Laser radar system
By adopting confocal optical imaging device and timing control technology in the lidar system, the problem of reduced lateral resolution when the detection distance increases and the imaging quality in a high-concentration particulate environment is solved, and high-quality imaging and detection of long-distance targets in a low-visibility environment is achieved.
Patent Information
- Application Number
- CN202510283357.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-11
- Publication Date
- 2025-05-30
AI Technical Summary
When the detection distance increases, the lateral resolution of the existing lidar system decreases, and in a high-concentration particle environment, the image contrast and spatial resolution are affected, and the echo signal intensity is attenuated, affecting the detection and recognition capabilities.
The confocal optical imaging device is adopted to focus the laser beam on a certain point on the target object, and receive the echo beam, and point-to-point conjugation imaging is formed through the signal processing unit. At the same time, timing control is realized through the control unit to avoid background noise and backscatter noise.
Achieve high-quality imaging and detection of long-distance targets in low-viability environments, improving the lateral resolution and signal-to-noise ratio of the lidar system.
Smart Images
Figure CN120065244A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of radar technology, and more particularly, to a lidar system. Background Art
[0002] With the development of science and technology, the demand for target detection and three-dimensional imaging technology in the fields of scientific research, industry, and national defense is increasing. The core of lidar three-dimensional imaging is optical imaging, and resolution is a key performance of optical imaging ability. However, with the expansion of the detection range, the spot area and field of view size on the target surface increase accordingly, limiting the lateral resolution of the system, restricting the imaging result, and seriously affecting the detection and recognition ability; in a visually degraded environment, the scattering of high-concentration particulate matter such as fog or smoke will further deteriorate the image contrast and spatial resolution, and at the same time attenuate the intensity of the echo signal. Summary of the Invention
[0003] In order to at least overcome the above deficiencies in the prior art, the purpose of this application is to provide a lidar system.
[0004] In a first aspect, an embodiment of this application provides a lidar system, which includes a light-emitting unit, a first control unit, a signal processing unit, and a confocal optical imaging device;
[0005] The light-emitting unit is connected to the confocal optical imaging device, and the light-emitting unit is used to provide a laser beam for the confocal optical imaging device;
[0006] The confocal optical imaging device is connected to the signal processing unit, and the confocal optical imaging device is used to focus the laser beam on a certain point on the target object, receive the echo beam returned from the target object, and send the echo beam to the signal processing unit;
[0007] The signal processing unit is used to receive the echo beam and form a point-to-point conjugate imaging according to the echo beam;
[0008] The first control unit is respectively connected to the confocal optical imaging device, the light-emitting unit, and the signal processing unit. The first control unit is used to collect the working timings of the confocal optical imaging device, the light-emitting unit, and the signal processing unit, and send timing control instructions to the confocal optical imaging device, the light-emitting unit, and the signal processing unit.
[0009] In a possible implementation manner, the confocal optical imaging device includes a collimation unit, a beam splitting unit, a deflection unit, and a telescope;
[0010] The collimation unit is used to expand the received laser beam to obtain a parallel emission beam, and the emission beam is incident on the telescope via the beam splitting unit and the deflection unit;
[0011] The telescope is used to adjust the focal point of the emission beam, focus the emission beam on the target object, and receive the echo beam returned from the target object;
[0012] The beam splitting unit is used to split the emission beam and the echo beam, so that the emission beam is focused on a certain point position of the target object, and the echo beam is transmitted to the signal processing unit via the collimation unit, so that the signal processing unit forms a point-to-point conjugate imaging according to the echo beam;
[0013] The deflection unit is connected to the control unit. The deflection unit is used to receive the deflection control instruction sent by the control unit and control the deflection direction of the emission beam based on the deflection control instruction, so that the emission beam is focused on different positions of the target object.
[0014] In a possible implementation, the magnification of the telescope is 2 to 35.
[0015] In a possible implementation, the collimation unit includes a first collimation sub-unit and a second collimation sub-unit;
[0016] The first collimation sub-unit is connected to the light emitting unit. The first collimation sub-unit is used to expand the received laser beam to obtain a parallel emission beam;
[0017] The second collimation sub-unit is connected to the signal processing unit. The second collimation sub-unit is used to receive the echo beam split from the beam splitting unit and couple the echo beam to the signal processing unit.
[0018] In a possible implementation, the light emitting unit includes an optical switch and a laser. The optical switch is connected to the control unit, the laser is connected to the first control unit, and the optical switch is connected to the first collimation sub-unit;
[0019] The laser is used to send a laser beam. The optical switch is used to receive the laser beam and perform a switching action based on the timing control instruction of the first control unit.
[0020] In a possible implementation, the first control unit includes a signal acquisition sub-unit and a timing control sub-unit connected;
[0021] The signal acquisition sub-unit is connected to the light emitting unit or the lidar system, and is used to acquire the starting moment of the flight of photons in the laser beam;
[0022] The signal acquisition sub-unit is also connected to the signal processing unit, and is used to acquire the ending moment of the flight of photons in the laser beam, and calculate the photon flight time based on the starting moment and the ending moment;
[0023] The timing control sub-unit is used to receive the photon flight time sent by the signal acquisition sub-unit, and control the on / off of the signal processing unit based on the photon flight time.
[0024] In a possible implementation manner, the control unit further includes a photon splitting sub-unit, and the signal acquisition sub-unit includes a photoelectric sensor and a timer;
[0025] The photon splitting sub-unit is respectively connected to the first collimation sub-unit and the signal acquisition sub-unit. The photon splitting sub-unit is used to split the incident light beam emitted by the first collimation sub-unit, and make at least part of the incident light beam enter the signal acquisition sub-unit;
[0026] The photodetector is used to generate a synchronous timing signal based on part of the incident light beam, and send the synchronous timing signal to the timer. The timer obtains the starting moment of the photon flight based on the synchronous timing signal.
[0027] In a possible implementation manner, the lidar system further includes a second control unit;
[0028] The second control unit is connected to the signal processing unit, and the second control unit restores the three-dimensional image of the target object based on the photon data sent by the signal processing unit.
[0029] In a possible implementation manner, the photon splitting sub-unit includes a beam splitting cube, a perforated mirror, a perforated reflector or a center-coated mirror;
[0030] The signal acquisition sub-unit includes a photoelectric sensor.
[0031] In a possible implementation manner, the signal processing unit includes a single photon detector, and the single photon detector includes a Geiger avalanche diode, a photomultiplier tube or a superconducting nanowire single photon detector.
[0032] Based on any of the above aspects, the lidar system provided by the embodiments of the present application includes a light emitting unit, a first control unit, a signal processing unit, and a confocal optical imaging device. The confocal optical imaging device can focus the laser beam generated by the light emitting unit on a certain point on the target object, and can also receive the echo beam returned from the target object and send the echo beam to the signal processing unit to form point-to-point conjugate imaging, realizing the detection and imaging of distant targets in low visibility environments while improving the imaging quality. At the same time, through the first control unit, the timing control operation of the lidar system can be realized, which can avoid the signal processing unit from collecting irrelevant background noise, effectively eliminate the backscattering noise, improve the signal-to-noise ratio of the lidar system, and thus improve the lateral resolution of the lidar system. BRIEF DESCRIPTION OF THE DRAWINGS
[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required to be called in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.
[0034] Figure 1 A schematic diagram of a module of the lidar system provided by the embodiments of the present application Figure 1 ;
[0035] Figure 2 A schematic diagram of a module of the confocal optical imaging device provided by the embodiments of the present application;
[0036] Figure 3 A schematic diagram of a module of the lidar system provided by the embodiments of the present application Figure 2 ;
[0037] Figure 4 A schematic diagram of a module of the lidar system provided by the embodiments of the present application Figure 3 ;
[0038] Figure 5 A schematic diagram of a module of the lidar system provided by the embodiments of the present application Figure 4 ;
[0039] Figure 6 A schematic diagram of a partial optical path of the lidar system provided by the embodiments of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0040] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the following will clearly and completely describe the technical solutions in the embodiments of this application with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, rather than all of them. Components of the embodiments of this application usually described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.
[0041] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of this application claimed, but merely represents selected embodiments of this application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts belong to the scope of protection of this application.
[0042] It should be noted that similar reference numerals and letters indicate similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.
[0043] In the description of this application, it should be noted that the orientation or positional relationship indicated by terms such as "upper" and "lower" is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this application is usually placed when in use. It is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. In addition, terms such as "first" and "second" are only used for descriptive distinction and cannot be understood as indicating or implying relative importance.
[0044] In the description of this application, it should also be noted that unless otherwise clearly specified and limited, the terms "arranged", "communicated", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.
[0045] It should be noted that, without conflict, different features in the embodiments of this application can be combined with each other.
[0046] To solve the problems in the prior art, please refer to Figure 1 , an embodiment of this application provides a lidar system 100, and the lidar system 100 includes a light emitting unit 110, a first control unit 120, a signal processing unit 130, and a confocal optical imaging device 200.
[0047] The light-emitting unit 110 is connected to the confocal optical imaging device 200. The light-emitting unit 110 is used to provide a laser beam for the confocal optical imaging device 200. Among them, the laser beam can be in a band with high atmospheric transmittance and low solar background radiation, reducing the attenuation of the laser beam by the atmosphere and increasing the propagation distance of the laser beam. At the same time, it can also reduce the influence of solar radiation on the imaging quality. The specific wavelength can be selected according to the actual atmospheric transmission window and solar radiation spectrum.
[0048] The confocal optical imaging device 200 is connected to the signal processing unit 130. The confocal optical imaging device 200 can not only focus the laser beam on a certain point on the target object, but also receive the echo beam returned from the target object and send the echo beam to the signal processing unit 130. The signal processing unit 130 can receive the echo beam and form a point-to-point conjugate imaging according to the echo beam to achieve three-dimensional imaging of a long-distance target.
[0049] The first control unit 120 is respectively connected to the confocal optical imaging device 200, the light-emitting unit 110 and the signal processing unit 130. The first control unit 120 is used to collect the working timings of the confocal optical imaging device 200, the light-emitting unit 110 and the signal processing unit 130, and send timing control instructions to the confocal optical imaging device 200, the light-emitting unit 110 and the signal processing unit 130.
[0050] In the above structure, the confocal optical imaging device 200 can not only focus the laser beam generated by the light-emitting unit 110 on a certain point on the target object, but also receive the echo beam returned from the target object and send the echo beam to the signal processing unit 130 to form a point-to-point conjugate imaging, realizing the detection and imaging of a long-distance target in a low visibility environment while improving the imaging quality. At the same time, through the first control unit 120, the signal acquisition and timing control of the lidar system 100 can be realized, which can avoid the signal processing unit 130 from collecting irrelevant background noise, effectively eliminate the backscattering noise, improve the signal-to-noise ratio of the lidar system 100, and thus improve the lateral resolution of the lidar system 100.
[0051] In some possible implementation manners, please refer to Figure 2 , the confocal optical imaging device 200 includes a collimating unit 210, a beam splitting unit 220, a deflection unit 230 and a telescope 240.
[0052] The collimation unit 210 can convert the received laser beam into a parallel incident beam and expand the incident beam to improve the uniformity and consistency of the incident beam. The incident beam is incident on the telescope 240 via the beam splitting unit 220 and the deflection unit 230. The telescope 240 can adjust the focal point of the incident beam, focus the incident beam on the target object, form a point illumination source on the target object, and receive the echo beam returned from the target object, that is, the same light spot returned from the target object. Among them, the magnification of the telescope 240 can be 2 to 35. Preferably, the magnification of the telescope 240 can be 8 times, and the focal point of the incident beam can be adjusted by adjusting the distance between the objective lens and the eyepiece in the telescope 240.
[0053] The beam splitting unit 220 can separate the incident beam and the echo beam, so that the echo beam is transmitted to the signal processing unit 130 via the collimation unit 210, so that the signal processing unit 130 forms a point-to-point conjugate imaging according to the echo beam. Among them, the beam splitting unit 220 can include, but is not limited to, optical elements such as a beam splitting cube, a perforated mirror, or a center-coated mirror.
[0054] The deflection unit 230 is connected to the first control unit 120. The deflection unit 230 can receive the deflection control instruction sent by the first control unit 120 and control the deflection direction of the incident beam based on the deflection control instruction, so that the incident beam is focused on different positions of the target object.
[0055] In addition, the lidar system 100 can further include a feedback unit, and the feedback unit is respectively connected to the deflection unit 230 and the first control unit 120. The first control unit 120 can first send a deflection control instruction to the deflection unit 230. After the deflection unit 230 deflects to the specified position based on the deflection control instruction, the feedback unit sends a feedback signal to the first control unit 120, and the first control unit 120 sends a synchronous timing signal and a control instruction to the confocal optical imaging device 200, the light emitting unit 110, and the signal processing unit 130 based on the feedback signal.
[0056] It should be noted that the first control unit 120 can store a scanning algorithm for controlling the deflection unit 230 to control the incident beam to focus on different positions of the target object through the deflection unit 230, so as to realize the scanning of the target object. It should be noted that the size and accuracy of the scanning range can be determined according to the size and accuracy of the actual detection area, and the specific scanning method and scanning path are not specifically limited here.
[0057] In the above structure, the deflection unit 230 and the telescope 240 cooperate to focus the incident light beam on different positions of the target object, realizing point illumination of the target object. At the same time, the echo light beam returned from the target object is received, and the echo light beam is separated by the beam splitting unit 220, so that the echo light beam can be focused at the output pinhole, forming conjugate imaging of point illumination - point detection. With such a design, not only can the attenuation of the incident light beam caused by environmental factors be reduced, realizing super-resolution imaging of a long-distance target in low visibility weather, but also the interference of background noise such as the incident light beam on imaging can be reduced, improving the imaging quality.
[0058] Furthermore, please refer to Figure 3 , the collimation unit 210 includes a first collimation sub-unit 211 and a second collimation sub-unit 212. The first collimation sub-unit 211 can be connected to the light emitting unit 110 through an optical fiber. The first collimation sub-unit 211 is used to expand the received laser beam to obtain a parallel incident light beam.
[0059] The second collimation sub-unit 212 can be connected to the signal processing unit 130 through an optical fiber. The second collimation sub-unit 212 is used to receive the echo light beam split from the beam splitting unit 220, couple the echo light beam into the optical fiber, and transmit it to the signal processing unit 130 through the optical fiber, forming point-to-point conjugate imaging.
[0060] Among them, the first collimation sub-unit 211 and the second collimation sub-unit 212 can be collimators or collimation optical paths composed of multiple lenses.
[0061] Please refer to Figure 4 , the confocal optical imaging device 200 may further include a linear polarizer 250 and a half-wave plate 260. The linear polarizer 250 and the half-wave plate 260 are sequentially located between the first collimation sub-unit 211 and the beam splitting unit 220. The linear polarizer 250 can convert the incident light beam emitted by the first collimation sub-unit 211 into a linearly polarized incident light beam. The half-wave plate 260 can adjust the polarization direction of the linearly polarized incident light beam to vertical polarization and transmit the vertically polarized incident light beam to the beam splitting unit 220. By controlling the polarization state of the incident light beam through the above-mentioned linear polarizer 250 and half-wave plate 260, the stray light caused by atmospheric scattering or reflection on the surface of optical elements can be reduced, and the signal-to-noise ratio of imaging can be improved.
[0062] Even further, please refer to Figure 4, To ensure the transmission accuracy of the incident light beam and the echo light beam, the confocal optical imaging device 200 may further include a first mirror 271, a second mirror 272, and a third mirror 273. The first mirror 271 is located between the half-wave plate 260 and the beam splitting unit 220. The incident light beam emitted by the half-wave plate 260 is transmitted to the beam splitting unit 220 via the first mirror 271. The second mirror 272 and the third mirror 273 are arranged in sequence between the beam splitting unit 220 and the second collimation subunit 212. The echo light beam emitted by the beam splitting unit 220 reaches the second collimation subunit 212 via the second mirror 272 and the third mirror 273 in sequence.
[0063] Please refer to again Figure 4 , the confocal optical imaging device 200 may further include a coupling unit 280 and a filtering unit 290. The coupling unit 280 and the filtering unit 290 are arranged in sequence between the beam splitting unit 220 and the second collimation subunit 212. The coupling unit 280 can be used to focus the echo light beam emitted by the beam splitting unit 220 and accurately transmit the focused echo light beam to the second collimation subunit 212 via the filtering unit. Among them, the coupling unit 280 includes a coupling lens, and the filtering unit 290 may include a narrowband filter. The specific filtering device is not limited here. The narrowband filter can suppress or reflect light of other wavelengths from entering the signal processing unit 130, reduce the influence of backscattered light on the signal processing unit 130, and improve the imaging quality.
[0064] In the above structure, the confocal optical imaging device 200 is used to process the laser beam, and the processed incident light beam is focused on the target object through the telescope 240. At the same time, through the cooperation of the beam splitting unit 220, the filtering unit, and the coupling unit 280, etc., the interference of the incident light beam and the backscattered light on the imaging can be reduced, and the imaging quality can be effectively improved.
[0065] In some possible implementation manners, please refer to Figure 5 , the light emitting unit 110 includes an optical switch 111 and a laser 112. The laser 112 is connected to the first control unit 120, and the optical switch 111 is connected to the first collimation subunit 211.
[0066] The laser 112 can receive the laser parameters sent by the first control unit 120 and generate corresponding laser beams based on the laser parameters. The optical switch 111 can receive the laser beams emitted by the laser and perform switching actions based on the timing control instructions of the first control unit 120, providing pulsed laser beams with a repetition frequency for the confocal optical imaging device 200. Among them, the laser parameters can include parameters such as the wavelength, repetition frequency, and pulse width of the laser beam, and the timing control instructions can determine the repetition frequency of the switching actions of the optical switch 111. Specifically, the wavelength can depend on the atmospheric transmission window and the solar radiation spectrum, the repetition frequency can be calculated by the first control unit 120 based on the range ambiguity principle, and the pulse width can depend on the actual depth measurement accuracy. Exemplarily, the laser beam can be a picosecond pulsed laser with a wavelength of 1550 nm and a repetition frequency of 1 MHz.
[0067] Further, please refer again to Figure 5 , the first control unit 120 can include a connected signal acquisition sub-unit 121 and a timing control sub-unit 122. The signal acquisition sub-unit 121 is connected to the signal processing unit 130 and can be used to directly or indirectly acquire the start time and end time of the photon flight in the emitted laser, calculate the photon flight time based on the start time and end time, and send the photon flight time to the main control sub-unit 122. Exemplarily, the timing acquisition sub-unit 121 includes a timer. The timing control sub-unit 122 can control the on / off of the laser 112, the deflection unit 230, and the signal processing unit 130 based on the photon flight time, realizing the timing control of the lidar system 100 and avoiding the signal processing unit 130 from acquiring irrelevant background noise. Among them, the timing control sub-unit can include a Field-Programmable Gate Array (FPGA).
[0068] Further, exemplarily, the signal acquisition sub-unit 121 can include a timer and a photodetector, and the signal acquisition sub-unit 121 can directly or indirectly acquire the start time of the photon flight in the emitted laser in the following two ways.
[0069] First, when the timing control sub-unit 122 sends laser parameters to the laser 112, the timing control sub-unit 122 can also send a synchronous timing signal to the timer, and the timer can directly obtain the start time of the photon flight in the emitted laser based on the synchronous timing signal.
[0070] Or, please refer to Figure 6 , the first control unit 120 can also include a photon splitting sub-unit 123. The photon splitting sub-unit 123 is respectively connected to the first collimating sub-unit 211 and the photodetector. The photon splitting sub-unit 123 can split the incident light beam emitted by the first collimating sub-unit 211 and make at least part of the incident light beam incident on the photodetector.
[0071] The photodetector can be connected to a timer. The photodetector generates a synchronous timing signal based on a part of the incident light beam and sends the synchronous timing signal to the timer, and the timer obtains the starting moment of the photon flight based on the synchronous timing signal. Among them, the photon splitting unit 123 includes, but is not limited to, optical elements such as a beam splitting cube, a perforated mirror, a perforated reflector, or a center-coated mirror, etc.
[0072] Furthermore, the lidar system 10 may further include a second control unit 140, and the second control unit 140 can be connected to the signal processing unit 130. The signal processing unit 130 includes a single photon detector, and the single photon detector includes, but is not limited to, a Geiger avalanche diode (Gm-APD), a photomultiplier tube (PMT), a superconducting nanowire single photon detector (SNSPD), etc. After the single photon detector receives the echo light beam, it can not only send a response electrical signal to the timer, and the timer obtains the termination moment of the photon flight based on the response electrical signal, but also send photon data to the second control unit 140. The second control unit 140 can store a single photon reconstruction algorithm for processing photon data and restoring the three-dimensional image of the target object. Among them, the single photon reconstruction algorithm can be a traditional probability statistical single photon reconstruction algorithm or a deep learning reconstruction algorithm. In addition, the second control unit 140 can also measure the distance between the beam emitter and the target object based on the photon flight time. Specifically, assuming the photon flight time is T, the distance between the beam emitter and the target object where c is the speed of light.
[0073] Exemplarily, the working process of the lidar system 100 provided by the embodiments of the present application may be as follows:
[0074] First, the signal acquisition subunit 121 can first send a deflection control instruction to the deflection unit 230. After the deflection unit 230 deflects to the specified position based on the deflection control instruction, the feedback unit sends a feedback signal to the control unit 120, and the signal acquisition subunit 121 sends laser parameters to the laser 112 based on the feedback signal. The laser 112 generates a corresponding laser beam based on the laser parameters. The optical switch 111 can receive the laser beam emitted by the laser 112 and perform a switching action based on the timing control instruction of the first control unit 120 to provide a pulsed laser beam with a repetition frequency for the confocal optical imaging device 200.
[0075] When the timing control subunit 122 sends laser parameters to the laser 112, it can also send a synchronous timing signal to the timer, and the timer can directly obtain the starting moment of the photon flight in the emitted laser based on the synchronous timing signal.
[0076] The first collimation sub-unit 211 expands the laser beam to obtain a parallel incident beam. The echo beam is incident on the telescope 240 after passing through the beam splitting unit 220 and the deflection unit 230. The telescope 240 focuses the incident beam on the target object by adjusting the focal point of the incident beam, forms a point illumination source on the target object, and receives the echo beam returned from the target object.
[0077] The beam splitting unit 220 splits the incident beam and the echo beam, so that the echo beam is transmitted to the single-photon detector after passing through the collimation unit 210. After the single-photon detector receives the echo beam, it sends a response electrical signal and photon data to the timer and the timing control sub-unit 122 respectively. The timer obtains the termination time of the photon flight based on the response electrical signal, calculates the photon flight time based on the start time and the termination time, and sends the photon flight time to the timing control sub-unit 122.
[0078] The timing control sub-unit 122 controls the deflection of the deflection unit 230 according to the photon flight time, controls the modulation optical switch 111 to emit or stop emitting laser, and controls the single-photon detector to receive the echo beam or stop working according to the timing.
[0079] After receiving the echo beam, the single-photon detector can send the photon data to the second control unit 140, and the second control unit 140 processes the photon data to restore the three-dimensional image of the target object. In addition, the second control unit 140 can also receive the photon flight time sent by the timer, and calculate the distance between the emitter and the target object according to the photon flight time, so as to achieve the purpose of radar ranging.
[0080] In summary, the embodiment of the present application provides a lidar system. The lidar system includes a light emitting unit, a control unit, a signal processing unit, and a confocal optical imaging device. The confocal optical imaging device can focus the laser beam generated by the light emitting unit on a certain point on the target object, and can also receive the echo beam returned from the target object and send the echo beam to the signal processing unit to form a point-to-point conjugate imaging, so as to realize the detection and imaging of a long-distance target in a low visibility environment while improving the imaging quality. At the same time, through the control unit, the timing control of the lidar system is realized, which can avoid the signal processing unit from collecting irrelevant background noise, effectively eliminate the backscattering noise, improve the signal-to-noise ratio of the lidar system, and thus improve the lateral resolution of the lidar system.
[0081] The above are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. A laser radar system, characterized in that: The laser radar system includes a light emitting unit, a first control unit, a signal processing unit and a confocal optical imaging device; The light emitting unit is connected to the confocal optical imaging device, and the light emitting unit is used to provide a laser beam for the confocal optical imaging device; The confocal optical imaging device is connected to the signal processing unit, and is used to focus the laser beam on a certain point on the target object, receive an echo beam returned from the target object, and send the echo beam to the signal processing unit; The signal processing unit is used to receive the echo light beam and form a point-to-point conjugate imaging according to the echo light beam; The first control unit is respectively connected to the confocal optical imaging device, the light-emitting unit and the signal processing unit. The first control unit is used to collect the working timing of the confocal optical imaging device, the light-emitting unit and the signal processing unit, and send timing control instructions to the confocal optical imaging device, the light-emitting unit and the signal processing unit.
2. The laser radar system according to claim 1, characterized in that: The confocal optical imaging device comprises a collimation unit, a light splitting unit, a deflection unit and a telescope; The collimating unit is used to expand the received laser beam to obtain a parallel emission beam, and the emission beam is incident on the telescope via the light splitting unit and the deflection unit; The telescope is used to adjust the focus point of the emission light beam, focus the emission light beam on the target object, and receive the echo light beam returned from the target object; The light splitting unit is used to split the emission light beam and the echo light beam, so that the emission light beam is focused on a certain point position of the target object, and the echo light beam is transmitted to the signal processing unit after passing through the collimating unit, so that the signal processing unit forms a point-to-point conjugate imaging according to the echo light beam; The deflection unit is connected to the control unit, and is used to receive a deflection control instruction sent by the control unit, and control the deflection direction of the emission light beam based on the deflection control instruction so that the emission light beam is focused on different positions of the target object.
3. The laser radar system according to claim 2, characterized in that: The magnification of the telescope is 2-35.
4. The laser radar system according to claim 2, characterized in that: The collimation unit comprises a first collimation subunit and a second collimation subunit; The first collimating subunit is connected to the light emitting unit, and the first collimating subunit is used to expand the received laser beam to obtain a parallel emission beam; The second collimating subunit is connected to the signal processing unit, and is used to receive the echo light beam separated from the light splitting unit and couple the echo light beam to the signal processing unit.
5. The laser radar system according to claim 4, characterized in that: The light emitting unit comprises an optical switch and a laser, the laser is connected to the first control unit, and the optical switch is connected to the first collimation subunit; The laser is used to send a laser beam, and the optical switch is used to receive the laser beam and perform a switching action based on a timing control instruction of the first control unit.
6. The laser radar system according to claim 5, characterized in that: The first control unit includes a connected signal acquisition subunit and a timing control subunit; The signal acquisition subunit is connected to the light emitting unit or the laser radar system, and is used to collect the starting time of the flight of photons in the laser beam; The signal acquisition subunit is also connected to the signal processing unit, and is used to acquire the end time of the flight of the photons in the laser beam, and calculate the photon flight time based on the start time and the end time; The timing control subunit is used to receive the photon flight time sent by the signal acquisition subunit, and control the switching of the signal processing unit based on the photon flight time.
7. The laser radar system according to claim 6, characterized in that: The control unit also includes a photon subunit, and the signal acquisition subunit includes a photoelectric sensor and a timer; The photon splitting subunit is connected to the first collimating subunit and the signal collecting subunit respectively, and the photon splitting subunit is used to split the incident light beam emitted by the first collimating subunit, and to make at least part of the incident light beam incident to the signal collecting subunit; The photodetector is used to generate a synchronization timing signal based on a portion of the incident light beam, and send the synchronization timing signal to the timer, and the timer obtains the starting time of photon flight based on the synchronization timing signal.
8. The laser radar system according to claim 1, characterized in that: The laser radar system also includes a second control unit; The second control unit is connected to the signal processing unit, and the second control unit restores the three-dimensional image of the target object based on the photon data sent by the signal processing unit.
9. The laser radar system according to claim 8, characterized in that: The photon splitter unit includes a beam splitter cube, a perforated reflector, a perforated reflector or a central coated mirror; The signal acquisition subunit includes a photoelectric sensor.
10. The laser radar system according to claim 7, characterized in that: The signal processing unit includes a single photon detector, which includes a Geiger avalanche diode, a photomultiplier tube or a superconducting nanowire single photon detector.