Large Field of View Solid State LiDAR Device and Detection Method

Abstract

The present invention relates to a large field of view solid-state lidar device and a detection method. It is applicable to the technical field of lidar. The technical solution adopted by the present invention is as follows: A large field of view solid-state lidar device includes: a transmitting module for emitting an outgoing laser beam; a beam scanning device for changing the scanning angle of the outgoing laser beam emitted by the transmitting module within a preset angle range and making the outgoing laser beam irradiate a long-focus lens; the long-focus lens for focusing the outgoing laser beams with different scanning angles from the beam scanning device onto the rear focal plane of the long-focus lens; an ultra-wide-angle lens whose front focal plane coincides with the rear focal plane of the long-focus lens for expanding the scanning angle range of the outgoing laser beam focused on the front focal plane of the ultra-wide-angle lens.

Description

Technical Field

[0001] The present invention relates to a large field of view solid-state lidar device and a detection method, which is applicable to the technical field of lidar. Background Art

[0002] With the development of lidar technology, people have higher and higher performance requirements for lidar, and the cost requirements are also becoming more and more strict. In the existing common TOF lidar technology, according to different laser scanning mechanisms, it can be divided into semi-solid-state lidar and fully solid-state lidar. For commercial lidar in the field of autonomous driving, different application scenarios (such as long-distance ranging, large field of view blind spot filling, etc.) require the installation of multiple different types of lidar, and it is difficult to have a lidar that can meet the needs of multiple application scenarios at the same time.

[0003] In the existing TOF lidar technology, semi-solid-state lidar is mainly divided into two types: one-dimensional rotating mirror scheme and two-dimensional MEMS micro-vibrating mirror scheme. Among them, the one-dimensional rotating mirror scheme can only achieve the coverage of one-dimensional large field of view, which poses a greater challenge to the system reliability, and has higher requirements for the array performance of laser emission and receiving chips; the MEMS micro-vibrating mirror scheme only relies on the scanning of two-dimensional MEMS micro-vibrating mirrors, and it is difficult to achieve the scanning coverage of a large field of view detection area. If a large field of view needs to be covered, multiple modules are required for field of view stitching, which increases the complexity and cost of the system.

[0004] In the prior art, fully solid-state lidar mainly uses the Flash scheme. Although this scheme can achieve the coverage of a large field of view in two-dimensional space, limited by the power limit of eye safety, its detection distance in the two-dimensional large field of view is difficult to break through the bottleneck. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: in view of the above problems, to provide a large field of view solid-state lidar device and a detection method.

[0006] The technical solution adopted by the present invention is: a large field of view solid-state lidar device, comprising:

[0007] A transmitting module for emitting an outgoing laser beam;

[0008] A beam scanning device for changing the scanning angle of the outgoing laser beam emitted by the transmitting module within a preset angle range and making the outgoing laser beam shoot towards a long-focus lens;

[0009] The long-focus lens for focusing the outgoing laser beams with different scanning angles from the beam scanning device onto the rear focal plane of the long-focus lens;

[0010] An ultra-wide-angle lens, whose front focal plane coincides with the rear focal plane of the telephoto lens, is used to expand the scanning angle range of the outgoing laser beam focused on the front focal plane of the ultra-wide-angle lens.

[0011] It further includes:

[0012] A beam splitter, which is used to direct the outgoing laser beam emitted by the emission module towards the beam scanning device, and is also used to direct the echo laser beam from the beam scanning device towards the receiving module;

[0013] The receiving module is used to receive the echo laser beam from the beam splitter and convert the echo laser beam into an electrical signal;

[0014] The beam scanning device is also used to direct the echo laser beam that sequentially enters through the ultra-wide-angle lens and the telephoto lens towards the beam splitter.

[0015] The emission module includes:

[0016] A laser, which is used to emit an outgoing laser beam;

[0017] A collimating mirror, which is used to collimate and shape the outgoing laser beam emitted by the laser.

[0018] The collimating mirror includes: a fast-axis collimating lens group and a slow-axis collimating lens group;

[0019] The fast-axis collimating lens group is used for collimating and shaping the outgoing laser beam in the fast-axis direction; the slow-axis collimating lens group is used for collimating and shaping the outgoing laser beam in the slow-axis direction.

[0020] The beam scanning device includes a blazed grating and / or a MEMS micromirror;

[0021] The blazed grating is used for spatial dispersion separation of wavelength-tunable laser;

[0022] The MEMS micromirror is used for adjusting the spatial angle of the beam.

[0023] The telephoto lens is a telephoto lens group, and the ultra-wide-angle lens is an ultra-wide-angle lens group; the optical axes of the telephoto lens group and the ultra-wide-angle lens group are aligned with the optical center of the beam scanning device.

[0024] By adjusting the ratio of the equivalent focal lengths of the telephoto lens and the ultra-wide-angle lens, the expansion multiple of the scanning angle of the ultra-wide-angle lens for the outgoing laser beam is adjusted.

[0025] The receiving module includes:

[0026] An echo focusing mirror, which is used to focus the echo laser beam from the beam splitter onto the detector;

[0027] The detector is used to convert the echo laser beam into an electrical signal.

[0028] The echo focusing mirror is a converging lens group, which converges the echo laser beam from the beam splitter and focuses it on the target surface of the detector for signal detection.

[0029] A large field of view solid-state lidar detection method includes:

[0030] When detecting a target field of view area, the transmitting module emits an outgoing laser beam, which passes through the beam splitter and is subjected to two-dimensional spatial scanning within a certain angle range by the beam scanning device.

[0031] The outgoing laser beams at different spatial scanning angles are focused on its rear focal plane by the long focal length lens, forming corresponding focused beams with different spatial scales.

[0032] Then, it is expanded by the ultra-wide angle lens with the front focal plane coinciding with the rear focal plane of the long focal length lens, and the laser beams focused within different spatial scale ranges on the confocal plane are converted into outgoing laser beams scanned within a large angle range in the outgoing space.

[0033] The echo laser beam carrying the information of the target object reflected by the target object in the detection field of view area of the outgoing laser beam is received by the ultra-wide angle lens, collimated by the long focal length lens, reflected by the beam scanning device, deflected by the beam splitter to separate the optical path from the outgoing laser beam, and finally received by the receiving module.

[0034] The beneficial effects of the present invention are as follows: In the present invention, the long focal length lens focuses the collimated light at different scanning angles on its rear focal plane, forming corresponding focused beams with different spatial scales. By designing a longer focal length, a larger scale scanning range is obtained at the scanning focus point on its rear focal plane; the front focal plane of the ultra-wide angle lens coincides with the rear focal plane of the above long focal length lens, and the beam focused on its front focal plane and scanned within a large scale range is converted into a collimated beam scanned within a large angle range in the outgoing space through the expansion of the ultra-wide angle lens.

[0035] Through the cooperation of the long focal length lens and the ultra-wide angle lens, etc., the present invention greatly expands the limited spatial scanning field of view range, breaking through the limitation of the mutual restriction of the two key performances of the conventional semi-solid and all-solid lidars in the spatial field of view scanning range and ranging ability in design, and can simultaneously meet the functions of large field of view scanning and long-distance detection, enabling it to be used on various application scenarios.

[0036] The two-dimensional spatial scanning mechanism of the present invention is to use wavelength scanning of the dispersion device, scanning of the micro-vibrator, or a combination of both, without relying on mechanical mechanism components such as rotating mirrors, and the reliability is better than that of the lidar based on the rotating mirror scheme. Description of the Drawings

[0037] Figure 1 It is a schematic diagram of the principle of the scanning field of view magnification described in the present invention.

[0038] Figure 2 It is a schematic diagram of the optical path structure of Embodiment 2 of the present invention.

[0039] Figure 3 It is a schematic diagram of the optical path of Embodiment 3 of the present invention.

[0040] Figure 4 It is a schematic diagram of the optical path of Embodiment 4 of the present invention.

[0041] Figure 5 It is a schematic diagram of the optical path of Embodiment 5 of the present invention.

[0042] Figure 6 It is a schematic diagram of the structure of the one-dimensional MEMS micromirror in the present invention.

[0043] Figure 7 It is a schematic diagram of the structure of the blazed grating in the present invention.

[0044] Description of the reference numerals:

[0045] 10. Laser; 11. Single-wavelength laser; 12. Wavelength-tunable laser;

[0046] 20. Collimating mirror; 21. Fast-axis collimating lens group; 22. Slow-axis collimating lens group;

[0047] 30. Beam splitter; 31. Polarizing beam splitter prism; 32. Quarter-wave plate;

[0048] 40. Beam scanning device; 41. One-dimensional MEMS micromirror; 42. Two-dimensional MEMS micromirror; 411. Micromirror reflector; 412. Micromirror substrate; 43. Blazed grating;

[0049] 50. Long-focus lens;

[0050] 60. Ultra-wide-angle lens;

[0051] 70. Echo focusing mirror;

[0052] 80. Detector; 81. Single-pixel detector; 82. Linear array detector. Detailed implementation manners

[0053] In order to better understand the technical solution of the present application, the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0054] It should be clear that the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present application.

[0055] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms of "a", "the", and "said" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0056] Embodiment 1: This embodiment is a large field of view solid-state lidar device, including a transmitting module, a beam scanning device 40, a long-focus lens 50, and an ultra-wide-angle lens 60 arranged in sequence along the optical path of the emitted laser beam. The front focal plane of the ultra-wide-angle lens 60 coincides with the rear focal plane of the long-focus lens 50.

[0057] In this example, when the above-mentioned solid-state lidar device detects the target field of view area, an emitted laser beam is emitted by the transmitting module; the beam scanning device 40 performs spatial two-dimensional MEMS micromirror 42 scanning within a certain angle range. The beam scanning device 40 changes the scanning angle of the emitted laser beam emitted by the transmitting module within a preset angle range, and makes the emitted laser beam shoot towards the long-focus lens 50; the beams with different spatial scanning angles are focused on its rear focal plane by the long-focus lens 50, and corresponding focused beams with different spatial scales are formed; then through the expansion of the ultra-wide-angle lens 60 whose front focal plane coincides with it, the scanning beams focused within different spatial scale ranges on the confocal plane are converted into collimated beams scanned within a large angle range in the emitted space.

[0058] In some specific examples, the transmitting module includes a laser 10 and a collimating mirror 20, where the laser 10 is used to emit an emitted laser beam; the collimating mirror 20 is used to perform collimation and shaping processing on the emitted laser beam emitted by the laser 10.

[0059] In some more specific examples, the collimating mirror 20 is a collimating lens group for laser beam shaping, including a fast-axis collimating lens group 21 and a slow-axis collimating lens group 22. The fast-axis collimating lens group 21 is used for collimation and shaping of the emitted laser beam in the fast-axis direction; the slow-axis collimating lens group 22 is used for collimation and shaping of the emitted laser beam in the slow-axis direction. The fast-axis collimating lens group 21 and the slow-axis collimating lens group 22 include at least one cylindrical lens.

[0060] In some specific examples, the beam scanning device 40 may be a blazed grating 43, a MEMS micromirror, or a combination of both. The blazed grating 43 is used for spatial dispersion separation of the wavelength-tunable laser, and the MEMS micromirror is used for adjusting the spatial angle of the beam. The combination of the blazed grating 43 and the MEMS micromirror can achieve spatial scanning of the output laser beam in two dimensions, horizontal and vertical. Its scanning field of view is the spatial two-dimensional scanning field of view of the MEMS micromirror 42 within a certain angular range.

[0061] In some specific examples, the telephoto lens 50 is a telephoto lens group, and the ultra-wide-angle lens 60 is an ultra-wide-angle lens group. The optical axes of the telephoto lens group and the ultra-wide-angle lens group are aligned with the optical center of the beam scanning device 40.

[0062] In this embodiment, an optical system composed of the telephoto lens 50, the ultra-wide-angle lens 60, etc. is used to expand the scanning field of view of the output laser beam in the spatial two-dimensional scanning field of view of the MEMS micromirror 42. As Figure 1 shown, the telephoto lens 50 focuses the collimated light at different scanning angles onto its rear focal plane, forming corresponding focused beams with different spatial scales. By designing a longer focal length, the scanning focus points on its rear focal plane have a larger scanning range; the front focal plane of the ultra-wide-angle lens 60 coincides with the rear focal plane of the above-mentioned telephoto lens 50. The beam that is focused on its front focal plane and scanned within a large scale range is converted into a collimated beam scanned within a large angular range in the output space through the expansion of the ultra-wide-angle lens 60. Finally, the scanning in the horizontal and vertical dimensions of the output space respectively corresponds to the scanning in the two spatial dimensions of the beam scanning device 40.

[0063] In this embodiment, the magnification of the scanning field of view angle in each spatial dimension is determined by the ratio of the equivalent focal lengths of the telephoto lens group and the ultra-wide-angle lens group decided.

[0064] Embodiment 2: As Figure 2 shown, on the basis of Embodiment 1, this embodiment adds an echo receiving system for receiving the echo laser beam carrying the target object information that returns after the output laser beam is reflected by the target object after being emitted.

[0065] In this example, the echo receiving system includes a beam splitter 30 and a receiving module. The beam splitter 30 is arranged between the transmitting module and the beam scanning device 40, and the receiving module is arranged corresponding to the beam splitter 30.

[0066] In the solid-state lidar device of this embodiment, the optical path of the emitted laser beam and the optical path of the echo laser beam adopt a coaxial design. In parts such as the beam splitter 30, the beam scanning device 40, the long-focus lens 50, and the ultra-wide-angle lens 60, the optical paths of the emitted laser beam and the echo laser beam share a coaxial optical path; the ultra-wide-angle lens 60 serves as both the emission window of the laser and the collection window of the echo; the optical paths of the emitted laser beam and the echo laser beam are separated at the beam splitter 30.

[0067] In this example, when the above-mentioned solid-state lidar device detects a target field of view area, an emitted laser beam is emitted by the emission module, passes through the beam splitter 30, and is scanned by the spatial two-dimensional MEMS micromirror 42 of the beam scanning device 40 within a certain angle range. The beam scanning device 40 changes the scanning angle of the emitted laser beam emitted by the emission module within a preset angle range and makes the emitted laser beam shoot towards the long-focus lens 50; the light beams at different spatial scanning angles are focused on its rear focal plane by the long-focus lens 50 to form corresponding focused light beams of different spatial scales; then, through the expansion of the ultra-wide-angle lens 60 whose front focal plane coincides with it, the scanning light beams within different spatial scale ranges on the confocal plane are converted into collimated light beams scanned within a large angle range in the emission space.

[0068] After the emitted laser beam is reflected by the target object in the detection field of view area, the echo beam carrying the information of the target object is received by the ultra-wide-angle lens 60, collimated by the long-focus lens 50, reflected by the beam scanning device 40, and then deflected by the beam splitter 30 to separate from the optical path of the emitted laser beam, and finally detected and received by the receiving module.

[0069] In some specific examples, the receiving module includes an echo focusing mirror 70 and a detector 80. The echo focusing mirror 70 is used to focus the echo laser beam from the beam splitter 30 onto the detector 80, and the detector 80 is used to convert the optical signal of the echo laser beam into an electrical signal.

[0070] In some more specific examples, the echo focusing mirror 70 is a converging lens group, which converges the echo laser beam deflected by the beam splitter 30 and focuses it on the target surface of the detector 80 for signal detection.

[0071] In this embodiment, the emission spot of the laser 10 can pass through the optical system composed of a collimating lens and the long-focus lens 50, etc., to form a clear image point spot on the confocal plane of the long-focus lens 50 and the ultra-wide-angle lens 60. The laser beams passing through the image points at different positions correspond to the laser beams at different spatial field of view angles in the final emission scanning field of view; similarly, the receiving spot of the detector 80, passing through the optical system composed of a converging lens and the long-focus lens 50, has the same object-image relationship with the spot on the confocal plane.

[0072] Embodiment 3: As Figure 3As shown, this embodiment is a further optimized solution of Embodiment 2. In this embodiment, the laser 10 is a single-wavelength laser 11 for emitting a single-wavelength laser beam. The laser includes any one of the following: semiconductor lasers, fiber lasers. The above semiconductor lasers include: Edge-Emitting Laser (EEL), Vertical-Cavity Surface-Emitting Laser (VCSEL).

[0073] The collimating mirror 20 of this embodiment is a collimating lens group for performing collimating and shaping processing on the emitted laser beam in the fast-axis and slow-axis directions respectively. The collimating lens group is composed of a fast-axis collimating lens group 21 and a slow-axis collimating lens group 22; optionally, the fast-axis collimating lens group 21 and the slow-axis collimating lens group 22 are each composed of several lenses, including any one of the following: spherical lenses, cylindrical lenses, aspherical lenses, and gradient-index lenses.

[0074] The collimating effect of the collimating mirror 20 on the emitted laser beam plays a decisive role in the collimation and detection angular resolution of the emitted beam of the entire lidar device. Therefore, during the installation and debugging of the above laser 10 and collimating mirror 20, the divergence angle can be calculated by measuring the spot size of the laser beam emitted by the entire lidar device. After the divergence angle meets the angular resolution requirements of the lidar system, it can be confirmed that the debugging is completed.

[0075] The beam splitter 30 of this embodiment is composed of a polarization beam splitter prism 31 and a quarter-wave plate 32 for separating the emitted beam and the echo beam in the coaxial optical path system; the quarter-wave plate 32 is placed on the transmission side of the polarization beam splitter prism 31 to change the incident laser beam transmitted from the polarization beam splitter prism 31 from the P polarization state to the circular polarization state, and change the reflected echo beam from the circular polarization state to the S polarization state; the echo beam in the S polarization state is reflected at the interface of the polarization beam splitter prism 31, so that the optical path of the echo beam is deflected and separated from the optical path of the incident laser beam of the original polarization beam splitter prism 31.

[0076] It should be emphasized that the implementation form of the beam splitter 30 can be a perforated partial reflector, a semi-transmissive semi-reflective mirror, a polarization beam splitter, or a polarization beam splitter prism, etc., combined with a combination module composed of several quarter-wave plates or half-wave plates, and this application does not make special limitations.

[0077] In this embodiment, the beam scanning device 40 is a one-dimensional MEMS micromirror 41, which is used to change the direction of the emitted beam and fold the optical path, and adjust the one-dimensional MEMS micromirror 41 in the adjustment dimension corresponding to the horizontal dimension of the final exit field of view, so as to realize the spatial scanning of the emitted beam within a certain angular range in the above dimension. According to the principle of optical path reversibility, for the echo beams at different angles within the spatial scanning range in the above dimension, the one-dimensional MEMS micromirror 41 can also reflect them and return them along the optical path of the incident beam.

[0078] As Figure 6 shown, the basic structure of the one-dimensional MEMS micromirror 41 includes: a micromirror reflector 411 and a micromirror substrate 412. The micromirror reflector 411 is used to reflect the optical path. The spot size of the incident beam after collimation should be within the size limit range of the micromirror reflector 411. Moreover, an absorbent layer should be coated on the surface of the micromirror substrate 412 to eliminate as much as possible the stray light reflected by the incident beam at the micromirror substrate 412.

[0079] The long-focus lens 50 in this embodiment can be a long-focus lens group, which focuses the collimated beams at different spatial scanning angles through the long-focus lens to its rear focal plane, thereby forming focused beams with corresponding different spatial scales; optionally, the above long-focus lens group is composed of several lenses, including any one of the following: spherical lens, cylindrical lens, aspherical lens, and gradient refractive index lens.

[0080] The ultra-wide-angle lens 60 in this embodiment can be an ultra-wide-angle lens group, whose front focal plane coincides with the rear focal plane of the above long-focus lens group, which can realize the expansion of the spatial two-dimensional scanning field of view of the emitted beam, and is also used for the convergent collection of echo beams at different angles within the target detection area. Optionally, the above ultra-wide-angle lens group can also be a fish-eye lens group, which is composed of several lenses, including any one of the following: spherical lens, cylindrical lens, aspherical lens, and gradient refractive index lens.

[0081] The echo beams at different angles within the field of view reflected by the target object in the detection area, in the coaxial optical path system of the solid-state lidar in this embodiment, sequentially pass through the above ultra-wide-angle lens group, long-focus lens group, and the reflection of the one-dimensional MEMS micromirror 41, and then become a polarization state orthogonal to the laser beam incident on the polarization beam splitter 31 through the above quarter-wave plate 32, and then deflect the optical path at the above polarization beam splitter 31, and finally are detected and received by the receiving system composed of the echo focusing mirror 70 and the detector 80.

[0082] Among them, the above echo focusing mirror 70 is used to focus the spot of the echo beam after reflection and deflection by the above polarization beam splitter prism 31; optionally, it can be a converging lens group composed of several lenses, including any one of the following: spherical lens, cylindrical lens, aspherical lens, and gradient index lens.

[0083] The above detector 80 is used to detect the above echo beam after spot focusing, and is a linear array detector 82; optionally, the above linear array detector 82 can be: Balanced Photo Diode (BPD), Avalanche Photo Diode (APD), Silicon Photomultiplier (SiPM), Photomultiplier Tube (PMT), or Single-Photon Avalanche Diode (SPAD), etc.

[0084] In this embodiment, since the beam scanning device 40 of the solid-state lidar device is a one-dimensional MEMS micromirror 41, it can only achieve one-dimensional spatial scanning, and its spatial scanning dimension corresponds to the horizontal dimension of the final exit field of view; the coverage of the spatial scanning field of view corresponding to the vertical dimension of the final exit field of view can be achieved by using a Focal Plane Array (FPA) scheme based on an array detector. The specific implementation of this scheme is as follows: the photodetector of the above detector 80 uses a linear array detector 82 with N pixels, where N is the number of laser channels in the vertical dimension of the final exit field of view (for example, N = 128); optionally, the above single-wavelength laser 11 can be a single-point laser or an array laser, and is reshaped into a line light source through the fast-axis collimating lens group 21 and the slow-axis collimating lens group 22; as Figure 3 shown, the spot of the above line light source can be imaged on the above linear array detector 82 through the converging lens group, and each pixel of the linear array detector can obtain the detection information corresponding to each channel in the vertical dimension of the final exit field of view. At the confocal plane of the above long-focus lens group and the ultra-wide-angle lens group, the laser beams of the N channels in the above vertical dimension are focused into N spots here, and finally an extended large field of view can also be obtained in the vertical dimension of the exit field of view.

[0085] In addition, several reflectors can be added to the solid-state lidar device in this embodiment, and the purpose is to fold and compress the optical path, thereby reducing the space length occupied by the optical path and making the structure of the entire device more compact. It is not shown in the optical path schematic diagram ( Figure 3 ) of this embodiment, which does not mean that there are no reflectors in the optical path, and this situation is not specifically limited in this application.

[0086] In the solid-state lidar device of this embodiment, the one-dimensional MEMS micromirror 41 realizes the one-dimensional spatial field-of-view scanning of the emitted light beam within a certain angular range. Then, in combination with the equivalent line light source based on optical shaping and the focal plane array (FPA) scheme of the linear array detector, and then through the above-mentioned long-focus lens group and ultra-wide-angle lens group to expand the field of view, the two-dimensional large field-of-view scanning detection of the final emitted space can be realized. The above-mentioned one-dimensional MEMS micromirror 41 adjusts the angle in the adjustment dimension corresponding to the horizontal dimension of the final emitted space field of view (the maximum adjustment range of the mirror surface can reach 15°, and the angular scanning range of the reflected light beam is twice the adjustment range of the mirror surface), and the angular scanning range of the reflected light beam in the above dimension is ; the field-of-view angle ranges of the two-dimensional field of view of the final emitted space are respectively (the above horizontal dimension) and (the above vertical dimension), and their field-of-view expansion relationships are as follows:

[0087] ;

[0088] ;

[0089] Among them, and are the equivalent focal lengths of the above-mentioned long-focus lens group and ultra-wide-angle lens group respectively, and the field-of-view magnification factor is ; is the field-of-view angle resolution in the above vertical dimension, which is determined by the optical system parameters of the entire lidar device.

[0090] Example 4: As Figure 4 shown, this embodiment is a further optimized solution of Embodiment 2. The laser 10 in this embodiment is a single-wavelength laser 11 for emitting a single-wavelength laser beam; optionally, the laser includes any one of the following: semiconductor lasers, fiber lasers; optionally, the above semiconductor lasers include: edge-emitting lasers (EELs), vertical-cavity surface-emitting lasers (VCSELs).

[0091] The collimating mirror 20 in this embodiment is a collimating lens group, which performs collimation and shaping processing on the above-mentioned emitted laser beam in the fast-axis and slow-axis directions respectively. The above collimating lens group is composed of a fast-axis collimating lens group 21 and a slow-axis collimating lens group 22; optionally, the above fast-axis collimating lens group 21 and slow-axis collimating lens group 22 are each composed of several lenses, including any one of the following: spherical lenses, cylindrical lenses, aspherical lenses, and gradient-index lenses.

[0092] The collimation effect of the collimating mirror 20 on the emitted laser beam is decisive for the collimation of the emitted beam and the detection angular resolution of the entire lidar device. Therefore, during the installation and debugging of the above-mentioned laser 10 and collimating mirror 20, the divergence angle can be calculated by measuring the spot size of the laser beam emitted by the entire lidar device. After the divergence angle meets the angular resolution requirements of the lidar system, the debugging can be confirmed to be completed.

[0093] The beam splitter 30 in this embodiment is composed of a polarization beam splitter prism 31 and a quarter-wave plate 32, and is used for separating the emitted beam and the echo beam in the coaxial optical path system; the above-mentioned quarter-wave plate 32 is placed on the transmission side of the polarization beam splitter prism 31, and the incident laser beam transmitted from the polarization beam splitter prism 31 is changed from the P polarization state to the circular polarization state, and the reflected echo beam is changed from the circular polarization state to the S polarization state; the echo beam in the S polarization state is reflected at the interface of the above-mentioned polarization beam splitter prism 31, so that the optical path of the echo beam is deflected and separated from the optical path of the incident laser beam of the original polarization beam splitter prism 31.

[0094] It should be emphasized that the implementation form of the beam splitter 30 can be a perforated partial reflector, a semi-transmissive semi-reflective mirror, a polarization beam splitting film or a polarization beam splitter prism, etc., and a combination module composed of several quarter-wave plates or half-wave plates is not particularly limited in this application.

[0095] The beam scanning device 40 in this embodiment is a two-dimensional MEMS micromirror 42, which is used to change the direction of the emitted beam and fold the optical path, and adjust the two-dimensional MEMS micromirror 42 in the adjustment dimensions corresponding to the horizontal and vertical dimensions of the final exit field of view, respectively, so as to realize the spatial scanning of the emitted beam within a certain angle range in the above two dimensions; according to the principle of optical path reversibility, for the echo beams at different angles within the spatial scanning range of the above two dimensions, the two-dimensional MEMS micromirror 42 can also reflect them and return along the optical path of the incident beam. Here, the basic structure of the two-dimensional MEMS micromirror 42 and the limitation requirements for the spot size of the incident beam are similar to those of the above-mentioned one-dimensional MEMS micromirror 41, and an absorbing layer also needs to be coated on the surface of the micromirror substrate to eliminate the stray light reflected by the incident beam at the micromirror substrate as much as possible.

[0096] The long-focus lens 50 in this embodiment can be a long-focus lens group, which focuses the collimated beams at different spatial scanning angles onto its rear focal plane through the long-focus lens, and forms corresponding focused beams with different spatial scales; optionally, the above-mentioned long-focus lens group is composed of several lenses, including any one of the following: spherical lens, cylindrical lens, aspherical lens and gradient refractive index lens.

[0097] The ultra-wide-angle lens 60 of this embodiment can be an ultra-wide-angle lens group, whose front focal plane coincides with the rear focal plane of the above-mentioned telephoto lens group, which can realize the expansion of the spatial two-dimensional scanning field of the emitted light beam, and is also used for the convergent collection of echo light beams at different angles within the target detection area; optionally, the above-mentioned ultra-wide-angle lens group can also be a fish-eye lens group, which is composed of several lenses, including any one of the following: spherical lens, cylindrical lens, aspherical lens, and gradient refractive index lens.

[0098] The echo light beams at different angles within the field of view reflected by the target object in the detection area, in the coaxial optical path system of the solid-state lidar of this embodiment, sequentially pass through the above-mentioned ultra-wide-angle lens group, telephoto lens group, and the reflection of the two-dimensional MEMS micromirror 42, and then become orthogonal to the polarization state of the laser beam incident on the polarization beam splitter 31 through the above-mentioned quarter-wave plate 32, and then deflect the optical path at the above-mentioned polarization beam splitter 31, and finally are detected and received by the receiving system composed of the echo focusing mirror 70 and the detector 80.

[0099] Among them, the above-mentioned echo focusing mirror 70 is used for focusing the spot of the echo light beam deflected by the reflection of the above-mentioned polarization beam splitter 31; optionally, it can be a converging lens group, which is composed of several lenses, including any one of the following: spherical lens, cylindrical lens, aspherical lens, and gradient refractive index lens. The above-mentioned detector 80 is used for detecting the above-mentioned echo light beam after spot focusing, and is a single-pixel detector 81; optionally, the above-mentioned single-pixel detector 81 can be: Balanced Photo Diode (BPD), Avalanche Photo Diode (APD), Silicon Photomultiplier (SiPM), Photomultiplier Tube (PMT), or Single-Photon Avalanche Diode (SPAD), etc.

[0100] In addition, several reflectors can be added to the solid-state lidar device of this embodiment, and the purpose is to fold and compress the optical path, thereby reducing the spatial length occupied by the optical path and making the structure of the entire device more compact. In the optical path schematic diagram of this embodiment ( Figure 4 ) it is not shown, which does not mean that there are no reflectors in the optical path, and this situation is not specifically limited in this application.

[0101] In the solid-state lidar device of this embodiment, the two-dimensional MEMS micromirror 42 realizes the spatial two-dimensional field of view scanning of the emitted light beam within a certain angular range, and then expands the field of view through the above-mentioned long-focus lens group and ultra-wide-angle lens group, so as to realize the scanning detection of the final large two-dimensional field of view in space. The above two-dimensional MEMS micromirror 42 adjusts the angles and (the maximum adjustment range of the mirror surface can reach 15°, and the angular scanning range of the reflected light beam is twice that of the mirror surface adjustment range) on the adjustment dimensions corresponding to the horizontal and vertical dimensions of the final emitted space field of view respectively, and the angular scanning ranges of its reflected light beam corresponding to the above two dimensions are respectively and ; the field of view angle ranges of the final emitted two-dimensional space field of view are respectively (the above horizontal dimension) and (the above vertical dimension), and their field of view expansion relationships are as follows:

[0102] ;

[0103] ;

[0104] Among them, and are the equivalent focal lengths of the above-mentioned long-focus lens group and ultra-wide-angle lens group respectively, and the field of view magnification factor is . Of course, it should be noted that the adjustment angles and of the above two-dimensional MEMS micromirror 42 can also correspond to the vertical dimension and horizontal dimension of the final emitted two-dimensional space field of view respectively, and no special limitation is made here.

[0105] Embodiment 5: As Figure 5 shown, this embodiment is a further optimized solution of Embodiment 2. The laser 10 in this embodiment is a wavelength-tunable laser 12 for emitting a wavelength-tunable laser beam; optionally, the laser includes any one of the following: semiconductor laser, fiber laser; optionally, the above semiconductor laser includes: edge-emitting laser (EEL), vertical-cavity surface-emitting laser (VCSEL).

[0106] The collimating mirror 20 of this embodiment is a collimating lens group, which collimates and shapes the emitted laser beam in the fast axis and slow axis directions respectively. The collimating lens group is composed of a fast axis collimating lens group 21 and a slow axis collimating lens group 22. Optionally, the fast axis collimating lens group 21 and the slow axis collimating lens group 22 are each composed of several lenses, including any one of the following: spherical lens, cylindrical lens, aspherical lens, and gradient refractive index lens. Further, since the emitted beam in this embodiment needs to cover a certain range in the direction where the blazed grating 43 is arranged along the grating tooth surface, in the corresponding fast axis direction (or slow axis direction), the fast axis collimating lens group 21 (or slow axis collimating lens group 22) needs to expand the laser beam to a certain extent, and some lenses of the lens group for beam expansion can be placed on the transmission side of the beam splitter 30 to compress the length of the optical path.

[0107] The collimating effect of the collimating mirror 20 on the emitted laser beam plays a decisive role in the collimation and detection angle resolution of the emitted beam of the entire lidar device. Therefore, during the installation and debugging of the laser 10 and the collimating mirror 20, the divergence angle can be calculated by measuring the spot size of the laser beam emitted by the entire lidar device. After the divergence angle meets the angular resolution requirements of the lidar system, it can be confirmed that the debugging is completed.

[0108] The beam splitter 30 of this embodiment is composed of a polarization beam splitting prism 31 and a quarter-wave plate 32, and is used for separating the emitted beam and the echo beam in the coaxial optical path system. The quarter-wave plate 32 is placed on the transmission side of the polarization beam splitting prism 31, which changes the incident laser beam transmitted from the polarization beam splitting prism 31 from the P polarization state to the circular polarization state, and changes the reflected echo beam from the circular polarization state to the S polarization state. The echo beam in the S polarization state is reflected at the interface of the polarization beam splitting prism 31, so that the optical path of the echo beam is deflected and separated from the optical path of the incident laser beam of the original polarization beam splitting prism 31.

[0109] It should be emphasized that the implementation form of the beam splitter 30 can be a perforated partial reflector, a semi-transparent semi-reflective mirror, a polarization beam splitting film, or a polarization beam splitting prism, etc., combined with a combination module composed of several quarter-wave plates or half-wave plates. This application does not make special limitations.

[0110] The beam scanning device 40 of this embodiment is jointly composed of a blazed grating 43 and a one-dimensional MEMS micromirror 41, which is used to change the direction of the emitted beam and fold the optical path, and can realize the two-dimensional spatial scanning of the emitted beam within a certain angular range in the adjustment dimensions corresponding to the horizontal and vertical spatial dimensions of the final exit field of view. According to the principle of optical path reversibility, for the echo beams at different angles within the spatial scanning range of the above dimensions, the one-dimensional MEMS micromirror 41 and the blazed grating 43 can also reflect it and return along the optical path of the incident beam. Optionally, as Figure 6 shown, the basic structure of the one-dimensional MEMS micromirror 41 includes: a micromirror reflector 411 and a micromirror substrate 412. The micromirror reflector 411 is used to reflect the optical path. The spot size of the incident beam after collimation should be within the size limit range of the micromirror reflector 411. Moreover, an absorbing layer should be coated on the surface of the micromirror substrate 412 to eliminate the stray light reflected by the incident beam at the micromirror substrate 412 as much as possible.

[0111] The long-focus lens 50 of this embodiment can be a long-focus lens group, which focuses the collimated beams at different spatial scanning angles through the long-focus lens to its rear focal plane, and forms corresponding focused beams with different spatial scales; optionally, the above long-focus lens group is composed of several lenses, including any one of the following: spherical lens, cylindrical lens, aspherical lens, and gradient refractive index lens.

[0112] The ultra-wide-angle lens 60 of this embodiment can be an ultra-wide-angle lens group, whose front focal plane coincides with the rear focal plane of the above long-focus lens group, can realize the expansion of the two-dimensional spatial scanning field of view of the emitted beam, and is also used for the convergent collection of echo beams at different angles within the target detection area; optionally, the above ultra-wide-angle lens group can also be a fish-eye lens group, which is composed of several lenses, including any one of the following: spherical lens, cylindrical lens, aspherical lens, and gradient refractive index lens.

[0113] The echo beams at different angles within the field of view reflected by the target object in the detection area, in the coaxial optical path system of the solid-state lidar of this embodiment, pass through the above ultra-wide-angle lens group, long-focus lens group, one-dimensional MEMS micromirror 41 and blazed grating 43 in sequence, and then become a polarization state orthogonal to the laser beam incident on the polarization beam splitter 31 through the above quarter-wave plate 32, and then deflect the optical path at the above polarization beam splitter 31, and finally are detected and received by the receiving system composed of the echo focusing mirror 70 and the detector 80.

[0114] Among them, the above echo focusing mirror 70 is used to focus the spot of the echo beam after reflection and deflection by the above polarization beam splitter prism 31; optionally, it can be a converging lens group composed of several lenses, including any one of the following: spherical lens, cylindrical lens, aspherical lens, and gradient refractive index lens. The above detector 80 is used to detect the above echo beam after spot focusing, and is a single-pixel detector 81; optionally, the above single-pixel detector 81 can be: Balanced Photo Diode (BPD), Avalanche Photo Diode (APD), Silicon Photomultiplier (SiPM), Photomultiplier Tube (PMT), or Single-Photon Avalanche Diode (SPAD), etc.

[0115] In addition, several reflectors can be added to the solid-state lidar device of this embodiment. The purpose is to fold and compress the optical path, thereby reducing the space length occupied by the optical path and making the structure of the entire device more compact. In the optical path schematic diagram of this embodiment ( Figure 5 ), it is not shown, which does not mean that there are no reflectors in the optical path. This situation is not specifically limited in this application.

[0116] In the solid-state lidar device of this embodiment, the blazed grating 43 and the one-dimensional MEMS micromirror 41 jointly achieve the spatial two-dimensional field of view scanning of the emitted beam within a certain angular range, and then by expanding the field of view with the above long-focus lens group and ultra-wide-angle lens group, the spatial two-dimensional large field of view scanning detection of the final outgoing light can be achieved. The diffraction principle of the above blazed grating 43 is as Figure 7 shown. The above emitted beam passing through the beam splitter 30 is used as the incident beam and is incident on the tooth surface of the above blazed grating 43. After diffraction, the dispersion separation of the lasers with different wavelengths in the reflected beam in the diffraction angle is achieved. By tuning the wavelength of the laser , the diffraction angle of the grating diffracted beam can be adjusted ; based on the principle of blazed grating diffraction, the relationship between the diffraction angle adjustment amount of the diffracted beam and the laser wavelength tuning amount is as follows:

[0117] ;

[0118] Among them, the angular dispersion coefficient is obtained from the grating equation of the blazed grating:

[0119] ;

[0120] In the above formula, is the diffraction order of the blazed grating, is the period of the blazed grating, is the incident angle of the incident light beam. The laser wavelength tuning range is , and through the diffraction of the above blazed grating 43, it can be converted into the spatial angle change of the diffracted light beam, and the scanning range is , corresponding to the horizontal dimension of the final output spatial field of view; adjusting the angle of the above one-dimensional MEMS micromirror 41 (the maximum adjustment range of the mirror surface can reach 15°, and the angle scanning range of the reflected light beam is twice the adjustment range of the mirror surface), the angle scanning range of the reflected light beam can be obtained as , corresponding to the vertical dimension of the final output spatial field of view; the field of view angle ranges of the final output spatial two-dimensional field of view are respectively (the above horizontal dimension) and (the above vertical dimension), and their field of view expansion relationship is as follows:

[0121] ;

[0122] ;

[0123] Among them, and are the equivalent focal lengths of the above long-focus lens group and ultra-wide-angle lens group respectively, and the field of view magnification factor is . Of course, it should be noted that the diffraction angle scanning range of the above blazed grating 43 and the adjustment angle of the above one-dimensional MEMS micromirror 41 can also respectively correspond to the vertical dimension and the horizontal dimension of the final output spatial two-dimensional field of view, and no special limitation is made here.

Claims

1. A solid-state laser radar device with a large field of view, characterized in that: include: A transmitting module, used for transmitting an outgoing laser beam; A beam scanning device, used to change the scanning angle of the outgoing laser beam emitted by the emission module within a preset angle range, and to direct the outgoing laser beam toward the telephoto lens; The telephoto lens is used to focus the outgoing laser beams with different scanning angles from the beam scanning device onto the back focal plane of the telephoto lens; The ultra-wide-angle lens has a front focal plane that coincides with the rear focal plane of the telephoto lens, and is used to expand the scanning angle range of the outgoing laser beam focused on the front focal plane of the ultra-wide-angle lens.

2. The large field of view solid-state laser radar device according to claim 1, characterized in that: Also includes: A beam splitter, used to direct the outgoing laser beam emitted by the transmitting module toward the beam scanning device, and also used to direct the echo laser beam from the beam scanning device toward the receiving module; The receiving module is used to receive the echo laser beam from the spectroscope and convert the echo laser beam into an electrical signal; The beam scanning device is also used to direct the echo laser beam incident sequentially through the ultra-wide-angle lens and the telephoto lens toward the beam splitter.

3. The large-field-of-view solid-state laser radar device according to claim 1 or 2, characterized in that: The transmitting module comprises: A laser for emitting an outgoing laser beam; The collimator is used to collimate and shape the laser beam emitted by the laser.

4. The large-field-of-view solid-state laser radar device according to claim 3, characterized in that: The collimator lens comprises: a fast axis collimator lens group and a slow axis collimator lens group; The fast-axis collimating lens group is used for collimating and shaping the outgoing laser beam in the fast-axis direction; the slow-axis collimating lens group is used for collimating and shaping the outgoing laser beam in the slow-axis direction.

5. The large field of view solid-state laser radar device according to claim 1 or 2, characterized in that: The beam scanning device includes a blazed grating and / or a MEMS micro-vibration mirror; Blazed gratings for spatial dispersion separation of wavelength-tunable lasers; MEMS micro-vibration mirror is used to adjust the spatial angle of the light beam.

6. The large field of view solid-state laser radar device according to claim 1 or 2, characterized in that: The telephoto lens is a telephoto lens group, and the ultra-wide-angle lens is an ultra-wide-angle lens group; the optical axes of the telephoto lens group and the ultra-wide-angle lens group are aligned with the optical center of the light beam scanning device.

7. The large field of view solid-state laser radar device according to claim 1 or 2, characterized in that: By adjusting the ratio of the equivalent focal lengths of the telephoto lens and the ultra-wide-angle lens, the expansion multiple of the scanning angle of the outgoing laser beam by the ultra-wide-angle lens is adjusted.

8. The large-field-of-view solid-state laser radar device according to claim 2, characterized in that: The receiving module comprises: An echo focusing mirror, used for focusing the echo laser beam from the beam splitter onto a detector; The detector is used to convert the echo laser beam into an electrical signal.

9. The large field of view solid-state laser radar device according to claim 8, characterized in that: The echo focusing mirror is a converging lens group, which performs converging processing on the echo laser beam from the spectroscope and focuses it on the target surface of the detector for signal detection.

10. A large field of view solid-state laser radar detection method, characterized in that: include: When detecting the target field of view, the transmitting module emits an outgoing laser beam, which passes through the beam splitter and is scanned two-dimensionally in a certain angle range by the beam scanning device; The outgoing laser beams with different spatial scanning angles are focused to the rear focal plane through the telephoto lens to form corresponding focused beams with different spatial scales; Then, the laser beams focused on different spatial scales on the confocal plane are expanded by an ultra-wide-angle lens whose front focal plane coincides with the rear focal plane of the telephoto lens, and converted into outgoing laser beams that scan within a larger angular range of the outgoing space; The outgoing laser beam is reflected by the target object in the detection field of view, and the echo laser beam carrying the target object information is received by the ultra-wide-angle lens and collimated by the telephoto lens. After being reflected by the beam scanning device, it is deflected by the beam splitter and separated from the outgoing laser beam path, and finally received by the receiving module.

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