Lidar

Abstract

A kind of laser radar, laser radar includes at least one laser transmission detection channel, laser transmission detection channel includes: light emission / reception end, is configured to emit combined probe laser, combined probe laser includes first probe laser, second probe laser and third probe laser, combined probe laser is reflected to produce combined reflection laser after meeting obstacle, light emission / reception end is also configured to receive combined reflection laser;Probe wavelength beam splitter, combined reflection laser is divided into first reflection laser, second reflection laser and third reflection laser;And detection device, including first detection device, second detection device and third detection device, receive first reflection laser, second reflection laser and third reflection laser and carry out detection respectively based on the detection information of first detection device, second detection device and third detection device Determine detection result, improve the measurement detection probability, increase the test point density.

Description

Technical Field

[0001] This invention relates to the field of lidar technology, and more specifically, to a lidar system. Background Technology

[0002] LiDAR (Light Detection and Ranging) is a radar system that uses emitted laser beams to detect the position, velocity, and other characteristics of targets. Its working principle involves emitting a detection signal towards the target, then comparing the received signal reflected back from the target with the emitted signal. After appropriate processing, information about the target can be obtained, such as its distance, azimuth, altitude, velocity, attitude, and even shape. This allows for the detection, tracking, and identification of targets such as aircraft and missiles. LiDAR is now widely deployed in various scenarios, including autonomous vehicles. While scanning a scene, LiDAR can actively estimate the distance and velocity of environmental features and generate a point position cloud indicating the three-dimensional shape of the environment. Summary of the Invention

[0003] Some embodiments of the present invention provide a lidar, the lidar including at least one laser transmission and detection channel.

[0004] The laser transmission detection channel includes:

[0005] An optical transmitter / receiver is configured to emit a beam-combining detection laser, which includes a first detection laser, a second detection laser, and a third detection laser. At least two of the first, second, and third detection lasers are frequency-modulated lasers and have the same frequency sweep period. Within any frequency sweep period, one of the first, second, and third detection lasers has a frequency-increasing band, another has a frequency-decreasing band, and the third has a constant frequency band. The beam-combining detection laser is reflected after encountering an obstacle to generate a beam-combining reflected laser. The optical transmitter / receiver is also configured to receive the beam-combining reflected laser.

[0006] A wavelength beam splitter separates the combined reflected laser beam into a first reflected laser beam, a second reflected laser beam, and a third reflected laser beam; and

[0007] The detection device includes a first detection device, a second detection device, and a third detection device. The first detection device, the second detection device, and the third detection device respectively receive a first reflected laser, a second reflected laser, and a third reflected laser and perform detection. The detection result is determined based on the detection information from the first detection device, the second detection device, and the third detection device.

[0008] In some embodiments, the laser transmission detection channel further includes:

[0009] A polarization rotating beam splitter is positioned between the optical transmitter / receiver and the probe wavelength beam splitter, configured as follows:

[0010] Receive the combined detection laser beam entering the laser transmission detection channel, and transmit the combined detection laser beam to the optical transmitter / receiver; and

[0011] The beam-combined reflected laser is received from the optical transmitter / receiver, and the polarization direction of the beam-combined reflected laser is changed so that the beam-combined reflected laser is transmitted to the probe wavelength beam splitter.

[0012] In some embodiments, the center frequencies of the first detection laser, the second detection laser, and the third detection laser are different.

[0013] In some embodiments, the detection results include the distance and / or speed of the obstacle relative to the lidar.

[0014] In some embodiments, the distance R of the obstacle relative to the lidar is determined by the following set of formulas:

[0015]

[0016]

[0017] Where C0 is the speed of light, T0 is the sweep period, and f BW For the sweep bandwidth, f d Δf1 is the beat frequency caused by distance, Δf2 is the beat frequency of the up-frequency band, Δf3 is the beat frequency of the down-frequency band, and Δf3 is the beat frequency of the constant frequency band.

[0018] In some embodiments, the velocity v of the obstacle relative to the lidar is determined by the following set of formulas:

[0019]

[0020]

[0021]

[0022] Where C0 is the speed of light, f0 is the center frequency of the laser, and f v f is the beat frequency caused by velocity. d Δf1 is the beat frequency caused by distance, Δf2 is the beat frequency of the up-frequency band, Δf3 is the beat frequency of the down-frequency band, and Δf3 is the beat frequency of the constant frequency band.

[0023] In some embodiments, the lidar further includes:

[0024] A wavelength beam combiner is configured to receive a first laser, a second laser, and a third laser, and combine the first laser, the second laser, and the third laser into a combined laser beam; and

[0025] A beam splitter, configured to split the combined laser beam into a combined probe laser and a combined local oscillator laser; and

[0026] The local oscillator wavelength beam splitter is configured to receive the combined local oscillator laser beam and split the combined local oscillator laser beam into a first local oscillator laser beam, a second local oscillator laser beam, and a third local oscillator laser beam.

[0027] The first detection device receives the first reflected laser and the first local oscillator laser, and detects the beat frequency of the first reflected laser and the first local oscillator laser to output first detection information; the second detection device receives the second reflected laser and the second local oscillator laser, and detects the beat frequency of the second reflected laser and the second local oscillator laser to output second detection information; the third detection device receives the third reflected laser and the third local oscillator laser, and detects the beat frequency of the third reflected laser and the third local oscillator laser to output third detection information, wherein the first detection information, the second detection information, and the third detection information constitute the detection information.

[0028] In some embodiments, the lidar further includes:

[0029] The first laser source is configured to emit the first laser;

[0030] A second laser source, configured to emit a second laser; and

[0031] The third laser source is configured to emit a third laser.

[0032] In some embodiments, the lidar further includes:

[0033] The first beam splitter is configured to receive the first laser and split the first laser into a first probe laser and a first local oscillator laser.

[0034] The second beam splitter is configured to receive the second laser and split the second laser into a second probe laser and a second local oscillator laser.

[0035] The third beam splitter is configured to receive the third laser and split it into a third probe laser and a third local oscillator laser.

[0036] The wavelength combiner is configured to receive a first probe laser, a second probe laser, and a third probe laser, and combine the first probe laser, the second probe laser, and the third probe laser into a combined probe laser.

[0037] The first detection device receives the first reflected laser and the first local oscillator laser, and detects the beat frequency of the first reflected laser and the first local oscillator laser to output first detection information; the second detection device receives the second reflected laser and the second local oscillator laser, and detects the beat frequency of the second reflected laser and the second local oscillator laser to output second detection information; the third detection device receives the third reflected laser and the third local oscillator laser, and detects the beat frequency of the third reflected laser and the third local oscillator laser to output third detection information, wherein the first detection information, the second detection information, and the third detection information constitute the detection information.

[0038] In some embodiments, the lidar further includes:

[0039] The first laser source is configured to emit the first laser;

[0040] A second laser source, configured to emit a second laser; and

[0041] The third laser source is configured to emit a third laser. Compared with related technologies, the above-described solution of this embodiment of the invention has at least the following beneficial effects:

[0042] This invention employs a beam-combined detection laser to detect obstacles. In any frequency sweep cycle, the beam-combined detection laser includes three test lasers, each with a frequency-increasing band, a frequency-decreasing band, and a constant frequency band. The beam-combined reflected laser reflected back from the obstacle is divided into a first reflected laser, a second reflected laser, and a third reflected laser. The first, second, and third reflected lasers are detected separately to obtain detection information, thereby determining the detection result. This improves the measurement and detection probability and increases the density of test points. Attached Figure Description

[0043] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0044] Figure 1 The waveforms of the transmitted and received beams using the conventional FWCW frequency sweep method in related technologies are shown.

[0045] Figure 2 This is a schematic diagram of the structure of a lidar provided in some embodiments of the present invention;

[0046] Figure 3 The waveform diagrams showing the frequency variation of the combined detection laser and the combined reflected laser of the lidar provided in some embodiments of the present invention are shown, where the vertical axis represents the normalized frequency.

[0047] Figure 4 The waveform diagram of the laser beam combining detection laser provided for some embodiments of the present invention, wherein the vertical axis represents the actual frequency;

[0048] Figure 5 This is a schematic diagram of the structure of a lidar provided in some embodiments of the present invention. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0050] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0051] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0052] It should be understood that although the terms first, second, third, etc., may be used in the embodiments of the present invention, these are not intended to limit the scope of the invention. These terms are used only to distinguish the parts. For example, first may also be referred to as second, and similarly, second may also be referred to as first, without departing from the scope of the embodiments of the invention.

[0053] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one" does not exclude the presence of other identical elements in the article or device that includes said element.

[0054] In related technologies, existing lidar based on ranging methods mainly includes the following two technical routes: ToF (Time of Flight) and FMCW (Frequency-Modulated Continuous Wave).

[0055] The Time-of-Flight (ToF) ranging principle calculates distance by multiplying the time of flight of a light pulse between the target and the lidar by the speed of light. ToF lidar employs pulse amplitude modulation (PWM) technology. In contrast, Frequency-Modulated Wavelength (FMCW) lidar primarily works by transmitting and receiving continuous laser beams, interfering the reflected light with the local light, and using frequency mixing detection technology to measure the frequency difference between the transmitted and received beams. The distance to the target is then calculated from this frequency difference. In short, ToF uses time to measure distance, while FMCW uses frequency.

[0056] Compared to Time-of-Flight (ToF), FMCW has the following advantages: ToF light waves are easily affected by ambient light interference, while FMCW light waves have strong anti-interference capabilities; ToF has a low signal-to-noise ratio, while FMCW has a high signal-to-noise ratio; ToF has low velocity dimension data quality, while FMCW can acquire velocity dimension data for each pixel.

[0057] LiDAR using the FMCW technology approach has significant technical advantages, but its practical application presents the following problems:

[0058] For traditional FMCW lidar, the detection laser is a frequency-sweeping laser with a single center wavelength, and its frequency changes periodically. In order to measure the distance and / or velocity of an obstacle relative to the FMCW lidar, each frequency change cycle of the frequency-sweeping laser with a single center wavelength usually needs to include a frequency-increasing segment, a constant frequency segment, and a frequency-decreasing segment. Figure 1 The waveforms of the transmitted and received beams using the conventional FWCW frequency sweeping method in related technologies are shown below. Figure 1 The solid line represents the transmitted beam, and the dashed line represents the received beam. Each frequency change period Tc is used as a measurement point. Each measurement point can only be used as a valid measurement point if it fully receives the up-frequency band, constant-frequency band, and down-frequency band of the received beam, so as to realize the measurement of the distance and / or speed of the obstacle relative to the FMCW lidar.

[0059] However, for a single-center-wavelength swept laser, it cannot receive all the up-frequency band, constant-frequency band, and down-frequency band at every measurement point, resulting in a certain loss rate. If the detection probability of each frequency band in each frequency change period Tc of a single-center-wavelength swept laser is 50%, then the probability of the measurement point corresponding to that frequency change period Tc becoming a valid measurement point is 12.5%, leading to poor measurement results.

[0060] This invention provides a lidar, comprising at least one laser transmission and detection channel, the laser transmission and detection channel comprising: an optical transmitter / receiver configured to transmit a combined detection laser, the combined detection laser comprising a first detection laser, a second detection laser, and a third detection laser, at least two of the first, second, and third detection lasers being frequency-modulated lasers and having the same frequency sweep period; within any frequency sweep period, one of the first, second, and third detection lasers having a frequency upsampling band, another having a frequency downsampling band, and the third having a constant frequency band; the combined detection laser being reflected upon encountering an obstacle to generate a combined reflected laser; the optical transmitter / receiver also configured to receive the combined reflected laser; a detection wavelength beam splitter dividing the combined reflected laser into a first reflected laser, a second reflected laser, and a third reflected laser; and a detection device comprising a first detection device, a second detection device, and a third detection device, the first detection device, the second detection device, and the third detection device respectively performing detection on the first reflected laser, the second reflected laser, and the third reflected laser, and determining the detection result based on the detection information from the first detection device, the second detection device, and the third detection device.

[0061] This invention employs a beam-combined detection laser to detect obstacles. In any frequency sweep cycle, the beam-combined detection laser includes three test lasers, each with a frequency-increasing band, a frequency-decreasing band, and a constant frequency band. The beam-combined reflected laser reflected back from the obstacle is divided into a first reflected laser, a second reflected laser, and a third reflected laser. The first, second, and third reflected lasers are detected separately to obtain detection information, thereby determining the detection result. This improves the measurement and detection probability and increases the density of test points.

[0062] The optional embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0063] Figure 2 This is a schematic diagram of the structure of a lidar provided in some embodiments of the present invention, which only shows one laser transmission and detection channel. Figure 3 The following are frequency variation waveforms of the combined detection laser and the combined reflected laser of a lidar provided in some embodiments of the present invention, wherein the vertical axis represents the normalized frequency. Figure 4 The image shows a waveform of the laser beam combining detection laser provided in some embodiments of the present invention, where the vertical axis represents the actual frequency. For example... Figures 2 to 4 As shown, some embodiments of the present invention provide a lidar 1000, which includes at least one laser transmission detection channel 100. Although Figure 2Only one laser transmission detection channel 100 is shown in the figure. Those skilled in the art will understand that the lidar 1000 may include multiple parallel laser transmission detection channels 100, each of which can independently perform measurement work and emit detection lasers corresponding to different positions of obstacles.

[0064] For any laser transmission detection channel 100, the laser transmission detection channel 100 includes an optical transmitter / receiver 10, a detection wavelength beam splitter 20, and a detection device 30.

[0065] The optical transmitter / receiver 10 is configured to emit a beam-combining detection laser, which includes a first detection laser L1, a second detection laser L2, and a third detection laser L3. At least two of the first detection laser L1, the second detection laser L2, and the third detection laser L3 are frequency-modulated lasers and have the same sweep period T0. Within any sweep period T0, one of the first detection laser L1, the second detection laser L2, and the third detection laser L3 has a frequency-increasing segment, another has a frequency-decreasing segment, and the third has a constant frequency segment. The beam-combining detection laser is reflected after encountering an obstacle to generate a beam-combining reflected laser. The optical transmitter / receiver 10 is also configured to receive the beam-combining reflected laser. In this embodiment, the optical transmitter / receiver 10 is a single-structure device, which can realize coaxial transmission and reception of the beam-combining detection laser and the beam-combining reflected laser. In other embodiments, the optical transmitter / receiver 10 can be divided into an independent optical transmitter and an optical receiver, in which case the two cannot transmit and receive coaxially.

[0066] The detection wavelength beamsplitter 20 splits the combined reflected laser beam into a first reflected laser RL1, a second reflected laser RL2, and a third reflected laser RL3. In some embodiments, when the first detection laser L1, the second detection laser L2, and the third detection laser L3 in the combined detection laser beam encounter an obstacle, they are reflected to generate the first reflected laser RL1, the second reflected laser RL2, and the third reflected laser RL3, respectively. The first reflected laser RL1, the second reflected laser RL2, and the third reflected laser RL3 maintain the center frequency and frequency variation pattern of the first reflected laser RL1, the second reflected laser RL2, and the third reflected laser RL3, respectively, and they are delayed compared to the first detection laser L1, the second detection laser L2, and the third detection laser L3. The first reflected laser RL1, the second reflected laser RL2, and the third reflected laser RL3 are received by the optical transmitter / receiver 10 in the form of a combined reflected laser beam. The detection wavelength beamsplitter 20 can separate the first reflected laser RL1, the second reflected laser RL2, and the third reflected laser RL3 in the combined reflected laser beam to detect the first reflected laser RL1, the second reflected laser RL2, and the third reflected laser RL3 separately.

[0067] The detection device 30 includes a first detection device 31, a second detection device 32, and a third detection device 33. The first detection device 31, the second detection device 32, and the third detection device 33 respectively detect a first reflected laser RL1, a second reflected laser RL2, and a third reflected laser RL3, and determine the detection result based on the detection information from the first detection device 31, the second detection device 32, and the third detection device 33. The detection result may include, for example, the distance and / or velocity of an obstacle relative to the lidar. Each of the first detection device 31, the second detection device 32, and the third detection device 33 is, for example, a coherent detection device.

[0068] like Figure 3 and Figure 4 As shown, in some embodiments, the first detection laser L1 is a periodic up-frequency waveform, the second detection laser L2 is a periodic down-frequency waveform, and the third detection laser L3 is a constant-frequency waveform. The sweep periods of the first detection laser L1 and the second detection laser L2 are the same, for example, both have a sweep period T0. Figure 3 and Figure 4 As shown, in any sweep cycle T0, the frequency-increasing segment of the first probe laser L1, the frequency-decreasing segment of the second probe laser L2, and the constant-frequency segment of the third probe laser L3 coexist, thus each sweep cycle T0 can be considered a measurement point. Compared to Figure 1 The related technologies shown Figure 3 and Figure 4 The sweep period T0 in the middle is Figure 1 The frequency change period Tc is 1 / 3 of the frequency change period, therefore, the test point density of this embodiment is increased by 2 times compared to related technologies. Furthermore, given that the frequency-upper band of the first detection laser L1, the frequency-downper band of the second detection laser L2, and the constant-frequency band of the third detection laser L3 all simultaneously detect the same point on the object within a single frequency sweep period T0, assuming that the detection probability of each frequency band in each frequency sweep period T0 is 50%, the probability that the measurement point corresponding to the frequency sweep period T0 becomes a valid measurement point is 50%, thus improving the measurement effect.

[0069] This invention employs a combined detection laser to detect obstacles. The combined detection laser comprises three detection lasers, each with a frequency-increasing band, a frequency-decreasing band, and a constant frequency band, in any frequency sweep cycle. The combined reflected laser beams reflected back from the obstacle are divided into a first reflected laser, a second reflected laser, and a third reflected laser. The first, second, and third reflected lasers are detected separately to obtain detection information, thereby determining the detection result. This improves the measurement and detection probability and increases the density of test points.

[0070] In some embodiments, such as Figure 2As shown, the laser transmission detection channel 100 further includes a polarization rotating beam splitter 40. The polarization rotating beam splitter 40 is positioned between the optical transmitter / receiver 10 and the detection wavelength beam splitter 20. The polarization rotating beam splitter 40 receives the combined detection laser entering the laser transmission detection channel 100 and transmits the combined detection laser to the optical transmitter / receiver 10; it also receives the combined reflected laser from the optical transmitter / receiver 10 and changes the polarization direction of the combined reflected laser, for example, converting a TM mode combined reflected laser to a TE mode combined reflected laser. This allows the combined reflected laser to be transmitted to the detection wavelength beam splitter 20. By setting the polarization rotating beam splitter 40, interference between the combined detection laser and the combined reflected laser can be reduced, ensuring that the coaxially returning combined reflected laser can be transmitted to the detection wavelength beam splitter 20.

[0071] In some embodiments, the center frequencies of the first detection laser L1, the second detection laser L2, and the third detection laser L3 are different. In the field of FMCW lidar, the sweep bandwidth of a typical linear frequency-sweeping laser is usually within 2 GHz, and it typically sweeps linearly within the sweep bandwidth centered on the center frequency of the laser. To facilitate the subsequent beam splitting of the combined and reflected lasers, the center frequencies of the first detection laser L1, the second detection laser L2, and the third detection laser L3 need to be set to be different, and the differences between them should be small. For example, Figure 3 and Figure 4 As shown, the center frequency of the first detection laser L1 is, for example, 193.3 THz, the center frequency of the second detection laser L2 is, for example, 193.4 THz, and the center frequency of the third detection laser L3 is, for example, 193.5 THz. Thus, the center frequencies of the first reflected laser RL1, the second reflected laser RL2, and the third reflected laser RL3 generated by the first detection laser L1, the second detection laser L2, and the third detection laser L3 after reflection from the obstacle T are also 193.3 THz, 193.4 THz, and 193.5 THz, respectively. The first reflected laser RL1, the second reflected laser RL2, and the third reflected laser RL3 are received by the optical transmitter / receiver 10 in the form of a combined reflected laser beam. When the combined reflected laser beam including the first reflected laser RL1, the second reflected laser RL2, and the third reflected laser RL3 is incident on the detection wavelength beamsplitter 20, the first reflected laser RL1, the second reflected laser RL2, and the third reflected laser RL3 can be conveniently and accurately separated according to the wavelength. In some embodiments, the first detection laser L1 and the second detection laser L2, for example, have the same sweep bandwidth f. BW ,like Figure 3 As shown.

[0072] Figure 3To better illustrate the relative relationships between the combined detection laser, the combined reflected laser, and their respective center wavelengths, the vertical axis uses the normalized frequency F', and the horizontal axis represents the time axis t. Figure 3 This does not represent the actual center frequencies of the first detection laser L1, the second detection laser L2, and the third detection laser L3. Figure 4 The vertical axis represents the actual frequency, reflecting the true frequencies of the first detection laser L1, the second detection laser L2, and the third detection laser L3, while the horizontal axis is the time axis t. For example... Figure 4 It can be seen that the center frequencies of the first detection laser L1, the second detection laser L2, and the third detection laser L3 are relatively close.

[0073] In some embodiments, the detection result of the LiDAR 1000 detecting an obstacle T includes the distance and / or velocity of the obstacle T relative to the LiDAR 1000. In some embodiments, the distance R of the obstacle T relative to the LiDAR 1000 is determined by the following set of formulas:

[0074]

[0075]

[0076] Where C0 is the speed of light, T0 is the sweep period, and f BW For the sweep bandwidth, f d The beat frequency is determined by distance. Δf1 is the beat frequency of the up-frequency band, for example, the beat frequency of the first probe laser L1 and the first reflected laser RL1 in a sweep cycle T0. Δf2 is the beat frequency of the down-frequency band, for example, the beat frequency of the second probe laser L2 and the second reflected laser RL2 in a sweep cycle T0. Δf3 is the beat frequency of the constant frequency band, for example, the beat frequency of the third probe laser L3 and the third reflected laser RL3 in a sweep cycle T0.

[0077] In some embodiments, the velocity v of the obstacle T relative to the lidar 1000 is determined by the following set of formulas:

[0078]

[0079]

[0080]

[0081] Where C0 is the speed of light, f0 is the center frequency of the laser, and f v f is the beat frequency caused by velocity. dLet Δf1 be the beat frequency caused by distance, for example, the beat frequency of the first probe laser L1 and the first reflected laser RL1 in one sweep cycle T0; Δf2 be the beat frequency of the second probe laser L2 and the second reflected laser RL2 in one sweep cycle T0; and Δf3 be the beat frequency of the third probe laser L3 and the third reflected laser RL3 in one sweep cycle T0. Since the different frequencies of each probe laser are relatively small compared to their center frequencies, the difference in velocity beat frequencies introduced by this is also very small and can be ignored. Under this approximation, the above formula can be obtained. The laser center frequency f0 can be any one of the center frequencies of the first probe laser L1, the second probe laser L2, and the third probe laser L3, or the average of the center frequencies of the first probe laser L1, the second probe laser L2, and the third probe laser L3.

[0082] In some embodiments, such as Figure 2 As shown, the lidar 1000 further includes a wavelength combiner 50, a beam splitter 60, and a local oscillator wavelength beam splitter 70. The wavelength combiner 50 is configured to receive a first laser, a second laser, and a third laser with different center frequencies and combine them into a combined laser beam. The beam splitter 60 is configured to split the combined laser beam into a beam detection laser and a beam local oscillator laser. The beam splitter 60 is, for example, a 1×n beam splitter, where n is greater than or equal to 2, and splits the combined laser beam into at least one beam detection laser and at least one beam local oscillator laser. The beam detection laser and the beam local oscillator laser can, for example, be the same, both comprising a portion of each of the first, second, and third lasers. In some embodiments, the beam splitter 60 can split the combined laser beam into multiple beam detection lasers and multiple beam local oscillator lasers, and transmit these multiple beam detection lasers and multiple beam local oscillator lasers to multiple laser transmission detection channels 100, each laser transmission detection channel 100 receiving one beam detection laser and one beam local oscillator laser.

[0083] The local oscillator wavelength beam splitter 70 is configured to receive the combined local oscillator laser beam and split it into a first local oscillator laser Lo1, a second local oscillator laser Lo2, and a third local oscillator laser Lo3. The first local oscillator laser Lo1, the second local oscillator laser Lo2, and the third local oscillator laser Lo3 have the same center frequency, phase, and frequency modulation as the first detector laser L1, the second detector laser L2, and the third detector laser L3, respectively. The center frequencies of the first local oscillator laser Lo1, the second local oscillator laser Lo2, and the third local oscillator laser Lo3 are all different, but the difference is small. Using the local oscillator wavelength beam splitter 70, the first local oscillator laser Lo1, the second local oscillator laser Lo2, and the third local oscillator laser Lo3 can be easily and accurately separated.

[0084] In some embodiments, the local oscillator wavelength beam splitter 70 is disposed in the laser transmission detection channel 100, and each laser transmission detection channel 100 includes one wavelength beam splitter 70.

[0085] In some embodiments, such as Figure 2 As shown, the first detection device 31, for example a coherent detection device, receives the first reflected laser RL1 and the first local oscillator laser Lo1, and detects the beat frequency of the first reflected laser RL1 and the first local oscillator laser Lo1 to output first detection information. The second detection device 32 receives the second reflected laser RL2 and the second local oscillator laser Lo2, and detects the beat frequency of the second reflected laser RL2 and the second local oscillator laser Lo2 to output second detection information; the third detection device 33 receives the third reflected laser RL3 and the third local oscillator laser Lo3, and detects the beat frequency of the third reflected laser RL3 and the third local oscillator laser Lo3 to output third detection information. The first detection information, the second detection information, and the third detection information constitute the detection information.

[0086] In some embodiments, such as Figure 2 As shown, the first detection device 31 includes a first mixer 311 and a first detector 312. The first mixer 311 receives the first reflected laser RL1 and the first local oscillator laser Lo1, and performs a mixing operation on the first reflected laser RL1 and the first local oscillator laser Lo1 to output a first mixed beam. The first detector 312 receives the first mixed beam and performs a beat frequency operation to output first detection information, such as first beat frequency information.

[0087] In some embodiments, such as Figure 2 As shown, the second detection device 32 includes a second mixer 321 and a second detector 322. The second mixer 321 receives the second reflected laser RL2 and the second local oscillator laser Lo2, and performs a mixing operation on the second reflected laser RL2 and the second local oscillator laser Lo2 to output a second mixed beam. The second detector 322 receives the second mixed beam and performs a beat frequency operation to output second detection information, such as second beat frequency information.

[0088] In some embodiments, such as Figure 2 As shown, the third detection device 33 includes a third mixer 331 and a third detector 332. The third mixer 331 receives the third reflected laser RL3 and the third local oscillator laser Lo3, and performs a mixing operation on the third reflected laser RL3 and the third local oscillator laser Lo3 to output a third mixed beam. The third detector 332 receives the third mixed beam and performs a beat frequency operation to output third detection information, such as third beat frequency information.

[0089] In some embodiments, any one of the first mixer 311, the second mixer 321, and the third mixer 331 is, for example, a 2x2 coupler, a 90-degree mixer, etc., and any one of the first detector 312, the second detector 322, and the third detector 332 is, for example, a photodetector, a balance detector, etc.

[0090] In some embodiments, such as Figure 2 As shown, the lidar 1000 also includes a data acquisition and processing unit 80. The data acquisition and processing unit 80 receives detection information from the detection device 30, including, for example, first detection information, second detection information, and third detection information. It then acquires and processes this detection information to determine the distance and velocity of the detected obstacle T relative to the lidar 1000. The data acquisition and processing unit 80 includes, for example, a data acquisition unit and a processor. The data acquisition unit can convert the detection information, which is an analog signal, into a digital signal, for example, using an analog-to-digital converter. The processor processes the digital signal to determine the distance and velocity of the detected obstacle T relative to the lidar 1000. The processor can be, for example, a field-programmable gate array (FPGA), a digital signal processor (DSP), etc.

[0091] In some embodiments, such as Figure 2 As shown, the lidar also includes a first laser source 91, a second laser source 92, and a third laser source 93. The first laser source 91 is configured to emit a first laser beam, which is a periodic up-frequency waveform, as can be referenced. Figure 3 and Figure 4 The waveform of the first detection laser L1 is shown; the second laser source 92 is configured to emit a second laser, which is a periodic down-frequency waveform, as can be referenced. Figure 3 and Figure 4 The waveform of the second detection laser L2 is shown; the third laser source 92 is configured to emit the third laser, which has a constant frequency waveform, as can be referenced. Figure 3 and Figure 4 The waveform of the third probe laser L3. Any one of the first laser source 91, the second laser source 92, and the third laser source 93 can be a solid-state laser, a semiconductor laser, etc., specifically a distributed feedback laser (DFB), a vertical cavity surface-emitting laser (VCSEL), an external cavity laser, etc.

[0092] In some embodiments, such as Figure 2 As shown, the lidar 1000 further includes a lens assembly L. The lens assembly L is disposed between the light emitting / receiving end 10 and the obstacle T, and is configured to collimate the combined detection laser emitted from the light emitting / receiving end 10, and to focus the combined reflected laser to couple it into the light emitting / receiving end 10.

[0093] In some embodiments, the lidar 1000 further includes a beam scanning guide device disposed between the lens assembly L and the obstacle T to achieve light deflection and scanning.

[0094] Figure 5 This is a schematic diagram of the structure of a lidar provided in some embodiments of the present invention, in which only one laser transmission and detection channel is shown. Figure 5 The illustrated embodiments and Figure 2 The embodiments shown are largely the same, and the similarities between the two will not be repeated here. The following only describes the differences between the two.

[0095] and Figure 2 The difference between the embodiments shown is that the lidar 1000 in this embodiment does not have a local oscillator wavelength beam splitter 70 and a beam splitter 60. Instead, a first beam splitter 71, a second beam splitter 72, and a third beam splitter 73 are added for the first laser, the second laser, and the third laser, respectively.

[0096] Specifically, see Figure 5 The first beam splitter 71 is configured to receive the first laser and split the first laser into a first probe laser L1 and a first local oscillator laser Lo1; the second beam splitter 72 is configured to receive the second laser and split the second laser into a second probe laser L2 and a second local oscillator laser Lo2; the third beam splitter 73 is configured to receive the third laser and split the third laser into a third probe laser L3 and a third local oscillator laser Lo3.

[0097] The wavelength combiner 50 is configured to receive the first probe laser L1, the second probe laser L2 and the third probe laser L3 and combine the first probe laser L1, the second probe laser L2 and the third probe laser L3 into a combined probe laser, which is then incident into the laser transmission detection channel 100.

[0098] The first local oscillator laser Lo1, the second local oscillator laser Lo2, and the third local oscillator laser Lo3 are directly transmitted to the first detection device 31, the second detection device 32, and the third detection device 33, respectively.

[0099] like Figure 5As shown, the first detection device 31 receives the first reflected laser RL1 and the first local oscillator laser Lo1, and detects the beat frequency of the first reflected laser RL1 and the first local oscillator laser Lo1 to output first detection information. The second detection device 32 receives the second reflected laser RL2 and the second local oscillator laser Lo2, and detects the beat frequency of the second reflected laser RL2 and the second local oscillator laser Lo2 to output second detection information; the third detection device 33 receives the third reflected laser RL3 and the third local oscillator laser Lo3, and detects the beat frequency of the third reflected laser RL3 and the third local oscillator laser Lo3 to output third detection information. The first detection information, the second detection information, and the third detection information constitute the detection information.

[0100] In some embodiments, such as Figure 5 As shown, the lidar also includes a first laser source 91, a second laser source 92, and a third laser source 93. The first laser source 91 is configured to emit a first laser beam, which is a periodic up-frequency waveform, as can be referenced. Figure 3 and Figure 4 The waveform of the first detection laser L1 is shown; the second laser source 92 is configured to emit a second laser, which is a periodic down-frequency waveform, as can be referenced. Figure 3 and Figure 4 The waveform of the second detection laser L2 is shown; the third laser source 92 is configured to emit the third laser, which has a constant frequency waveform, as can be referenced. Figure 3 and Figure 4 The waveform of the third probe laser L3. Any one of the first laser source 91, the second laser source 92, and the third laser source 93 can be a solid-state laser, a semiconductor laser, etc., specifically a distributed feedback laser (DFB), a vertical cavity surface-emitting laser (VCSEL), an external cavity laser, etc.

[0101] The various parts of this manual are described in a combination of parallel and progressive methods. Each part focuses on the differences between the other parts, and the same or similar parts can be referred to each other.

[0102] The features described above regarding the disclosed embodiments can be substituted or combined with each other to enable those skilled in the art to implement or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0103] Finally, it should be noted that the various embodiments in this specification are described by way of example, and each embodiment focuses on the differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems or apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant parts can be referred to the method section.

[0104] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions 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 the present invention.

Claims

1. A lidar, characterized in that, The lidar includes at least one laser transmission and detection channel. The laser transmission detection channel includes: An optical transmitter / receiver is configured to transmit a beam-combining detection laser, which includes a first detection laser, a second detection laser, and a third detection laser. At least two of the first, second, and third detection lasers are frequency-modulated lasers with the same frequency sweep period. Within any frequency sweep period, one of the first, second, and third detection lasers has a frequency-increasing segment, another has a frequency-decreasing segment, and the third has a constant frequency segment. The center frequencies of the first, second, and third detection lasers are all different. The beam-combining detection laser is reflected after encountering an obstacle to generate a beam-combining reflected laser. The optical transmitter / receiver is also configured to receive the beam-combining reflected laser. A wavelength beam splitter separates the combined reflected laser beam into a first reflected laser beam, a second reflected laser beam, and a third reflected laser beam; and The detection device includes a first detection device, a second detection device, and a third detection device. The first detection device, the second detection device, and the third detection device respectively receive a first reflected laser, a second reflected laser, and a third reflected laser and perform detection. The detection result is determined based on the detection information from the first detection device, the second detection device, and the third detection device.

2. The lidar according to claim 1, wherein, The laser transmission detection channel also includes: A polarization rotating beam splitter is positioned between the optical transmitter / receiver and the probe wavelength beam splitter, configured as follows: Receive the combined detection laser beam entering the laser transmission detection channel, and transmit the combined detection laser beam to the optical transmitter / receiver; and The beam-combined reflected laser is received from the optical transmitter / receiver, and the polarization direction of the beam-combined reflected laser is changed so that the beam-combined reflected laser is transmitted to the probe wavelength beam splitter.

3. The lidar according to claim 1 or 2, wherein, The detection results include the distance and / or speed of the obstacle relative to the lidar.

4. The lidar according to claim 3, wherein, The distance of the obstacle relative to the lidar Determined by the following set of formulas: Where C0 is the speed of light, T0 is the sweep period, and f BW For the sweep bandwidth, f d Beat frequency caused by distance, f1 is the up-frequency beat frequency of the up-frequency band. f2 is the beat frequency of the down-frequency band. f3 is the constant frequency beat frequency of the constant frequency band.

5. The lidar according to claim 3, wherein, The speed of the obstacle relative to the lidar Determined by the following set of formulas: Where C0 is the speed of light, f0 is the center frequency of the laser, and f v f is the beat frequency caused by velocity. d Beat frequency caused by distance, f1 is the up-frequency beat frequency of the up-frequency band. f2 is the beat frequency of the down-frequency band. f3 is the constant frequency beat frequency of the constant frequency band.

6. The lidar according to claim 1 or 2, wherein, The lidar also includes: A wavelength beam combiner is configured to receive a first laser, a second laser, and a third laser, and combine the first laser, the second laser, and the third laser into a combined laser beam; and A beam splitter, configured to split the combined laser beam into a combined probe laser beam and a combined local oscillator laser beam; and The local oscillator wavelength beam splitter is configured to receive the combined local oscillator laser beam and split the combined local oscillator laser beam into a first local oscillator laser beam, a second local oscillator laser beam, and a third local oscillator laser beam. The first detection device receives the first reflected laser and the first local oscillator laser, and detects the beat frequency of the first reflected laser and the first local oscillator laser to output first detection information; the second detection device receives the second reflected laser and the second local oscillator laser, and detects the beat frequency of the second reflected laser and the second local oscillator laser to output second detection information; the third detection device receives the third reflected laser and the third local oscillator laser, and detects the beat frequency of the third reflected laser and the third local oscillator laser to output third detection information, wherein the first detection information, the second detection information, and the third detection information constitute the detection information.

7. The lidar according to claim 6, wherein, The lidar also includes: The first laser source is configured to emit the first laser; A second laser source, configured to emit a second laser; and The third laser source is configured to emit a third laser.

8. The lidar according to claim 1 or 2, wherein, The lidar also includes: The first beam splitter is configured to receive the first laser and split the first laser into a first probe laser and a first local oscillator laser. The second beam splitter is configured to receive the second laser and split the second laser into a second probe laser and a second local oscillator laser. The third beam splitter is configured to receive the third laser and split it into a third probe laser and a third local oscillator laser. The wavelength combiner is configured to receive a first probe laser, a second probe laser, and a third probe laser, and combine the first probe laser, the second probe laser, and the third probe laser into a combined probe laser. The first detection device receives the first reflected laser and the first local oscillator laser, and detects the beat frequency of the first reflected laser and the first local oscillator laser to output first detection information; the second detection device receives the second reflected laser and the second local oscillator laser, and detects the beat frequency of the second reflected laser and the second local oscillator laser to output second detection information; the third detection device receives the third reflected laser and the third local oscillator laser, and detects the beat frequency of the third reflected laser and the third local oscillator laser to output third detection information, wherein the first detection information, the second detection information, and the third detection information constitute the detection information.

9. The lidar according to claim 8, wherein, The lidar also includes: The first laser source is configured to emit the first laser; A second laser source, configured to emit a second laser; and The third laser source is configured to emit a third laser.

Images