Laser radar system

Abstract

The invention discloses a laser radar system, and the system comprises a light source which is used for outputting a laser beam, and the laser beam is a frequency-modulated continuous wave beam; the first beam splitter is used for splitting the laser beam into a local oscillator beam and a detection beam, and the detection beam is transmitted to the beam scanner; the light beam scanner is used for receiving the detection light beam and emitting the detection light beam to the detection space; and the dispersion structure is located at the light emitting side of the light beam scanner and is used for changing the emitting direction of the detection light beam before the detection light beam reaches the detection space so as to enlarge the scanning range of the emitted detection light beam. A mode of performing light beam steering scanning by using a light beam scanner has the problem of small scanning angle.

Description

Technical Field

[0001] This application relates to the technical field of lidar, and more particularly, to a lidar system. Background Art

[0002] Currently, in order to obtain a large field of view, lidar usually uses a beam scanner for beam steering scanning. When the laser wavelength and phase input to the beam scanner change, the beam output angle (the scanning angle of the lidar) will change. By changing the output wavelength of the laser and adjusting the laser phase of the beam scanner, the function of optical scanning can be achieved. The larger the scanning angle of the lidar, the stronger its sensing ability, and the more extensive the environmental information and more accurate the positioning data it can provide. However, due to the performance defects of the beam scanner itself, when the laser wavelength changes, the change in the beam output angle is not large enough to reach the commercial level.

[0003] It can be seen that the method of using a beam scanner for beam steering scanning in the related art has the problem of a small scanning angle. Summary of the Invention

[0004] An embodiment of this application provides a lidar system to at least solve the problem of a small scanning angle in the method of using a beam scanner for beam steering scanning in the related art.

[0005] According to one aspect of the embodiments of this application, a lidar system is provided, including: a light source for outputting a laser beam, where the laser beam is a frequency-modulated continuous-wave beam; a first beam splitter for splitting the laser beam into a local oscillator beam and a probe beam, where the probe beam is transmitted to a beam scanner; the beam scanner for receiving the probe beam and emitting the probe beam to a detection space; and a dispersion structure located on the light-emitting side of the beam scanner for changing the emission direction of the probe beam before the probe beam reaches the detection space to increase the scanning range of the emitted probe beam.

[0006] In the embodiments of the present application, a method of combining a beam scanner with a dispersion structure to expand the scanning angle of a lidar system is adopted. The lidar system includes: a light source for outputting a laser beam, where the laser beam is a frequency-modulated continuous-wave beam; a first beam splitter for splitting the laser beam into a local oscillator beam and a detection beam, where the detection beam is transmitted to the beam scanner; the beam scanner for receiving the detection beam and emitting the detection beam into the detection space; the dispersion structure located on the light-emitting side of the beam scanner for changing the emission direction of the detection beam before the detection beam reaches the detection space to increase the scanning range of the emitted detection beam. Since the light of different wavelengths in the beam has different output angles after passing through the beam scanner, a certain scanning range is obtained. After the light output by the beam scanner passes through the dispersion structure, due to the dispersion ability of the dispersion structure, the light of different angles and different wavelengths will be deflected to different degrees, and the emission angle range of the detection beam will be expanded, so that a larger scanning range is obtained compared with the light output from the beam scanner, thereby achieving the technical effect of expanding the scanning angle of the lidar system, and further solving the problem of the small scanning angle in the related art when using the beam scanner for beam steering scanning. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The accompanying drawings herein are incorporated into the specification and constitute a part of this specification, showing embodiments consistent with the present application and used together with the specification to explain the principles of the present application.

[0008] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0009] Figure 1 is a schematic diagram of an optional lidar system according to an embodiment of the present application;

[0010] Figure 2 is a perspective view schematic diagram of an optional beam scanning module according to an embodiment of the present application;

[0011] Figure 3A is a schematic diagram of the system layout of an optional lidar system according to an embodiment of the present application;

[0012] Figure 3B is a schematic diagram of the system layout of another optional lidar system according to an embodiment of the present application;

[0013] Figure 3C is a schematic diagram of the system layout of yet another optional lidar system according to an embodiment of the present application;

[0014] Figure 3D It is a schematic diagram of the system layout of another optional lidar system according to an embodiment of the present application;

[0015] Figure 4A It is a schematic diagram of an optional beam scanner according to an embodiment of the present application;

[0016] Figure 4B It is a schematic diagram of another optional beam scanner according to an embodiment of the present application;

[0017] Figure 5A It is a schematic diagram of an optional light source according to an embodiment of the present application;

[0018] Figure 5B It is a schematic diagram of another optional light source according to an embodiment of the present application;

[0019] Figure 5C It is a schematic diagram of yet another optional light source according to an embodiment of the present application;

[0020] Figure 5D It is a schematic diagram of yet another optional light source according to an embodiment of the present application;

[0021] Figure 6A It is a schematic diagram of an optional dispersion structure according to an embodiment of the present application;

[0022] Figure 6B It is a schematic diagram of another optional dispersion structure according to an embodiment of the present application;

[0023] Figure 7 It is a schematic diagram of an optional scanning angle comparison according to an embodiment of the present application;

[0024] Figure 8 It is a schematic diagram of the system layout of yet another optional lidar system according to an embodiment of the present application. Detailed implementation manners

[0025] In order to enable those skilled in the art to better understand the solution of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of 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 protection scope of the present application.

[0026] It should be noted that the terms "first", "second", etc. in the specification, claims and the above-mentioned drawings of the present application are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application described here can be implemented in an order other than those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0027] According to one aspect of the embodiments of the present application, a lidar system is provided, as Figure 1 shown, the system may include:

[0028] A light source 101 for outputting a laser beam, wherein the laser beam is a frequency-modulated continuous-wave beam;

[0029] A first beam splitter 201 for splitting the laser beam into a local oscillator beam and a detection beam, wherein the detection beam is transmitted to the beam scanner;

[0030] A beam scanner 401 for receiving the detection beam and emitting the detection beam to the detection space;

[0031] A dispersion structure 402 located on the light-emitting side of the beam scanner for changing the emission direction of the detection beam before the detection beam reaches the detection space, so as to increase the scanning range of the detection beam after emission.

[0032] A lidar is a radar system that emits laser beams to detect the position, speed and other characteristic quantities of a target. Its working principle is to emit a detection signal (laser beam) to a target (target object), and then compare the received signal reflected from the target with the emitted signal. After appropriate processing, relevant information about the target can be obtained, such as parameters such as target distance, azimuth, altitude, speed, attitude, and even shape, so as to detect, track and identify the target.

[0033] Lidar detection methods can be divided into two categories, including direct detection, mainly using TOF (Time of Flight, laser flight time) sensing technology and coherent detection. At present, most lidar systems use TOF technology because it uses common pulsed 905nm lasers and single-photon avalanche diodes, etc. However, recently, coherent lidar has attracted people's interest due to its advantages such as insensitivity to ambient light, direct detection speed, and laser power and wavelength (especially at 1550nm) for eye safety considerations.

[0034] In coherent lidar, modulation is performed in the laser phase / frequency domain, while the intensity generally remains constant. The reflected light is optically mixed with the local oscillator (LO) laser. Finally, the time-of-flight (TOF) is inferred from the down-converted electrical signal output from the optical mixer, which is the conventional FMCW (Frequency Modulated Continuous Wave) lidar. Here, the local oscillator laser (local oscillator light) can be used to modulate and demodulate the optical signal, and is usually used as a reference signal for comparison and modulation with other signals.

[0035] To obtain a larger field of view, FMCW lidar usually uses a beam scanning device for beam steering scanning. The beam scanning solutions of lidar systems are generally divided into mechanical and solid-state solutions. However, mechanical solutions, such as pan-tilt heads or rotating mirror groups, etc., will reduce the reliability of the system, limit the scanning rate, increase the structural size, and increase the overall cost.

[0036] Therefore, solid-state beam control has become an optimal solution for lidar systems, and optical phased array is one of the best solutions for solid-state beam control. Radio frequency / millimeter-wave phased arrays have been widely used in radar and wireless communication. With the progress of silicon photonics technology, OPA (Optical Phased Array) can also achieve the same applications in the optical field, so this technology has received a lot of attention. However, due to the defects of the solution itself, there are still some problems such as the scanning angle range that need to be solved urgently.

[0037] To at least partially solve the above technical problems, in this embodiment, in combination with the dispersion ability of the dispersion structure, an FMCW lidar system with an expanded scanning angle is proposed, so that the one-dimensional scanning angle of the beam emitted from the FMCW beam scanning module is expanded to meet the application requirements of large-angle scanning of FMCW lidar, and at the same time, it also has the advantages of small size and easy installation.

[0038] In this embodiment, the lidar system may include a light source, a first beam splitter, and a beam scanning module. The beam scanning module may include a beam scanner and a dispersion structure. The dispersion structure is located on the light output side of the beam scanner. Optionally, the lidar system may further include an optical receiving and processing unit.

[0039] The light source is used to output a laser beam. Among them, the laser beam is an FMCW (Frequency Modulated Continuous Wave) beam. In an FMCW lidar, the laser transmitter sends a laser beam in the form of a continuous wave, and the frequency of the laser can be modulated by a modulator during the emission process.

[0040] The laser beam output by the light source is split into two parts by a first beam splitter, namely, the local oscillator beam and the detection beam. The detection beam is transmitted to the beam scanner, and the local oscillator beam is input into the optical receiving and processing unit. The dispersion structure is located on the light output side of the beam scanner and is used to change the output direction of the detection beam before the detection beam reaches the detection space, so as to increase the scanning range of the detection beam after output. That is, the detection beam is connected to the input end of the beam scanner through an optical fiber, and the light exits through the beam scanner. After the output beam passes through the dispersion structure, the propagation direction changes to a certain extent and is emitted into the detection space. Here, the detection space can be a space including the scanning range of the light source. When the beam propagates to the target object in the detection space and is reflected, the reflected beam is received by the receiving module, and the optical receiving and processing unit analyzes and processes the local oscillator beam and the received reflected light to obtain the object information of the target object.

[0041] The three-dimensional schematic diagram of the beam scanning module is as Figure 2 shown, which is characterized by including a beam scanner 401 and a dispersion structure 402. Light with a certain wavelength range, such as λ A ~λ B after passing through the beam scanner 401, has different output angles, so as to obtain a certain scanning angle. Light with different angles and different wavelengths, with a certain angle range and a certain wavelength range, after passing through the dispersion structure 402, undergoes different degrees of deflection, and the angle range is expanded, so as to obtain a larger scanning range compared with the light output from the beam scanner 401.

[0042] Optionally, in this embodiment, as Figure 3A shown, it is characterized by including a light source 101, a beam scanning module 102, a target object 103 in the detection space, and an optical receiving and processing unit 104. In the Figure 3A arrangement, laser beams with different wavelengths from the light source 101 are transmitted to the beam scanning module 102. The light with different wavelengths exits from the beam scanning module 102 at different angles, so there is a certain scanning angle. After being reflected by the target object 103, the reflected light is received by the optical receiving and processing unit 104 and analyzed and processed to obtain information about the target object including distance, etc.

[0043] In a variant, as Figure 3B shown, it includes a light source 101, a beam scanning module 102, and a target object 103. In the Figure 3B arrangement, light with different wavelengths from the light source 101 is transmitted to the beam scanning module 102. The light with different wavelengths exits from the beam scanning module 102 at different angles, so there is a certain scanning angle for the target object 103, which is used as a scanner.

[0044] In another variant, as Figure 3CAs shown, it includes a light source 101, a beam splitter 105, beam scanning modules 102A, 102B, 102C, and optical receiving and processing units 104A, 104B, 104C. In Figure 3C the arrangement, light of different wavelengths from the light source 101, after passing through the beam splitter 105, is equally divided into multiple portions and respectively transmitted to the beam scanning modules 102A, 102B, 102C, etc. After being reflected by the target object, it is received and analyzed by the optical receiving and processing units 104A, 104B, 104C. Among them, the beam scanning modules 102A, 102B, 102C, etc. work for different wavelength ranges respectively, so as to obtain a larger-angle scanning range of the target object as a whole.

[0045] In another variant, as Figure 3D shown, it includes light sources 101A, 101B, 101C, 101D, beam scanning modules 102A, 102B, 102C, 102D, optical receiving and processing units 104A, 104B, 104C, 104D, and a total processing unit 106. In Figure 3D the arrangement, light of different wavelengths from the light sources 101A, 101B, 101C, 101D, etc. is respectively transmitted to the beam scanning modules 102A, 102B, 102C, 102D, etc. Among them, the light emitted by the beam scanning modules 102A, 102B, 102C, 102D, etc. faces different directions. After being reflected by the target object, it is received and analyzed by the optical receiving and processing units 104A, 104B, 104C, 104D, etc. Finally, the obtained results are summarized and input into the total processing unit 106, so as to achieve a 360-degree scanning range of the entire space.

[0046] Through the above lidar system, the lidar system includes: a light source for outputting a laser beam, where the laser beam is a frequency-modulated continuous-wave beam; a first beam splitter for splitting the laser beam into a local oscillator beam and a detection beam, where the detection beam is transmitted to a beam scanner; a beam scanner for receiving the detection beam and emitting the detection beam to a detection space; a dispersion structure located on the light-emitting side of the beam scanner for changing the emission direction of the detection beam before the detection beam reaches the detection space to increase the scanning range of the emitted detection beam, solving the problem of the small scanning angle in the related art using the beam scanner for beam steering scanning, and expanding the scanning angle of the lidar system.

[0047] In an exemplary embodiment, the beam scanner is used to emit detection beams of different wavelengths at different angles.

[0048] In this embodiment, the function of the beam scanner is to control and adjust the scanning range of the laser beam, enabling the laser beam to be scanned in different directions. The beam scanner can achieve fast and accurate scanning of the detection space to obtain the three-dimensional point cloud data of the target object. By adjusting the rotation speed and scanning angle of the beam scanner, scans with different ranges and resolutions can be achieved to meet the requirements of different application scenarios.

[0049] In this embodiment, the beam scanner can be used to emit input light of different wavelengths at different angles, and emit incident light within a certain wavelength range through a certain angle range. For the above-mentioned beam scanner, when the wavelengths of the input light are different, the angles of the light emitted from the beam scanner are also different. For the above-mentioned beam scanner, when the input light has a certain wavelength range, the beam emitted from the beam scanner also has a certain angle range.

[0050] In an exemplary embodiment, the beam scanner includes any one of an optical phased array, an optical switch antenna array, and a waveguide grating antenna array.

[0051] Here, the optical phased array is a technology that uses optical principles to achieve beam pointing and beam shape control, and realizes beam pointing and shape control by adjusting the phase of each transmitting or receiving element; the optical switch antenna array is a technology that uses optical switch technology to achieve beam pointing and shape control of the antenna array, and realizes beam pointing and shape control of the antenna array by controlling the optical switch; the waveguide grating antenna array is a technology that uses the waveguide grating structure to achieve beam pointing and shape control of the antenna array, and realizes beam pointing and shape control of the antenna array by designing a suitable waveguide grating structure.

[0052] In an exemplary embodiment, the beam scanner includes an optical phased array, where the optical phased array includes a second beam splitter, a phase shifter, and an optical antenna array, where,

[0053] The second beam splitter includes a plurality of cascaded beam splitters and is used to split the detection beam.

[0054] The phase shifter is used to adjust the phase of the split detection beam.

[0055] The optical antenna array is used to receive the phase-adjusted detection beam and emit it into the detection space.

[0056] In this embodiment, the beam scanner can be an OPA, a liquid crystal cladding waveguide, an on-chip flat lens, a metamaterial subwavelength grating, a silicon photonic crystal slow light waveguide, or a MEMS (Micro-Electro-Mechanical System), etc.

[0057] The optical phased array may include a second beam splitter, a phase modulator, and an optical antenna array. The second beam splitter includes a plurality of cascaded beam splitters for splitting the detection beam. In one exemplary embodiment, the beam splitter is a directional coupler or a multimode interference coupler. For example, a one-to-two beam splitter (1*2 beam splitter), and the 1*2 beam splitter can be a directional coupler or a multimode interference coupler. The phase modulator includes any one of a thermal phase modulator, a PN-type phase modulator, and a PIN-type phase modulator. The optical antenna array includes any one of a grating array antenna, an optical switch antenna array, and an AWG (Arrayed Waveguide Grating) antenna array.

[0058] Here, the 1*2 beam splitter is an optical device that can be used to split one optical signal into two output signals. It has one input end and two output ends, and can evenly distribute the optical signal at the input end to the two output ends, so that the optical powers of the two output ends are equal. Such a beam splitter is usually used in fiber optic communication systems to distribute optical signals to different receivers or sensors. A directional coupler is an optical device used to couple an optical signal from one waveguide to another waveguide, with a certain coupling efficiency. A multimode interference coupler is a device that uses the multimode interference effect to achieve optical signal coupling, and can achieve efficient optical signal coupling and separation. A thermal phase modulator is a device that adjusts the phase of an optical wave using the thermal effect, and can achieve phase adjustment and modulation of an optical signal. A PN-type phase modulator is an optical modulation device using the PN structure of a semiconductor material, and can achieve phase modulation of an optical signal. A PIN-type phase modulator is an optical modulation device using the PIN structure of a semiconductor material, and can achieve phase modulation of an optical signal. The optical antenna array can control the beam and its direction by controlling the phase and amplitude of the optical elements, thereby achieving high-resolution target detection and tracking. Compared with traditional electromagnetic wave antennas, the optical antenna array has higher frequency and angular resolution, as well as larger bandwidth and smaller size. A grating array antenna is an antenna array constructed using grating technology. An optical switch antenna array is an antenna array that can control the transmission direction and intensity of light through an electrical signal. An AWG antenna array is an antenna array based on waveguide technology.

[0059] For example, as Figure 4A shown, the light output from the light source 101 is split into multiple optical signals after passing through the second beam splitter 501, and after being phase-modulated by multiple phase modulators 502, it is input to the optical antenna array 503 and then output. In another configuration, as Figure 4BAs shown, it is characterized by including second beam splitters 501A and 501B, phase modulators 502A and 502B, and an optical antenna array 503. Lights with different wavelength ranges are split into multiple optical signals after passing through the second beam splitters 501A and 501B, and after being phase-modulated by the multiple phase modulators 502A and 502B, they are input to both ends of the optical antenna array (also called a grating array unit) 503, so as to improve the scanning angle to a certain extent. For example, the scanning angle of the light incident from one end is 0 - 10°, and the light incident from the other end is responsible for the scanning angle of -10° - 0°. The overall scanning angle thus becomes -10° to 10°. Here, for the grating array unit, the input at both ends can also enable the system to process multiple input signals simultaneously, thereby improving the efficiency and speed of data processing.

[0060] For example, in this embodiment, taking the optical phased array as an example, during the transmission of light, it is output via the on-chip grating array, and the output angle satisfies the equation shown in formula (1):

[0061]

[0062] where θ is the output angle of the light from the OPA, Λ is the grating period, λ0 is the wavelength of the transmitted light, and n ct is the refractive index. When the wavelengths of the lights input to the OPA are different, the output angles are also different. When the light input to the OPA has a certain wavelength range Δλ, the output light has a certain angle range Δθ. When the wavelength range of the light input to the silicon-based OPA is about 100 nm, the angle range of the output light is about 15°.

[0063] Optionally, the light source includes a modulator and a laser. The modulator is connected to the laser and is used to add a modulation signal to the laser. The laser can be modulated by the modulator and output lasers with different wavelengths. The laser can include a tunable laser, a multi-wavelength laser, or multiple single-wavelength lasers with different wavelengths. A tunable laser is a laser that can adjust the output wavelength within a certain range, usually by adjusting some elements inside the laser (such as filters, gratings, etc.) to change the output wavelength; a multi-wavelength laser refers to a laser that can output multiple wavelengths simultaneously, usually achieved by using multiple laser sources or by controlling the internal elements of the laser; a single-wavelength laser refers to a laser that can only output a single wavelength, usually having a narrow spectral line width and high optical purity.

[0064] For example, as Figure 5A shown, the light source 101 mainly consists of a modulator 301 and a tunable laser 302. The modulator 301 mainly performs frequency modulation on the tunable laser 302; in another arrangement, as Figure 5B shown, the modulator 301 mainly performs intensity modulation on the tunable laser 302; in another arrangement, as Figure 5CAs shown, the modulator 301 mainly performs frequency modulation on the multi-wavelength laser 303; in another arrangement, as Figure 5D shown, the modulators 301A, 301B, 301C, etc. respectively perform frequency modulation on the single-wavelength lasers 304A, 304B, 304C, etc. with different wavelengths, which is essentially equivalent to performing frequency modulation on the outputs of multiple wavelengths.

[0065] The laser is at least one of the following lasers:

[0066] A tunable laser with a wavelength tunable range, where the tunable laser is one of the following: distributed feedback laser, distributed Bragg reflector laser, quantum wire laser, quantum dot laser, silicon-based hybrid external cavity laser;

[0067] A multi-wavelength laser, where the multi-wavelength laser is one of the following: optical frequency comb light source, multi-channel tunable laser, laser group including multiple tunable lasers;

[0068] Multiple single-wavelength lasers with different wavelengths, where the single-wavelength laser is one of the following: distributed feedback laser, Fabry-Perot laser, quantum wire laser, quantum dot laser.

[0069] Similar to the foregoing embodiments, in this embodiment, the laser included in the light source may be a tunable laser with a certain wavelength tunable range, or a multi-wavelength laser, or multiple single-wavelength lasers with different wavelengths.

[0070] The tunable laser includes but is not limited to DFB (Distributed Feed Back) lasers, DBR (Distributed Bragg Reflector) lasers, quantum wires, quantum dot lasers or silicon-based hybrid external cavity lasers; the single-wavelength laser may be a DFB laser, FP (Fabry-Perot) laser, quantum wire, quantum dot laser, etc.

[0071] A distributed feedback laser is a type of laser that uses a distributed feedback structure to achieve laser output, and has advantages such as high efficiency, low threshold current, wide bandwidth, and low phase noise; a distributed Bragg reflector laser is a type of laser that uses a Bragg grating to achieve distributed reflection. By forming a periodic refractive index change in the laser material, light reflection and amplification are achieved, resulting in laser output, and has characteristics such as high power output, narrow linewidth, and good stability; a quantum wire laser is a type of laser that uses a quantum wire structure to achieve lasing oscillation. By forming a nanoscale linear structure in the material, the quantum confinement effect is realized, significantly improving the performance of the laser, and has characteristics such as high efficiency, high output power, and low threshold current; a quantum dot laser is a type of laser that uses a quantum dot structure to achieve lasing oscillation. By forming a nanoscale quantum dot structure in the material, the quantum confinement effect is realized, significantly improving the performance of the laser, and has characteristics such as high efficiency, high output power, and low threshold current; a silicon-based hybrid external cavity laser is a type of laser made by combining silicon-based materials and other semiconductor materials. By integrating other semiconductor materials in the silicon-based material, the fabrication of silicon-based lasers is realized, thus overcoming the difficulty that traditional silicon-based materials cannot directly achieve laser output, and has advantages such as high integration, low fabrication cost, and strong compatibility.

[0072] The multi-wavelength laser can be an optical frequency comb light source, a multi-channel tunable laser, or a combination of multiple tunable lasers. The optical frequency comb light source is a type of light source that can generate highly stable and evenly distributed optical frequencies. Through optical frequency comb technology, a continuous spectrum is converted into a series of evenly distributed optical frequencies, and the intervals between these optical frequencies are equal; the multi-channel tunable laser is a type of laser that can generate multiple tunable optical frequencies, usually composed of an external cavity mirror, a laser medium, and a tuning element. By adjusting the position of the external cavity mirror or the characteristics of the tuning element, the optical frequency output by the laser can be changed.

[0073] In an exemplary embodiment, the dispersion structure 402 includes a dispersion element, and the dispersion element is at least one of the following:

[0074] A reflective diffraction grating, wherein an antireflection film is coated on the grating surface of the reflective diffraction grating;

[0075] A transmissive diffraction grating, wherein an antireflection film is coated on the back of the transmissive diffraction grating;

[0076] A prism;

[0077] A volume phase grating;

[0078] A virtual imaging phase array;

[0079] An array diffraction element;

[0080] Plasma sub-wavelength pixel

[0081] Metasurface

[0082] The dispersion element has different refractive indices for different wavelengths. In this embodiment, the dispersion element can be a reflective diffraction grating, a transmissive diffraction grating, a prism, a volume phase grating, VIPA (Virtual Imaged Phased Array), an array diffraction element, a plasma sub-wavelength pixel, a metasurface, etc.

[0083] Specifically, the grating surface of the reflective diffraction grating is coated with an antireflection film, which is an optical element that reflects and disperses incident light. It is usually composed of a series of parallel grooves or rulings. When light is incident on the grating, a diffraction phenomenon occurs, and light of different wavelengths is reflected at different angles, thus achieving the effect of dispersing the spectrum.

[0084] The back surface of the transmissive diffraction grating is coated with an antireflection film, which is an optical element that transmits and disperses incident light. It is usually composed of a series of parallel grooves or rulings. When light is incident on the grating, a diffraction phenomenon occurs, and light of different wavelengths is transmitted at different angles, thus achieving the effect of dispersing the spectrum.

[0085] For example, as Figure 6A shown in the diffraction grating, it satisfies the grating equation shown in formula (2):

[0086] d(sini ± sinθ) = ±mλ (m = 0, ±1, ±2,...) Formula (2)

[0087] where i is the grating incident angle, θ is the grating diffraction angle, d is the grating constant, m is the order of light diffraction. When the incident angle of the input diffraction grating is different, the angle of the output light is also different. When the incident angle of the input diffraction grating has a certain range Δi, the output angle of the diffraction grating also has a certain range Δθ.

[0088] Prism: As Figure 6B shown, a prism is a transparent optical element, usually made of optical glass or other transparent materials. Its shape is composed of the intersection interfaces of two or more planes or curved surfaces. When light passes through the prism, a refraction phenomenon occurs, causing the light to change direction.

[0089] Volume phase grating: A volume phase grating is an optical element that realizes the modulation and control of light by changing the phase at different positions in the light beam. The phase grating is usually composed of a volume phase structure passing through an optical material, and can be used to separate or combine light beams, as well as generate interference effects, etc.

[0090] Virtual imaging phase array: A virtual imaging phase array is an optical element composed of a two-dimensional phase array. By controlling the phase of each pixel in the phase array, modulation and control of light beams can be achieved. Virtual imaging phase arrays can be used in fields such as optical display, optical sensing, and optical communication.

[0091] Array diffraction element: An array diffraction element is an optical element composed of a two-dimensional array of multiple small holes or slits. When light passes through the array diffraction element, diffraction occurs, causing interference and diffraction effects on the light beam. Array diffraction elements can be used in applications such as optical imaging, spectral analysis, and light wavefront modulation.

[0092] Plasmonic sub-wavelength element: A plasmonic sub-wavelength element is an optical element composed of nano-sized metal structures. When light passes through the plasmonic sub-wavelength element, it interacts with the metal structures, generating a local surface plasmon resonance effect.

[0093] Metasurface: A metasurface is an artificially fabricated two-dimensional structure composed of micro-scale elements that can precisely control and regulate the propagation and distribution of light. Metasurfaces are usually composed of micro-structures of metal or dielectric materials. By adjusting the size, shape, and arrangement of the micro-structures, high-precision control of light reflection, transmission, and diffraction can be achieved. Metasurfaces have the characteristics of being compact, thin, and adjustable.

[0094] Optionally, in this embodiment, the tunable laser can be modulated by a modulator to output lasers of different wavelengths. The lasers of different wavelengths pass through a beam scanner, such as an OPA, and the output light has different angles. When the input light to the beam scanner has a certain wavelength range Δλ, the output light has a certain angle range Δi. The light of different angles passes through a dispersion element, such as a diffraction grating, and the output light of the diffraction grating also has different angles. When the input angle to the diffraction grating has a certain range Δi, the output angle of the diffraction grating also has a certain range Δθ. Then, formula (3) can be obtained:

[0095]

[0096] where d is the grating constant, which is inversely proportional to the number of grating lines. When the wavelength range of the input light is about 100 nm, the angle range of the output light is about 25°. As Figure 7 shown, the large-angle beam scanning module (i.e., the aforementioned beam scanning module, including a beam scanner and a dispersion structure) greatly expands the scanning angle of the output light compared to a single beam scanner over the same wavelength range.

[0097] In an exemplary embodiment, the lidar system includes two dispersive elements, wherein the two dispersive elements are disposed on one side of the light-emitting surface of the beam scanning device and are axisymmetric about the center of the light-emitting surface.

[0098] Here, both of the two dispersive elements are disposed on one side of the light-emitting surface of the beam scanning device to expand the emission angle of the detection beam output by the beam scanning device. The symmetric arrangement can make the angle of the detection beam change uniformly, reduce the system error, and improve the measurement stability and reliability of the lidar.

[0099] In an exemplary embodiment, when the dispersive element is a grating, the emitted detection beam is emitted at the -1st order or +1st order of the grating to increase the emission angle of the detection beam.

[0100] Here, the -1st order or +1st order of the grating may refer to the diffraction order of the grating. The diffraction order of the grating represents the diffraction effect of the grating on the incident light. The -1st order means that the grating performs a negative first-order diffraction on the incident light, and the +1st order means that the grating performs a positive first-order diffraction on the incident light. Different diffraction orders will result in different diffraction effects.

[0101] In an exemplary embodiment, the lidar system further includes a receiving module and a data processing unit, wherein,

[0102] The first beam splitter is further configured to transmit the local oscillator beam to the receiving module;

[0103] The receiving module is electrically connected to the first beam splitter and is configured to receive the reflected beam formed after the detection beam is reflected by the object to be detected in the detection space, perform beat frequency processing on the reflected beam and the local oscillator beam, and obtain a difference frequency signal;

[0104] The data processing unit is electrically connected to the receiving module and is configured to receive the difference frequency signal and calculate the object information of the object to be detected based on the difference frequency signal.

[0105] Here, the beat frequency processing may refer to performing beat frequency on the reflected beams of multiple laser beams received by the lidar and their corresponding local oscillator beams to obtain the beat frequency signal of the local oscillator beam and the reflected beam, and then calculating information such as the distance, speed, and angle of the target object based on the beat frequency signal to achieve the detection and measurement of the target object. The beat frequency signal may refer to the signal containing beat frequency information received by the lidar system. Beat frequency refers to the frequency change caused by the relative motion between the target and the lidar. When the laser beam irradiates a moving target, the frequency of the reflected optical signal will change, and this changed frequency is the beat frequency. By analyzing the beat frequency signal, information such as the distance, speed, and azimuth of the target and the lidar can be calculated.

[0106] The foregoing optical reception processing unit may include a reception module and a data processing unit. In this embodiment, the data processing unit may be configured to perform fusion processing on the object information obtained by multiple reception modules. The foregoing object information may be for the same target object in the detection space, or for different target objects in the detection space. Optionally, the object information obtained by multiple reception modules may be for the same target object or for different target objects. The fusion processing may be to summarize multiple pieces of object information of one target object to obtain more comprehensive object information for the target object; or it may be to summarize multiple pieces of object information of multiple target objects to obtain more comprehensive information about the detection space, such as the spatial layout, etc., to achieve a more comprehensive perception of the spatial environment of the detection space. This embodiment does not make any limitation in this regard.

[0107] In an exemplary embodiment, the reception module includes:

[0108] An optical reception device for receiving the reflected light beam;

[0109] A coherent receiver electrically connected to the optical reception device for performing beat frequency processing on the reflected light beam and the local oscillator light beam to obtain a difference frequency signal.

[0110] In this embodiment, the reception module may be used to receive the laser beam emitted by the light source and process and analyze the received optical signals (local oscillator light beam, detection light beam). The reception module may include an optical reception device and a coherent receiver. The coherent receiver includes a first input end and a second input end. The optical reception device may be an optical reception antenna or a receiving lens. The optical reception device may be used to receive the reflected light beam (i.e., the detection light beam reflected by the target object in the detection space) and input the reflected light beam into the coherent receiver through the first input end; the coherent receiver may be used to receive the reflected light beam through the first input end and receive the local oscillator light beam through the second input end, perform beat frequency processing on the reflected light beam using the local oscillator light beam as the local oscillator light to obtain a difference frequency signal, and then analyze and process the difference frequency signal to obtain the object information of the target object.

[0111] It should be noted that the scanning ranges of the light sources corresponding to different reception modules may not be exactly the same, that is, the scanning ranges of different light sources may partially overlap or may all be directed at the same detection space.

[0112] The lidar system in this embodiment will be explained below with reference to optional examples. The lidar system in this optional example may be an FMCW lidar system combined with a dispersion structure. Taking the laser as a tunable laser as an example, as Figure 8As shown, the lidar system may include a light source 101, an optical beam splitter (also referred to as the first beam splitter) 201, a beam scanning module 102, a target object 103 in the detection space, and an optical receiving and processing unit 104. The light source 101 includes a modulator 301 and a tunable laser 302. The beam scanning module 102 includes a beam scanner 401 and a dispersion structure 402. The optical receiving and processing unit 104 includes an optical receiving device 202, a coherent receiver 203, and a data processing unit (also referred to as a signal processing module) 204.

[0113] In the configuration as Figure 8 shown, by modulating the tunable laser 302 through the modulator 301, a system light source can be obtained. The system light source is split into two beams by the optical beam splitter 201. One of the beams is a local oscillator beam, which is directly transmitted to an input of the coherent receiver 203, while the other beam (detection beam) is transmitted to the beam scanner 401. Lights of different wavelengths are output at different angles by the beam scanner 401, thereby obtaining a certain scanning range. After the light output by the beam scanner 401 passes through a dispersion structure 402, due to the dispersion ability of the dispersion structure, lights of different angles and different wavelengths are deflected to different extents, and the angle range is expanded. Thus, a larger scanning range can be obtained compared to the light output from the beam scanner 401. After the light output by the beam scanning module 102 is reflected by the target object 103, the reflected light is received and processed by the optical receiving and processing unit 104. It is mainly received by the optical receiving device 202 and then transmitted to another input of the coherent receiver 203. After being mixed with the local oscillator beam directly input from the light source 101, it is transmitted to the signal processing module 204 for analysis and processing.

[0114] Through this optional example, the scanning angle of the lidar system is expanded by combining with the dispersion structure, so that the lidar system can more comprehensively sense the surrounding environment, including roads, obstacles, pedestrians, vehicles, etc. At the same time, by expanding the scanning angle, the lidar system can cover a larger area, reduce the existence of blind spots, and help improve the global perception ability; by expanding the scanning angle, the lidar system can also obtain more data points, thereby improving the accuracy of target detection and tracking.

[0115] It should be noted that for the foregoing method embodiments, for the sake of simple description, they are all expressed as a series of action combinations. However, those skilled in the art should know that this application is not limited by the described action sequence, because according to this application, certain steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0116] Through the description of the above embodiments, those skilled in the art can clearly understand that the method according to the above embodiments can be implemented by means of software plus a necessary general hardware platform. Of course, it can also be implemented by hardware, but in many cases the former is a better implementation. Based on such an understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM (Read-Only Memory), RAM (Random Access Memory), magnetic disk, optical disc), and includes several instructions for causing a terminal device (which can be a mobile phone, computer, server, or network device, etc.) to execute the methods of the various embodiments of the present application.

[0117] Those of ordinary skill in the art can understand that all or part of the steps in the various methods of the above embodiments can be completed by instructing the relevant hardware of the terminal device through a program. This program can be stored in a computer-readable storage medium, and the storage medium can include: flash drive, ROM, RAM, magnetic disk, or optical disc, etc.

[0118] The serial numbers of the above embodiments of the present application are only for description and do not represent the superiority or inferiority of the embodiments.

[0119] If the integrated unit in the above embodiments is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in the above computer-readable storage medium. Based on such an understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing one or more computer devices (which can be personal computers, servers, or network devices, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present application.

[0120] In the above embodiments of the present application, the descriptions of the various embodiments have their own emphases. For the parts not detailed in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0121] In several embodiments provided by the present application, it should be understood that the disclosed client can be implemented in other ways. Among them, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed coupling or direct coupling or communication connection to each other can be through some interfaces. The indirect coupling or communication connection of units or modules can be in an electrical or other form.

[0122] The units described as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution provided in this embodiment.

[0123] In addition, in each embodiment of the present application, the functional units can be integrated in a processing unit, or each unit can exist physically alone, or at least two units can be integrated in one unit. The above integrated units can be implemented in the form of hardware or in the form of software functional units.

[0124] The above is only the preferred embodiment of the present application. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present application, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present application.

Claims

1. A lidar system, characterized in that, Comprising: A light source for outputting a laser beam, wherein the laser beam is a frequency-modulated continuous wave beam; A first beam splitter for splitting the laser beam into a local oscillator beam and a detection beam, wherein the detection beam is transmitted to a beam scanner; The beam scanner for receiving the detection beam and emitting the detection beam to a detection space; A dispersion structure located on the light-emitting side of the beam scanner for changing the emission direction of the detection beam before the detection beam reaches the detection space to increase the scanning range of the emitted detection beam.

2. The lidar system according to claim 1, wherein The beam scanner for emitting the detection beams of different wavelengths at different angles.

3. The lidar system according to claim 1, wherein The beam scanner includes any one of an optical phased array, an optical switch antenna array, and a waveguide grating antenna array.

4. The lidar system according to claim 1, wherein The beam scanner includes an optical phased array, wherein the optical phased array includes a second beam splitter, a phase modulator, and an optical antenna array, wherein The second beam splitter includes a plurality of cascaded beam splitters for splitting the detection beam; The phase modulator for phase-modulating the split detection beam; The optical antenna array for receiving the phase-modulated detection beam and emitting it to the detection space.

5. The lidar system according to claim 4, characterized in that, The beam splitter is a directional coupler or a multimode interference coupler; the phase modulator includes any one of a thermal phase modulator, a PN-type phase modulator, and a PIN-type phase modulator, and the optical antenna array includes any one of a grating array antenna, an optical switch antenna array, and an AWG antenna array.

6. The lidar system according to claim 1, wherein The dispersion structure includes a dispersion element, and the dispersion element is at least one of the following: A reflective diffraction grating, wherein an anti-reflection film is coated on the grating surface of the reflective diffraction grating; A transmissive diffraction grating, wherein an anti-reflection film is coated on the back of the transmissive diffraction grating; A volume phase grating; A virtual imaging phase array; An array diffraction element; A prism; A plasma sub-wavelength element; A metasurface.

7. The lidar system according to claim 6, characterized in that, The lidar system includes two dispersion elements, wherein the two dispersion elements are arranged on one side of the light-emitting surface of the beam scanning device and are axisymmetric about the center of the light-emitting surface.

8. The lidar system according to claim 6, characterized in that, When the dispersion element is a grating, the emitted detection beam is emitted at the -1st order or +1st order of the grating to increase the emission angle of the detection beam.

9. The lidar system according to claim 1, wherein The lidar system further includes a receiving module and a data processing unit, wherein The first beam splitter is further used to transmit the local oscillator beam to the receiving module; The receiving module, electrically connected to the first beam splitter, for receiving the reflected beam formed after the detection beam is reflected by an object to be detected in the detection space, performing beat frequency processing on the reflected beam and the local oscillator beam to obtain a difference frequency signal; The data processing unit, electrically connected to the receiving module, for receiving the difference frequency signal and calculating the object information of the object to be detected based on the difference frequency signal.

10. The lidar system according to claim 9, characterized in that, The receiving module includes: An optical receiving device for receiving the reflected beam; A coherent receiver, electrically connected to the optical receiving device, for performing beat frequency processing on the reflected beam and the local oscillator beam to obtain the difference frequency signal.

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