Hyperspectral laser radar optical receiving system and detection method and detection system thereof

Abstract

The invention relates to a hyperspectral laser radar optical receiving system and a detection method and a detection system thereof, and the detection method comprises the steps: a monochromator separates light beams with different wavelengths from a specific light source, transmits the light beams to an optical signal receiving unit in a to-be-detected laser radar system, and emits monochromatic light rays with different wavelengths to corresponding optical fibers; spectral scanning is carried out on the detection channel corresponding to each single-tube detector, spectral responsivity curves of all the detection channels are obtained, and the bandwidth of each detection channel is partially overlapped with the bandwidths of the left and right adjacent detection channels; and acquiring the central wavelength and bandwidth of the corresponding channel according to the spectral responsivity curves of all the detection channels, and determining the spectral coverage range of the laser radar system and / or the spectral resolution of all the detection channels and / or determining whether the optical fiber is damaged and determining the position of the damaged optical fiber. According to the method, theoretical design parameters of the hyperspectral laser radar can be verified, and particularly design deviation occurring in a specific detection channel can be subjected to key analysis.

Description

Technical Field

[0001] The present invention relates to the technical field of laser radar, and in particular to a hyperspectral laser radar optical receiving system and a detection method and a detection system thereof. Background Art

[0002] As an important air-to-earth observation technology, airborne LiDAR technology plays an increasingly important role in many applications such as forest remote sensing, environmental monitoring, urban planning, and ocean exploration through active laser remote sensing detection combined with technologies such as the Global Positioning System (GPS) and the Inertial Navigation System (IMU). As the core means of earth observation, remote sensing technology has gradually developed into a comprehensive technical system covering passive multispectral imaging, hyperspectral imaging, LiDAR remote sensing, and other means in terms of information acquisition technology. It can be carried on multiple platforms such as ground, aerospace, and aviation for earth observation. At the same time, in order to cope with many difficulties and challenges arising in the process of global environmental change, rapid urban development, and national defense construction. Realizing full-band, all-day, all-weather, and high-spectral resolution earth observation is an important opportunity for the development of remote sensing technology. In particular, the high-resolution integrated acquisition and application of three-dimensional information and spectral information of the target space is a frontier scientific problem that needs to be solved in the development of earth observation technology.

[0003] Among the remote sensing technologies currently used, both active and passive remote sensing detection methods have shown unique advantages. Active laser radar ranging can achieve all-day, high-resolution three-dimensional information acquisition of ground objects. However, due to the limited ability of laser radar to acquire target spectral physical property information due to its single-wavelength detection mechanism, its application is restricted to a certain extent. Passive hyperspectral imaging can obtain rich high-resolution spectral information, but its imaging mechanism is greatly affected by factors such as weather and light, and its spatial information detection ability is weak. The existing active and passive remote sensing technologies have outstanding advantages in one aspect, but there are certain deficiencies in the simultaneous acquisition of spatial three-dimensional information and spectral information. Therefore, facing the demand for integrated acquisition of high-resolution three-dimensional spatial information and spectral information of ground objects, while retaining the spatial detection advantages of airborne laser radar, developing new remote sensing technologies to enhance the spectral detection capability of laser radar has become an important direction for the development of remote sensing technology. Among them, by increasing the number of laser radar detection bands to improve the spectral acquisition capability, and then truly combining the advantages of active and passive remote sensing technologies on one sensor, the integrated acquisition of high-resolution three-dimensional spatial information and spectral information of the target is successfully achieved, which has become a research hotspot at home and abroad. Aiming at the integrated acquisition demand of earth observation remote sensing information, airborne hyperspectral laser radar has developed into a new type of active remote sensing detection technology, which can achieve full waveform data acquisition of dozens or even hundreds of spectrum bands of ground object targets, and has the ability to detect all day, all weather, full spectrum and high spatial resolution. However, during the use of the system, data anomalies occurred, and the performance evaluation of the hyperspectral laser radar optical receiving system urgently needs to be solved. Summary of the invention

[0004] In order to solve the above technical problems, the present invention proposes a hyperspectral laser radar optical receiving system and a detection method and a detection system thereof. The specific technical solutions are as follows:

[0005] A detection method for a hyperspectral laser radar optical receiving system comprises the following steps:

[0006] The monochromator separates light beams of different wavelengths from a specific light source and transmits them to the optical signal receiving unit in the laser radar system to be tested. The monochromatic light beams of different wavelengths are incident on the corresponding optical fiber, and the spectrum of the detection channel corresponding to each single-tube detector is scanned to obtain the spectrum responsivity curves of all detection channels, wherein the bandwidth of each detection channel partially overlaps with the bandwidth of the detection channels adjacent to the left and right.

[0007] The central wavelength and bandwidth of the corresponding channel are obtained according to the spectral responsivity curves of all detection channels, and the spectral coverage of the lidar system and / or the spectral resolution of all detection channels and / or whether the optical fiber is damaged and the position of the damaged optical fiber are determined.

[0008] Optionally, obtaining spectral responsivity curves of all detection channels comprises the following steps:

[0009] The light beams of different wavelengths separated from the specific light source by the monochromator are emitted into the calibration detector, the detector signal is obtained, and the spectral responsivity and output signal intensity of the corresponding channel of the calibration detector are obtained;

[0010] Obtaining the output signal intensity of the detection channel corresponding to each single-tube detector based on the light beam emitted by the monochromator to the optical signal receiving unit;

[0011] According to the relative spectral responsivity of the standard detector and the output signal intensity of the standard detector;

[0012] Calculate and obtain the spectral responsivity of each single-tube detector corresponding to the detection channel of the laser radar system to be tested.

[0013]

[0014] Optionally, obtaining the central wavelength and bandwidth of the corresponding channel according to the spectral responsivity curves of all detection channels to determine the coverage of the spectrum includes the following steps:

[0015] Count the spectral responsivity curves of all detection channels to obtain the central wavelength and bandwidth of the corresponding channels;

[0016] The spectral coverage of the lidar system is determined based on the minimum central wavelength and the maximum central wavelength, and the bandwidth of the lidar system is determined based on the bandwidth fitting of all detection channels.

[0017] Optionally, determining whether the optical fiber is damaged according to the spectral responsivity curves of all detection channels includes the following steps:

[0018] Obtain spectral responsivity curves corresponding to all detection channels and compare them with theoretical corresponding curves; when the spectral responsivity curve of the first detection channel is deformed to a greater extent than a set degree, determine whether the spectral response wavelength of the first detection channel is within a first set wavelength range, and when it is within the first set wavelength range, determine that the optical fiber is damaged; the first set wavelength range is the wavelength range corresponding to the first detection channel when the responsivity change rate of the first detector is less than a first set value.

[0019] Optionally, determining the location of the damaged optical fiber comprises the following steps:

[0020] Obtaining spectral responsivity curves of the left and right detection channels of the first detection channel;

[0021] According to the same wavelength, when it is determined that the degree of overlap between the spectral responsivity curve of the first detection channel and the spectral responsivity curve of the left detection channel is less than a first set range, it is judged that the optical fiber adjacent to the left detection channel in the first detection channel is damaged; when it is determined that the degree of overlap between the spectral responsivity curve of the first detection channel and the spectral responsivity curve of the right detection channel is less than a second set range, it is judged that the optical fiber adjacent to the right detection channel in the first detection channel is damaged, otherwise the optical fiber in the middle is damaged.

[0022] A hyperspectral laser radar optical receiving system using the above detection method includes a continuous spectrum laser light source, an optical signal receiving unit, and a signal acquisition and processing unit;

[0023] The optical signal receiving unit is used to receive the light beam reflected after being emitted by the continuous spectrum laser light source to the ground target object and the light beams of different wavelengths separated from the specific light source by the monochromator and perform optical processing;

[0024] The signal acquisition processing unit comprises

[0025] Optical fibers designed in parallel are used to receive wavelengths output in parallel;

[0026] A plurality of single-tube detectors, each of which is matched and connected with at least three adjacent optical fibers, for receiving light beams of all wavelengths and processing them to obtain electrical signals;

[0027] The computer obtains the electrical signals of all single-tube detectors for processing.

[0028] Optionally, the single-tube detector includes a PMT detector and an APD detector.

[0029] Optionally, the optical signal receiving unit includes:

[0030] an off-axis parabolic mirror for receiving the light beam;

[0031] A small aperture diaphragm to limit stray light that can act as infection;

[0032] Grating spectrometer is used to suppress stray light and output light beams in parallel according to wavelengths through a transmission grating into optical fibers designed in parallel.

[0033] A detection system using the above detection method comprises

[0034] A specific light source is used to provide a light beam within a certain wavelength range;

[0035] A monochromator separates light beams of different wavelengths from a particular light source;

[0036] The standard detector is used to receive the light beam emitted by the monochromator and process it to form an electrical signal, and then send the detected electrical signal to the computer.

[0037] Optionally, the specific light source is a halogen lamp.

[0038] The advantages of the present invention are that the present invention can verify the theoretical design parameters of the hyperspectral lidar optical receiving system, evaluate the performance of the hyperspectral lidar optical receiving system, and especially focus on analyzing the design deviations occurring in specific detection channels. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Schematic diagram of the optical receiving system for hyperspectral lidar measurements using a monochromator.

[0040] Figure 2 Schematic diagram of halogen lamp calibration using a monochromator and a calibration detector.

[0041] FIG3( a ) is a schematic diagram showing the distribution of 168 optical fibers in an embodiment.

[0042] FIG3( b ) is a schematic diagram of a monochromatic light spot filled with an optical fiber.

[0043] Figure 3(c) is a graph showing the spectral response of a single detection channel.

[0044] Figure 4 This is a graph showing the laboratory test results of the hyperspectral lidar optical receiving system.

[0045] Figure 5 This is the relative spectral responsivity diagram of the hyperspectral lidar optical receiving system under normal conditions.

[0046] Figure 6 This is the spectrum coverage result diagram of the hyperspectral lidar optical receiving system.

[0047] FIG7( a ) is a diagram showing the relative spectral responsivity of some channels of the optical receiving system of the hyperspectral laser radar when the detector responsivity is not stable;

[0048] Figure 7(b) shows the calibration responsivity curves of the detector for three different signals.

[0049] Figure 8 This is the relative spectral responsivity diagram of the abnormal channel.

[0050] Fig. 9 Spectral responsivity diagram of abnormal channel 17 and adjacent detection channels 16 and 18 on the left and right.

[0051] Fig.10 Schematic diagram of the structure of the hyperspectral lidar optical receiving system.

[0052] In the figure:

[0053] 1. LiDAR system; 11. Continuous spectrum laser light source; 121. Off-axis parabolic mirror; 122. Reflector; 123. Pinhole aperture; 124. Grating spectrometer; 131. Optical fiber; 132. Single-tube detector; 2. Data acquisition card; 3. Computer; 41. Halogen lamp; 42. Power supply; 43. Monochromator; 44. Standard detector; 45. Impedance. DETAILED DESCRIPTION

[0054] With the development of LiDAR systems, how to detect some actual parameters of LiDAR, there is a risk of system damage during use, and how to detect the system and determine system problems is an important task. When the LiDAR system uses optical fiber to transmit light beams, the optical fiber is easy to break, and most of the breaks cannot obtain information from the surface. How to obtain some real parameters of the LiDAR system and find the broken optical fiber from a large number of optical fibers is a technical problem that needs to be solved urgently.

[0055] In order to solve the above problems, the present application discloses a detection method of a hyperspectral laser radar optical receiving system, comprising the following steps:

[0056] The monochromator separates light beams of different wavelengths from a specific light source and transmits them to the optical signal receiving unit in the laser radar system to be tested. The monochromatic light beams of different wavelengths are incident on the corresponding optical fiber, and the spectrum of the detection channel corresponding to each single-tube detector is scanned to obtain the spectrum responsivity curves of all detection channels, wherein the bandwidth of each detection channel partially overlaps with the bandwidth of the detection channels adjacent to the left and right.

[0057] The central wavelength and bandwidth of the corresponding channel are obtained according to the spectral responsivity curves of all detection channels, and the spectral coverage of the lidar system and / or the spectral resolution of all detection channels and / or whether the optical fiber is damaged and the position of the damaged optical fiber are determined.

[0058] The spectral resolution of this hyperspectral imaging lidar system is different from the uniform distribution of spectra in each channel of traditional passive hyperspectral measurement instruments. The optical receiving system of this hyperspectral lidar adopts multi-fiber spectroscopy technology to ensure that the spectral resolution of each channel can be designed according to the application requirements of ground object classification.

[0059] The spectral resolution of the hyperspectral lidar optical receiving system is determined by the passband width of each spectral channel and is usually described by the half-peak width.

[0060] Wherein, obtaining the spectral responsivity curves of all detection channels includes the following steps:

[0061] The light beams of different wavelengths separated from the specific light source by the monochromator are emitted into the calibration detector, the detector signal is obtained, and the spectral responsivity and output signal intensity of the corresponding channel of the calibration detector are obtained;

[0062] Obtain the output signal intensity V(λ) of the detection channel corresponding to each single-tube detector based on the monochromator emitting the light beam to the optical signal receiving unit LiDAR ;

[0063] According to the relative spectral responsivity R(λ) of the standard detector Std And the output signal strength V(λ) of the standard detector Std ;

[0064] Calculate and obtain the spectral responsivity R(λ) of each single-tube detector corresponding to the detection channel of the laser radar system to be tested.

[0065]

[0066] The wavelength value when the maximum value of the spectral response is 50% is the starting wavelength and ending wavelength of the channel. The wavelength range surrounded by the starting wavelength of the first channel and the ending wavelength of the last channel is the spectral range of the hyperspectral laser radar optical receiving system.

[0067] This application obtains the central wavelength and bandwidth of the corresponding channel by obtaining the spectral response curves of all detection channels, such as Figure 4 As shown in the figure, the central wavelength and bandwidth of each channel of a hyperspectral lidar optical receiving system were obtained through experimental testing.

[0068] The spectral resolution of most receiving channels of the hyperspectral laser radar optical receiving system is about 9nm. The results show that the theoretical calculation value and the results obtained by actual testing are basically consistent. In this embodiment, the optical signals of three optical fibers are coupled to the target surface of a detector in the laser radar system, and the spectral resolution of each optical fiber is about 3nm. In actual airborne flight tests, wavelength selection can be performed according to the actual situation of the ground object target, and the bandwidth and center wavelength of each channel can be flexibly set. The spectral resolution of 3nm of a single optical fiber can accurately classify the spectrum of most ground objects. When the hyperspectral laser radar optical receiving system works during the day when the sky background light is strong, coupling three optical fibers to one detection channel can also further improve the signal-to-noise ratio of each channel. It is ensured that the hyperspectral laser radar optical receiving system can achieve all-day detection.

[0069] Combination Figure 4 The corresponding table shows the laboratory test results of the hyperspectral lidar optical receiving system. According to the minimum center wavelength and the maximum center wavelength, the spectral coverage of the lidar system is determined, and the following is obtained: Figure 5The graph of the central wavelength coverage of all detection channels of the hyperspectral laser radar shown in Figure 1 is shown. The results show that the spectrum of the optical receiving system of the hyperspectral laser radar covers 400-900nm. According to the bandwidth fitting of all detection channels, the bandwidth of all detection channels of the hyperspectral laser radar is about 9nm. The processing accuracy of adjacent optical fibers will lead to slight differences in the bandwidth between the detection channels. The spectral accuracy of the transmission grating used in the optical receiving system of the hyperspectral laser radar will also lead to bandwidth differences between the detection channels. In addition, the processing accuracy of each optical component of the system is also one of the reasons.

[0070] From the above, it can be seen that in order to achieve detection, this application uses a monochromator to complete the scanning of all detection channels of the hyperspectral laser radar optical receiving system to determine the spectral coverage of each channel. Then, in order to eliminate the influence of the energy difference caused by the halogen light source after the monochromator splits the light on the laboratory test accuracy, the self-calibration of the paired halogen light source is used. The entire test work is completed in a dark room.

[0071] When testing the hyperspectral lidar optical receiving system in the laboratory, it is mainly divided into two parts: spectral band scanning and data synchronization acquisition and processing. The light emitted by the monochromator is directly incident on the hyperspectral lidar optical receiving system through the window of the telescope of the optical signal receiving unit. After being split by the grating spectrometer, the monochromatic light of different wavelengths is incident on the corresponding optical fiber. The monochromator is controlled by a computer to perform step scans on all detection channels respectively, and the other end of the optical fiber is directly coupled to the detector. The acquisition card is controlled by a computer, and the acquisition card transmits the collected signals to the computer for real-time storage. Through the control of the time domain, the synchronization of the monochromator light output and the acquisition card acquisition signal is achieved.

[0072] In this application, in order to diagnose whether the optical fiber is broken, it is determined at which specific position of the optical fiber filament has an abnormality. The invention can verify the theoretical design parameters of the hyperspectral laser radar, evaluate the performance of the hyperspectral laser radar prototype system, and especially focus on analyzing the design deviations in specific detection channels.

[0073] Determining whether the optical fiber is damaged based on the spectral responsivity curves of all detection channels includes the following steps:

[0074] Obtain the spectral responsivity curves corresponding to all detection channels and compare them with the theoretical corresponding curves; when the spectral responsivity curve of the first detection channel is deformed to a greater extent than the set degree, determine whether the spectral response wavelength of the first detection channel is within the first set wavelength range, and when it is within the first set wavelength range, determine that the optical fiber is damaged; the first set wavelength range is the wavelength range corresponding to the first detector responsivity change rate corresponding to the first detection channel is less than the first set value. When it is outside the first set range, it means that the wavelength where the detector is located is in the band where the detector detection wavelength is not stable. It is not caused by optical fiber damage, as shown in Figure 7, where the spectral responsivity of channels 1-channel 5 shows that when the wavelength is less than 400nm, the spectral curve is deformed to a greater extent than the set degree. According to the detector responsivity curve of Figure 7 (b), it can be seen that the change rate of the wavelength between 400-500nm is much smaller than the change rate of the wavelength less than 400nm and the wavelength greater than 500nm. Therefore, the spectral deformation of channels 1-channel 4 is not due to optical fiber breakage, but due to the performance of the detector itself.

[0075] Locating the damaged fiber includes the following steps:

[0076] Obtaining spectral responsivity curves of the detection channels on the left and right sides of the first detection channel;

[0077] According to the same wavelength, when it is determined that the degree of overlap between the spectral responsivity curve of the first detection channel and the spectral responsivity curve of the left detection channel is less than a first set range, it is judged that the optical fiber adjacent to the left detection channel in the first detection channel is damaged; when it is determined that the degree of overlap between the spectral responsivity curve of the first detection channel and the spectral responsivity curve of the right detection channel is less than a second set range, it is judged that the optical fiber adjacent to the right detection channel in the first detection channel is damaged, otherwise the optical fiber in the middle is damaged.

[0078] against Figure 4 Normal detection channel such as Figure 6 As shown in the figure, the bandwidth of some abnormal detection channels is about 5nm. Analysis shows that it may be caused by the breakage of optical fiber. Figure 8 As shown in the figure, the relative spectral responsivity curves of channel 17, channel 25, channel 40, channel 44, and channel 53 are fitted. The results show that there are only two peak inflection points for each of the five channels. The two peak inflection points in channel 53 show an obvious downward trend, and the reason for the analysis is consistent with that in the ultraviolet band. In the near-infrared band, the conversion efficiency of the detector also shows a downward trend.

[0079] Taking the hyperspectral lidar optical receiving system using 168 optical fibers as an example, there are 56 single-tube detectors, including PMT detectors and APD detectors, and each single-tube detector corresponds to 3 optical fibers.

[0080] Taking channel 17 as an example, the causes of bandwidth abnormality are analyzed, such as Fig. 9 As shown, a comparative analysis is performed in combination with the spectral response fitting curves of adjacent channels 16 and 18. The central wavelength of channel 16 is 526.5nm, and the bandwidth is 8.9nm. The central wavelength of channel 17 is 534.2nm, and the bandwidth is 6nm. The central wavelength of channel 18 is 544.9nm, and the bandwidth is 8.7nm. Since a single detection channel is coupled with three optical fibers, the reason for the bandwidth anomaly is that one of the optical fibers is broken. By comparing and analyzing the adjacent channels, it is obvious that the reason for the bandwidth anomaly of channel 17 is that the optical fiber in the direction of the infrared band is broken, that is, Fig. 9 The optical fiber on the right side of the center is abnormal.

[0081] like Figure 1 and Fig.10 As shown, the present application also discloses a hyperspectral laser radar optical receiving system using the above detection method, including a continuous spectrum laser light source 11, an optical signal receiving unit, and a signal acquisition processing unit;

[0082] The optical signal receiving unit is used to receive the light beam reflected after being emitted by the continuous spectrum laser light source 11 to the ground target object and the light beams of different wavelengths separated from the specific light source by the monochromator 43 and perform optical processing;

[0083] The signal acquisition and processing unit includes optical fibers 131 and multiple single-tube detectors 132 designed in parallel. The optical fibers 131 designed in parallel are used to receive wavelengths output in parallel; each single-tube detector 132 in the multiple single-tube detectors 132 is matched and connected with at least three adjacent optical fibers 131 to receive light beams of all wavelengths and process them to obtain electrical signals; the computer 3 in the subsequent processing part obtains the electrical signals of all single-tube detectors 132 through the data acquisition card 2 for processing.

[0084] The optical signal receiving unit includes an off-axis parabolic mirror 121, a reflector 122, a pinhole diaphragm 123, and a grating spectrometer 124, which are arranged in sequence according to the optical path. The off-axis parabolic mirror 121 has no central obstruction, and can make full use of the effective receiving area of ​​the mirror to reflect the echo signal, which can solve the problems of weak echo signals and small field of view reception of the hyperspectral laser radar optical receiving system 1. At the same time, a high-reflection film is evaporated on the surface of the off-axis parabolic mirror 121 to further improve the echo signal reception efficiency. The pinhole diaphragm 123 can limit the receiving field of view of the hyperspectral laser radar optical receiving system 1, and play a certain limiting role on the sky background light and system stray light. The grating spectrometer 124 includes a transmission grating spectrometer and a telecentric focusing lens to form the grating spectrometer 124 structure of the hyperspectral laser radar optical receiving system 1. In order to further suppress stray light signals, the telecentric focusing lens is consistent with the numerical aperture of the hyperspectral laser radar optical receiving system.

[0085] In this solution, the single tube detector 132 includes a PMT detector and an APD detector. Specifically, the laser radar system 1 uses a PMT detector with higher quantum efficiency in the short-wave band for detection of extremely weak signals. In particular, the PMT detector selected in the ultraviolet band is a Hamamatsu PMT detector, model H10721-210. The quantum conversion efficiency of the detector in the ultraviolet band rises sharply, which is also the main reason why the peak point of a single detection channel of the hyperspectral laser radar optical receiving system 1 in the ultraviolet band shows an upward trend.

[0086] In the laser radar system 1, the optical signals of three optical fibers 131 are coupled to the target surface of a detector. The spectral resolution of each optical fiber 131 is about 3nm. In this scheme, 168 optical fibers 131 are used. As shown in FIG3(a), the core diameter of a single optical fiber 131 is 0.4mm, and the interval between adjacent optical fibers 131 is 0.57mm. In the theoretical derivation process, taking the spectral channel with a central wavelength of 650nm as an example, according to the design parameters of the optical receiving system of the hyperspectral laser radar, the diameter of the monochromatic spot is calculated to be about 0.47mm, which basically fills the core diameter of the single optical fiber 1310.4mm. As shown in FIG3(b), the red spot represents the spot size of the 650nm monochromatic light after passing through the optical receiving system of the hyperspectral laser radar. Since the end face of the optical fiber 131 is facing the focal plane of the telecentric focusing lens, when the light emitted by the monochromator 43 is scanned at an interval of 0.2nm, the monochromatic spot needs to scan all optical fibers 131 of the single channel. Through theoretical simulation, the single-channel spectral responsivity curve can be obtained as shown in Figure 3(c).

[0087] It should be noted that a hyperspectral lidar optical receiving system is used in this application, and this application is applicable to all lidar systems.

[0088] Combination Figure 1 and Figure 2 The present application also discloses a detection system using the above detection method, including a specific light source, a monochromator 43, and a standard detector 44. The specific light source is used to provide a light beam within a certain wavelength range; the monochromator 43 separates light beams of different wavelengths from the specific light source. In this embodiment, the specific light source includes a halogen lamp 41 and a power supply 42 for providing electrical energy to the halogen lamp 41; the standard detector 44 is used to receive the light beam emitted by the monochromator 43 and process it to form an electrical signal, and collect the detected electrical signal through the data acquisition card 2 and send it to the computer 3. Optimally, an impedance 45 is provided between the standard detector 44 and the data acquisition card 2.

[0089] The detection system is mainly divided into spectral scanning of the laser radar system 1 and self-calibration of the halogen lamp 41. First, the monochromator 43 is used to complete the scanning of all detection channels of the hyperspectral laser radar optical receiving system 1 to determine the spectral coverage of each channel. Then, in order to eliminate the influence of the energy difference caused by the halogen lamp 41 light source after the monochromator 43 splits the light on the laboratory test accuracy, the self-calibration of the paired halogen lamps 41 is used. The entire test work is completed in a dark room.

[0090] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A detection method for a hyperspectral laser radar optical receiving system, characterized in that: The following steps are involved: The monochromator separates light beams of different wavelengths from a specific light source and transmits them to the optical signal receiving unit in the laser radar system to be tested. The monochromatic light beams of different wavelengths are incident on the corresponding optical fiber, and the spectrum of the detection channel corresponding to each single-tube detector is scanned to obtain the spectrum responsivity curves of all detection channels, wherein the bandwidth of each detection channel partially overlaps with the bandwidth of the detection channels adjacent to the left and right. The central wavelength and bandwidth of the corresponding channel are obtained according to the spectral responsivity curves of all detection channels, and the spectral coverage of the lidar system and / or the spectral resolution of all detection channels and / or whether the optical fiber is damaged and the position of the damaged optical fiber are determined.

2. The detection method according to claim 1, characterized in that: Obtaining the spectral responsivity curves of all detection channels includes the following steps: The light beams of different wavelengths separated from the specific light source by the monochromator are emitted into the calibration detector, the detector signal is obtained, and the spectral responsivity and output signal intensity of the corresponding channel of the calibration detector are obtained; Obtain the output signal intensity V(λ) of the detection channel corresponding to each single-tube detector based on the monochromator emitting the light beam to the optical signal receiving unit LiDAR ; According to the relative spectral responsivity R(λ) of the standard detector Std And the output signal strength V(λ) of the standard detector Std ; Calculate and obtain the spectral responsivity R(λ) of each single-tube detector corresponding to the detection channel of the laser radar system to be tested.

3. The detection method according to claim 1 or 2, characterized in that: The central wavelength and bandwidth of the corresponding channel are obtained according to the spectral responsivity curves of all detection channels, and the coverage of the spectrum is determined, including the following steps: Count the spectral responsivity curves of all detection channels to obtain the central wavelength and bandwidth of the corresponding channels; The spectral coverage of the lidar system is determined based on the minimum central wavelength and the maximum central wavelength, and the bandwidth of the lidar system is determined based on the bandwidth fitting of all detection channels.

4. The detection method according to claim 3, characterized in that: Determining whether the optical fiber is damaged based on the spectral responsivity curves of all detection channels includes the following steps: Obtain spectral responsivity curves corresponding to all detection channels and compare them with theoretical corresponding curves; when the spectral responsivity curve of the first detection channel is deformed to a greater extent than a set degree, determine whether the spectral response wavelength of the first detection channel is within a first set wavelength range, and when it is within the first set wavelength range, determine that the optical fiber is damaged; the first set wavelength range is the wavelength range corresponding to the first detection channel when the responsivity change rate of the first detector is less than a first set value.

5. The detection method according to claim 4, characterized in that: Locating the damaged fiber includes the following steps: Obtaining spectral responsivity curves of the left and right detection channels of the first detection channel; According to the same wavelength, when it is determined that the degree of overlap between the spectral responsivity curve of the first detection channel and the spectral responsivity curve of the left detection channel is less than a first set range, it is judged that the optical fiber adjacent to the left detection channel in the first detection channel is damaged; when it is determined that the degree of overlap between the spectral responsivity curve of the first detection channel and the spectral responsivity curve of the right detection channel is less than a second set range, it is judged that the optical fiber adjacent to the right detection channel in the first detection channel is damaged, otherwise the optical fiber in the middle is damaged.

6. A hyperspectral laser radar optical receiving system using the detection method according to any one of claims 1 to 5, characterized in that: It includes a continuous spectrum laser light source, an optical signal receiving unit, and a signal acquisition and processing unit; The optical signal receiving unit is used to receive the light beam reflected after being emitted by the continuous spectrum laser light source to the ground target object and the light beams of different wavelengths separated from the specific light source by the monochromator and perform optical processing; The signal acquisition processing unit comprises Optical fibers designed in parallel are used to receive wavelengths output in parallel; A plurality of single-tube detectors, each of which is matched and connected with at least three adjacent optical fibers, for receiving light beams of all wavelengths and processing them to obtain electrical signals; The computer obtains the electrical signals of all single-tube detectors for processing.

7. The hyperspectral laser radar optical receiving system according to claim 6, characterized in that: The single-tube detector includes a PMT detector and an APD detector.

8. The hyperspectral laser radar optical receiving system according to claim 7, characterized in that: The optical signal receiving unit includes: an off-axis parabolic mirror for receiving the light beam; A small aperture diaphragm to limit stray light that can act as infection; Grating spectrometer is used to suppress stray light and output light beams in parallel according to wavelength through a transmission grating into parallel designed optical fibers.

9. A detection system using the detection method according to any one of claims 1 to 6, characterized in that: include A specific light source is used to provide a light beam within a certain wavelength range; A monochromator separates light beams of different wavelengths from a particular light source; The standard detector is used to receive the light beam emitted by the monochromator and process it to form an electrical signal, and then send the detected electrical signal to the computer.

10. The detection system according to claim 9, characterized in that: The specific light source is a halogen lamp.

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