Lidar return detection system for scanning detection

Abstract

The present application relates to the technical field of laser wind measurement radar, in particular to a laser radar echo detection system for scanning detection. The laser radar echo detection system for scanning detection comprises an echo detection optical path and a detection and collection module; the echo detection optical path comprises a fiber coupler and a fiber mode field adapter, an input end of the fiber coupler is used for inputting backscattering light, and an output end is connected with a large-mode-field fiber end of the fiber mode field adapter through an optical fiber; a single-mode fiber end of the fiber mode field adapter and a light source are respectively connected with two input ends of the detection and collection module through optical fibers. The laser radar echo detection system for scanning detection provided by the present application can ensure high echo coupling efficiency, enhance the signal-to-noise ratio of the detection signal, effectively improve the detection distance and scanning speed of the laser radar, and improve the working performance of the laser radar when the fiber mode field adapter is applied as a core device for echo detection and a field of view is introduced during laser radar scanning.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser wind-radar, in particular to a laser radar echo detection system for scanning detection. BACKGROUND

[0002] The laser radar is an important instrument and equipment in the field of wind field detection, and has important value in the application fields of weather forecast, flight safety, wind power generation, etc. The laser radar can emit a laser beam to the space to be measured. The aerosol particles in the atmosphere produce backscattering light after being irradiated by the laser. When the aerosol particles move due to the influence of the wind field, the backscattering light produces Doppler frequency shift, which is related to the movement speed of the aerosol particles. The backscattering light is received and spectrum analyzed, and the wind field speed can be solved with high precision.

[0003] The wind speed solved by the laser radar is generally the radial wind speed along the direction of the laser beam. In order to obtain the actual wind speed and direction information and the wind field distribution information, the wind speeds of multiple paths are often synthesized and calculated. In order to obtain the wind speeds of multiple paths, the laser radar is usually provided with a scanning structure. The scanning structure scans the space to be measured at a certain angular velocity. Since the laser has a flight time in space, the time of the backscattering light of the aerosol particles at different positions reaching the scanning head is proportional to the distance. Thus, when the backscattering light of the aerosol particles far away returns to the laser radar, the scanning head is no longer aligned with the laser path of the aerosol particles, that is, the field of view is deviated. Moreover, with the increase of the detection distance and the scanning speed, the field of view deviation will be more serious, which makes it difficult to improve the detection distance and the scanning speed of the existing laser radar. SUMMARY

[0004] The present application aims to provide a laser radar echo detection system for scanning detection, so as to solve the technical problem that the detection distance and the scanning speed of the existing laser radar are difficult to improve.

[0005] The laser radar echo detection system for scanning detection provided by the present application comprises an echo detection optical path and a detection and collection module.

[0006] The echo detection optical path comprises a fiber coupler and a fiber mode field adapter. The input end of the fiber coupler is used for inputting backscattering light, and the output end is connected with the large mode field fiber end of the fiber mode field adapter through an optical fiber. The single mode fiber end of the fiber mode field adapter and the light source are respectively connected with two input ends of the detection and collection module through optical fibers.

[0007] Preferably, as an implementation manner, the echo detection light path further comprises a beam splitter, a first port of the beam splitter is used to receive the outgoing laser emitted by the light source; a second port of the beam splitter is used to emit the outgoing laser and is used to receive the backscattered light; the beam splitter is used to distinguish the propagation direction of the outgoing laser and the backscattered light, and guide the backscattered light to a third port of the beam splitter; the third port of the beam splitter is used to emit the backscattered light to the input end of the fiber coupler.

[0008] Preferably, as an implementation manner, the laser radar echo detection system for scanning detection further comprises an optical antenna, the optical antenna is arranged between the second port of the beam splitter and the scanning head, and is used to emit the outgoing laser to the scanning head after beam expansion and collimation, and is used to guide the received backscattered light to the beam splitter.

[0009] Preferably, as an implementation manner, the two side surfaces of the ocular lens of the optical antenna are concave spherical surfaces, and are used to expand the outgoing laser;

[0010] And / or, the surface of the objective lens of the optical antenna facing the scanning head is an even aspheric surface, and the surface of the objective lens of the optical antenna facing away from the scanning head is a spherical surface, and is used to collimate the outgoing laser;

[0011] And / or, the surface of the coupling lens of the fiber coupler facing the third port of the beam splitter is an aspheric surface, and the focal length of the coupling lens ranges from 20 to 30 mm.

[0012] Preferably, as an implementation manner, the surface of the objective lens of the optical antenna is coated with a film layer with high transmittance to the backscattered light;

[0013] And / or, the surface of the ocular lens of the optical antenna is coated with a film layer with high transmittance to the backscattered light;

[0014] And / or, the surface of the coupling lens of the fiber coupler is coated with a film layer with high transmittance to the backscattered light.

[0015] Preferably, as an implementation manner, the ocular end and / or the objective end of the optical antenna is provided with a spacing adjustment structure, and the spacing adjustment structure is used to adjust the spacing between the ocular lens and the objective lens of the optical antenna.

[0016] Preferably, as an implementation manner, the optical antenna has a locking structure, and the locking structure is used to lock the ocular lens and / or the objective lens.

[0017] Preferably, as an implementable mode, the fiber coupler is provided with a fiber adjusting structure for adjusting the relative positions of the input fiber and the output fiber in the fiber coupler.

[0018] Preferably, as an implementable mode, the probe acquisition module comprises a balanced detector and a data processor, two input ends of the balanced detector are connected to the single-mode fiber end of the fiber field adapter and the light source through optical fibers respectively, and an output end is connected to the data processor.

[0019] Preferably, as an implementable mode, the optical splitter and the optical antenna are arranged between the light source and the scanning head, the optical splitter can guide the outgoing laser emitted by the light source to the optical antenna, and the optical antenna can guide the outgoing laser to the scanning head; the scanning head can reflect the outgoing laser to the target airspace to be detected, and can receive the backscattered light and guide it to the optical antenna.

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] The laser radar echo detection system for scanning detection provided by the present application can ensure high echo coupling efficiency when introducing field of view offset in laser radar scanning, enhance the signal-to-noise ratio of the detection signal, effectively improve the detection distance and scanning speed of the laser radar, and improve the working performance of the laser radar. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of the provided drawings.

[0023] Figure 1 The structure schematic diagram of the laser radar echo detection system for scanning detection provided by the present application is shown in the figure.

[0024] Figure 2 The structure schematic diagram of the laser radar echo detection system for scanning detection provided by the present application is shown in the figure.

[0025] Figure 3 The field of view offset schematic diagram of the laser radar echo detection system for scanning detection provided by the present application in the scanning state is shown in the figure.

[0026] Figure 4The simulation calculation result of the fiber coupling of the laser radar echo detection system for scanning detection provided by the embodiment of the present application in the non-scanning state is shown in the following table:

[0027] Figure 5 The simulation calculation result of the fiber coupling of the laser radar echo detection system for scanning detection provided by the embodiment of the present application in the 5° / s scanning state is shown in the following table:

[0028] Figure 6 The simulation calculation result of the fiber coupling of the laser radar echo detection system for scanning detection provided by the embodiment of the present application in the 10° / s scanning state is shown in the following table.

[0029] Explanation of reference numerals:

[0030] 110-fiber coupler; 111-coupling lens; 120-fiber field adapter; 130-balanced detector; 140-data processor; 150-optical splitter; 160-optical antenna; 161-ocular; 162-objective;

[0031] 200-light source;

[0032] 300-scanning head. DETAILED DESCRIPTION

[0033] The technical solutions of the present application will be described clearly and completely below with reference to the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0034] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the term "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements. For those skilled in the art, the specific meaning of the above-mentioned term in the present application can be understood according to the specific circumstances.

[0035] The present application will be described in further detail below with reference to specific embodiments and in conjunction with the drawings.

[0036] Reference is made to Figure 1The embodiment provides a laser radar echo detection system for scanning detection, which comprises an echo detection light path and a detection collection module; the echo detection light path comprises a fiber coupler 110 and a fiber mode field adapter 120; an input end of the fiber coupler 110 is used for inputting backscattering light, and an output end is connected with a large-mode-field fiber end of the fiber mode field adapter 120 through an optical fiber; and a single-mode fiber end of the fiber mode field adapter 120 and a light source 200 are respectively connected with two input ends of the detection collection module through optical fibers.

[0037] The aerosol particles in the atmosphere can enter the fiber coupler 110 of the echo detection light path after backscattering light generated by laser irradiation, the fiber coupler 110 can couple the received backscattering light into the connected fiber mode field adapter 120, the fiber mode field adapter 120 receives the backscattering light through the large-mode-field fiber end, performs mode field compression, and performs optical transmission through the single-mode fiber; the backscattering light after mode field compression by the fiber mode field adapter 120 can enter the detection collection module along the fiber light path, and the intrinsic light from the light source 200 is subjected to coherent frequency mixing and photoelectric conversion, the detection collection module can analyze and process the photocurrent to obtain the wind field information. It should be noted that the use of a large-mode-field fiber to couple backscattering light can obtain higher coupling efficiency, and in turn, higher signal-to-noise ratio; and the single-mode fiber can ensure that the polarization, spectrum and other information of the optical signal remain complete during transmission in the fiber light path.

[0038] Therefore, the laser radar echo detection system for scanning detection provided by the embodiment can ensure high echo coupling efficiency when introducing field offset in laser radar scanning, enhance the signal-to-noise ratio of the detection signal, effectively improve the detection distance and scanning speed of the laser radar, and improve the working performance of the laser radar by applying the fiber mode field adapter 120 as the core device for echo detection.

[0039] In the specific structure of the above echo detection light path, a beam splitter 150 is further included, the first port of the beam splitter 150 receives the outgoing laser emitted by the light source 200, the outgoing laser entering the beam splitter 150 can propagate towards the second port of the beam splitter 150 and can be emitted through the second port, so that the laser can propagate to the target airspace to be detected; the backscattering light generated by the aerosol particles in the target airspace to be detected after laser irradiation can return to the second port of the beam splitter 150, since the backscattering light is reversely passed, the polarization state thereof is different from that of the outgoing laser, so the beam splitter 150 can distinguish the propagation directions of the outgoing laser and the backscattering light, and can guide most of the backscattering light entering through the second port to the third port of the beam splitter 150; after the backscattering light is emitted through the third port of the beam splitter 150, the backscattering light can propagate to the input end of the fiber coupler 110, so that the fiber coupler 110 receives the backscattering light.

[0040] When the laser radar echo detection system for scanning detection is applied to a solid laser radar, a combination structure of a polarization beam splitter prism and a wave plate can be selected as the above-mentioned beam splitter 150, or a combination structure of a thin film polarizer and a wave plate can be selected as the above-mentioned beam splitter 150 to distinguish the optical paths.

[0041] The laser radar echo detection system for scanning detection provided in the embodiment further includes an optical antenna 160, which is arranged between the second port of the beam splitter 150 and the scanning head 300. The optical antenna 160 can expand and collimate the outgoing laser emitted by the second port of the beam splitter 150. The outgoing laser expanded and collimated by the optical antenna 160 can be emitted to the scanning head 300, so that the scanning head 300 reflects the outgoing laser to the target airspace to be detected. The backscattered light generated by the aerosol particles in the target airspace to be detected after being irradiated by the outgoing laser can return to the scanning head 300 and be reflected to the optical antenna 160 by the scanning head 300. The backscattered light entering the optical antenna 160 can be guided by the optical antenna 160 to propagate to the second port of the beam splitter 150, so that the beam splitter 150 receives the backscattered light.

[0042] The echo detection optical path provided in the embodiment can collect as much backscattered light in space as possible into the fiber optical path and transmit the backscattered light to the detection and collection module with low loss.

[0043] Specifically, the first port of the beam splitter 150 is arranged opposite to the light source 200, so that the outgoing laser emitted by the light source 200 can smoothly enter the beam splitter 150 through the first port of the beam splitter 150. The second port of the beam splitter 150 is arranged opposite to the ocular 161 of the optical antenna 160, so that the outgoing laser output by the second port of the beam splitter 150 can smoothly enter the optical antenna 160 through the ocular 161 of the optical antenna 160, and the backscattered light output by the ocular 161 of the optical antenna 160 can smoothly enter the beam splitter 150 through the second port of the beam splitter 150. The third port of the beam splitter 150 is arranged opposite to the input end of the fiber coupler 110, so that the backscattered light output by the third port of the beam splitter 150 can smoothly enter the fiber coupler 110 through the input end of the fiber coupler 110.

[0044] The objective lens 161 of the optical antenna 160 can be a spherical lens. Specifically, both sides of the objective lens 161 are provided with concave spherical surfaces, which are used for diverging the outgoing laser or collimating the backscattered light converged by the objective lens 162. The objective lens 162 of the optical antenna 160 can be an aspherical lens. Specifically, the surface of the objective lens 162 facing the scanning head 300 is provided with an even aspherical surface, and the surface of the objective lens 162 facing away from the scanning head 300 is provided with a spherical surface, which are used for collimating the outgoing laser or converging the backscattered light. The coupling lens 111 of the fiber coupler 110 can be a finished aspherical lens. Specifically, the surface of the coupling lens 111 facing the third port of the beam splitter 150 is provided with an aspherical surface, so that the coupling lens 111 can focus and couple the backscattered light into the optical fiber. The focal length range of the coupling lens 111 is set to 20-30 mm, which can reduce the volume of the fiber coupler 110. By reasonably using the aspherical lens, the spatial optical path of the echo detection can be simplified, which is conducive to the compact integration of the system and reduces the volume of the system. At the same time, the aberration and optical loss in the optical transceiver can also be reduced.

[0045] Table 1 below is a data table for fiber coupling simulation using simulation software ZEMAX. In the simulation, the reflected light path between the optical antenna 160 and the fiber coupler 110 is simplified for calculation simplicity, which actually has little effect on simulation analysis. Surface 2 and surface 3 constitute the objective lens 162 of the optical antenna 160, which are even aspherical lenses. Surface 2 is the surface of the objective lens 162 facing away from the objective lens 161, and surface 3 is the surface of the objective lens 162 facing the objective lens 161. Surface 4 and surface 5 constitute the objective lens 161 of the optical antenna 160. Surface 4 is the surface of the objective lens 161 facing the objective lens 162, and surface 5 is the surface of the objective lens 161 facing away from the objective lens 162. Surface 6 and surface 7 constitute the coupling lens 111 of the fiber coupler 110. Surface 6 is the surface of the coupling lens 111 facing the optical antenna 160, and surface 7 is the surface of the coupling lens 111 facing away from the optical antenna 160. Figure 2 The 2D structure of the optical antenna for fiber coupling simulation corresponds to the optical system design parameters in Table 1. Under these design parameters, the spatial optical path of the laser radar echo detection system for scanning detection can be simplified to about 324 mm.

[0046] Table 1

[0047]

[0048] Preferably, a film layer with high transmittance to backscattered light can be coated on the surface of the objective lens 162 of the optical antenna 160 to reduce the loss caused by the backscattered light transmitting through the objective lens 162; the wavelength of the outgoing laser is consistent with that of the backscattered light, so the loss caused by the outgoing laser transmitting through the objective lens 162 can also be reduced.

[0049] Preferably, a film layer with high transmittance to backscattered light can be coated on the surface of the eyepiece 161 of the optical antenna 160 to reduce the loss caused by the backscattered light transmitting through the eyepiece 161; the wavelength of the outgoing laser is consistent with that of the backscattered light, so the loss caused by the outgoing laser transmitting through the eyepiece 161 can also be reduced.

[0050] Preferably, a film layer with high transmittance to backscattered light can be coated on the surface of the coupling lens 111 of the fiber coupler 110 to reduce the loss caused by the backscattered light transmitting through the coupling lens 111.

[0051] Preferably, a spacing adjustment structure can be arranged at either or both of the eyepiece end and the objective lens end of the optical antenna 160 to adjust the spacing between the eyepiece 161 and the objective lens 162 by using the spacing adjustment structure, to achieve fine adjustment of the collimation state of the outgoing laser and adjustment of the coupling state of the backscattered light, so that a higher signal-to-noise ratio of the echo signal can be obtained; the spacing adjustment structure can be arranged at the eyepiece end of the optical antenna 160 to enable the eyepiece 161 to translate along the axial direction of the optical antenna 160, so as to adjust the spacing between the eyepiece 161 and the objective lens 162.

[0052] Specifically, a housing and a lens clamping structure can be arranged in the specific structure of the optical antenna 160, the lens clamping structure clamps the eyepiece 161 or the objective lens 162, threads can be arranged on the housing and the lens clamping structure, the lens clamping structure is threadedly connected with the housing, at this time, the threads on the housing and the lens clamping structure can be used as the main structure of the spacing adjustment structure, and screwing the lens clamping structure can drive the lens clamping structure to translate the eyepiece 161 or the objective lens 162 along the axial direction of the optical antenna 160, so as to adjust the spacing between the eyepiece 161 and the objective lens 162. Of course, the spacing adjustment structure can also be selected to replace the thread structure to adjust the spacing between the eyepiece 161 and the objective lens 162 by using a mechanical structure such as a sliding groove and a stopper.

[0053] Preferably, the housing can be made of carbon fiber material as the main material, the lens clamping structure and the spacing adjustment structure can be made of 6061 aluminum material, and the optical antenna 160 can be combined by thread connection, adhesion and other processes. As an alternative, the housing can be made of 6061 aluminum or stainless steel throughout, which can improve the integrity and strength of the optical antenna 160.

[0054] Further, a locking structure can be arranged on the optical antenna 160 to lock one or both of the eyepiece 161 and the objective 162 by the locking structure. Specifically, if the eyepiece end is provided with the spacing adjustment structure, after the eyepiece 161 is adjusted to the appropriate position, the eyepiece 161 is locked by the locking mechanism to lock the spacing between the objective 162 and the eyepiece 161; if the objective end is provided with the spacing adjustment structure, after the objective 162 is adjusted to the appropriate position, the objective 162 is locked by the locking mechanism to lock the spacing between the objective 162 and the eyepiece 161. Specifically, a glue injection hole can be reserved on the optical antenna 160, and after the adjustment is completed, glue is injected into the glue injection hole to achieve complete locking.

[0055] Preferably, a fiber adjustment structure can be arranged on the fiber coupler 110 to adjust the relative positions of the input and output fibers in the fiber coupler 110 by the fiber adjustment structure, so as to align the backscattered light as much as possible to the core of the fiber, thereby improving the spatial-fiber coupling efficiency.

[0056] In the specific structure of the detection and collection module, the balanced detector 130 and the data processor 140 can be arranged, and the backscattered light after the mode field compression by the fiber mode field adapter 120 can enter the balanced detector 130 along the fiber optical path, and the intrinsic light from the light source 200 can be coherent frequency mixed and photoelectrically converted, and the photoelectric current generated by the conversion of the balanced detector 130 can enter the data processor 140, and the data processor 140 can analyze and process the received photoelectric current to obtain the wind field information.

[0057] Specifically, the data processor 140 can perform analog-to-digital conversion, filtering, incoherent accumulation denoising, distance gate division, fast FFT, Gaussian fitting inversion of wind speed data, and coherent synthesis of wind speed calculation on the coherent frequency mixing electrical signal output by the balanced detector 130 to obtain the wind field information.

[0058] The above-mentioned data processor 140 can specifically include a high-speed data acquisition board, and the high-speed data acquisition board can be selected to be a board based on FPGA (Field-Programmable Gate Array) as the core, and the board is loaded with a data processing program.

[0059] The above-mentioned balanced detector 130 can be selected to be an InGaAs balanced detector, and the response light wave band range is 1.5-1.6 μm and 2 μm, which can be applicable to most laser radars.

[0060] As shown in FIG. 1, the laser radar 100 can include a light source 200, a fiber coupler 110, an optical antenna 160, a balanced detector 130, and a data processor 140. Figure 3As shown, when the laser radar is in a scanning state, the time towards each detection direction is limited, so when the detection distance is far, the backscattering light located in the rear of the detection range reaches the laser radar, and the angle relative to the optical antenna 160 has changed, that is, the field of view has shifted. Taking a laser radar with a detection range of 20 km as an example, when the scanning speed of the scanning head of the laser radar is 5° / s, the backscattering light generated by the aerosol particles at 20 km returns to the laser radar, and the flight time is: Where t is the flight time, L is the flight distance, and v is the speed of light; and in this process, the scanning head 300 is also moving, and the scanning angle corresponding to the flight time is: Ω = w x t = 1.33 x 10 -4 ° x 5 = 6.67 x 10 -4 °. That is, after the backscattering light generated by the aerosol particles at 20 km reaches the position of the laser radar, it has produced a field of view shift of 6.67 x 10 -4 ° relative to the optical antenna 160, which has a huge impact on the reception of backscattering light.

[0061] Figures 4-6 is the simulation calculation result of fiber coupling under different scanning conditions by ZEMAX. ZEMAX has a special single-mode fiber coupling and multi-mode fiber coupling calculation function, which can be used to compare the large-mode field fiber end coupling of backscattering light after the commonly used single-mode fiber and the fiber mode field adapter 120. The simulation uses a single-mode fiber with a numerical aperture (NA) of 0.125, and a multi-mode fiber with a NA of 0.08.

[0062] As shown in Figure 4 , set the laser radar not in a scanning state, then the field of view will not shift. The optical system is optimized using the corresponding operation number (FICL operation number) to maximize the single-mode fiber coupling efficiency. After optimization, the single-mode fiber coupling is evaluated using the single-mode fiber coupling function of ZEMAX, and the coupling efficiency is calculated to be 58.237%. Under the same conditions, the large-mode field fiber coupling is evaluated using the multi-mode fiber coupling function of ZEMAX, and the coupling efficiency is calculated to be 86.064%, indicating that the large-mode field fiber coupling of backscattering light is better.

[0063] As shown in Figure 5 , when the laser radar is in a scanning state of 5° / s, the object field of view will shift, so the field of view shift is set to 6.67 x 10 -4At this time, the structure is no longer optimized to simulate the working state of the actual instrument after packaging. In this case, the coupling efficiency is 19.043% calculated by using the single-mode fiber coupling function of ZEMAX, and the coupling efficiency is 84.236% calculated by using the multi-mode fiber coupling function of ZEMAX, which indicates that when the laser radar is in a scanning motion, the coupling efficiency of the backscattered light will decrease, and the use of a large-mode-field fiber to couple the backscattered light will obtain a higher coupling efficiency, which corresponds to a higher signal-to-noise ratio and will better ensure the effective detection distance.

[0064] As shown in Figure 6 When the laser radar is in a 10° / s scanning state, the scanning speed increases, and the corresponding field of view offset is 1.33x10 -3 °. After setting the field of view offset in ZEMAX, the coupling efficiency is 0.257% calculated by using the single-mode fiber coupling function of ZEMAX, and the coupling efficiency is 33.876% calculated by using the multi-mode fiber coupling function of ZEMAX under the same conditions, which indicates that when the scanning speed is too fast, the single-mode fiber will no longer be suitable for coupling the backscattered light. Therefore, for application cases that require to ensure a long detection distance and a fast wind field scanning, the laser radar echo detection system for scanning detection provided in the embodiment has great advantages.

[0065] Referring to Figure 1 , the embodiment also provides a laser radar, which comprises a light source 200, a scanning head 300 and the above-mentioned laser radar echo detection system for scanning detection, the laser radar echo detection system for scanning detection is arranged between the light source 200 and the scanning head 300, the laser radar echo detection system for scanning detection can guide the outgoing laser emitted by the light source 200 to the scanning head 300, and the scanning head 300 can reflect the outgoing laser to the target airspace to be measured and can emit the backscattered light to the laser radar echo detection system for scanning detection.

[0066] The laser radar provided in the embodiment can make the outgoing laser emitted by the light source 200 propagate to the scanning head 300 through the laser radar echo detection system for scanning detection, reflect the outgoing laser to the target airspace to be measured through the scanning head 300, and the scanning head 300 can scan the target airspace to be measured at a certain angular velocity; the aerosol particles in the target airspace to be measured produce backscattered light under laser irradiation, which can return to the scanning head 300 and be reflected to the laser radar echo detection system for scanning detection through the scanning head 300, be converted into a photoelectric current through the laser radar echo detection system for scanning detection, and the photoelectric current is analyzed and processed to obtain wind field information (such as wind speed distribution, wind direction distribution, etc.).

[0067] The laser radar provided by the embodiment has all the advantages of the laser radar echo detection system for scanning detection, can ensure high echo coupling efficiency when the laser radar scanning introduces field of view offset, enhances the signal-to-noise ratio of the detection signal, can effectively improve the detection distance and the scanning speed, and has better working performance.

[0068] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A lidar backscattering detection system for scanning detection, characterized in that The echo detection optical path and the detection collection module are included. The echo detection optical path includes a fiber coupler and a fiber mode field adapter, an input end of the fiber coupler is used for inputting backscattered light, and an output end is connected with a large mode field fiber end of the fiber mode field adapter through an optical fiber; a single mode fiber end of the fiber mode field adapter and a light source are respectively connected with two input ends of the detection collection module through optical fibers; The echo detection optical path further includes a beam splitter, a first port of the beam splitter is used for receiving outgoing laser light emitted by the light source; a second port of the beam splitter is used for emitting the outgoing laser light and receiving the backscattered light; the beam splitter is used for distinguishing the propagation directions of the outgoing laser light and the backscattered light, and guiding the backscattered light to a third port of the beam splitter; and the third port of the beam splitter is used for emitting the backscattered light to the input end of the fiber coupler.

2. The lidar backscattering detection system for scanning detection according to claim 1, characterized in that, The laser radar echo detection system for scanning detection further includes an optical antenna, which is arranged between the second port of the beam splitter and a scanning head, and is used for expanding and collimating the outgoing laser light and emitting the outgoing laser light to the scanning head, and is used for guiding the received backscattered light to the beam splitter.

3. The lidar backscattering detection system for scanning detection according to claim 2, characterized in that, Both side surfaces of the objective lens of the optical antenna are concave spherical surfaces, which are used for expanding the outgoing laser light; And / or, a surface of the objective lens of the optical antenna, which faces the scanning head, is an even aspheric surface, and a surface of the objective lens, which faces away from the scanning head, is a spherical surface, which are used for collimating the outgoing laser light; And / or, a surface of the coupling lens of the fiber coupler, which faces the third port of the beam splitter, is an aspheric surface, and a focal length range of the coupling lens is 20-30 mm.

4. The lidar backscattering detection system for scanning detection according to claim 2, characterized in that, A surface of the objective lens of the optical antenna is coated with a film layer with high transmittance to the backscattered light; And / or, a surface of the objective lens of the optical antenna is coated with a film layer with high transmittance to the backscattered light; And / or, a surface of the coupling lens of the fiber coupler is coated with a film layer with high transmittance to the backscattered light.

5. The lidar backscattering detection system for scanning detection according to claim 2, characterized in that, The objective lens end and / or the objective lens end of the optical antenna is provided with a spacing adjustment structure, which is used for adjusting the spacing between the objective lens and the objective lens of the optical antenna.

6. The lidar backscattering detection system for scanning detection according to claim 5, characterized in that The optical antenna has a locking structure, which is used for locking the objective lens and / or the objective lens.

7. The lidar backscattering detection system for scanning detection according to claim 2, characterized in that, The fiber coupler is provided with a fiber adjustment structure, which is used for adjusting the relative positions of the input optical fiber and the output optical fiber in the fiber coupler.

8. The lidar backscattering detection system for scanning detection according to any one of claims 1-7, characterized in that, The detection collection module includes a balanced detector and a data processor, two input ends of the balanced detector are respectively connected with the single mode fiber end of the fiber mode field adapter and the light source through optical fibers, and an output end is connected with the data processor.

9. The lidar backscattering detection system for scanning detection of claim 2, wherein, The beam splitter and the optical antenna are arranged between the light source and the scanning head, the beam splitter can guide the outgoing laser light emitted by the light source to the optical antenna, and the optical antenna can guide the outgoing laser light to the scanning head; The scanning head can reflect the outgoing laser light to the target airspace to be detected, and can receive the backscattered light and guide it to the optical antenna.

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