Laser radar
By designing laser emission modules and beam adjustment modules in lidar, using the interval-set transmitters and beam adjustment technology, the human eye safety risks and cost problems of lidar when improving measurement distance and resolution are solved, and safe and efficient laser detection.
Patent Information
- Application Number
- CN202411491676.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2022-07-31
- Publication Date
- 2025-01-03
AI Technical Summary
When existing lidars improve measurement distance and resolution, they often need to increase the exit frequency and power, resulting in human eye safety risks. The transceiver and reception devices of long-band radar are expensive and difficult to popularize.
Design a lidar, including a laser emission module and a beam adjustment module, emits a laser beam through at least two emitters arranged at intervals, and adjusts the beam within a preset distance, so that the spot diameter is larger than the preset value, ensuring that only a part of the laser energy is Enter the human eye, and set the emission channel angle interval and emission time interval at the same time to avoid overlapping the spot and excessive total energy.
Ensure the safety of the human eye without reducing the resolution, avoid the harm of excessive laser energy to the human eye, and reduce the cost and complexity of the radar by optimizing the design of the beam adjustment module.
Smart Images
Figure CN119247324A_ABST
Abstract
Description
[0001] This application is a divisional application. The application number of the original application is 202210913026.X, and the filing date of the original application is July 31, 2022. The entire contents of the original application are incorporated into this application by reference. Technical Field
[0002] The present application belongs to the field of radar detection, and in particular to a laser radar. Background Art
[0003] LiDAR can construct the surrounding environment in three dimensions, so it has great application prospects in autonomous driving. The current development trend of LiDAR is to improve the measured distance and resolution to improve the accurate perception of the surrounding environment. However, the improvement of distance and resolution generally comes at the cost of increasing the laser emission power. The current mainstream LiDARs include two bands: long-wave band (such as 1550nm) and medium-long-wave band (such as 900nm, 905nm or 940nm). Although the long-wave LiDAR has a high eye safety threshold, the current transceiver devices are relatively expensive and difficult to popularize. Relatively low-cost LiDARs generally need to increase the emission frequency and power to improve ranging because of the need for continuous performance improvement. Limited by conventional architecture, excessive emission frequency and power will bring risks to human eye safety. Summary of the invention
[0004] In view of this, an embodiment of the present application provides a laser radar that can solve the problem of being detrimental to human eye safety during target detection by the laser radar.
[0005] The embodiment of the present application provides a laser radar, comprising: a laser emission module and a beam adjustment module, wherein the laser emission module comprises at least two emitters arranged at intervals; the emitter is used to emit a laser beam, and the beam adjustment module is used to adjust the laser beam so that the diameter of a light spot formed by the laser beam within a first preset distance is greater than a first preset value;
[0006] The angular interval between emission channels of two adjacent emitters that emit laser beams simultaneously is greater than a preset angle, and / or the emission time interval between two adjacent emitted laser beams is greater than a preset duration.
[0007] Optionally, the beam adjustment module includes an exit lens assembly, and the focal length of the exit lens assembly is greater than a second preset value, so that the diameter of the spot formed by the laser beam within the first preset distance is greater than the first preset value.
[0008] Optionally, the beam adjustment module includes a divergence angle increasing component, and the beam adjustment module includes a spot adjustment component, which is used to make the diameter of the spot formed by the laser beam within a first preset distance larger than a first preset value.
[0009] Optionally, the beam adjustment module further includes a divergence angle reduction component, and the divergence angle reduction component is used to reduce the divergence angle of the laser beam at a distance greater than a second preset distance.
[0010] Optionally, the at least two emitters emit laser beams at the same time, and the at least two emitters continuously emit laser beams at a first time interval to scan the detection space; during the t-th scan, the horizontal angle interval between the first light spots formed by two adjacent laser beams emitted is a first preset angle, and during the t+1-th scan, the horizontal angle interval between the second light spots formed by two adjacent laser beams emitted is the first preset angle, and the horizontal angle interval between the adjacent first light spots and the second light spots is a second preset angle, and the second preset angle is smaller than the first preset angle.
[0011] Optionally, the time interval between two adjacent laser beam emissions in the region of interest is a first time length, and the time interval between two adjacent laser beam emissions in a region outside the region of interest is a second time length, and the first time length is smaller than the second time length.
[0012] Optionally, the beam adjustment module also includes a scanning device. The laser beam changes its emission direction after being reflected by the scanning device. The laser beam continuously emitted by the same emitter forms a scanning surface within the first preset distance. The scanning device scans in the first scanning direction according to a preset step amount, and the step amount is determined by the density requirement of the scanning line of the scanning surface in the first scanning direction.
[0013] Optionally, the changing time of the step amount is determined based on the scanning angle of the scanning device in a scanning cycle in the second scanning direction, the detection field angle in the second scanning direction and the scanning speed of the scanning device in the second scanning direction, and the angle between the second scanning direction and the first scanning direction is less than or equal to 180 degrees.
[0014] Optionally, the preset angle is 3 times the divergence angle of the laser beam.
[0015] Optionally, the laser radar also includes a laser receiving device, and the diameter of the receiving aperture of the laser receiving device ranges from 20 to 25 mm.
[0016] Compared with the prior art, the embodiments of the present application have the following beneficial effects: the laser radar includes a laser emission module and a beam adjustment module, the laser emission module includes at least two emitters arranged at intervals, the emitter is used to emit a laser beam, and the beam adjustment module is used to adjust the laser beam so that the diameter of the light spot formed by the laser beam within a first preset distance is greater than the first preset value, so that only a part of the energy emitted by the laser enters the human eye, thereby ensuring the safety of the human eye without reducing the resolution. In addition, the angular interval of the emission channels of two adjacent emitters that simultaneously emit laser beams is greater than the preset angle, so that the light spots formed by the two laser beams emitted simultaneously will not overlap on the retina of the human eye, thereby ensuring the safety of the human eye. And / or, the emission time interval of two adjacent laser beams emitted is greater than the preset duration, so that the total energy of the laser entering the human eye within a certain duration is small, thereby ensuring the safety of the human eye. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below.
[0018] Figure 1 is a schematic diagram of a laser radar provided in one embodiment of the present application;
[0019] Figure 2a is a schematic diagram of the arrangement of a transmitting group provided in one embodiment of the present application;
[0020] Figure 2b This is another schematic diagram of an arrangement of a transmitting group provided by an embodiment of the present application;
[0021] Figure 3 is a schematic diagram of an arrangement of a transmitting group provided by another embodiment of the present application;
[0022] Figure 4 is a schematic diagram of the arrangement of two groups of transmitters provided in one embodiment of the present application;
[0023] Figure 5 is a schematic diagram of the arrangement of two groups of transmitters provided in another embodiment of the present application;
[0024] Figure 6 This is a schematic diagram of the arrangement of light spots formed in the case of two scans provided in an embodiment of the present application;
[0025] Figure 7 is a schematic diagram of different scan line densities in different areas provided by an embodiment of the present application;
[0026] Figure 8a is a schematic cross-sectional view of an irregular six-sided mirror provided in an embodiment of the present application;
[0027] Figure 8bis a schematic cross-sectional view of a regular four-sided mirror provided in an embodiment of the present application;
[0028] Fig. 9 It is a schematic diagram of a laser radar detection device provided in an embodiment of the present application. DETAILED DESCRIPTION
[0029] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.
[0030] It should be noted that the terms "vertical", "horizontal", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are merely relative concepts or are based on the normal use status of the product. They are for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limitations on the present application.
[0031] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.
[0032] It should be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or their collections. "Multiple" means two or more, unless otherwise clearly and specifically limited.
[0033] It should also be understood that the terms used in this application specification are only for the purpose of describing specific embodiments and are not intended to limit the application. As used in this application specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.
[0034] In order to improve the measurement distance and resolution, existing medium and long wave band (900nm, 905nm or 940nm) lidars generally need to increase the emission frequency and power to improve the ranging. However, due to the limitations of conventional architecture, excessive emission frequency and power will bring risks to human eye safety.
[0035] To this end, the present application provides a laser radar, including a laser emission module and a beam adjustment module, the laser emission module includes at least two emitters arranged at intervals, the emitters are used to emit laser beams, and the beam adjustment module is used to adjust the laser beam so that the diameter of the light spot formed by the laser beam within a first preset distance is greater than the first preset value, so that only a part of the energy emitted by the laser enters the human eye, thereby ensuring the safety of the human eye without affecting the resolution. In addition, the angular interval of the emission channels of two adjacent emitters that simultaneously emit laser beams is greater than the preset angle, so that the light spots formed by the two laser beams emitted simultaneously will not overlap on the retina of the human eye, so as to ensure the safety of the human eye. And / or, the emission time interval of two adjacent laser beams emitted is greater than the preset duration, so that the total energy of the laser entering the human eye within a certain duration is small, thereby ensuring the safety of the human eye.
[0036] The laser radar provided in this application is exemplarily described below.
[0037] Please see attached Figure 1 , the laser radar provided in one embodiment of the present application includes a laser emitting module 11 and a beam adjustment module 12, the laser emitting module 11 includes at least two emitters 110 arranged at intervals, and the emitter 110 can be arranged on a transmitting board. The emitter 110 is used to emit a laser beam, and the beam adjustment module 12 is used to adjust the laser beam so that the diameter of the light spot formed by the laser beam within a first preset distance is greater than a first preset value. Among them, the first preset distance refers to the near-field range of the emitter. Optionally, the first preset distance is the distance from the emitter 110 to the window. If the light spot formed in the near-field range is greater than the first preset value, the light spot in the far-field range must also be greater than the first preset value. Since the resolution of the far-field range of the emitter depends on the divergence angle of the laser beam, the increase in the near-field light spot will not affect the resolution of the laser radar in the far-field range. The first preset value can be a pre-set approximate diameter of the human eye pupil, for example, the first preset value can be 10 mm, so that the light spot is larger than the human eye pupil, and then only a part of the energy emitted by the laser enters the human eye, ensuring the safety of the human eye.
[0038] It can be understood that the emitter in this application can be a vertical cavity surface emitting laser (Vertical-Cavity Surface-Emitting Laser, referred to as VCSEL) or an edge emitter (EdgeEmitting Laser, referred to as EEL), and this embodiment does not limit the type of emitter. It can be understood that on the basis of determining the type of emitter, the wavelength of the emitter is in the medium and long wave band (for example, 905nm, 940nm), and a longer-wave transmitting and receiving device is preferred, which can effectively improve the human eye safety threshold.
[0039] In one embodiment, the beam adjustment module 12 includes an output lens assembly, and the laser beam emitted by the transmitter is emitted through the output lens assembly. The focal length of the output lens assembly is greater than a second preset value, so that the diameter of the spot formed by the laser beam within the first preset distance is greater than the first preset value, thereby ensuring the safety of human eyes.
[0040] In one embodiment, the beam adjustment module 12 includes a spot adjustment component. The laser beam emitted by the transmitter is emitted through the spot adjustment component so that the diameter of the spot formed by the laser beam within a first preset distance is greater than a first preset value, thereby ensuring eye safety.
[0041] In one embodiment, the beam adjustment module 12 also includes a divergence angle reduction component. The laser beam emitted by the spot adjustment component is emitted through the divergence angle reduction component. The divergence angle reduction component is used to reduce the divergence angle of the laser beam at a distance greater than the second preset distance. The second preset distance refers to the far field range of the laser beam (for example, the far field range can be defined as a range greater than ten meters, wherein the present application does not limit the specific value of the far field range), thereby avoiding excessive divergence angle of the laser beam in the far field range, which affects the resolution. Wherein, while reducing the divergence angle of the laser beam at a distance greater than the second preset distance, it is necessary to ensure that the diameter of the spot formed at the Gaussian beam waist of the laser beam is greater than the first preset value to ensure the safety of human eyes.
[0042] It should be noted that the output lens assembly, the spot adjustment assembly, and the divergence angle reduction assembly can all include one or more lens optical devices, and parameters such as the number of lenses, the type of lenses, and the distance between adjacent lenses can all be flexibly configured according to actual needs. There is no restriction here, and it is only necessary to meet the corresponding focal length conditions, spot adjustment effects, and beam adjustment effects.
[0043] After the laser beam enters the human eye, the lens of the human eye will focus the light spot on the retina. The size of the light spot is related to the divergence angle of the laser. At the same time, in order to meet the resolution requirements, a certain number of laser pulses need to be emitted in a short time. For example, under normal circumstances, about 10 or more pulses must be emitted within 5 microseconds to meet the resolution requirements. Due to the size limitation of the laser radar, these pulses will overlap in space. If multiple emitters emit laser beams through the emission channel at the same time, a portion of the energy of the laser beam emitted by each emission channel enters the human eye, thereby forming multiple light spots on the retina of the human eye. If multiple light spots overlap, it will cause the laser energy entering the human eye to increase, thereby affecting the safety of the human eye. To this end, in one embodiment, at least two emitters emit laser beams at the same time, and the angle interval of the emission channels of the two adjacent emitters that emit laser beams at the same time is greater than the preset angle, so that the light spots formed on the retina by the laser beams emitted by each emission channel do not overlap with each other, avoiding affecting the safety of the human eye. The preset angle may be 2 to 3 times the divergence angle of the laser beam, for example, the preset angle is 3 times the divergence angle of the laser beam, so that the light spots formed on the retina by the laser beams emitted by the emission channels of two adjacent emitters do not overlap.
[0044] In one embodiment, the time interval between two adjacent laser beam emissions is greater than a preset time length, so that the total energy of the laser beam entering the human eye within a certain time length is small, thereby ensuring the safety of the human eye.
[0045] In one embodiment, the laser emission module includes at least two emitters, and the time when the at least two emitters emit laser beams is consistent, that is, the at least two emitters form an emission group, that is, the laser emission module includes an emission group, and the emission time interval between two adjacent laser beams emitted by an emission group is greater than a preset duration.
[0046] In some embodiments, a transmitting group may include multiple transmitters, and the multiple transmitters may be arranged in one column, two columns, or multiple columns.
[0047] In one embodiment, a firing group is arranged into two rows, and the two rows of emitters can be arranged as follows: Figure 2a The two columns of emitters are arranged in a staggered manner. The angular interval of the emission channels of the two adjacent emitters refers to the angular interval of the emission channels of the emitters that are closest in the direction perpendicular to the light emitting direction of the laser beam. The angular interval of the emission channels of the two adjacent emitters is greater than the preset angle. Thereby, the light spots formed on the retina by the laser beam emitted by each emission channel do not overlap each other. At the same time, by arranging the two columns of emitters in a staggered manner, the distance between two adjacent light spots in the light spot formed by the laser beam emitted by one emission group can be shortened, that is, the density of the light spot formed by the laser beam emitted by one emission group can be increased.
[0048] It is understandable that when the emitters in a transmitting group are arranged into two rows, the two rows of emitters can be partially staggered according to the requirements of the detection field of view, such as Figure 2b As shown. Among them, in the transmitter in the central area, the angular interval between the transmission channels of two adjacent transmitters is a first angle δθ1, and in the transmitter in the edge area, the angular interval between the transmission channels of two adjacent transmitters is a second angle δθ2. The first angle δθ1 is smaller than the second angle δθ2. By setting different angular intervals of transmitters corresponding to different detection areas, the density of the light spot formed by the laser beam in the area of interest can be increased. It can be understood that when the angles between the transmission channels of two adjacent transmitters are not equal, the minimum angle between the two adjacent transmission channels should be greater than the preset angle. For example, Figure 2b As shown, the first angle δθ1 should be greater than the preset angle. Wherein, the region of interest (ROI) refers to the area that needs to be focused on in the preset area of the laser scan. Wherein, it can be understood that the region of interest generally corresponds to the central area of the detection field of view (i.e., the transmission channel corresponding to the central area of the transmission group). Wherein, the detection field of the radar includes a general detection area in addition to the region of interest, and the general detection area is other areas in the detection field of view except the region of interest. Wherein, it can be understood that the general detection area generally corresponds to the edge area of the detection field of view (i.e., the transmission channel corresponding to the edge area of the transmission group).
[0049] In one embodiment, a transmitting group is arranged in a row, and the angular intervals between the transmitting channels of each transmitter may be equal or unequal.
[0050] Optional, such as Figure 3 As shown, an emission group is arranged in a row. According to the detection requirements, in the emitters in the center area, the angular interval between the emission channels of two adjacent emitters is a first angle δθ1, and in the emitters in the edge area, the angular interval between the emission channels of two adjacent emitters is a second angle δθ2. The first angle δθ1 is smaller than the second angle δθ2. By setting different angular intervals of emitters corresponding to different detection areas, the density of the light spot formed by the laser beam in the area of interest can be increased. It can be understood that when the angles between the emission channels of two adjacent emitters are not equal, the minimum angle between the two adjacent emission channels should be greater than the preset angle. For example, Figure 3 As shown, the first angle δθ1 should be greater than the preset angle.
[0051] In another optional embodiment, at least two emitters may also be divided into at least two groups. In the same emission group, the angular interval between the emission channels of two adjacent emitters is greater than a preset angle, and the time interval between the two groups of emitters that sequentially emit laser beams is greater than a preset duration, thereby avoiding damage to human eyes during target detection by the laser radar.
[0052] In one embodiment, at least two emitters are divided into a first emitter group and a second emitter group, each emitter in the first emitter group emits a laser beam at the same time, and each emitter in the second emitter group emits a laser beam at the same time. Figure 4 As shown, Figure 4 is an optional emission group, the arrangement direction of the first emission group 41 is parallel to the arrangement direction of the second emission group 42, and the first emission group 41 and the second emission group 42 emit at a set time interval to form a light spot array or a scanning line. Figure 5 As shown, the first emission group 51 and the second emission group 52 can also be located in the same column. When the first emission group 51 and the second emission group 52 are located in the same column, the position arrangement of each emitter can be determined according to actual needs. The first emission group 51 and the second emission group 52 emit laser beams at a set time interval and a set angle, and can also form a spot array or a scanning line, thereby increasing the resolution during the target detection process.
[0053] In other embodiments, at least two emitters may be divided into multiple groups. The multiple groups of emitters may be arranged in parallel or in the same column. Each group of emitters emits light in sequence at a set time interval to form a light spot or a scanning line in the detection field of view.
[0054] In one embodiment, at least two emitters emit laser beams at the same time, that is, the laser emission module includes an emission group, and an emission group continuously emits laser beams at a first time interval to form a scanning line to scan the detection space; during the tth (t represents an integer greater than 0) scan, the horizontal angle interval between the first light spots formed by two adjacent laser beams emitted is the first preset angle, and during the t+1th scan, the horizontal angle interval between the second light spots formed by two adjacent laser beams emitted is the first preset angle, and the horizontal angle interval between the adjacent first light spots and the second light spots is the second preset angle, and the second preset angle is less than the first preset angle, thereby improving the horizontal resolution during the target detection process. Exemplarily, the first preset angle is twice the second preset angle, so that uniformly distributed light spots can be formed.
[0055] For example, Figure 6 As shown in the figure, the number of emitters is set to 4. During the first scanning process, the horizontal angles of the light spots formed by the laser beam at each scanning moment are 0, δθ\\ , 2δθ \\ ..., that is, Figure 6 The first, third, fifth, seventh, and ninth columns of light spots. \\ Greater than 0. During the second scanning process, the horizontal angles of the light spots formed by the laser beam at each scanning moment are Get Figure 6 The second, fourth, sixth, eighth and tenth columns of light spots are arranged in the horizontal angle. The spot arrangement of two scans is the combination of the spots corresponding to the horizontal resolution of The spot combination, that is, two scans can make the horizontal resolution reach Therefore, when the time interval between two emitters emitting laser beams in sequence is greater than a preset time length, and the angular interval between the emission channels of two adjacent emitters is greater than a preset angle value, the horizontal and vertical resolutions in the target detection process can still be improved by controlling the step amount and step time of the scanning device. Among them, the vertical and / or horizontal angles of the light spot formed by each emitted laser beam can be changed by adjusting the parameters of the laser emission module and / or the beam adjustment module (for example, the vertical and / or horizontal angles of the light spot formed by the laser beam emitted at the same time can be adjusted by controlling the position and number of emitters emitted at the same time), and the vertical and / or horizontal angles of the light spot formed by each emitted laser beam can also be changed by controlling the scanning device, thereby obtaining the above-mentioned light spot combination.
[0056] In other embodiments, the horizontal angle of the light spot corresponding to two adjacent scans may be further reduced, or the number of scans may be increased to further improve the horizontal resolution.
[0057] In one embodiment, the light spots formed by the laser beams continuously emitted by a transmitter are combined into a scan line. In the process of one or more groups of transmitters emitting lasers, the position of the scan line can be changed accordingly by adjusting the position of the transmitter or adjusting the parameters of the beam adjustment module. In order to ensure the safety of human eyes, it is necessary to meet the angle interval of the emission channels of two adjacent transmitters greater than the preset angle, or the emission time interval of the laser beams emitted twice adjacently is greater than the preset duration, which will cause the interval between the two adjacent scan lines in the formed scan line to be larger, thereby affecting the resolution. Therefore, it can be determined whether the currently scanned area is an area of interest during the movement of the scan line. If it is an area of interest, the time interval for the continuous emission of the laser beam by the transmitter is reduced, or the moving speed of the scan line is reduced. If it is an area outside the area of interest (i.e., a non-area of interest), the time interval for the continuous emission of the laser beam by the transmitter is increased, or the moving speed of the scan line is increased, so that the resolution can be improved when scanning the area of interest. Among them, it can be determined whether the currently scanned area is an area of interest based on the application scenario of the laser radar, the size of the target currently detected, or the needs of the user.
[0058] Optionally, the time interval between two adjacent laser beam emissions in the region of interest is a first time length, and the time interval between two adjacent laser beam emissions in a region outside the region of interest is a second time length, and the first time length is shorter than the second time length.
[0059] During the movement of the scanning lines, the density of the scanning lines formed by each laser beam in the area of interest can be made greater than the density of the scanning lines formed in the non-interest area, thereby meeting the high-resolution requirements of the area of interest while ensuring the safety of human eyes.
[0060] In one embodiment, the beam adjustment module also includes a scanning device, and the laser beam changes its emission direction after being reflected by the scanning device. During the rotation of the scanning device, the laser beam continuously emitted by the same emitter or an emission group formed by multiple emitters forms a scanning surface within the first preset distance.
[0061] Wherein, the scanning direction of the scanning module includes a first scanning direction (for example, a vertical scanning direction) and a second scanning direction (for example, a horizontal scanning direction). Wherein, it can be understood that when the scanning of the entire horizontal detection field of view and the scanning of the vertical detection field of view are completed simultaneously, it is called a scanning cycle. Wherein, it can be understood that the scanning in the two scanning directions are independently controlled, and the scanning device includes a scanning device in the first scanning direction and a scanning device in the second scanning direction. When the scanning device in the first scanning direction is used as the stepping amount to implement the device, the scanning cycle for completing one scan can be controlled by controlling the scanning time of the scanning device in the second scanning direction, wherein the scanning cycle of one scan is equal to the emission time interval between two adjacent laser beams, and is also equal to the time for the scanning device in the first scanning direction to complete one step.
[0062] Among them, the scanning in the two scanning directions is independently controlled; the angle between the second scanning direction and the first scanning direction is less than or equal to 180 degrees. Optionally, as an optional embodiment, the second scanning direction is perpendicular to the first scanning direction. For example, the first scanning direction is a vertical scan relative to the up and down direction of the target object (also called column scanning), and the second scanning direction is a horizontal scan relative to the left and right direction of the target object in a preset area (also called row scanning). At this time, the preset angle formed by the first scanning direction and the second scanning direction is 90°. The two scanning directions form a preset angle, which is set according to the needs of the laser radar, for example, it can also be 30°, 60°, 120° and 150°.
[0063] The scanning device in the first scanning direction may be, for example, any scanning device selected from a rotating mirror, a one-dimensional galvanometer, and a rotating platform. The scanning device in the second scanning direction may also be, for example, any scanning device selected from a rotating mirror, a one-dimensional galvanometer, and a rotating platform; the present application does not limit the type of scanning device in any of the two scanning directions. It is understood that the types of the scanning device in the first scanning direction and the scanning device in the second scanning direction may be the same or different, and the present application does not limit this. As a preferred embodiment, the scanning devices in the two scanning directions may be independently controlled.
[0064] Among them, it can be understood that the scanning device scans according to a preset step amount in the first scanning direction, and the step amount is determined by the density requirement of the scanning line of the scanning surface in the first scanning direction, so that the step amount of the scanning device can be controlled in different detection areas or according to different detection requirements, thereby forming different scanning line densities in the detection area to meet the corresponding resolution requirements. If the laser emission module includes an emission group, and an emission group is arranged in a row, the first scanning direction is consistent with the arrangement direction of the emitter.
[0065] Specifically, according to the formula Determine the step size. Wherein, δβ represents the step size; δθ represents the interval angle between the scan lines in the first scanning direction, that is, the angular interval between two adjacent scan lines in a scan group, wherein the scan group is N scan lines formed by the detection laser emitted by the laser emission module at one time, and N is an integer. Wherein, when the emission module includes an emission group, δθ is the angular interval between the emission channels of two adjacent emitters in the emission group; wherein, it can be understood that when the angular interval between the emission channels of two adjacent emitters in the emission group is unequal, the step size is calculated with the minimum angular interval. N represents the number of scan lines in a scan group. When the laser emission module includes an emission group, the number of scan lines is equal to the number of emitters included in an emission group, and N is an integer; n represents the multiple of the scan line encryption in the detection area, and n is an integer and n≧0.
[0066] It can be understood that when the encryption multiple n is a prime number that cannot be divided by the number N of transmitters in the same transmission group, the interval between two transmitted scan lines can realize the encryption of the scan lines in the vertical direction.
[0067] It can be understood that when the encryption multiple n is an integer divisible by the number N of transmitters in the same transmission group, the interval between two transmitted scan lines can realize the encryption of the scan lines in the horizontal direction.
[0068] In one embodiment, the changing time of the step amount is determined according to the scanning angle of the scanning device in one scanning cycle in the second scanning direction, the detection field angle in the second scanning direction, and the scanning speed of the scanning device in the second scanning direction.
[0069] Specifically, when the stepping amount of the scanning device in the first scanning direction is the same, different stepping amount change times correspond to different scanning speeds, and the component interval is the angular interval between two adjacent scanning groups. The scanning group is N scanning lines formed by the detection laser emitted by the emission module once, and N is an integer. In addition, the interval angle between two adjacent scanning groups emitted by the laser emission module is also called the inter-group interval, wherein the component interval can be defined by the angular interval between the same scanning lines of the two scanning groups, for example, the component interval can be defined by the interval angle between the first scanning lines of the two scanning groups.
[0070] It can be understood that by controlling the step amount and step time of the scanning device, the point cloud density of the point cloud (i.e., the light spot) in the first scanning direction and / or the second scanning direction can be controlled to meet the detection requirements of the radar.
[0071] In one embodiment, according to the formula When the step size δβ in the first scanning direction is known, the step speed in the first scanning direction can be determined by the scanning angle of a scanning cycle in the second scanning direction, the detection field angle in the second scanning direction, and the scanning speed of the scanning device in the second scanning direction. δβ represents the step size; α period represents the scanning angle of one scanning cycle in the second scanning direction; α FOV represents the detection field angle in the second scanning direction, and α period >α FOV ω1 represents the first scanning speed in the first scanning direction; ω2 represents the second scanning speed in the second scanning direction. Figure 7 As shown, by setting different stepping amounts and stepping times in different detection areas, the interval between two adjacent scanning lines can be made smaller when the emitter scans the area of interest 71, and the interval between two adjacent scanning lines can be made larger when scanning the non-interesting area 72. Thus, while ensuring eye safety, the detection resolution of the area of interest is further improved. Similarly, by setting different stepping amount change times at different times, the stepping speed of the first scanning device in different areas can be controlled to ensure the scanning stability of the scanning device.
[0072] It can be understood that by controlling the step amount and step time of the scanning device, the point cloud density in the first scanning direction and / or the second scanning direction can be controlled, and different group intervals of scanning lines can be achieved in different areas, so that a resolution of less than 0.1 degrees can be achieved in the area of interest.
[0073] In other embodiments, the corresponding scanning line interval may be obtained by controlling the rotation speed of the first scanning device, and the corresponding inter-group interval may be achieved by controlling the rotation speed of the second scanning device.
[0074] For example, the first scanning device is a galvanometer, and the second scanning device is a rotating mirror. The galvanometer rotates at a first preset speed in a first preset period, so that the laser beam forms a plurality of first scanning lines in the region of interest, and the interval between two adjacent first scanning lines is a third preset value; the galvanometer rotates at a second preset speed in a second preset period, so that the laser beam forms a plurality of second scanning lines in the region outside the region of interest, and the interval between two adjacent second scanning lines is a fourth preset value; the first preset speed is less than the second preset speed, and the third preset value is less than the fourth preset value. That is, in the second preset direction, the density of the scanning lines in the region of interest is greater than the density of the scanning lines in the non-interest region, so that while ensuring the safety of human eyes, the high resolution requirement of the region of interest in the direction perpendicular to the scanning lines can be met.
[0075] The rotating mirror rotates at the third preset speed in the first preset period, so that the component interval between two adjacent groups of scanning lines is the fifth preset value; the rotating mirror rotates at the fourth preset speed in the second preset period, so that the component interval between two adjacent groups of scanning lines is the sixth preset value; the third preset speed is less than the fourth preset speed, and the fifth preset value is less than the sixth preset value. That is, the density of the scanning lines in the area of interest is greater than the density of the scanning lines in the non-interest area, so that the high resolution requirement of the area of interest in the direction parallel to the scanning line can be met while ensuring the safety of human eyes.
[0076] It should be noted that, in order to improve the resolution, when the transmitter scans the set area, the galvanometer can be controlled to stop rotating, so that the laser beam emitted by the transmitter repeatedly scans at the same position, so as to further improve the resolution in the first scanning direction. When the transmitter scans the set area, the galvanometer can also be controlled to stop rotating, so that the laser beam emitted by the transmitter repeatedly scans at the same position, so as to further improve the resolution in the second scanning direction.
[0077] Among them, it can be understood that if the detection field of view includes multiple detection areas, when the multiples n of the scan line encryption between different detection areas differ greatly, the change of the step amount of the scanning module from one area to another area is large. If the step time remains unchanged, the step speed changes greatly, which will be detrimental to the stability of the scanning movement of the scanning device in the first scanning direction. Therefore, when the detection field of view of the radar includes multiple detection areas, when the scanning device enters another detection area for scanning from one detection area, and the scanning density of the two detection areas changes greatly, the change time of the step amount can be increased by setting the detection field angle of the scanning device in the second scanning direction. Optionally, the change time of the step amount can be increased by increasing the redundant angle of the scanning device in the second scanning direction. For example, if the scanning device in the second scanning direction is a polygonal mirror, the change time of the inter-group interval can be increased by increasing the empty scanning surface of the polygonal mirror, so that the scanning speed of the scanning device changes as evenly as possible, so as to reduce the motion vibration caused by the speed change of the scanning device in the first scanning direction, and maintain the stability of the scanning movement of the scanning device in the first scanning direction. Therefore, the calculation formula of the inter-group interval is also:
[0078]
[0079] Among them, δβ is the scanning step size;
[0080] α period An angle scanned by the scanning group for one scanning cycle in the second scanning direction;
[0081] α FOV is the detection field angle of the second scanning direction;
[0082] α is the field of view angle corresponding to each face of the multi-prism mirror;
[0083] k is the number of faces of the polygonal mirror;
[0084] ω1 is the first scanning speed in the first scanning direction;
[0085] ω2 is the second scanning speed in the second scanning direction.
[0086] It can be understood that in another scanning mode of the laser radar, the scanning device can also scan as follows.
[0087] Among them, the polygonal rotating mirror can be a regular rotating mirror or an irregular rotating mirror. A regular rotating mirror is a rotating mirror in which the central angle corresponding to each face is equal, and an irregular rotating mirror is a rotating mirror in which the central angle corresponding to at least one face is not equal to the central angles corresponding to other faces.
[0088] It can be understood that by setting the size of the central angle corresponding to the empty scanning surface and the scanning surface of the scanning device in the second scanning direction, the scanning speed of the scanning device in the first scanning direction can be changed as evenly as possible, thereby ensuring the stability of the movement of the scanning device in the first scanning direction.
[0089] like Figure 8a As shown in the figure, a schematic diagram of a cross section of an irregular six-sided mirror is shown, where surface A and surface D are the first scanning surfaces, and the opening angles of the corresponding rotating mirror centers are the same, and surfaces B, C, D and E are the second scanning surfaces, and the opening angles of the corresponding rotating mirror centers are the same. Considering the width of the beam, a 10-degree redundant angle is set, with 5 degrees on the left and right.
[0090] Among them, face A corresponds to the largest detection field of view, that is, the total detection field of view, and the field of view angle is 120 degrees. Therefore, it can be determined that the opening angle of the rotating mirror center corresponding to face A is 120 / 2+10=70 degrees, and 60 degrees of it are used here for scanning. Similarly, the opening angle of the rotating mirror center corresponding to face D is 70 degrees. Face F corresponds to the detection field of view angle of one of the preset sub-areas. It can be seen that the field of view angle corresponding to face F is 90 degrees, and the opening angle of the rotating mirror center corresponding to face F is 55 degrees. Similarly, the opening angles of the rotating mirror centers corresponding to faces B, C, E, and F are all 55 degrees. It can be understood that the irregular rotating mirror here is symmetrically arranged along the central axis to ensure the stability of the scanning rotation.
[0091] like Figure 8b The figure shows a schematic diagram of the cross section of a regular four-sided mirror, where the opening angles of the A, B, C, and D surfaces corresponding to the center of the rotating mirror are the same, which is 90 degrees. Considering the width of the light beam, a 20-degree redundant angle is set, 10 degrees on each side, so the total detection field of view is 140 degrees.
[0092] Among them, the redundant angle corresponding to the scanning surface is related to the size of the light spot and the proportion of the light spot to the entire scanning surface. It is understandable that the larger the light spot, the larger the redundant angle is set; the larger the proportion of the light spot to the entire scanning surface, the larger the redundant angle needs to be set. It is understandable that by setting a reasonable redundant angle, the stray light interference in the cavity of the scanning device can be better reduced.
[0093] In one embodiment, the laser radar further includes a laser receiving device, and the diameter of the receiving aperture of the laser receiving device ranges from 20 to 25 mm. In the medium and long wave band (e.g., 940 nm), when the human eye safety threshold reaches the order of 60 to 100 watts, the diameter range meets the above requirements, and the laser radar can achieve a ranging range of 250 to 300 meters.
[0094] like Fig. 9 As shown, the embodiment of the present application further provides a laser radar, including:
[0095] A laser emitting module 91, used for emitting a laser beam;
[0096] A beam adjustment module 92, used for adjusting the laser beam so that the diameter of the light spot formed by the laser beam within a first preset distance is greater than a first preset value;
[0097] At the same time, the laser emitting module 91 needs to satisfy that the angular interval between the emission channels of two adjacent emitters emitting laser beams is greater than a preset angle, and / or the emission time interval between two adjacent emitted laser beams is greater than a preset duration.
[0098] The beam adjustment module 92 includes an output lens assembly, and the focal length of the output lens assembly is greater than a second preset value, so that the diameter of the spot formed by the laser beam within the first preset distance is greater than the first preset value.
[0099] The beam adjustment module 92 may further include a spot adjustment component, which is used to increase the divergence angle of the laser beam so that the diameter of the spot formed by the laser beam within a first preset distance is greater than a first preset value.
[0100] The beam adjustment module 92 includes a divergence angle reduction component, and the divergence angle reduction component is used to reduce the divergence angle of the laser beam at a distance greater than a second preset distance.
[0101] The beam adjustment module 92 also includes a scanning device, which is used to connect to the detection laser and emit the detection laser to a preset area, and scan the preset area using a preset scanning mode corresponding to the preset area. The scanning device is also used to receive the echo laser reflected from the preset area and output the echo laser. By setting the scanning step amount and scanning speed of the scanning device, the laser radar can further improve the detection resolution of the laser radar while meeting the requirements of human eye safety, thereby meeting the detection requirements of the laser radar.
[0102] The laser radar also includes a receiving detection module 93, which is used to receive the echo laser and convert it into an electrical signal;
[0103] The laser radar also includes a signal acquisition and processing module 94 for acquiring electrical signals and processing the electrical signals to obtain detection information of a preset area.
[0104] It should be noted that the embodiments of the present application do not limit the other components included in the laser radar, and do not limit the name of each component in the laser radar. It should be noted that the embodiments of the present application do not limit the application scenarios of the laser radar. For example, the laser radar can be applied to the fields of smart transportation, automatic driving, assisted driving, navigation, mapping, meteorology, aerospace, robotics, etc., to achieve space scanning, obstacle avoidance, route planning, weather forecasting, etc.
[0105] In the above embodiment, by adjusting the spot size of the laser beam in the near field area and setting the angle between the emission channels or the time interval for emitting the laser beam, the detection resolution of the laser radar can be met while ensuring the safety of human eyes.
[0106] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.
Claims
1. A laser radar, characterized in that: The invention comprises: a laser emission module and a beam adjustment module, wherein the laser emission module comprises at least two emitters arranged at intervals; the emitter is used to emit a laser beam, and the beam adjustment module is used to adjust the laser beam so that the diameter of a light spot formed by the laser beam within a first preset distance is greater than a first preset value; wherein the first preset value is the diameter of a human eye pupil; The angular interval between the emission channels of two adjacent emitters that emit laser beams simultaneously is greater than a preset angle; Wherein, the preset angle is 2 to 3 times the divergence angle of the laser beam; The beam adjustment module is also used to reduce the divergence angle of the laser beam at a distance greater than the second distance; The first preset distance refers to the near-field range of the transmitter, and the second preset distance refers to the far-field range of the laser beam.
2. The laser radar according to claim 1, characterized in that: The beam adjustment module includes a light spot adjustment component, which is used to make the diameter of the light spot formed by the laser beam within a first preset distance larger than a first preset value.
3. The laser radar according to claim 1, characterized in that: The beam adjustment module further includes a divergence angle reduction component, and the divergence angle reduction component is used to reduce the divergence angle of the laser beam at a distance greater than a second preset distance.
4. The laser radar according to claim 1, characterized in that: The at least two emitters emit laser beams at the same time, and the at least two emitters continuously emit laser beams at a first time interval to scan the detection space; during the t-th scan, the horizontal angle interval between the first light spots formed by two adjacent laser beams emitted is a first preset angle, during the t+1-th scan, the horizontal angle interval between the second light spots formed by two adjacent laser beams emitted is the first preset angle, and the horizontal angle interval between the adjacent first light spots and the second light spots is a second preset angle, and the second preset angle is smaller than the first preset angle.
5. The laser radar according to claim 1, characterized in that: The time interval between two adjacent laser beam emissions in the region of interest is a first time length, and the time interval between two adjacent laser beam emissions in a region outside the region of interest is a second time length, and the first time length is smaller than the second time length.
6. The laser radar according to claim 1, characterized in that: The beam adjustment module also includes a scanning device. The laser beam changes its emission direction after being reflected by the scanning device. The laser beam continuously emitted by the same emitter forms a scanning surface within the first preset distance. The scanning device scans in the first scanning direction according to a preset step amount. The preset step amount is determined by the density requirement of the scanning line of the scanning surface in the first scanning direction.
7. The laser radar according to claim 6, characterized in that: The preset step amount is determined by the scanning line density requirement of the scanning surface in the first scanning direction, and specifically includes: According to the formula Determine the step size; Wherein, δβ represents the step amount; δθ represents the interval angle between the scanning lines in the first scanning direction, that is, the angular interval between two adjacent scanning lines in a scanning group, wherein the detection laser emitted by the scanning group once forms N scanning lines, N is an integer; n represents the multiple of the scanning line encryption in the detection area, n is an integer and n≧0.
8. The laser radar according to claim 7, characterized in that: The scanning device also includes a second scanning direction, and the scanning device in the second scanning direction is a polygonal mirror. Among them, δβ is the scanning step size; α period An angle of scanning of the scanning group in one scanning cycle of the second scanning direction; α FOV is the detection field angle of the second scanning direction; α is the field of view angle corresponding to each face of the polygonal rotating mirror; k is the number of faces of the polygonal rotating mirror; ω1 is the first scanning speed in the first scanning direction; ω2 is the second scanning speed in the second scanning direction.
9. The laser radar according to claim 1, characterized in that: The preset angle is 3 times the divergence angle of the laser beam.
10. The laser radar according to claim 1, characterized in that: The laser radar also includes a laser receiving device, and the diameter of the receiving aperture of the laser receiving device ranges from 20 to 25 mm.