Laser radar

Abstract

The invention provides a laser radar. The laser radar comprises a light source, a grating assembly, a scanning assembly and a receiving assembly. The light source is used for outputting laser beams with different wavelengths, the grating assembly comprises a wavelength separation device and a first polarization device, and the wavelength separation device outputs the laser beams with different wavelengths from different channels; the scanning assembly converts a laser beam into circularly polarized light and then emits the circularly polarized light to a detection area, and converts an echo beam into linearly polarized light and then emits the linearly polarized light to the wavelength separation device, and the first polarization device converts polarized light in a second linear polarization mode in the echo beam into polarized light in a first linear polarization mode and emits the polarized light in the first linear polarization mode to the receiving assembly; and the receiving assembly determines detection information of the detection area according to the received echo light beams. The laser beam is the polarized light in the first linear polarization mode, and the detection information of the detection area is determined according to the polarized light in the second linear polarization mode in the echo beam, so that signal interference does not exist, and the ranging capability of the laser radar is improved.

Description

Technical Field

[0001] This application belongs to the field of laser detection, and particularly relates to a lidar. Background Art

[0002] Lidar is widely used in aspects such as autonomous driving, 3D printing, virtual reality, augmented reality, and intelligent transportation. With the wide application of lidar, the performance requirements for lidar are getting higher and higher. For example, it is required that the lidar meet requirements such as high frame rate, large field of view, low cost, and small volume. In response to the above requirements, frequency-modulated continuous-wave lidar has emerged. In order to achieve beam scanning, it is necessary to switch the wavelength of the laser beam directed at the detection area during the detection process of the frequency-modulated continuous-wave lidar. In order to meet large field-of-view scanning and make full use of the signal transmission channel, the laser beam directed at the detection area and the laser beam reflected back from the detection area share the same transmission channel. This method will cause interference of the emitted laser beam on the laser beam reflected from the detection area, and accurate detection information cannot be obtained by analyzing the laser beam reflected from the detection area subsequently, thus affecting the ranging ability of the lidar. Summary of the Invention

[0003] In view of this, an embodiment of this application provides a lidar for solving the problem of signal interference caused by the emitted laser beam and the received laser beam sharing the same channel.

[0004] A first aspect of the embodiment of this application provides a lidar, including: a light source, a grating assembly, a scanning assembly, and a receiving assembly;

[0005] The light source is used to output laser beams of different wavelengths, and the laser beams are polarized light in the first linear polarization mode;

[0006] The grating assembly includes a wavelength separation device and a first polarization device. The first polarization device is optically connected to the light source, the wavelength separation device, and the receiving assembly, and is used to input the laser beam into the wavelength separation device. The wavelength separation device is used to output the laser beams of different wavelengths from different channels respectively;

[0007] The scanning assembly is optically connected to the wavelength separation device, and is used to receive the laser beam output from the wavelength separation device, convert the laser beam into circularly polarized light and then emit it to the detection area, and convert the echo beam reflected from the detection area into linearly polarized light and then emit it to the wavelength separation device. The echo beam in the linear polarization mode includes polarized light in the first linear polarization mode and polarized light in the second linear polarization mode;

[0008] The first polarization device receives the echo beam output by the wavelength separation device, converts the polarized light of the second linear polarization mode in the echo beam into polarized light of the first linear polarization mode, and emits it to the receiving component;

[0009] The receiving component is used to determine the detection information of the detection area according to the received echo beam.

[0010] In one embodiment, the first polarization device includes a polarization beam splitter and a polarization rotator. The polarization beam splitter is used to receive the echo beam output by the wavelength separation device and input the polarized light of the second linear polarization mode in the echo beam into the polarization rotator. The polarization rotator is used to convert the polarized light of the second linear polarization mode in the echo beam into polarized light of the first linear polarization mode and then emit it to the receiving component.

[0011] In one embodiment, the wavelength separation device is a waveguide array grating.

[0012] In one embodiment, the scanning component includes a quarter-wave plate. The quarter-wave plate is used to receive the laser beam output by the wavelength separation device, convert the laser beam into circularly polarized light and emit it to the detection area, and convert the echo beam reflected by the detection area into linearly polarized light and then emit it to the wavelength separation device.

[0013] In one embodiment, the scanning component further includes a scanning device. The scanning device is used to emit the laser beam converted into circularly polarized light to different positions of the detection area, and input the echo beam into the wavelength separation device.

[0014] In one embodiment, the scanning device is an OPA, a rotating mirror, a polygon mirror or a MEMS micromirror.

[0015] In one embodiment, the grating component further includes a beam splitter. The first polarization device is optically connected to the light source through the beam splitter. The beam splitter is used to divide the laser beam into a detection beam and a reference beam, emit the detection beam to the first polarization device, and emit the reference beam to the receiving component.

[0016] In one embodiment, the receiving component includes a mixer and a detector. The mixer is used to perform beat frequency on the reference beam and the echo beam to obtain a beat frequency signal, and input the beat frequency signal into the detector. The detector is used to determine the detection information of the detection area according to the beat frequency signal.

[0017] In one embodiment, the light source includes a multi-wavelength tunable laser.

[0018] In one embodiment, after the receiving component completes the detection of the echo beam of the current wavelength, the multi-wavelength tunable laser emits the laser beam of the next wavelength.

[0019] In one embodiment, the grating component and the receiving component are integrated on a chip, and the lidar further includes an input coupler for coupling the laser beam onto the chip.

[0020] The beneficial effects of the embodiments of the present application compared with the prior art are as follows: The laser beam output by the light source is polarized light in the first linear polarization mode. After the laser beam is output by the wavelength separation device, the scanning component converts the laser beam into circularly polarized light and emits it to the detection area, and converts the echo beam reflected by the detection area into linearly polarized light and emits it to the wavelength separation device. The echo beam in the linear polarization mode includes polarized light in the first linear polarization mode and the second linear polarization mode. The first polarization device converts the polarized light in the second linear polarization mode in the echo beam into polarized light in the first linear polarization mode and emits it to the receiving component, and the receiving component determines the detection information of the detection area according to the echo beam. Since the laser beam emitted to the detection area is polarized light in the first linear polarization mode, among the echo beams reflected by the detection area, only the polarized light in the second linear polarization mode enters the first polarization device as a detection signal, and the polarized light in the first linear polarization mode will not interfere with the polarized light in the second linear polarization mode. Therefore, the polarized light in the second linear polarization mode will not be affected by the reflection signal generated by the emitted laser beam during transmission in the optical path, and the polarized light in the second linear polarization mode can accurately reflect the detection information of the detection area. Then, the polarized light in the second linear polarization mode is converted into polarized light in the first linear polarization mode and emitted to the receiving component, and the receiving component can determine the accurate detection information of the detection area according to the received beam, thereby improving the ranging ability of the lidar. Description of the Drawings

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art.

[0022] Figure 1 is a schematic diagram of a lidar provided by an embodiment of the present application;

[0023] Figure 2 is a schematic diagram of a lidar provided by another embodiment of the present application;

[0024] Figure 3 is a schematic diagram of the working principle of a lidar provided by an embodiment of the present application;

[0025] Figure 4 is a schematic diagram of the detection principle of a lidar provided by an embodiment of the present application. Detailed Embodiments

[0026] In the following description, specific details such as specific system architectures and technologies are presented for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, those skilled in the art should understand that the present application can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid unnecessary details from obscuring the description of the present application.

[0027] It should be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of the described features, wholes, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0028] It should also be further understood that the term "and / or" used in the specification and appended claims of the present application refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0029] In a lidar, sharing the same transmission channel for the laser beam emitted towards the detection area and the laser beam reflected back from the detection area can make full use of the transmission channel and increase the scanning range of the lidar. However, this method will cause the emitted laser beam to interfere with the laser beam reflected from the detection area, affecting the detection accuracy of the lidar and further affecting the ranging ability of the lidar.

[0030] To this end, the present application provides a lidar. The laser beam output by the light source is a polarized light in the first linear polarization mode. After converting the laser beam into circularly polarized light, it is emitted to the detection area. After converting the echo beam reflected from the detection area into linearly polarized light, it is emitted to the wavelength separation device. The polarized light in the second linear polarization mode in the echo beam enters the first polarization device as a detection signal. Since the polarized light in the first linear polarization mode does not interfere with the polarized light in the second linear polarization mode, the polarized light in the second linear polarization mode will not be affected by the reflected signal generated by the emitted laser beam during transmission in the optical path. The polarized light in the second linear polarization mode can accurately reflect the detection information of the detection area. Therefore, by converting the polarized light in the second linear polarization mode into polarized light in the first linear polarization mode and emitting it to the receiving component, the receiving component can determine the accurate detection information of the detection area based on the obtained echo beam in the first linear polarization mode, thereby improving the ranging ability of the lidar.

[0031] To illustrate the technical solutions described in the present application, specific embodiments are used for illustration below.

[0032] Please refer to the appendix Figure 1, an embodiment of the present application provides a lidar, which includes a light source 10, a grating assembly 20, a scanning assembly 30, and a receiving assembly 40.

[0033] The light source 10 is used to output laser beams of different wavelengths, and the laser beams are polarized light in the first linear polarization mode. The grating assembly 20 includes a wavelength separation device 21 and a first polarization device 22. The first polarization device 22 is optically connected to the light source 10, the wavelength separation device 21, and the receiving assembly 40, and is used to input the laser beam into the wavelength separation device 21. The wavelength separation device 21 is used to output laser beams of different wavelengths from different channels respectively. The scanning assembly 30 is optically connected to the wavelength separation device 21, and is used to receive the laser beam output from the wavelength separation device 21, convert the laser beam into circularly polarized light and emit it to the detection area. The laser beam reflected by the detected area is an echo beam. The echo beam is directed to the scanning assembly 30. The scanning assembly 30 converts the echo beam into linearly polarized light and emits it to the wavelength separation device 21, that is, the echo beam emitted to the wavelength separation device 21 is an echo beam in the linear polarization mode. The echo beam in the linear polarization mode includes polarized light in the first linear polarization mode and polarized light in the second linear polarization mode. The first polarization device 22 receives the echo beam output from the wavelength separation device 21, converts the polarized light in the second linear polarization mode in the echo beam into polarized light in the first linear polarization mode, and emits it to the receiving assembly 40. The receiving assembly 40 is used to determine the detection information of the detection area according to the received echo beam. Among them, the detection information includes the distance and speed information of the target object. The optical connection can be through fiber optic connection, or through free space optical path or waveguide connection.

[0034] Since the laser beam transmitted in the optical path system of the lidar is polarized light in the first linear polarization mode, in the echo beam obtained after reflection by the detection area, only the polarized light in the second linear polarization mode enters the wavelength separation device, and the polarized light in the first linear polarization mode will not interfere with the polarized light in the second linear polarization mode. Therefore, the obtained echo beam in the second linear polarization mode can reflect the accurate detection information of the detection area. Therefore, converting the polarized light in the second linear polarization mode in the echo beam into polarized light in the first linear polarization mode and then emitting it to the receiving assembly can enable the receiving assembly to receive the echo beam reflecting accurate detection information, and further enable the receiving assembly to obtain accurate detection information, improving the ranging ability of the lidar. At the same time, the laser beam emitted by the light source and the echo beam reflected by the detection area share the grating assembly, which can further improve the detection accuracy of the lidar while reducing the system complexity and cost.

[0035] Such as Figure 1 and Figure 2As shown, in one embodiment, the first polarization device 22 includes a polarization beam splitter 221 and a polarization rotator 222. The polarization beam splitter 221 is a three-port device, where one port is for receiving a laser beam, and the other two ports are optically connected to the wavelength separation device 21 and the receiving component 40 respectively. Laser beams of the first linearly polarized mode with different wavelengths are input into the wavelength separation device 21 through the polarization beam splitter 221 and output from different channels of the wavelength separation device 21 to the scanning component 30. The scanning component 30 converts the laser beams into circularly polarized light and then projects them to the detection area. The echo beams reflected by the detection area are converted into polarized light including the first linearly polarized mode and echo beams of the second linearly polarized mode after passing through the scanning component 30. The echo beams are input into the polarization beam splitter 221 after passing through the wavelength separation device 21. The polarization beam splitter 221 inputs the polarized light of the second linearly polarized mode in the echo beams into the polarization rotator 222 and inputs the polarized light of the first linearly polarized mode in the echo beams into the light source 10. Therefore, the polarized light of the second linearly polarized mode is not affected by the laser beams of the first linearly polarized mode and can reflect accurate detection information of the detection area. Therefore, the emitted laser beams and the received echo beams can share one wavelength separation device 21. Correspondingly, the lidar only needs one light source, a pair of detection devices, and corresponding circuit control elements, reducing the complexity of the system and the production cost. The polarization rotator 222 is used to convert the polarized light of the second linearly polarized mode in the echo beams into polarized light of the first linearly polarized mode, and then obtain echo beams with the same polarization mode as the emitted laser beams, and emit the echo beams to the receiving component 40.

[0036] Among them, the polarized light of the first linearly polarized mode is TE polarized light (transverse electric wave), and the polarized light of the second linearly polarized mode is TM polarized light (transverse magnetic wave), or the polarized light of the first linearly polarized mode is TM polarized light, and the polarized light of the second linearly polarized mode is TE polarized light.

[0037] In one embodiment, the grating assembly 20 further includes a beam splitter 23. The first polarization device 22 is optically connected to the light source 10 through the beam splitter 23. The beam splitter 23 is used to divide the laser beam into a detection beam and a reference beam, emit the detection beam to the first polarization device 22, and emit the reference beam to the receiving component 40. The receiving component 40 determines the detection information of the detection area according to the frequency difference between the reference beam and the echo beam.

[0038] In one embodiment, as Figure 3As shown, the wavelength separation device 21 is a waveguide array grating. The waveguide array grating includes array waveguides. By utilizing the phase delay and mutual interference effect of the array waveguides, beam separation can be achieved. Specifically, the laser beam input into the waveguide array grating first passes through a group of array waveguides. Each waveguide in the array waveguide has a different length, causing different wavelengths of light beams to have different phase delays after passing through. Then, the light beams of different wavelengths with phase delays interfere again at the output end of the array waveguide, resulting in the light beams of different wavelengths being assigned to different waveguide channels. By adjusting the design parameters of the array waveguide, selective output of a specific wavelength can be achieved, enabling the waveguide array grating to be used as a wavelength division multiplexing device to achieve beam separation.

[0039] The light source 10 outputs laser beams with different central wavelengths. The central wavelength of each laser beam corresponds one-to-one with the central wavelength of each waveguide channel of the waveguide array grating, enabling light beams of different wavelengths to be output from different waveguide channels and then directed to different positions in the detection area, thereby achieving beam scanning.

[0040] It can be understood that by designing the parameters of the waveguide array grating, the interval between adjacent waveguide channels, the bandwidth of the waveguide channels, and the number of waveguide channels of the waveguide array grating can be adjusted, thereby achieving the required scanning range and resolution.

[0041] In the above embodiment, by switching the wavelength of the laser beam emitted by the light source and sequentially inputting laser beams of different wavelengths into the waveguide array grating, wavelength switching can be performed, and then beam scanning can be achieved. Since the waveguide array grating does not require additional power feeding and has low loss, there are no problems of complex control and high insertion loss. At the same time, the waveguide array grating also has the characteristics of a large number of channels, dense wavelength intervals, and high stability, and can achieve a larger range of beam scanning and higher stability.

[0042] In one embodiment, the receiving component 40 is an integrated device with the functions of signal beat frequency and signal analysis. The grating component 20 and the receiving component 40 are integrated on a chip, thereby improving the integration of the lidar and reducing the size of the lidar.

[0043] Among them, the chip on which the grating component 20 and the receiving component 40 are integrated can be a silicon-based integrated optical chip. The silicon-based integrated optical chip includes, but is not limited to, silicon-on-insulator, silicon nitride, silicon oxide waveguide, etc. integrated optical platforms with a thickness less than 400 nm. The grating component 20 and the receiving component 40 are manufactured based on the silicon-based integrated optical chip.

[0044] In another embodiment, the receiving component 40 includes a mixer 41 and a detector 42. The mixer 41 is configured to perform beat frequency on the reference beam and the echo beam to obtain a beat frequency signal, and input the beat frequency signal into the detector 42. The detector 42 is configured to determine the detection information of the detection area according to the beat frequency signal. Exemplarily, the reference beam and the echo beam with the same polarization mode interfere within the mixer 41 to output an interference signal. The detector 42 may include a balanced detector to determine the detection information of the detection area according to the frequency of the interference signal. The grating component 20 and the mixer 41 are coupled on-chip, and the detector 42 is optically connected to the mixer 41 through an optical fiber.

[0045] In one embodiment, the lidar further includes an input coupler 50, which is configured to couple the laser beam onto the chip. Correspondingly, the lidar further includes an output coupler 60, which is configured to input the laser beam emitted from the grating component onto the scanning component 30, and couple the beam reflected by the scanning component 30 onto the chip.

[0046] Wherein, the input coupler 50 includes a plurality of first couplers, and the output coupler 60 each includes a plurality of second couplers. Exemplarily, as Figure 2 shown, the beam splitter 23 is connected to the optical fiber through the first coupler, so that the laser beam emitted by the light source 10 enters the beam splitter 23 through the optical fiber and the first coupler. The mixer 41 is connected to the optical fiber through the first coupler, and transmits the mixed beam to the detector 42 through the first coupler and the optical fiber. The beams output from different waveguide channels of the waveguide array grating enter the optical fiber through the second coupler respectively, and then are input into the scanning component 30 through the optical fiber.

[0047] In one embodiment, the scanning component 30 includes a quarter-wave plate 31 optically connected to the wavelength separation device 21. The quarter-wave plate 31 is configured to receive the laser beam output from the wavelength separation device 21, convert the laser beam into circularly polarized light and emit it to the detection area, and convert the echo beam reflected by the detection area into linearly polarized light and emit it to the wavelength separation device 21. That is, the quarter-wave plate separates the echo beam into polarized light of the first linearly polarized mode and polarized light of the second linearly polarized mode. The polarization of both the emitted laser beam and the echo beam reflected by the detection area can be adjusted simultaneously through the quarter-wave plate, reducing the structural complexity of the lidar.

[0048] In one embodiment, the scanning component 30 further includes a lens component 32 optically connected to the wavelength separation device 21 and the quarter-wave plate 31. The lens component 32 may include one or more optical lenses, which are configured to collimate the laser beam emitted from the wavelength separation device 21 and then emit it to the quarter-wave plate 31, and collimate the echo beam emitted from the quarter-wave plate 31 and then emit it to the wavelength separation device 21.

[0049] In one embodiment, asFigure 3 As shown, the scanning component 30 further includes a scanning device 33. The scanning device 33 is used to emit the laser beam after being converted into circularly polarized light to different positions in the detection area, and input the echo beam into the wavelength separation device 21. The laser beams output from different channels of the wavelength separation device 21 are emitted to different positions in the detection area to achieve beam scanning in the first dimension, and the laser beams output from the same channel are emitted to different positions in the detection area after passing through the scanning device 33 to achieve beam scanning in the second dimension. Therefore, the wavelength separation device 21 and the scanning device 33 cooperate to achieve two-dimensional scanning.

[0050] In one embodiment, the scanning device 33 can be an optical phased array (OPA), a rotating mirror, a polygon mirror or a MEMS mirror. The OPA shoots the beam to different positions in the detection area through the phase delay generated by the grating antenna inside, and the rotating mirror, the polygon mirror and the MEMS mirror shoot the beam to different positions in the detection area by controlling the rotation of the mirror.

[0051] In one embodiment, the light source 10 includes a multi-wavelength tunable laser. The multi-wavelength tunable laser can achieve wavelength modulation based on current control, mechanical control or temperature control techniques, so as to continuously output laser beams of different wavelengths.

[0052] In one embodiment, the multi-wavelength tunable laser can perform wavelength switching through internal modulation. After the receiving component 40 completes the detection of the echo beam of the current wavelength, it emits the laser beam of the next wavelength. Exemplarily, as Figure 4 shown, the abscissa represents time t, the ordinate represents frequency f, and the triangular waveform is the laser beam used for detection and the corresponding echo beam. The multi-wavelength tunable laser first performs triangular wave modulation at a frequency of f = c / λ1 and outputs it through the corresponding waveguide channel. After receiving the echo beam of the corresponding wavelength and determining the frequency difference f b1 and f b2 , the lidar enters the wavelength switching time, and there is a certain relaxation and stabilization time for wavelength switching. After waiting for the system to stabilize, the multi-wavelength tunable laser performs triangular wave modulation at a frequency of f = c / λ2 and outputs it through the corresponding waveguide channel. After receiving the echo beam of the corresponding wavelength and determining the frequency difference f b1 and f b2 , the lidar enters the wavelength switching time. After waiting for the system to stabilize, the multi-wavelength tunable laser performs triangular wave modulation at a frequency of f = c / λ3. It can be understood that Figure 4 the triangular wave modulation shown is only for illustration, and in actual use, the number of modulation cycles of the triangular wave modulation can be multiple.

[0053] In the above embodiments, the lidar uses a waveguide array grating component to replace the traditional electro-optic and thermo-optic switches. The waveguide array grating of the waveguide array grating component does not require additional power feeding and has relatively low loss, and there are no problems of complex control and high insertion loss. The beam scanning can be performed only by switching the wavelength of the laser beam emitted by the multi-wavelength tunable laser. By providing a first polarization device to separate the polarized light beams, the echo light beam used for detection can be made not affected by other reflected light when only one wavelength separation device is used, and the detection accuracy of the lidar is improved while reducing the system complexity and cost.

[0054] In the above embodiments, the descriptions of the respective embodiments have their own emphases. For the parts not described or recorded in a certain embodiment, reference may be made to the relevant descriptions of other embodiments.

[0055] Those of ordinary skill in the art can realize that the units and algorithm steps of the examples described in combination with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. A professional technician can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of this application.

[0056] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them; although this application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included in the protection scope of this application.

Claims

1. A lidar, characterized in that, Comprising: A light source, a grating component, a scanning component, and a receiving component; The light source is used to output laser beams of different wavelengths, and the laser beams are polarized light in a first linear polarization mode; The grating component includes a wavelength separation device and a first polarization device. The first polarization device is optically connected to the light source, the wavelength separation device, and the receiving component, and is used to input the laser beam into the wavelength separation device. The wavelength separation device is used to output the laser beams of different wavelengths from different channels respectively; The scanning component is optically connected to the wavelength separation device, and is used to receive the laser beam output from the wavelength separation device, convert the laser beam into circularly polarized light and emit it to the detection area, and convert the echo beam reflected by the detection area into linearly polarized light and emit it to the wavelength separation device. The echo beam in the linear polarization mode includes polarized light in the first linear polarization mode and polarized light in the second linear polarization mode; The first polarization device receives the echo beam output from the wavelength separation device, converts the polarized light in the second linear polarization mode in the echo beam into polarized light in the first linear polarization mode, and emits it to the receiving component; The receiving component is used to determine the detection information of the detection area according to the received echo beam.

2. The lidar according to claim 1, wherein The first polarization device includes a polarization beam splitter and a polarization rotator. The polarization beam splitter is used to receive the echo beam output from the wavelength separation device, input the polarized light in the second linear polarization mode in the echo beam into the polarization rotator, and the polarization rotator is used to convert the polarized light in the second linear polarization mode in the echo beam into polarized light in the first linear polarization mode and then emit it to the receiving component.

3. The lidar according to claim 1, wherein The wavelength separation device is a waveguide array grating.

4. The lidar according to claim 1, wherein, The scanning component includes a quarter-wave plate. The quarter-wave plate is used to receive the laser beam output from the wavelength separation device, convert the laser beam into circularly polarized light and emit it to the detection area, and convert the echo beam reflected by the detection area into linearly polarized light and emit it to the wavelength separation device.

5. The lidar according to claim 1, characterized in that The scanning component further includes a scanning device. The scanning device is used to emit the laser beam converted into circularly polarized light to different positions of the detection area, and input the echo beam into the wavelength separation device.

6. The lidar according to claim 5, characterized in that, The scanning device is an OPA, a rotating mirror, a polygon mirror, or a MEMS micromirror.

7. The lidar according to claim 1, wherein The grating component further includes a beam splitter. The first polarization device is optically connected to the light source through the beam splitter. The beam splitter is used to divide the laser beam into a detection beam and a reference beam, emit the detection beam to the first polarization device, and emit the reference beam to the receiving component.

8. The lidar according to claim 7, characterized in that, The receiving component includes a mixer and a detector. The mixer is used to perform beat frequency on the reference beam and the echo beam to obtain a beat frequency signal, and input the beat frequency signal into the detector. The detector is used to determine the detection information of the detection area according to the beat frequency signal.

9. The lidar according to claim 1, wherein The light source includes a multi-wavelength tunable laser.

10. The lidar according to claim 9, characterized in that, After the multi-wavelength tunable laser completes the detection of the echo beam at the current wavelength in the receiving component, it emits the laser beam at the next wavelength.

11. The lidar according to claim 1, wherein The grating component and the receiving component are integrated on-chip, and the lidar further includes an input coupler for coupling the laser beam onto the chip.

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