Exit optics

[0188] 27 Converging lens

[0189] 28 Beam profile

[0190] 30 optical receiving units

[0191] 31 Beam path

[0192] 32 Photodetector

[0193] 34 Photodetector

[0194] 36 backscattered light beam

[0195] 38 Telescope

[0196] 40 Converging lens

[0197] 42 Converging lens

[0198] 44 bandpass filters

[0199] 46 Delay plate

[0200] 48 beam splitters

[0201] 50 lens

[0202] 52 lens

[0203] 54 limiters

[0204] 56 limiters

[0205] 58 Resistance

[0206] 60 resistance

[0207] 62 Analog-to-Digital Converters

[0208] 64 Analog-to-Digital Converters

[0209] 66 Power supply 24V

[0210] DLR-4354WO

[0211] 2025-12-17 68 Power supply unit

[0212] 70 Signal processing unit

[0213] 72 input buffers

[0214] 74 Input buffers

[0215] 76 averaging unit

[0216] 78 averaging unit

[0217] 80 Memory Management Unit

[0218] 82 storage units

[0219] 84 counters

[0220] 86 trigger units

[0221] 88 Data processing unit

[0222] 90 computing units

[0223] 92 servers

[0224] 94 output units

[0225] 96 5V supply

[0226] 98 12V power supply

[0227] 99 emergency switches

[0228] 100 optical devices

[0229] 110 surroundings

[0230] 120 Aerosol cloud

[0231] 122 buildings

[0232] 200 System

[0233] 210 mobile system carriers

[0234] 212 vehicles

[0235] 214 Telescopic arm

[0236] 216 vertical swivel range

[0237] 218 horizontal swivel range

[0238] 220 captured environmental contours

[0239] 300 computer systems

[0240] DLR-4354WO

[0241] 2025-12-17

Claims

Claims 1. Optical device (100) for a polarization lidar system (200), comprising an optical transmitter unit (10) with at least one laser source (12) for emitting a pulsed, polarized light beam (14), wherein the light beam (14) is configured for raster scanning of an environment (110), an optical receiver unit (30) with at least two photodetectors (32, 34) for receiving a light beam (36) backscattered from the environment (110), wherein the optical receiver unit (30) is configured for determining an intensity of the backscattered light beam (36) in at least two polarization planes, a signal processing unit (70) for processing, in particular electrical, signals from the at least two photodetectors (32, 34) of the optical receiver unit (30), wherein the signal processing unit (70) is configuredto simultaneously generate spatial information of the environment (110) from the same signals based on a temporal correlation of the pulsed light beam (14) and the backscattered light beam (36), and to determine a polarization of the backscattered light beam (36) at least for the localization and / or classification of one or more aerosols.

2. Optical device according to claim 1, wherein the optical transmitting unit (10) comprises a preamplifier (16) and / or an amplifier (18) for amplifying the light beam (14).

3. Optical device according to claim 1 or 2, wherein the optical transmitting unit (10) has an exit optic (26) with an aperture of at least one inch, and / or DLR-4354WO 2025-12-17 wherein the laser source (12) has a laser wavelength between at least 1400 nm and at most 2100 nm, preferably 1550 nm, in particular wherein the exit optics (26) has at least one converging lens (27), preferably at least one plano-convex lens.

4. Optical device according to one of the preceding claims, wherein the optical receiving unit (30) has a beam path (31) with a telescope (38), in particular with at least two converging lenses (40, 42), preferably at least two aspherical lenses, for receiving the backscattered light beam (36), wherein a beam splitter (48) for splitting the backscattered light beam (36) onto the at least two photodetectors (32, 34) is arranged in the beam path (31), wherein at least one bandpass filter (44) and / or a delay plate (46), in particular a half-wave plate, is arranged between the telescope (38) and the beam splitter (48).

5. Optical device according to one of the preceding claims, comprising at least two analog-to-digital converters (62, 64) for digitizing the electrical signals of the at least two photodetectors (32, 34) and for forwarding the digitized signals to the signal processing unit (70).

6. Optical device according to claim 5, wherein at least one limiter (54, 56) and / or at least one resistor (58, 60), in particular a 50 ohm resistor, are arranged between the at least two photodetectors (32, 34) and the at least two analog-to-digital converters (62, 64) for conditioning the electrical signals. DLR-4354WO 2025-12-17 7. Optical device according to one of the preceding claims, wherein the signal processing unit (70) comprises at least two input buffers (72, 74) for receiving the digitized signals, at least two averaging units (76, 78) coupled to the at least two input buffers (72, 74), a memory management unit (80) coupled to the at least two averaging units (76, 78), a storage unit (82), in particular a dynamic RAM memory, coupled to the memory management unit (80), a counter (84) configured for counting averaging cycles of the averaging units (76, 78), a trigger unit (86) coupled to the counter (84) and the averaging units (76, 78), and a data processing unit (88) coupled to the storage unit (82), in particular wherein the data processing unit (88) comprises at least one arithmetic unit (90) and has a server (92),wherein the trigger unit (86) is coupled to a control unit (20) of the optical transmitter unit (10) and the data processing unit (88).

8. Optical device according to one of the preceding claims, wherein the signal processing unit (70) comprises an FPGA and / or an ASIC for digital real-time signal processing or is configured as an FPGA and / or as an ASIC.

9. Optical device according to one of the preceding claims, wherein the signal processing unit (70) is coupled to an output unit (94), in particular a computer. DLR-4354WO 2025-12-17 10. Optical device according to one of claims 3 to 9, wherein the exit optics (26) of the optical transmitting unit (10) and the telescope (38) of the optical receiving unit (30) are designed as a common transmitting / receiving optics.

11. Method for operating an optical device (100) for a polarization lidar system (200) according to one of the preceding claims, comprising Emitting a pulsed, polarized light beam (14), wherein the light beam (14) scans an environment (110) in a rasterized manner; Receiving the light beam (36) scattered back from the surroundings (110); Determining the intensity of the backscattered light beam (36) in at least two polarization planes by at least two photodetectors (32, 34); Processing of, in particular electrical, signals from at least two photodetectors (32, 34) in a Signal processing unit (70); Creating spatial information of the environment (110) from a temporal correlation of the pulsed light beam (14) and the backscattered light beam (36); Determining a polarization of the backscattered light beam (36) by the signal processing unit (70); and simultaneously from the same signals localizing and / or classifying one or more aerosols from the determined spatial information as well as from the determined polarization of the backscattered light beam (36).

12. Method according to claim 11, wherein the emitted light beam (14) is amplified by means of a preamplifier (16) and / or an amplifier (18). DLR-4354WO 2025-12-17 13. Method according to claim 11 or 12, wherein an exit optic (26) with an aperture of at least one inch is used to emit the light beam (14), and / or wherein a laser wavelength between at least 1400 nm and at most 2100 nm, preferably 1550 nm, is used, in particular wherein at least one converging lens (27), preferably at least one plano-convex lens, is used as the exit optic (26).

14. Method according to any one of claims 11 to 13, wherein the backscattered light beam (36) is received by a telescope (38), in particular with at least two converging lenses (40, 42), preferably at least two aspherical lenses, wherein the received backscattered light beam (36) is split by a beam splitter (48) onto the at least two photodetectors (32, 34), wherein the received backscattered light beam (36) is guided between the telescope (38) and the beam splitter (48) through at least one bandpass filter (44) and / or a delay plate (46), in particular a half-wave plate.

15. Method according to one of claims 11 to 14, wherein the electrical signals of the at least two photodetectors (32, 34) are digitized in at least two analog-to-digital converters (62, 64) and the digitized signals are forwarded to the signal processing unit (70).

16. Method according to claim 15, wherein the electrical signals are conditioned by at least one limiter (54, 56) and / or at least one resistor (58, 60), in particular a 50 ohm resistor, which are arranged between the at least two photodetectors (32, 34) and the at least two analog-to-digital converters (62, 64). DLR-4354WO 2025-12-17 17. Method according to any one of claims 11 to 16, further comprising Receiving the digitized signals into at least two input buffers (72, 74) of the signal processing unit (70); Averaging of the digitized signals by at least two averaging units (76, 78) which are coupled to the at least two input buffers (72, 74); Forwarding the averaged digitized signals through a memory management unit (80) which is coupled to the at least two averaging units (76, 78); Storing the averaged digitized signals in a storage unit (82), in particular a dynamic RAM memory, which is coupled to the memory management unit (80); Counting averaging cycles of the averaging units (76, 78) by a counter (84); Triggering the storage process of the averaged digitized signals by means of a trigger unit (86) which is coupled to the counter (84) and the averaging units (76, 78); Processing the averaged digitized signals by a data processing unit (88) which is coupled to the storage unit (82); Correlate the averaged digitized signals with information from a control (20) of the optical transmitting unit (10).

18. Method according to any one of claims 11 to 17, wherein the backscattered light beam (36) is processed in real time.

19. Method according to any one of claims 11 to 18, wherein the signals processed in the signal processing unit (70) are transmitted to an output unit (94), in particular a computer. DLR-4354WO 2025-12-17 20. Polarization lidar system (200) with an optical device (100) according to one of claims 1 to 10, wherein the optical device (100) is arranged on a mobile system carrier (210) which is designed to scan a vertical and / or horizontal extent of an environment (110) with a light beam (14) of the optical device (100) and to simultaneously detect a spatial contour (220) of the environment (110) from the same signals as well as to locate and / or classify an aerosol or several aerosols in the environment (110).

21. System according to claim 20, wherein the mobile system carrier (210) is a vehicle (212), in particular with a telescopic arm (214) at the free end of which the device (100) is arranged.

22. System according to claim 20, wherein the mobile system carrier (210) is an aircraft.

23. Computer program product for a polarization lidar system (200) with an optical device (100) according to one of claims 1 to 10, wherein the computer program product comprises at least one computer-readable storage medium which includes program instructions that are executable on a computer system (300) and cause the computer system (300) to execute a method according to at least one of claims 11 to 19.

24. Data processing system (300) for executing a data processing program comprising computer-readable program instructions for executing a method for operating an optical device (100) according to any one of claims 11 to 19. DLR-4354WO 2025-12-17 25. Signal processing unit (70) for an optical device (100) of a polarization lidar system (200) according to any one of claims 1 to 10, comprising computer-readable program instructions for executing a method for operating the optical device (100) according to any one of claims 11 to 19.

26. Signal processing unit according to claim 25, configured as an integrated microelectronic component for digital real-time signal processing, comprising an FPGA and / or an ASIC or configured as an FPGA and / or as an ASIC. DLR-4354WO 2025-12-17

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