Optical efficiency adjusting method of laser radar coaxial transceiver system

Abstract

The invention discloses an optical efficiency adjusting method of a laser radar coaxial transmit-receive system, which comprises transmit-receive system parameter design and device assembly position adjustment, and the transmit-receive system parameter design comprises through hole reflector parameter design, collimator parameter design and focusing lens parameter design. The device assembly position adjustment comprises position adjustment of a collimator and a through hole reflector of the transmitting unit, position adjustment of a through hole reflector and a focusing lens of the receiving unit, and position adjustment of the focusing lens and a photoelectric detector of the receiving unit. The transmitting light and the receiving light are calibrated through the coaxial target, so that the transmitting light and the receiving light are coaxial, the position of the photoelectric detector corresponding to the maximum amplitude of the received signal is determined to be the optimal focusing position by adjusting the position of the photoelectric detector, and effective adjustment of the optical efficiency of the laser radar coaxial transmitting and receiving system is achieved. According to the method, optimal adjustment of the optical efficiency of the coaxial laser radar system is realized through parameter design of a transmitting and receiving system and linkage adjustment of a device assembly position.

Description

Technical Field

[0001] The present invention relates to the field of laser radar measurement, and in particular to an optical efficiency adjustment method for a laser radar coaxial transceiver system. The laser radar coaxial transceiver system is composed of a laser emitting unit and a receiving unit. The optical efficiency adjustment method realizes effective adjustment of the optical efficiency of the laser radar coaxial transceiver system by optimizing the design of transceiver system parameters and selecting the optimal assembly position of the device. Background Art

[0002] LiDAR technology is an intelligent remote sensing technology that can accurately obtain the distance and shape information of objects. It is widely used in environmental monitoring, intelligent perception, and autonomous driving. Three-dimensional imaging LiDAR usually uses pulse measurement method for ranging, that is, the laser emits a pulse laser to the detection target at the time of emission. After the pulse laser reaches the target surface, it generates a target backscattered echo signal due to target scattering. The backscattered echo signal is transmitted through the LiDAR transceiver system and converged to the detector at the time of reception through the focusing lens. The distance measurement is achieved by measuring the difference between the emission time and the reception time. Traditional LiDAR only stores the echo points that reach the set threshold, which simplifies the data volume to a certain extent but also loses some waveform information. Three-dimensional imaging LiDAR can fully record the waveform position and amplitude information of the target backscatter, and obtain the orientation information of the point cloud through solution to achieve three-dimensional point cloud imaging.

[0003] In the laser radar system, the transceiver system is the core of the laser radar. The transmitting unit is responsible for transmitting the laser, and the receiving unit is responsible for accurately receiving the target backscattered echo signal to achieve the measurement of key parameters such as the distance and angle of the measured target. The performance of the transceiver system directly affects the detection capability, detection accuracy and reliability of the three-dimensional imaging laser radar system. According to the transceiver mode, the three-dimensional imaging laser radar can be divided into a non-coaxial three-dimensional imaging laser radar system and a coaxial three-dimensional imaging laser radar system. The optical paths of the transmitting unit and the receiving unit of the non-coaxial three-dimensional imaging laser radar system are separated, and it has a larger field of view and can detect targets within a wider field of view. However, due to the separation of the transceiver unit, the non-coaxial three-dimensional imaging laser radar system is larger in size and weight and sensitive to the environment. Under complex conditions, such as bad weather and sunny days, the echo signal will be weakened, thereby affecting the three-dimensional imaging quality of the laser radar system. The transmitting unit and the receiving unit of the coaxial three-dimensional imaging laser radar system share an optical path, which has a simple optical path, compact structure, high signal consistency, strong anti-interference ability, and significant advantages in miniaturization integration.

[0004] According to the patent search provided by the existing patent office, the transmitting optical module of the existing patent application includes a hole-drilling reflector, and the receiving optical module includes a receiving reflector and a receiving shaping lens. Patents involving coaxial transceiver systems include "Coaxial transceiver system and laser radar for laser radar" disclosed in Chinese patent CN118244239A. The transmitting unit of the above-mentioned patent uses a through-hole reflector that is a curved hole-drilling reflector, a receiving reflector that is a curved receiving reflector, and a receiving shaping lens that includes at least one spherical lens to realize a coaxial transceiver system. The differences between this application and the above patents include: first, the transmitting unit device is different. The through-hole reflector used in this application is a plane through-hole reflector. The outgoing light passes through the through hole of the plane through-hole reflector, and the reflecting surface reflects the received light to the focusing lens. No receiving reflector is used. By reducing the number of optical devices, the optical efficiency is improved; second, the receiving unit device is different. The receiving shaping lens group of this application includes a spherical lens or an aspherical lens and a filter. The aspherical lens is used to accurately focus the incident light beam, reduce spherical aberration, and improve the imaging quality of the optical system; the filter adopts a bandpass filter design, and the central wavelength matches the working wavelength of the laser radar, so as to achieve large field of view beam reception and effectively filter out stray light, and improve the optical efficiency of the coaxial laser radar system; third, this application adjusts the amplitude of the received signal to achieve effective adjustment of the optical efficiency of the coaxial laser radar transceiver system, thereby improving the performance of the coaxial laser radar transceiver system. The optical receiving system of the patent of this application includes a photodetector, a filter, and an aspherical lens, which is used to focus and receive the echo light signal after diffuse reflection. Patents involving coaxial transceiver systems include "Optical transceiver system and radar for MEMS laser radar" disclosed in Chinese patent CN119001676A. The differences between this application and the above patents include: first, the above patents include meniscus lens groups, while this application does not use meniscus lens groups, which reduces the number of receiving lenses and improves optical efficiency; second, this application adjusts the optical efficiency based on the coaxial transceiver system of the laser radar, and reduces assembly errors by designing the optical path assembly to achieve effective adjustment of optical efficiency.

[0005] Optical efficiency is a way to evaluate the efficiency of energy transmission between the transmitting unit and the receiving unit of the laser radar transceiver system. Optical efficiency refers to the transmission efficiency between the light energy emitted by the laser and the useful light signal energy finally received by the detector. It reflects the effective utilization of light energy by the laser radar transceiver system during the emission, transmission, target scattering and reception of light. Improving the optical efficiency can increase the detection distance, that is, the energy attenuation is reduced under the same detection conditions; at the same time, the echo signal strength is improved, thereby improving the echo signal-to-noise ratio, which enables the laser radar system to more accurately distinguish target information, thereby achieving higher detection accuracy. Therefore, the present invention proposes a method for adjusting the optical efficiency of a laser radar coaxial transceiver system to achieve effective adjustment of the optical efficiency of the laser radar coaxial transceiver system.

[0006] According to the patent search provided by the existing patent office, the existing patent applications adjust the receiving optical path based on the output results of the photodetector. Patents involving laser radar adjustment methods include "a laser radar receiving optical path debugging device and method" disclosed in the Chinese patent CN114660580B. First, at the device level, the above patent debugs the transceiver system through the vehicle, but does not design the transceiver system parameters; the patent application designs the transceiver system parameters and the optical path assembly, and reduces the debugging difficulty and improves the optical efficiency of the laser radar coaxial transceiver system through the constraint coordination of each device of the transceiver system; second, at the adjustment method level, the position of the transmitting unit device of the above patent remains unchanged, and the XYZ three-dimensional receiving lens is adjusted to achieve the debugging of the optimal position of the photodetector; the patent application adjusts the optical device of the transmitting unit through the optical path assembly, so that the center of the optical device of the transceiver system is at the same height, reducing the debugging in the height direction and reducing the debugging difficulty of the transceiver system. The patent application includes the transceiver system parameter design and the transceiver system mechanical structure design, that is, the design of the optical path assembly to achieve effective adjustment of optical efficiency. Patents involving laser radar adjustment methods include "a method for realizing debugging-free laser radar light-receiving and light-emitting structures" disclosed in Chinese patent CN115993589A. The differences between this application patent and the above-mentioned patents include: first, the above-mentioned patents determine the parameters of the transceiver unit through design and selection, and design an integrated mechanical structure to achieve debugging-free; the present application patent determines the parameters of the transceiver system through design, designs the optical path assembly to reduce the difficulty of debugging, and achieves effective adjustment of optical efficiency by adjusting the amplitude of the receiving signal of the photodetector. Second, the receiving lens of the above-mentioned patents is a plano-convex lens, while the receiving lens of the present application patent is a spherical lens or an aspherical lens, a filter, which can achieve large field of view light beam reception and effective filtering of stray light, thereby improving the optical efficiency of the transceiver system.

[0007] In order to effectively adjust the optical efficiency of the laser radar coaxial transceiver system, improve the detection distance and detection accuracy of the laser radar coaxial transceiver system, reduce the power consumption of the laser radar system and extend the working time of the equipment. The present invention discloses a method for adjusting the optical efficiency of the laser radar coaxial transceiver system, through the transceiver system parameter design, that is, the through-hole reflector parameter design, the collimator parameter design, the focusing lens parameter design and the device assembly position adjustment, that is, the collimator and the through-hole reflector position of the transmitting unit are adjusted, the through-hole reflector and the focusing lens position of the receiving unit are adjusted; the focusing lens and the photodetector position of the receiving unit are adjusted, so as to achieve the effective adjustment of the optical efficiency of the laser radar coaxial transceiver system. The optical efficiency adjustment method of the laser radar coaxial transceiver system is simple to operate, and the optical efficiency of the whole link is optimized through the linkage adjustment of the transceiver system parameter design and the device assembly position, so as to achieve the improvement of the detection distance and detection accuracy. The present invention has broad application prospects in the field of laser radar measurement. Summary of the invention

[0008] The present invention discloses an optical efficiency adjustment method for a laser radar coaxial transceiver system, characterized in that the laser radar system is a three-dimensional imaging system composed of a laser emitting unit, a scanning unit, a receiving unit, a signal acquisition and processing unit, and a host computer; wherein the laser emitting unit and the receiving unit together constitute the laser radar coaxial transceiver system; the optical efficiency adjustment link of the laser radar coaxial transceiver system includes: transceiver system parameter design, device assembly position adjustment; the transceiver system parameter design includes: through-hole reflector parameter design, collimator parameter design, and focusing lens parameter design; the device assembly position adjustment is realized by an optical path assembly, and the optical path assembly is realized by a collimator. The road assembly is a clamping device for fixing the through-hole reflector, the focusing lens, and the collimator. The laser radar coaxial transceiver system is fixed on an adjustment platform. The device assembly position adjustment link includes: position adjustment of the collimator and the through-hole reflector of the transmitting unit, position adjustment of the through-hole reflector and the focusing lens of the receiving unit; position adjustment of the focusing lens and the photoelectric detector of the receiving unit; the optical efficiency adjustment method adjusts the amplitude of the receiving signal output by the photoelectric detector through the optimal design of the transceiver system parameters and the selection of the optimal assembly position of the device, so as to achieve effective adjustment of the optical efficiency of the laser radar coaxial transceiver system;

[0009] The transmitting unit of the laser radar coaxial transceiver system includes a laser, a collimator and a through-hole reflector, wherein the laser emits a high-energy laser signal, the collimator realizes the collimation function of the high-energy laser signal, and the scanning unit changes the scanning direction through a galvanometer and / or a prism; the receiving unit includes a through-hole reflector, a focusing lens and a photodetector, wherein the focusing lens converges the backscattered echo light to the photodetector, and the photodetector converts the backscattered echo light into an echo electrical signal, the signal acquisition and processing unit includes a high-speed data acquisition card and an echo online processing unit, wherein the function of the high-speed data acquisition card is to collect the echo electrical signal, and the function of the echo online processing unit is to perform high-speed online processing on the echo electrical signal; the host computer is composed of an industrial computer or a computer, and its function is to configure the parameters of the laser radar coaxial transceiver system and display a three-dimensional point cloud image;

[0010] The main working process of the laser radar coaxial transceiver system includes: a transmitting process and a receiving process; the transmitting process is: the laser transmits the high-energy laser signal, and the high-energy laser signal is collimated by the collimator to form a collimated light, and the collimated light is emitted from the through hole of the through-hole reflector and scans the target in the field of view through the scanning unit; the receiving process is: the target in the field of view scatters the collimated light, thereby generating the backscattered echo light, and the backscattered echo light passes through the scanning unit and the coaxial reflection of the through-hole reflector in turn, and is converged to the photodetector through the focusing lens, and the photodetector converts the backscattered echo light signal into an echo electrical signal, thereby completing the three-dimensional imaging of the target in the field of view;

[0011] The optical efficiency adjustment method of the laser radar coaxial transceiver system, wherein the optical efficiency is the transmission efficiency η between the transmission energy and the received signal amplitude of the laser radar coaxial transceiver system. sys , according to the measured received amplitude signal, the optical efficiency can be calculated as:

[0012]

[0013] Where U r is the received signal amplitude (V); R v is the voltage response of the photodetector (V / W); R is the detection distance (m); ρ is the target reflectivity; P t is the peak power of the laser (W); D min is the minimum receiving aperture (m) in the optical path transmission direction of the laser radar coaxial transceiver system; it can be seen that the greater the amplitude of the received signal of the system, the greater the optical efficiency of the system; therefore, the optical efficiency adjustment method of the laser radar coaxial transceiver system adjusts the positions between the components of the laser radar coaxial transceiver system so that the amplitude of the received signal reaches the maximum;

[0014] The optical efficiency adjustment method of the laser radar coaxial transceiver system has the following process:

[0015] (1) In the parameter design link of the through-hole reflector, the through-hole diameter, the opening direction and position, and the reflector size are designed; since the diameter D0 of the collimated light is a known design indicator, and the collimated light is emitted from the through-hole of the through-hole reflector, the through-hole diameter D0 of the through-hole reflector is determined by the collimated light diameter D0. hol ,Right now:

[0016] D hol =D0+Δd1 (2)

[0017] Wherein, Δd1 is 1 to 3 mm;

[0018] In order to ensure that the backscattered echo light can reach the focusing lens after being reflected by the through-hole reflector, the mirror direction of the through-hole reflector is designed to be at an angle of 45 degrees to the rear surface direction of the focusing lens, the opening position is located at the center of the reflector, and the opening direction is 45 degrees to the mirror surface of the through-hole reflector; since the detection performance of the laser radar is limited by the minimum receiving aperture D in the optical path transmission direction of the laser radar coaxial transceiver system min In order to ensure the best detection performance of the laser radar coaxial transceiver system, the projection area of ​​the through-hole reflector in the optical path transmission direction is larger than the projection area of ​​the minimum receiving aperture in the optical path transmission direction. Since the mirror direction of the through-hole reflector is at an angle of 45 degrees to the rear surface direction of the focusing lens, the size D of the reflector is ref Determined as:

[0019]

[0020] (2) In the collimator parameter design link, the collimator diameter and the collimator lens parameter design are included; since the collimator is placed at the through hole of the through hole reflector, the collimator diameter is smaller than the through hole diameter D of the through hole reflector. hol If the collimator lens is designed to use an aspherical lens, the focal length f of the collimator lens is determined according to the divergence half angle θ0 of the laser and the diameter D0 of the collimated light. col ,Right now:

[0021]

[0022] (3) In the focusing lens parameter design link, the focusing lens diameter and the focusing lens focal length are designed; since the detection performance of the laser radar is limited by the minimum receiving aperture D in the optical path transmission direction of the laser radar coaxial transceiver system, min Therefore, in order to ensure the detection performance of the laser radar coaxial transceiver system, the focusing lens diameter D foc It must be larger than the minimum receiving aperture D in the optical transmission direction of the laser radar coaxial transceiver system. min ,Right now:

[0023] D foc ≥D min (5)

[0024] In the focal length design link of the focusing lens, the optical efficiency is composed of the optical device efficiency and the optical path coupling efficiency. The optical device efficiency is the optical efficiency caused by the material and coating properties of the optical device itself; the optical path coupling efficiency is the optical efficiency caused by the coupling of factors such as the device installation position and distance when energy is transmitted between optical devices inside the system; the optical path coupling efficiency η from the focusing lens to the detector foc is the key link, so the optical path coupling efficiency η from the focusing lens to the detector foc , detection maximum distance R max Indicator and the minimum receiving aperture D in the transmission direction min Estimate the deflection half angle θ of the received light returned to the laser radar coaxial transceiver system def ,Right now:

[0025]

[0026] When the deflection half angle θ def The half angle θ of the photodetector receiving field of view r When the deflection half angle θ def The light energy can be received by the photodetector; due to the deflection half angle θ def The light in the field of view is non-parallel light, and the actual converged light spot converged by the focusing lens is larger than the photosensitive surface diameter of the photodetector. Therefore, the optical path coupling efficiency η of the actual converged light and the energy received by the detector is foc It can be simplified to θ r and θ def The ratio of

[0027]

[0028] Since the photodetector receives a half-angle of view θ r for:

[0029]

[0030] Therefore, the optical path coupling efficiency η from the focusing lens to the detector is determined by empirical values. foc , estimate the required receiving field of view half angle θ of the detector r , thereby determining the lens focusing lens diameter and the focusing lens focal length f foc ,Right now:

[0031]

[0032] Wherein, d is the diameter of the photosensitive surface of the photodetector, γf is the adjustment coefficient of the focal length, and the value is between 0.01 and 0.2. The smaller the adjustment coefficient, the larger the receiving field of view half angle;

[0033] (4) The collimator and the through-hole reflector position adjustment link of the transmitting unit, in order to reduce stray light and improve the optical efficiency of the laser radar coaxial transceiver system, the collimator is fixed to the through-hole of the through-hole reflector through the optical path assembly and the collimator and the through-hole reflector are adjusted to achieve the consistency between the opening direction and the direction of the collimated light beam;

[0034] (5) The position adjustment link of the through-hole reflector and the focusing lens of the receiving unit is to adjust the angle between the mirror direction of the through-hole reflector and the rear surface direction of the focusing lens to 45 degrees, and at the same time adjust the center height of the through-hole reflector and the focusing lens to be consistent, so that the focusing lens can effectively receive the backscattered echo light reflected by the through-hole reflector;

[0035] (6) The position adjustment link of the focusing lens and the photodetector of the receiving unit includes height adjustment and optimal focusing distance adjustment; in order to enable the photodetector to effectively receive the backscattered echo light focused by the focusing lens, the focusing lens and the photodetector are height-consistent through the optical path assembly; the optimal focusing distance adjustment includes the following steps: 1) Adjusting the optical path coaxiality: using a coaxial target to calibrate the emission light and the receiving light, the coaxial target is a concentric ring cross target, the emission light is the light collimated by the collimator after being emitted by the laser, and the receiving light is a collimated beam expansion light source, which is generated by a visible light band laser light source collimated by an adapted collimator and expanded by a beam expander in sequence; A displacement rotation platform is used to adjust the position of the spot of the received light on the coaxial target, so that the spot positions of the emitted light and the received light on the coaxial target coincide, thereby achieving coaxiality between the emitted light and the received light; 2) Coarse adjustment of optical efficiency: the photodetector is placed at the focal length position of the focusing lens, and then the position of the photodetector is adjusted, and the amplitude signal of the received light is obtained in real time by the signal acquisition and processing unit; 3) Fine adjustment of optical efficiency: the distance between the photodetector and the focusing lens in the focal length direction is adjusted, and when the amplitude of the received light shows a turning point where it first increases and then decreases, the position of the photodetector corresponding to the turning point is the optimal focusing distance, thereby achieving effective adjustment of optical efficiency;

[0036] The optical efficiency adjustment method of the laser radar coaxial transceiver system is characterized in that the laser emitting unit can be a pulsed laser, and its parameters mainly affect the laser emission peak power P of the optical efficiency adjustment method. t and the received signal amplitude U rThe scanning unit can be a one-dimensional or two-dimensional scanning controlled by a galvanometer and / or a multi-faceted prism, and its parameters mainly affect the minimum receiving aperture D of the transmission direction of the optical efficiency adjustment method. min ; The focusing lens includes a spherical lens or an aspherical lens and a filter. The aspherical lens is used to accurately focus the incident light beam, reduce spherical aberration, and improve the imaging quality of the optical system; the filter adopts a bandpass filter design, and the central wavelength matches the working wavelength of the laser radar, so as to achieve large field of view light beam reception and effectively filter out stray light, improve the signal-to-noise ratio and the overall optical efficiency of the system, and its parameters mainly affect the received signal amplitude U of the optical efficiency adjustment method r The receiving unit may be an avalanche photodiode (APD) detector, the parameters of which mainly affect the voltage response R of the optical efficiency adjustment method. v , photosensitive surface diameter d; the high-speed data acquisition card of the signal acquisition processing unit, whose parameters mainly affect the received signal amplitude U of the optical efficiency adjustment method r The target may be a diffuse reflection plane target with a known reflectivity, and its parameters mainly affect the target reflectivity ρ and the detection distance R of the optical efficiency adjustment method;

[0037] The optical efficiency adjustment method of a laser radar coaxial transceiver system is characterized in that the optical path assembly includes: an optical device fixing frame, a collimator clamping frame, and a photoelectric detector fixing frame; the optical device fixing frame is used to fix the through-hole reflector and the focusing lens; the collimator clamping frame is used to fix the collimator, and the collimator is placed at the through-hole of the through-hole reflector; the photoelectric detector fixing frame is used to fix and adjust the photoelectric detector, and a three-dimensional design and processing method is adopted, and the optical axis direction of the collimator is parallel to the rear surface of the focusing lens; the photoelectric detector and the focusing lens face center height are consistent.

[0038] The optical efficiency adjustment method of a laser radar coaxial transceiver system is characterized in that at least one displacement groove is embedded in the photoelectric detector fixing frame, and the displacement groove is used for the fine-tuning optical efficiency link to adjust the distance between the photoelectric detector and the rear surface of the focusing lens, with an adjustment range of 0 to 20 mm and an adjustment accuracy of 1 mm.

[0039] The optical efficiency adjustment method of the laser radar coaxial transceiver system is characterized in that the optical device fixing frame includes: a vertical groove, an inclined groove and a base embedded therein, according to the focusing lens size D foc Determine the size of the vertical groove; according to the size D of the through-hole reflector refDetermine the size of the inclined groove; the vertical groove and the plane where the inclined groove is located are rigidly connected to achieve an angle of 45 degrees between the vertical groove and the plane where the inclined groove is located and a height h of the center of the two surfaces. cen The base is used to fix the optical device holder on the adjustment platform; the vertical groove is used to fix the focusing lens, and the inclined groove is used to fix the through-hole reflector; based on the size D of the through-hole reflector ref , the focusing lens size D foc , the height h between the center of the photosensitive surface of the photodetector and the bottom surface of the photodetector det , determine the center height h cen , that is, satisfying:

[0040]

[0041] Wherein, Δd2 is between 5 and 40 mm;

[0042] The optical efficiency adjustment method of a laser radar coaxial transceiver system is characterized in that the collimator clamping frame includes a base and an isosceles right triangular prism, and the rectangular side surface where the triangular hypotenuse of the isosceles right triangular prism is located is rigidly connected to the base; of the two rectangular sides where the right-angled sides of the triangle are located, one of the rectangular sides includes a collimator through hole that penetrates the collimator clamping frame, and the size of the collimator through hole is 1 to 2 mm larger than the diameter of the collimator, and is used to place the collimator to achieve consistency between the opening direction of the through-hole reflector and the direction of the collimated light beam; the other rectangular side surface includes a fixing hole for fixing the collimator; the base is used for the matching connection between the collimator frame and the optical device fixing frame.

[0043] The optical efficiency adjustment method of a laser radar coaxial transceiver system is characterized in that the transceiver system parameter design link:

[0044] (1) According to the maximum detection distance R max Indicators, determining the laser parameters, namely: the laser's emission peak power Pt and the laser's divergence half angle θ0; the photodetector parameters, namely: the voltage response R v , the diameter d of the photosensitive surface of the photodetector and the height h between the center of the photosensitive surface of the photodetector and the bottom surface of the photodetector det The minimum receiving aperture D in the optical transmission direction of the laser radar coaxial transceiver system min and the diameter D0 of the collimated light; thereby estimating the optical path coupling efficiency η from the focusing lens to the detector foc ;

[0045] (2) Parameter design of the through-hole reflector: Determine the through-hole diameter D of the through-hole reflector according to the diameter D0 of the collimated light. hol ; According to the minimum receiving aperture D of the laser radar coaxial transceiver system in the optical path transmission direction min Determine the reflector size D ref ;

[0046] (3) Collimator parameter design: Determine the focal length f of the collimator lens based on the divergence half angle θ0 of the laser and the diameter D0 of the collimated light. col ;

[0047] (4) The focusing lens parameter design link: According to the minimum receiving aperture D in the optical transmission direction of the laser radar coaxial transceiver system min Determine the focusing lens diameter D foc ; According to the design required maximum detection distance R max , the minimum receiving aperture D of the laser radar coaxial transceiver system in the optical path transmission direction min , the optical path coupling efficiency η from the focusing lens to the detector foc Estimate the required receiving field of view half angle θ of the detector r , thereby determining the focal length f of the focusing lens foc ;

[0048] The device assembly position adjustment link:

[0049] (1) The collimator and the through-hole reflector position adjustment link of the emitting unit: according to the collimator diameter D col Design the collimator clamping frame to fix the collimator at the through hole of the through hole reflector so that the opening direction of the through hole reflector is consistent with the direction of the collimated light beam;

[0050] (2) The position adjustment link of the through-hole reflector and the focusing lens of the receiving unit: according to the size D of the reflector ref , the focusing lens diameter D foc , the thickness of the optical device holder base h0, determine the center height h of the vertical groove of the optical device holder cen , and then designing the optical device fixing frame to achieve an angle of 45 degrees between the mirror direction of the through-hole reflector and the rear surface direction of the focusing lens, and the through-hole reflector and the center height of the focusing lens are consistent;

[0051] (3) The focusing lens and the photodetector position adjustment link of the receiving unit: according to the center height h of the vertical groove cen, design the photoelectric detector fixing frame, adjust the optimal focusing distance, and achieve effective adjustment of optical efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0053] Figure 1 This is a LiDAR system diagram

[0054] Figure 2 Flow chart of the optical efficiency adjustment method

[0055] Figure 3 Through-hole reflector

[0056] Figure 4 Collimating lens design diagram

[0057] Figure 5 The detector receiving field of view

[0058] Figure 6 Collimator clamping frame

[0059] Figure 7 This is the location diagram of the photoelectric detector and the optical path assembly

[0060] Figure 8 The transmitted light and the received light are coaxial.

[0061] Fig. 9 This is a schematic diagram of the best focusing position DETAILED DESCRIPTION

[0062] The specific implementation methods of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0063] The present invention discloses a method for adjusting the optical efficiency of a laser radar coaxial transceiver system. The specific structure of an embodiment of the system is as follows: Figure 1 As shown, the laser radar system includes a laser transmitting unit 1, a receiving unit 2, a scanning unit 3, a signal acquisition and processing unit 4, and a host computer 5, wherein the transmitting unit 1 and the receiving unit 2 constitute the laser radar coaxial transceiver system.

[0064] The optical efficiency adjustment method of the laser radar coaxial transceiver system described in this embodiment has the following working process: the laser 10 emits a high-energy laser signal, and the high-energy laser signal is collimated by the collimator 11 to form a collimated light beam, which is emitted from the through hole of the through-hole reflector 12 and reaches the coaxial target 64 through the reflection of the galvanometer 31 and the prism 32; the receiving light beam is generated by the collimated beam expansion light source 65, and the receiving light beam is coaxially reflected by the galvanometer 31, the prism 32 and the through-hole reflector 12 in turn, and converged to the photodetector 22 through the focusing lens 21, and the photodetector 22 converts the received light beam into an echo electrical signal, which is transmitted to the signal acquisition and processing unit 4, and the amplitude of the received signal is observed by the host computer 5;

[0065] The optical efficiency adjustment method of the laser radar coaxial transceiver system described in this embodiment has the following process: Figure 2 Transceiver system parameters:

[0066] (1) Assume that the maximum detection distance of the designed laser radar system is R max is 100m, laser 10 is a fiber laser, and the output peak power P t is 1000W, the divergence half angle θ0 is 8.05°; the photodetector 22 is an APD detector, the voltage response is 90kV / W, the diameter d of the photosensitive surface 23 is 0.2mm, and the height h between the center of the photosensitive surface 23 and the bottom of the photodetector 22 is det 16.5mm; the minimum receiving aperture D in the optical transmission direction of the laser radar coaxial transceiver system min is 30 mm, the collimated light diameter D0 is 2 mm, and this embodiment assumes that the optical path coupling efficiency η from the focusing lens 21 to the photodetector 22 is foc It is 80% and can be replaced according to the actual value in practical applications.

[0067] (2) Parameter design of the through-hole reflector 12: including the determination of the through-hole diameter, the opening direction and the size of the reflector. The through-hole diameter D of the through-hole reflector 12 is determined according to the diameter D0 of the collimated light. hol ,Right now:

[0068] D hol =D0+Δd1 (11)

[0069] According to experience, Δd1 is taken as 2 mm, so D hol Determined to be 4mm.

[0070] The opening direction of the through-hole reflector 12 is designed to be 45 degrees to the mirror surface direction, and the opening position is located at the center of the reflector. Figure 3 The size of the reflector is determined by the minimum receiving aperture D in the optical transmission direction of the laser radar coaxial transceiver system. min Determine the reflector size Dref , that is, satisfying:

[0071]

[0072] According to formula (12), D ref ≥35.68mm, to ensure that the reflector size is much larger than the minimum receiving aperture size in the optical transmission direction, according to experience D ref Determined to be 50mm.

[0073] (3) The collimator 11 parameter design link: Figure 4 As shown, the focal length f of the collimating lens is determined according to the divergence half angle θ0 of the laser 10 and the diameter D0 of the collimated light. col ,Right now:

[0074]

[0075] From formula (13), we can get f col ≤7mm, in order to ensure a good collimation effect, the focal length of the collimator is 11 col Determined to be 3.5mm.

[0076] (4) The design of the focusing lens 21 parameters: including the design of the focusing lens diameter and the focusing lens focal length. According to the minimum receiving aperture D in the optical transmission direction of the laser radar coaxial transceiver system min Determine the focusing lens diameter D foc ,Right now:

[0077] D foc ≥D min (14)

[0078] According to formula (14), D foc ≥30mm, determined based on experience foc It is 40mm.

[0079] Focus lens focal length design: according to the design required detection of the farthest distance R max , the minimum receiving aperture D of the laser radar coaxial transceiver system in the optical path transmission direction min , the optical path coupling efficiency η from the focusing lens 21 to the photodetector 22 foc Estimate the required receiving field of view half angle θ of the photodetector 22 r , thereby determining the focal length f of the focusing lens 21 foc ,like Figure 5 First, estimate the deflection half angle θ of the received light returned to the laser radar coaxial transceiver system def ,Right now:

[0080]

[0081] Thus, the diameter d of the lens focusing lens 21 and the focal length f of the focusing lens 21 are determined. foc ,Right now:

[0082]

[0083] According to formula (15), θ def can be 0.15mrad. According to formula (16), γ f is the adjustment coefficient of focal length. The smaller the adjustment coefficient, the larger the receiving field of view half angle. According to the above field of view angle and detection distance, the value is between 0.01 and 0.2. In order to ensure a large field of view reception, this implementation scheme takes γ f f is 0.03 foc It is 25mm and can be replaced according to the actual value in application.

[0084] The device assembly position adjustment link:

[0085] (1) Position adjustment of the collimator 11 and the through-hole reflector 12 of the emitting unit 1: according to the diameter D of the collimator 11 col The collimator holder 62 is designed; the collimator holder 62 includes a base 621 and an isosceles right-angled triangular prism 622, and the rectangular side of the isosceles right-angled triangular prism 622 where the triangular hypotenuse is located is rigidly connected to the base, such as Figure 6 As shown; the collimator 11 is fixed at the collimator through hole 623 through the fixing hole 624, and the collimator 11 is passed through the through hole 121 of the through hole reflector 12, so that the opening direction of the through hole reflector 12 is consistent with the direction of the collimated light beam. The two rectangular side surfaces where the triangular right-angled sides of the isosceles right-angled triangular prism 622 are located, one of the rectangular side surfaces includes a collimator through hole 623 that passes through the collimator clamping frame 62, and the size of the collimator through hole is 1 to 2 mm larger than the diameter of the collimator 11. Since the diameter of the collimated light beam is 2 mm and the diameter of the collimator 11 is 3.8 mm, the diameter of the collimator through hole 623 is 4.8 mm, which is used to place the collimator 11; the other rectangular side surface includes a fixing hole 624 for fixing the collimator 11; the base 621 is used for the matching connection between the collimator clamping frame 62 and the optical device fixing frame 61.

[0086] (2) Position adjustment of the through-hole reflector 12 and the focusing lens 21 of the receiving unit 2: First, based on the size D of the through-hole reflector 12 ref 、Focusing lens 21 size D foc , the height h between the photosensitive surface 23 of the photodetector and the bottom surface of the photodetector 22 det , determine the center height h cen ,like Figure 7 As shown, it satisfies:

[0087]

[0088] According to formula (17), h cen =max{25,20,16.5}+Δd2, taking Δd2 as 10mm, we get h cen It is 35mm.

[0089] (3) Position adjustment link of the focusing lens 21 and the photodetector 22 of the receiving unit 2: according to the center height h of the vertical groove cen , design the photoelectric detector fixing frame 63, adjust the optimal focusing distance, and realize the effective adjustment of optical efficiency. The optimal focusing distance adjustment includes the following steps:

[0090] 1) Adjust the optical path coaxiality: Use a coaxial target to calibrate the emission light and the receiving light. The coaxial target is a concentric ring cross target. The emission light is the light that is collimated by the collimator 11 after being emitted by the laser 10. The receiving light is the collimated beam expansion light source 65, which is generated by a visible light band laser light source that is collimated by an adapted collimator and expanded by a beam expander in sequence; use a displacement rotating platform to adjust the position of the light spot of the receiving light on the coaxial target 64, so that the light spot positions of the emission light and the receiving light on the coaxial target 64 coincide, so that the emission light and the receiving light are coaxial, such as Figure 8 As shown;

[0091] 2) Coarse adjustment of optical efficiency: placing the photodetector 22 at the focal length position of the focusing lens 21, adjusting the position of the photodetector 22, and using the 4-signal acquisition and processing unit to obtain the amplitude signal of the received light in real time;

[0092] 3) Fine-tune the optical efficiency: adjust the distance between the photodetector 22 and the focusing lens 21 in the focal length direction, such as Fig. 9As shown. Adjust the photodetector 22 in the direction away from the focusing lens. If the received signal amplitude gradually decreases and there is no turning point where it increases first and then decreases, then perform step 2) to re-coarsely adjust the optical efficiency, and then adjust the photodetector 22 in the direction close to the focusing lens 21. When the position of the photosensitive surface 23 changes from position 3 to position 1, the received signal amplitude first increases and then decreases. The position 2 of the photosensitive surface 23 of the photodetector corresponding to the turning point is the optimal focusing distance, and the optical efficiency is effectively adjusted. Adjust the photodetector 22 in the direction away from the focusing lens. If the received signal amplitude first increases and then decreases, that is, when the position of the photosensitive surface 23 changes from position 1 to position 3, the position 2 of the photosensitive surface 23 of the photodetector corresponding to the turning point is the optimal focusing distance, and the optical efficiency is effectively adjusted. The above adjustment process is determined according to the change value of the received signal amplitude, and the algorithm for determining the optimal signal amplitude is specifically implemented with the changes in the adjustment means and the signal acquisition and processing means.

[0093] The above is only a basic scheme of the specific implementation method of the present invention, but the protection scope of the present invention is not limited thereto. Any changes and substitutions that can be thought of by any person familiar with the technical field within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims. All changes that fall within the equivalent meaning and scope of the claims will be included in the scope of the claims.

Claims

1. A method for adjusting the optical efficiency of a laser radar coaxial transceiver system, characterized in that: The laser radar system is a three-dimensional imaging system composed of a laser emitting unit, a scanning unit, a receiving unit, a signal acquisition and processing unit, and a host computer; wherein the laser emitting unit and the receiving unit together constitute the laser radar coaxial transceiver system; The optical efficiency adjustment link of the laser radar coaxial transceiver system includes: transceiver system parameter design, device assembly position adjustment; the transceiver system parameter design includes: through-hole reflector parameter design, collimator parameter design, and focusing lens parameter design; the device assembly position adjustment is achieved through an optical path assembly, and the optical path assembly is a clamping device for fixing the through-hole reflector, the focusing lens, and the collimator. The laser radar coaxial transceiver system is fixed on an adjustment platform, and the device assembly position adjustment link includes: position adjustment of the collimator and the through-hole reflector of the transmitting unit, position adjustment of the through-hole reflector and the focusing lens of the receiving unit; position adjustment of the focusing lens and the photoelectric detector of the receiving unit; the optical efficiency adjustment method adjusts the amplitude of the received signal output by the photoelectric detector through the optimal design of the transceiver system parameters and the selection of the optimal device assembly position, so as to achieve effective adjustment of the optical efficiency of the laser radar coaxial transceiver system; The transmitting unit of the laser radar coaxial transceiver system includes a laser, a collimator and a through-hole reflector, wherein the laser emits a high-energy laser signal, the collimator realizes the collimation function of the high-energy laser signal, and the scanning unit changes the scanning direction through a galvanometer and / or a prism; the receiving unit includes a through-hole reflector, a focusing lens and a photodetector, wherein the focusing lens converges the backscattered echo light to the photodetector, and the photodetector converts the backscattered echo light into an echo electrical signal, the signal acquisition and processing unit includes a high-speed data acquisition card and an echo online processing unit, wherein the function of the high-speed data acquisition card is to collect the echo electrical signal, and the function of the echo online processing unit is to perform high-speed online processing on the echo electrical signal; the host computer is composed of an industrial computer or a computer, and its function is to configure the parameters of the laser radar coaxial transceiver system and display a three-dimensional point cloud image; The main working process of the laser radar coaxial transceiver system includes: a transmitting process and a receiving process; the transmitting process is: the laser transmits the high-energy laser signal, and the high-energy laser signal is collimated by the collimator to form a collimated light, and the collimated light is emitted from the through hole of the through-hole reflector and scans the target in the field of view through the scanning unit; the receiving process is: the target in the field of view scatters the collimated light, thereby generating the backscattered echo light, and the backscattered echo light passes through the scanning unit and the coaxial reflection of the through-hole reflector in turn, and is converged to the photodetector through the focusing lens, and the photodetector converts the backscattered echo light signal into an echo electrical signal, thereby completing the three-dimensional imaging of the target in the field of view; The optical efficiency adjustment method of the laser radar coaxial transceiver system is described as the transmission efficiency η between the transmission energy and the received signal amplitude of the laser radar coaxial transceiver system. sys , according to the measured received amplitude signal, the optical efficiency can be calculated as: Where U r is the received signal amplitude (V); R v is the voltage response of the photodetector (V / W); R is the detection distance (m); ρ is the target reflectivity; P t is the peak power of the laser (W); D min is the minimum receiving aperture (m) in the optical path transmission direction of the laser radar coaxial transceiver system; it can be seen that the greater the amplitude of the received signal of the system, the greater the optical efficiency of the system; therefore, the optical efficiency adjustment method of the laser radar coaxial transceiver system adjusts the positions between the components of the laser radar coaxial transceiver system so that the amplitude of the received signal reaches the maximum; The optical efficiency adjustment method of the laser radar coaxial transceiver system has the following process: (1) In the parameter design link of the through-hole reflector, the through-hole diameter, the opening direction and position, and the reflector size are designed; since the diameter D0 of the collimated light is a known design indicator, and the collimated light is emitted from the through-hole of the through-hole reflector, the through-hole diameter D0 of the through-hole reflector is determined by the collimated light diameter D0. hol ,Right now: D hol =D0+Δd1 (2) Wherein, Δd1 is 1 to 3 mm; In order to ensure that the backscattered echo light can reach the focusing lens after being reflected by the through-hole reflector, the mirror direction of the through-hole reflector is designed to be at an angle of 45 degrees to the rear surface direction of the focusing lens, the opening position is located at the center of the reflector, and the opening direction is 45 degrees to the mirror surface of the through-hole reflector; since the detection performance of the laser radar is limited by the minimum receiving aperture D in the optical path transmission direction of the laser radar coaxial transceiver system min In order to ensure the best detection performance of the laser radar coaxial transceiver system, the projection area of ​​the through-hole reflector in the optical path transmission direction is larger than the projection area of ​​the minimum receiving aperture in the optical path transmission direction. Since the mirror direction of the through-hole reflector is at an angle of 45 degrees to the rear surface direction of the focusing lens, the size D of the reflector is ref Determined as: (2) In the collimator parameter design link, the collimator diameter and the collimator lens parameter design are included; since the collimator is placed at the through hole of the through hole reflector, the collimator diameter is smaller than the through hole diameter D of the through hole reflector. hol If the collimator lens is designed to use an aspherical lens, the focal length f of the collimator lens is determined according to the divergence half angle θ0 of the laser and the diameter D0 of the collimated light. col ,Right now: (3) In the focusing lens parameter design link, the focusing lens diameter and the focusing lens focal length are designed; since the detection performance of the laser radar is limited by the minimum receiving aperture D in the optical path transmission direction of the laser radar coaxial transceiver system, min Therefore, in order to ensure the detection performance of the laser radar coaxial transceiver system, the focusing lens diameter D foc It must be larger than the minimum receiving aperture D in the optical transmission direction of the laser radar coaxial transceiver system. min ,Right now: D foc ≥D min (5) In the focal length design link of the focusing lens, the optical efficiency is composed of the optical device efficiency and the optical path coupling efficiency. The optical device efficiency is the optical efficiency caused by the material and coating properties of the optical device itself; the optical path coupling efficiency is the optical efficiency caused by the coupling of factors such as the device installation position and distance when energy is transmitted between optical devices inside the system; the optical path coupling efficiency η from the focusing lens to the detector foc is the key link, so the optical path coupling efficiency η from the focusing lens to the detector foc , detection maximum distance R max Indicator and the minimum receiving aperture D in the transmission direction min Estimate the deflection half angle θ of the received light returned to the laser radar coaxial transceiver system def ,Right now: When the deflection half angle θ def The half angle θ of the photodetector receiving field of view r When the deflection half angle θ def The light energy can be received by the photodetector; due to the deflection half angle θ def The light in the field of view is non-parallel light, and the actual converged light spot converged by the focusing lens is larger than the photosensitive surface diameter of the photodetector. Therefore, the optical path coupling efficiency η of the actual converged light and the energy received by the detector is foc It can be simplified to θ r and θ def The ratio of Since the photodetector receives a half-angle of view θ r for: Therefore, the optical path coupling efficiency η from the focusing lens to the detector is determined by empirical values. foc , estimate the required receiving field of view half angle θ of the detector r , thereby determining the lens focusing lens diameter and the focusing lens focal length f foc ,Right now: Wherein, d is the diameter of the photosensitive surface of the photodetector, γf is the adjustment coefficient of the focal length, and the value is between 0.01 and 0.

2. The smaller the adjustment coefficient, the larger the receiving field of view half angle; (4) The collimator and the through-hole reflector position adjustment link of the transmitting unit, in order to reduce stray light and improve the optical efficiency of the laser radar coaxial transceiver system, the collimator is fixed to the through-hole of the through-hole reflector through the optical path assembly and the collimator and the through-hole reflector are adjusted to achieve the consistency between the opening direction and the direction of the collimated light beam; (5) The position adjustment link of the through-hole reflector and the focusing lens of the receiving unit is to adjust the angle between the mirror direction of the through-hole reflector and the rear surface direction of the focusing lens to 45 degrees, and at the same time adjust the center height of the through-hole reflector and the focusing lens to be consistent, so that the focusing lens can effectively receive the backscattered echo light reflected by the through-hole reflector; (6) The position adjustment link of the focusing lens and the photodetector of the receiving unit includes height adjustment and optimal focusing distance adjustment; in order to enable the photodetector to effectively receive the backscattered echo light focused by the focusing lens, the focusing lens and the photodetector are height-consistent through the optical path assembly; the optimal focusing distance adjustment includes the following steps: 1) Adjusting the optical path coaxiality: using a coaxial target to calibrate the emission light and the receiving light, the coaxial target is a concentric ring cross target, the emission light is the light collimated by the collimator after being emitted by the laser, and the receiving light is a collimated beam expansion light source, which is generated by a visible light band laser light source collimated by an adapted collimator and expanded by a beam expander in sequence; A displacement rotation platform is used to adjust the position of the spot of the received light on the coaxial target, so that the spot positions of the emitted light and the received light on the coaxial target coincide, thereby achieving coaxiality of the emitted light and the received light; 2) Coarse adjustment of optical efficiency: the photodetector is placed at the focal length position of the focusing lens, and then the position of the photodetector is adjusted, and the amplitude signal of the received light is obtained in real time by the signal acquisition and processing unit; 3) Fine adjustment of optical efficiency: the distance between the photodetector and the focusing lens in the focal length direction is adjusted, and when the amplitude of the received light reaches a turning point where it first increases and then decreases, the position of the photodetector corresponding to the turning point is the optimal focusing distance, thereby achieving effective adjustment of optical efficiency.

2. The optical efficiency adjustment method of a laser radar coaxial transceiver system according to claim 1, characterized in that: The laser emitting unit may be a pulsed laser, the parameters of which mainly affect the laser emission peak power P of the optical efficiency adjustment method. t and the received signal amplitude U r The scanning unit can be a one-dimensional or two-dimensional scanning controlled by a galvanometer and / or a multi-faceted prism, and its parameters mainly affect the minimum receiving aperture D of the transmission direction of the optical efficiency adjustment method. min ; The focusing lens includes a spherical lens or an aspherical lens and a filter. The aspherical lens is used to accurately focus the incident light beam, reduce spherical aberration, and improve the imaging quality of the optical system; the filter adopts a bandpass filter design, and the central wavelength matches the working wavelength of the laser radar, so as to achieve large field of view light beam reception and effectively filter out stray light, improve the signal-to-noise ratio and the overall optical efficiency of the system, and its parameters mainly affect the received signal amplitude U of the optical efficiency adjustment method r The receiving unit may be an avalanche photodiode (APD) detector, the parameters of which mainly affect the voltage response R of the optical efficiency adjustment method. v , photosensitive surface diameter d; the high-speed data acquisition card of the signal acquisition processing unit, whose parameters mainly affect the received signal amplitude U of the optical efficiency adjustment method r The upper limit of The target may be a diffuse reflection plane target with known reflectivity, and its parameters mainly affect the target reflectivity ρ and the detection distance R of the optical efficiency adjustment method.

3. The optical efficiency adjustment method of a laser radar coaxial transceiver system according to claim 1, characterized in that: The optical path assembly includes: an optical device fixing frame, a collimator clamping frame, and a photoelectric detector fixing frame; the optical device fixing frame is used to fix the through-hole reflector and the focusing lens; the collimator clamping frame is used to fix the collimator, and the collimator is placed at the through-hole of the through-hole reflector; the photoelectric detector fixing frame is used to fix and adjust the photoelectric detector, and adopts a three-dimensional design and processing method. The optical axis direction of the collimator is parallel to the rear surface of the focusing lens; the photoelectric detector and the focusing lens have the same center height.

4. The optical efficiency adjustment method of a laser radar coaxial transceiver system according to claim 1 and claim 2, characterized in that: The photoelectric detector fixing frame is embedded with at least one displacement slot, and the displacement slot is used for the fine adjustment of optical efficiency to adjust the distance between the photoelectric detector and the rear surface of the focusing lens, with an adjustment range of 0 to 20 mm and an adjustment accuracy of 1 mm.

5. The optical efficiency adjustment method of a laser radar coaxial transceiver system according to claim 1 and claim 2, characterized in that: The optical device fixing frame includes: a vertical groove, an inclined groove and a base embedded therein, according to the size D of the focusing lens foc Determine the size of the vertical groove; according to the size D of the through-hole reflector ref Determine the size of the inclined groove; the vertical groove and the plane where the inclined groove is located are rigidly connected to achieve an angle of 45 degrees between the vertical groove and the plane where the inclined groove is located and a height h of the center of the two surfaces. cen The base is used to fix the optical device holder on the adjustment platform; the vertical groove is used to fix the focusing lens, and the inclined groove is used to fix the through-hole reflector; based on the size D of the through-hole reflector ref , the focusing lens size D foc , the height h between the center of the photosensitive surface of the photodetector and the bottom surface of the photodetector det , determine the center height h cen , that is, satisfying: In the formula, Δd2 is between 5 and 40 mm.

6. The optical efficiency adjustment method of a laser radar coaxial transceiver system according to claim 1 and claim 2, characterized in that: The collimator clamping frame includes a base and an isosceles right triangular prism, and the rectangular side surface where the hypotenuse of the triangle of the isosceles right triangular prism is located is rigidly connected to the base; of the two rectangular side surfaces where the right-angled sides of the triangle are located, one of the rectangular side surfaces includes a collimator through hole that penetrates the collimator clamping frame, and the size of the collimator through hole is 1 to 2 mm larger than the diameter of the collimator, and is used to place the collimator to achieve consistency between the opening direction of the through-hole reflector and the direction of the collimated light beam; the other rectangular side surface includes a fixing hole for fixing the collimator; the base is used for the matching connection between the collimator frame and the optical device fixing frame.

7. The optical efficiency adjustment method of a laser radar coaxial transceiver system according to claim 1, characterized in that: The transceiver system parameter design link: (1) According to the maximum detection distance R max Indicators, determine the laser parameters, that is, the laser's peak output power P t and the divergence half angle θ0 of the laser; the photodetector parameters, namely: the voltage response R v , the diameter d of the photosensitive surface of the photodetector and the height h between the center of the photosensitive surface of the photodetector and the bottom surface of the photodetector det ; The minimum receiving aperture D of the laser radar coaxial transceiver system in the optical path transmission direction min and the diameter D0 of the collimated light; thereby estimating the optical path coupling efficiency η from the focusing lens to the photodetector foc ; (2) Parameter design of the through-hole reflector: Determine the through-hole diameter D of the through-hole reflector according to the diameter D0 of the collimated light. hol ; According to the minimum receiving aperture D of the laser radar coaxial transceiver system in the optical path transmission direction min Determine the reflector size D ref ; (3) Collimator parameter design: Determine the focal length f of the collimator lens based on the divergence half angle θ0 of the laser and the diameter D0 of the collimated light. col ; (4) The focusing lens parameter design link: According to the minimum receiving aperture D in the optical transmission direction of the laser radar coaxial transceiver system min Determine the focusing lens diameter D foc ; According to the design required maximum detection distance R max , the minimum receiving aperture D of the laser radar coaxial transceiver system in the optical path transmission direction min , the optical path coupling efficiency η from the focusing lens to the detector foc Estimate the required receiving field of view half angle θ of the detector r , thereby determining the focal length f of the focusing lens foc ; The device assembly position adjustment link: (1) The collimator and the through-hole reflector position adjustment link of the emitting unit: according to the collimator diameter D col Design the collimator clamping frame to fix the collimator at the through hole of the through hole reflector so that the opening direction of the through hole reflector is consistent with the direction of the collimated light beam; (2) The position adjustment link of the through-hole reflector and the focusing lens of the receiving unit: according to the size D of the reflector ref , the focusing lens diameter D foc , the thickness of the optical device holder base h0, determine the center height h of the vertical groove of the optical device holder cen , and then designing the optical device fixing frame to achieve that the angle between the mirror direction of the through-hole reflector and the rear surface direction of the focusing lens is 45 degrees, and the center height of the through-hole reflector is consistent with that of the focusing lens; (3) The focusing lens and the photodetector position adjustment link of the receiving unit: according to the center height h of the vertical groove cen , design the photoelectric detector fixing frame, adjust the optimal focusing distance, and achieve effective adjustment of optical efficiency.

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