Laser unit for lidar and lidar

Abstract

This invention provides a laser unit and a lidar for use in lidar. The laser unit includes a emitting surface for providing emitted light projected onto a target. The emitted light, after passing through the target, forms an echo beam, which is received by a light receiving device. The emitting surface includes a first end positioned close to the light receiving device and a second end positioned away from the light receiving device. The direction from the first end to the second end is a first direction, and the direction perpendicular to the first direction is a second direction. The emitting surface of the laser unit includes an effective emitting area with emitting points and an ineffective emitting area without emitting points. The effective emitting area includes multiple sub-emitting areas along the first direction, each used to detect targets at different distances. This invention can reduce the overall emission power of the laser unit, reduce the heat generated by the laser unit, and simultaneously reduce the number of emitting points in the laser unit, thus lowering the cost.

Description

Technical Field

[0001] This invention relates to the field of lidar, and more particularly to a laser unit for lidar and lidar. Background Technology

[0002] LiDAR plays an important role in autonomous driving, including curb detection, obstacle recognition, and real-time localization and mapping (SLAM).

[0003] Specifically, a LIDAR system includes a laser emitting system and a light receiving system. The laser emitting system includes a laser unit that generates emitted light pulses. These emitted light pulses are incident on a target object and reflected to produce an echo beam, which is ultimately received by the light receiving system. The receiving system accurately measures the propagation time of the incident light pulse from emission to its reflection. Because the light pulse propagates at the speed of light, and the speed of light is known, the propagation time can be converted into a distance measurement.

[0004] LiDAR can accurately measure the position (distance and angle), motion state (velocity, vibration, and attitude), and shape of targets, enabling it to detect, identify, distinguish, and track targets. Due to its advantages such as high measurement speed, high accuracy, and long range, LiDAR is widely used in autonomous vehicles.

[0005] However, publicly available technologies for lidar have issues with the high emission power of their laser units. Summary of the Invention

[0006] The problem solved by the present invention is to provide a laser unit for lidar and lidar for reducing laser emission power.

[0007] This invention provides a laser unit for lidar, comprising a emitting surface for providing emitted light projected toward a target. The emitted light, after passing through the target, forms an echo beam that is received by a light receiving device. The emitting surface includes a first end positioned close to the light receiving device and a second end positioned away from the light receiving device, wherein the direction from the first end to the second end is a first direction, and the direction perpendicular to the first direction is a second direction. The emitting surface of the laser unit includes an effective emitting area with emitting points arranged thereon and an ineffective emitting area without emitting points arranged thereon. The effective emitting area includes multiple sub-emitting areas along the first direction, each used to detect targets at different distances.

[0008] Optionally, along the first direction, the distribution density of light-emitting points in the plurality of sub-light-emitting regions gradually decreases.

[0009] Optionally, along the first direction, the size of the plurality of sub-light-emitting regions gradually decreases in the second direction.

[0010] Optionally, all light-emitting points in the effective light-emitting area emit light simultaneously, and / or select sub-light-emitting areas corresponding to different target distances to emit light.

[0011] Optionally, the distance between each sub-luminescent region and the target object along the first direction gradually decreases.

[0012] Optionally, the sub-light-emitting area near the first end is designated as the first sub-light-emitting area, used to detect targets at a distance greater than a first distance; the sub-light-emitting area near the second end is designated as the second sub-light-emitting area, used to detect targets at a distance less than a second distance, where the second distance is less than the first distance.

[0013] Optionally, a plurality of third sub-light-emitting areas are located between the first sub-light-emitting area and the second sub-light-emitting area for detecting targets between the second distance and the first distance.

[0014] Optionally, the first and second sub-light-emitting areas are rectangular, and the third sub-light-emitting area is trapezoidal or rectangular.

[0015] Optionally, the portion of the plurality of third sub-light-emitting regions near the first end is a reference portion, and the spacing between the reference portions of adjacent third sub-light-emitting regions gradually increases along the first direction.

[0016] Optionally, the effective light-emitting area has a larger dimension in the first direction than in the second direction. Optionally, the light-emitting points in the sub-light-emitting area are arranged alternately along the first direction and / or the second direction; or, the light-emitting points in the sub-light-emitting area are arranged in a matrix.

[0017] Optionally, the laser unit is a vertical cavity surface-emitting laser.

[0018] Accordingly, this embodiment of the invention also provides a lidar, comprising: a laser unit provided in this embodiment of the invention, used to provide emitted light projected toward a target, wherein the emitted light forms an echo beam after passing through the target; and a light receiving device disposed near a first end of the laser unit, used to detect the echo beam.

[0019] Optionally, it also includes: a control unit, used to control all light-emitting points in the effective light-emitting area to emit light, and to control the light receiving device to receive detection signals.

[0020] Optionally, the control unit obtains distance information of the target object based on the detection signal and controls the light-emitting points in the sub-light-emitting area corresponding to the distance information to emit light.

[0021] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0022] The laser unit in this invention comprises an effective luminous area with luminous dots arranged thereon and an ineffective luminous area without luminous dots arranged thereon. The effective luminous area includes multiple sub-luminous areas along a first direction, each used to measure targets at different distances. Compared to a laser unit where luminous dots are arranged on the entire luminous surface, the effective luminous area with luminous dots occupies a portion of the entire luminous surface, thereby reducing the area occupied by luminous dots on the entire luminous surface. The laser unit in this embodiment optimizes the arrangement of luminous dots by setting luminous dots on the luminous surface in a local area, while the multiple sub-luminous areas can detect targets at different distances. This optimizes the luminous dot arrangement while ensuring the ranging performance of the laser radar for targets at different distances, reducing the number of luminous dots on the luminous surface, thereby reducing the emission power of the laser unit and the heat generated by the laser unit.

[0023] In an alternative embodiment, along the first direction, the size of the plurality of sub-light-emitting regions gradually decreases, that is, the area of ​​the sub-light-emitting regions with light-emitting points gradually decreases, thereby further reducing the emission power of the laser unit and the heat generated by the laser unit.

[0024] In an alternative embodiment, along the first direction, the distribution density of light-emitting points in the plurality of sub-light-emitting regions gradually decreases. The decrease in the density of light-emitting points can further reduce the number of light-emitting points, thereby further reducing the emission power of the laser unit and the heat generated by the laser unit. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the optical path of a lidar.

[0026] Figure 2 for Figure 1 The diagram shows the variation of echo signal intensity detected by lidar with distance.

[0027] Figure 3 This is a schematic diagram of the optical path of the laser unit of the present invention in the first embodiment;

[0028] Figure 4 for Figure 3 A magnified view of a portion of the laser unit;

[0029] Figures 5 to 8 They respectively indicated Figure 4 The laser unit shown detects the echo spots generated by targets at different distances;

[0030] Figure 9 This is a schematic diagram of a second embodiment of the laser unit of the present invention;

[0031] Figure 10 This is a schematic diagram of the third embodiment of the laser unit of the present invention;

[0032] Figure 11 This is a schematic diagram of the fourth embodiment of the laser unit of the present invention;

[0033] Figure 12 This is a schematic diagram of the fifth embodiment of the laser unit of the present invention;

[0034] Figure 13 This is a schematic diagram of the sixth embodiment of the laser unit of the present invention;

[0035] Figure 14 This is a schematic diagram of an embodiment of the lidar of the present invention. Detailed Implementation

[0036] The following is combined Figure 1 and Figure 2 The diagram shows the optical path of a lidar and the change in echo signal intensity with distance, and the reasons for the high transmission power of the lidar are analyzed.

[0037] The laser unit 1 includes a light-emitting surface with multiple light-emitting points for providing emitted light projected onto the target object S1 (or S2). The emitted light reaches the target object S1 (or S2) through the first optical lens group 3, and then forms an echo beam after passing through the target object S1 (or S2). The echo beam passes through the second optical lens group 4 and forms a light spot T1 (or T2) on the detection surface of the light receiving device 2, and is detected by the light receiving device 2, thereby realizing the detection of the target object S1 (or S2).

[0038] In a lidar system, the emitting surface of the laser unit 1 and the detection surface of the light receiving device 2 are arranged in the same direction. The transmitting and receiving ends each have optical lens groups, which can achieve mutual isolation and non-interference between light emission and reception. However, the off-axis optical path will have a near-far effect, that is, when the distance to the target changes, the spot of the echo beam on the detection surface will move.

[0039] Specifically, such as Figure 1 As shown, the light spot formed on the light receiving device 2 by the distant target S1 is T1, while the light spot formed on the light receiving device 2 by the relatively close target S2 is T2. That is, as the distance to the target increases, the light spot moves towards the laser unit 1. The light receiving device 2 is placed on the focal plane of the second optical lens group 4. Then, the size D' of the light spot formed on the light receiving device 2 after the echo light spot reflected by the target is focused by the second optical lens group 4 satisfies the following formula:

[0040]

[0041] Where D is the size of the light spot incident on the second optical lens group 4, f is the focal length of the lens, and d is the distance between the target object and the second optical lens group 4. Since the light spot incident on the second optical lens group 4 (i.e., the echo light spot reflected by the target object) usually covers the entire second optical lens group 4, the size D of the light spot incident on the second optical lens group 4 is usually the same.

[0042] According to Formula 1 above, the size D' of the light spot formed on the light receiving device 2 is inversely proportional to the distance d between the target object and the second optical lens group 4. Specifically, the farther away the target object is (i.e., the larger d is), the smaller the size of the light spot formed on the light receiving device 2; the closer the target object is (i.e., the smaller d is), the larger the size of the light spot formed on the light receiving device 2.

[0043] like Figure 2 The diagram illustrates the variation of echo signal intensity of the laser unit with distance. At larger distances (above 10m), the echo spot is small, and energy loss occurs during the long light propagation path, resulting in a correspondingly weaker echo signal intensity. As the distance gradually decreases (between 1m and 10m), the energy loss decreases, the spot size increases slowly, and adjacent spots overlap, thus increasing the detected echo signal intensity. When the target distance is less than 1m, the spot size increases rapidly, and adjacent spots overlap, generating a large signal intensity. However, when the distance is less than 0.6m, the signal intensity gradually decreases as the spot moves out of the detection range of the light receiver 2. When the distance decreases to within 0.3m, the spot moves out of the detection surface of the light receiver 2.

[0044] For lidar ranging, the distance can be measured as long as the light receiving device 2 can detect the light signal. The echo signal of the object at close range is strong. However, the same light emission points are used as when detecting objects at a distance, which actually wastes the light emission power and results in a problem of high emission power.

[0045] To address the issue of high emission power in laser units of lidar systems, this invention provides a laser unit for lidar systems. The laser unit includes a emitting surface for providing emitted light projected onto a target object. The emitted light, after passing through the target object, forms an echo beam, which is received by a light receiving device. The emitting surface includes a first end positioned close to the light receiving device and a second end positioned away from the light receiving device. The direction from the first end to the second end is a first direction, and the direction perpendicular to the first direction is a second direction. The emitting surface of the laser unit includes an effective emitting area with emitting points and a non-effective emitting area without emitting points. The effective emitting area includes multiple sub-emitting areas along the first direction, each used to detect targets at different distances.

[0046] The laser unit in this invention comprises an effective luminous area with luminous dots arranged thereon and an ineffective luminous area without luminous dots arranged thereon. The effective luminous area includes multiple sub-luminous areas along a first direction, each used to measure targets at different distances. Compared to a laser unit where luminous dots are arranged on the entire luminous surface, the effective luminous area with luminous dots occupies a portion of the entire luminous surface, thereby reducing the area occupied by luminous dots on the entire luminous surface. In this embodiment, the laser unit can set luminous dots on the luminous surface in a local area, while the multiple sub-luminous areas can detect targets at different distances. This optimizes the arrangement of luminous dots while ensuring the ranging performance of the laser radar for targets at different distances, reducing the number of luminous dots on the luminous surface, thereby reducing the emission power of the laser unit and the heat generated by the laser unit.

[0047] refer to Figure 3 The diagram shows an optical path schematic of an embodiment of the laser unit of the present invention.

[0048] In this embodiment, the laser unit 10 is applied to a lidar system to generate emitted light for detecting the distance to a target object. Specifically, the laser unit 10 includes a light-emitting surface 104 with multiple light-emitting points for providing emitted light F projected toward the target object S1. The emitted light F reaches the target object S1 through a first lens group (not shown), and then forms an echo beam B after passing through the target object S1. The echo beam B passes through a second lens group (not shown) and is then received by a light receiving device 20, thereby realizing the detection of the target object.

[0049] In this embodiment, the laser unit 10 is a planar laser unit, and the light-emitting point on the light-emitting surface 104 is a vertical-cavity surface-emitting laser (VCSEL). Specifically, the VCSEL includes: a substrate, a resonant cavity located on the substrate, the resonant cavity including a bottom Bragg reflector, an active region, and a top Bragg reflector sequentially located on the substrate, and a light-emitting window above the resonant cavity. The VCSEL emits laser light perpendicular to the substrate from the light-emitting window.

[0050] Specifically, the active region can be a quantum well layer, which can generate photons when a voltage is applied. The photons oscillate in the resonant cavity to form laser light, and the laser light is emitted through the light-emitting window to form a light-emitting point.

[0051] To address the issue of high emission power in the laser unit, this embodiment improves the arrangement of the light-emitting points. Specifically, based on the aforementioned principle, when the distance to the target changes, the spot size of the echo beam on the detection surface will shift and change. According to Formula 1 and the lens parameters, the size of the echo spot is larger than the size of the detection surface (e.g., ...). Figure 5-8 As shown in the figure, in practical applications, the position of the detection surface remains unchanged. Based on the characteristic that the echo spot moves away from the laser unit and the characteristic that the size of the echo spot gradually increases as the distance to the target decreases, according to the principle of optical path reversibility, the light emission point corresponding to the echo spot that is not detected by the detection surface is omitted, thereby improving the arrangement of the light emission point.

[0052] Reference Figure 4 Shown Figure 3 An enlarged view of the laser unit. The light-emitting surface 104 includes a first end A1 disposed near the light receiving device 20 and a second end A2 disposed away from the light receiving device 20. The direction from the first end A1 to the second end A2 is a first direction X, and the direction perpendicular to the first direction X is a second direction Y.

[0053] In this embodiment, the light-emitting surface 104 is rectangular, with the end closer to the light-receiving device 20 being the first end A1 and the end farther from the light-receiving device being the second end A2.

[0054] Specifically, the light-emitting surface 104 includes: an area with light-emitting dots arranged thereon (e.g., Figure 3 and Figure 4 The area shown in the dashed box (i.e., the effective light-emitting area 105) and the area without light-emitting points (such as...) Figure 3 and Figure 4 The blank area is the non-effective light-emitting area 106. Laser emission occurs in areas with arranged light-emitting points, and is therefore defined as the effective light-emitting area 105. Areas without arranged light-emitting points are the non-effective light-emitting areas 106.

[0055] The light-emitting surface 104 of this embodiment includes a hexagonal effective light-emitting area 105, wherein the longer first side of the hexagon is close to the first end A1, and the second side opposite to the first side in the first direction X is close to the second end A2.

[0056] It should be noted that, here, the meaning of the effective light-emitting area 105 being hexagonal is that the outline of the area on the light-emitting surface 104 where the light-emitting points are arranged roughly forms a hexagon. In other embodiments, the effective light-emitting area 105 can also be other shapes, as long as it meets the requirement that the size in the second direction Y gradually decreases along the first direction X, and the area of ​​the region where the light-emitting points are arranged decreases along the first direction X.

[0057] like Figure 4As shown, the effective light-emitting area 105 in the first direction X includes multiple sub-light-emitting areas, each used to detect targets at different distances. The sub-light-emitting area near the first end A1 is the first sub-light-emitting area 101, used to detect targets at a distance greater than the first distance; the sub-light-emitting area near the second end A2 is the second sub-light-emitting area 102, used to detect targets at a distance less than the second distance, where the second distance is less than the first distance.

[0058] A plurality of third sub-light-emitting areas 103 are located between the first sub-light-emitting area 101 and the second sub-light-emitting area 102, for detecting targets between the second distance and the first distance, i.e. for detecting targets in the intermediate distance range.

[0059] For example, the first sub-luminescent area 101 is used to detect targets at a first distance (e.g., within the range of 15m to 25m); the second sub-luminescent area 102 is used to detect targets at a second distance (e.g., 0.3m to 0.6m); and multiple third sub-luminescent areas 103 located between the first sub-luminescent area 101 and the second sub-luminescent area 102 are respectively used to detect targets at distances of 10m-20m, 5m-10m, 2.5m-5m, 1.25m-2.5m, and 0.6m-1.25m.

[0060] Specifically, based on the above principle, when the distance to the target object changes, the spot of the echo beam on the detection surface will move and its size will change. According to Formula 1 and the lens parameters, the size of the echo spot is larger than the size of the detection surface (e.g., ...). Figure 5-8 (As shown). Therefore, in practical applications, the position of the detection surface remains unchanged. For distant targets (i.e., targets beyond the first distance), the echo spot corresponding to the first sub-emitting area 101 can be aligned with the detection surface first (e.g., as shown). Figure 5 As shown, as the distance to the target decreases (i.e., the target is between the second and first distances), the echo spot moves away from the laser unit, and the size of the echo spot gradually increases. Based on this characteristic, the echo spots corresponding to multiple third sub-emitting regions 103 are detected by the detection surface (e.g., ...). Figure 6 and 7 For near-range targets, the echo spot corresponding to the second sub-emitting region 102 is detected by the detection surface (e.g., ...). Figure 8 ).

[0061] Specifically, the effective light-emitting area 105 is hexagonal, including a first sub-light-emitting area 101 that is rectangular at the first end A1, a second sub-light-emitting area 102 that is rectangular at the second end A2, and a plurality of third sub-light-emitting areas 103. The light-emitting area formed by the plurality of third sub-light-emitting areas 103 is an isosceles trapezoid, with the lower base of the isosceles trapezoid close to the first end A1 and the upper base close to the second end A2.

[0062] The first sub-emitting region 101 is positioned close to the light receiving device 20 in the lidar, and correspondingly, the second sub-emitting region 102 is positioned away from the light receiving device 20 in the lidar. The central axis of the isosceles trapezoid is positioned in the plane containing the optical axes of the first and second lens groups, so that the light spot formed by the emitting point on the light receiving device 20 is offset along the direction of the central axis.

[0063] The effective light-emitting area 105 is divided into multiple sub-light-emitting areas from the first direction X. Each sub-light-emitting area is used to detect targets at different distances. Specifically, the light emitted by the light-emitting point of the sub-light-emitting area can be detected by the light receiving device 20 after being reflected by the target at the corresponding distance, thereby realizing the detection at the corresponding distance.

[0064] Specifically, the first sub-light-emitting area 101 near the first end A1 is used to detect distant target S1, the second sub-light-emitting area 102 near the second end A2 is used to detect near target S2, and one or more third sub-light-emitting areas 103 located between the first sub-light-emitting area 101 and the second sub-light-emitting area 102 are used to detect targets in the intermediate distance range; correspondingly, the distribution density of the light-emitting points of the multiple sub-light-emitting areas set along the first direction X gradually decreases.

[0065] like Figure 3 and Figure 4 As shown, the distribution density of light-emitting points in each sub-light-emitting region of the effective light-emitting region 105 gradually decreases in the first direction X. Specifically, the light-emitting points in the first sub-light-emitting region 101, which is closer to the first end A1, are the most densely packed, with the highest distribution density; the light-emitting points in the second sub-light-emitting region 102, which is closer to the second end A2, are the sparsest, with the lowest distribution density; and the light-emitting point distribution density in the third sub-light-emitting region 103, located between the first sub-light-emitting region 101 and the second sub-light-emitting region 102, is in the middle.

[0066] It should be noted that if there are multiple third sub-light-emitting regions 103, the distribution density of the light-emitting points in the multiple third sub-light-emitting regions 103 gradually decreases along the first direction X. Compared to a laser unit that arranges light-emitting points on the entire light-emitting surface, the effective light-emitting region 105 with light-emitting points in this invention occupies a portion of the entire light-emitting surface, thereby reducing the area occupied by light-emitting points on the entire light-emitting surface 104. Furthermore, the distribution density of light-emitting points in the multiple sub-light-emitting regions gradually decreases along the first direction. Therefore, the laser unit of this invention can set a smaller number of light-emitting points on a local light-emitting surface. At the same time, the multiple sub-light-emitting regions can detect targets at different distances respectively. This optimizes the arrangement of light-emitting points while ensuring the ranging performance of the laser radar for targets at different distances, reducing the emission power of the laser unit. In addition, a laser unit with fewer light-emitting points can be driven with a lower voltage, thereby reducing the heat generated by the laser unit.

[0067] Figure 5 , Figure 6 , Figure 7 , Figure 8 The diagrams illustrate the positional relationship between the echo light spots generated by target objects at distances of 20m, 1m, 0.7m, and 0.4m and the position of the light receiving device 20. Now, combined with... Figures 3 to 8 This document explains the principle behind how the technical solution in this embodiment addresses the technical problem.

[0068] It should be noted that the optical receiving device 20 is used as the detector in this description. Specifically, the optical receiving device 20 can convert optical signals into electrical signals. For example, the detector is an avalanche photodiode (APD), a silicon photomultiplier tube (SiPM), or a single-photon avalanche diode (SPAD) array.

[0069] like Figure 5 As shown, when the distance to the target is 20m, the echo spot size is small, and the echo spot generated by the light-emitting point of the first sub-light-emitting region near the first end A1 is detected by the detector.

[0070] like Figure 6 As shown, as the distance to the target decreases, when the distance to the target is 1m, the echo spot shifts position, and the echo spot detected by the detector is generated by the light-emitting point of the third sub-light-emitting area 103, which is close to the first sub-light-emitting area 101. The distribution density of the light-emitting points in the third sub-light-emitting area 103 is slightly smaller, but the size of the light spot increases as the distance to the target decreases. After the light spot becomes larger, adjacent echo spots overlap, thus covering the detection surface of the detector.

[0071] like Figure 7As shown, as the distance to the target object further decreases, at a distance of 0.7m, the position of the echo spot shifts rapidly, and the echo spot detected by the detector is generated by the luminous point of the third sub-luminous area 103, which is close to the second sub-luminous area 102. Relative to Figure 6 In the embodiment shown, the distribution density of the light-emitting points in the third sub-light-emitting region 103 is further reduced, but as the distance to the target object decreases, the size of the light spot increases rapidly, and adjacent echo light spots overlap and cover the detection surface of the detector.

[0072] like Figure 8 As shown, as the distance to the target object decreases further, at a distance of 0.4m, the position of the echo spot shifts rapidly, and the echo spot detected by the detector is generated by the luminous point of the second sub-luminous region 102. The distribution density of the luminous points in the second sub-luminous region 102 is the smallest, with only a few scattered luminous points. However, when the target object is close, because the size of the echo beam forming the spot is very large, the adjacent echo spots have a large overlap area and cover the detection surface of the detector.

[0073] Combination Figures 5-8 In summary, this embodiment utilizes the principle that the echo spots formed by targets at different distances will shift on the plane where the detector is located, and the closer the target is, the larger the corresponding echo spot size, to optimize the arrangement of the light-emitting points on the laser unit's light-emitting surface.

[0074] Specifically, based on the characteristics of echo spot offset, this embodiment sets multiple sub-light-emitting areas on the first direction X of the laser unit while keeping the area of ​​the detector and the relative position of the laser unit unchanged. The light emitted by the light-emitting point of each sub-light-emitting area is reflected by the target object at the corresponding distance and then detected by the detector. By setting the light-emitting points to extend and be arranged along the first direction X, the problem of echo spot offset on the detector along the first direction is solved, thereby realizing the function of detecting different target object distances through each sub-light-emitting area.

[0075] In an alternative embodiment, the effective light-emitting area 105 can be made larger in the first direction X than in the second direction Y. That is, by extending the effective light-emitting area of ​​the laser unit in this embodiment along the first direction X to become a long light source, not only can the spot offset be compensated, but the horizontal divergence angle of the laser unit can also be increased, thereby reducing the blind zone.

[0076] Based on the characteristic that the echo spot size gradually increases with the distance to the target, this embodiment gradually reduces the size of the sub-emitting area (the size along the second direction Y) along the first direction X. This ensures that the spot size at the boundary of each sub-emitting area in the second direction Y can still cover the detector after the spot size increases, thus not affecting the ranging function of the lidar. On the other hand, the light emission point density of each sub-emitting area in the first direction X gradually decreases. This is based on the characteristic of the echo spot size increasing. Although the light emission point density decreases when detecting nearby targets, the spots of adjacent light emission points become larger and overlap, thus still covering the detector and enabling the lidar ranging function. This embodiment of the invention optimizes the arrangement of light emission points in the laser unit, enabling the detection of targets at different distances with fewer light emission points, thereby reducing the emission power of the laser unit.

[0077] It should be noted that in this embodiment, the first sub-light-emitting area 101 and the second sub-light-emitting area 102 are rectangular, while the third sub-light-emitting area 103 located in the middle is trapezoidal. This is because the first sub-light-emitting area 101 is used to detect distant targets that have just entered the detector's detection range, and the spot size remains basically unchanged. Therefore, the light-emitting points are densely arranged in the first sub-light-emitting area 101 so that the shape of the spot arrangement area is the same as that of the detector. The multiple third sub-light-emitting areas 103 are located in areas where the spot size gradually increases. Taking this characteristic into account, the shape of the third sub-light-emitting area 103 is set as trapezoidal. The light-emitting points at the upper base of the trapezoid form a larger spot than the light-emitting points at the lower base, thus still covering the detector. The first sub-light-emitting area 101 is used to detect close-range targets near the blind zone. The light spots formed on the detector are very large and can overlap and completely cover the detector. Therefore, the first sub-light-emitting area 101 is set to have the same shape as the detector, with only a few light-emitting points scattered throughout.

[0078] As the detected target approaches from a distance, the size of the light spot gradually increases along the first direction X, and its coverage area on the detector also increases. Therefore, the interval between the multiple third sub-light-emitting areas along the first direction X can gradually increase. Specifically, the edge of the third sub-light-emitting area 103 closest to the first end A1 is the reference edge. The multiple third sub-light-emitting areas 103 include reference edges BB', CC', and DD'. The distance between the reference edges BB' and CC' of adjacent third sub-light-emitting areas 103 closest to the second end A1 is the spacing d1, and the distance between the reference edges CC' and DD' of adjacent third sub-light-emitting areas 103 closest to the first end A1 is the spacing d2. The spacing gradually increases along the first direction X, that is, d1 is greater than d2.

[0079] It should be noted that the laser unit of the present invention can divide the multiple third sub-light-emitting regions along the first direction in various ways, such as: the distance between the reference parts of adjacent third sub-light-emitting regions remains unchanged (i.e., the multiple third sub-light-emitting regions are evenly divided); or the distance between the reference parts of adjacent third sub-light-emitting regions gradually decreases along the first direction.

[0080] It should be noted that in practical applications, the arrangement of the light-emitting points is fitted by combining parameters such as the detector's detectable range, the area of ​​the detector surface and the emitting surface, and the parameters of the second optical lens group on the detector (e.g., focal length). Different sub-emitting regions are then defined, and the arrangement of light-emitting points in each sub-emitting region is set to determine whether the light spots formed by the light-emitting points in each sub-emitting region can cover the detector. Subsequently, based on the specifications of the lidar, the shape, spacing, first size, second size, and light-emitting point distribution density values ​​of each sub-emitting region can be further fine-tuned to obtain the optimized setting of the light-emitting points on the final emitting surface.

[0081] It should also be noted that the requirement that the density of light-emitting points between each sub-light-emitting region decreases along the first direction is sufficient. The distribution density value of light-emitting points within a single sub-light-emitting region can be a range, that is, the light-emitting points are arranged in a non-uniform manner within a sub-light-emitting region, or in other words, the density of light-emitting points in different local areas within a sub-light-emitting region can be different.

[0082] Furthermore, VCSELs achieve light emission by applying voltages to the bottom and top electrodes of the resonant cavity. In this embodiment, the laser unit can be formed with multiple optimized light-emitting points on a single substrate. By simultaneously applying voltages to the electrodes corresponding to each light-emitting point, all light-emitting points can emit light simultaneously. Because the number of light-emitting points is reduced in this embodiment, the total parallel resistance is increased, thereby reducing the power of the laser unit.

[0083] In other embodiments, the light-emitting points of each sub-light-emitting region may be fabricated on different substrates and integrated together. In this embodiment, the laser unit can simultaneously control the light-emitting points of each sub-light-emitting region to achieve simultaneous light emission, or it can individually control the light-emitting points of each sub-light-emitting region to select the sub-light-emitting region corresponding to different target distances to emit light.

[0084] It should be noted that, in Figure 3 and Figure 4 In the embodiment shown, the light-emitting area composed of a plurality of third sub-light-emitting areas 103 in the effective light-emitting area 105 is an isosceles trapezoid, and the side of the first sub-light-emitting area 101 is the same as the upper base of the isosceles trapezoid, the side of the second sub-light-emitting area 102 is the same as the lower base of the isosceles trapezoid, and the plurality of third sub-light-emitting areas 103 gradually decrease in size along the waist of the isosceles trapezoid in the second direction Y.

[0085] In the above embodiment, a third light-emitting region is further included between the first and second light-emitting regions. (See reference...) Figure 9 In the second embodiment of the laser unit shown, the effective emitting surface of the laser unit 30 may further include only a first sub-emitting region 201 located at the first end and a second sub-emitting region 202 located at the second end, which are used to detect distant targets and near targets, respectively. That is, in the second embodiment, the effective emitting surface does not include a third sub-emitting region.

[0086] like Figure 9 In the embodiment shown, the density of light-emitting points in the second sub-light-emitting region 202 is less than the density of light-emitting points in the first sub-light-emitting region 201, thereby reducing the number of light-emitting points and further reducing the light-emitting power.

[0087] It should also be noted that, Figure 9 In the illustrated embodiment, the light-emitting points of the first sub-light-emitting region 201 are arranged in an alternating pattern, while the light-emitting points of the second sub-light-emitting region 202 are arranged in a matrix pattern. In other embodiments, the first sub-light-emitting region may be arranged in a matrix pattern while the second sub-light-emitting region may be arranged in an alternating pattern. That is, different sub-light-emitting regions on the same effective light-emitting surface may adopt different arrangement methods. In other embodiments, each sub-light-emitting region may also adopt the same arrangement method (for example, each sub-light-emitting region may be arranged in an alternating pattern or in an array pattern).

[0088] In such Figure 10 In the third embodiment of the laser unit shown, the boundary of the effective light-emitting area 203 has a sawtooth bevel, and the first size of the multiple sub-light-emitting areas decreases abruptly along the first direction X, that is, the first size of adjacent sub-light-emitting areas differs greatly.

[0089] Specifically, in the embodiment, each sub-light-emitting area is rectangular in shape, with the long side of the rectangle along the Y direction and the short side along the X direction. The long side dimensions of adjacent rectangular sub-light-emitting areas are quite different, thus representing a change in an abrupt manner.

[0090] refer to Figure 11 The diagram illustrates a fourth embodiment of the laser unit of the present invention. In this embodiment, the light-emitting points 205 in the sub-light-emitting region are arranged alternately along the first direction X and the second direction Y. When arranged alternately, the light spots formed by the light emitted from adjacent light-emitting points are more likely to overlap, thereby covering the coverage area of ​​the light receiving device.

[0091] In other embodiments, the light-emitting dots in the sub-light-emitting region may be arranged alternately along one of the first or second directions, while being aligned along the other direction.

[0092] refer to Figure 12The diagram shows a fifth embodiment of the laser unit of the present invention. In this embodiment, the light-emitting points 305 in the sub-light-emitting region are arranged in a matrix, that is, the light-emitting points are aligned in both the first direction X and the second direction Y.

[0093] It should be noted that the shape of the light-emitting points in the aforementioned embodiments is circular. (Reference) Figure 13 In the sixth embodiment of the laser unit shown, the shape of the light-emitting point 405 is rectangular. However, in order for the light spot to cover the detection surface in both the first and second directions, the light-emitting point is square.

[0094] To address the issue of high emission power in laser units, this invention also provides a laser radar, for reference... Figure 14 The diagram shows an embodiment of the lidar of the present invention, the lidar comprising:

[0095] The laser unit 10 is used to provide emitted light projected toward a target, the emitted light forming an echo beam after passing through the target. A description of the laser unit is given in the foregoing embodiments and will not be repeated here.

[0096] A light receiving device 20 is disposed near the first end of the laser unit 10 and is used to detect the echo beam. In this embodiment, the light receiving device 20 is a photodetector, which may be an avalanche photodiode or a silicon photomultiplier tube, and is used to convert the light signal corresponding to the light spot falling into the detection range into an electrical signal.

[0097] like Figure 14 As shown, the effective light-emitting surface 103 of the laser unit 10 is an isosceles trapezoid. The light receiving device 20 includes a detection surface, which is arranged in the same direction as the light-emitting surface 104 of the laser unit. The detection surface is located on the central axis of the isosceles trapezoid and is adjacent to the lower base of the isosceles trapezoid.

[0098] The lidar also includes a control unit 30, used to control all light-emitting points in the effective light-emitting area 103 to emit light, and to control the light receiving device 20 to detect and acquire echo signals. Because the laser unit with optimized light-emitting point settings of the present invention uses only a small number of light-emitting points in local areas, the emission power of the laser unit in the lidar is relatively low.

[0099] Alternatively, the control unit 30 is further configured to control the light-emitting points in the sub-light-emitting area corresponding to the distance information to emit light based on the distance information in the echo signals obtained from the emission of all light-emitting points, and to control the light receiving device 20 to perform detection.

[0100] In this way, the lidar can first scan the surrounding objects by emitting light from all the light-emitting points and obtain echo signals. Then, based on the distance information in the echo signals, it controls the sub-light-emitting areas corresponding to the distance information to light up, thereby reducing the number of light-emitting points and further reducing the emitting power.

[0101] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A laser unit for lidar, the laser unit comprising a emitting surface for providing emitted light projected toward a target, the emitted light forming an echo beam after passing through the target and being received by a light receiving device; the emitting surface comprising: For a first end disposed near the optical receiving device and a second end disposed away from the optical receiving device, wherein the direction from the first end to the second end is a first direction, and the direction perpendicular to the first direction is a second direction; characterized in that, The light-emitting surface of the laser unit includes: an effective light-emitting area with light-emitting points arranged thereon; The effective light-emitting area includes multiple sub-light-emitting areas along the first direction; The plurality of sub-light-emitting regions include a first sub-light-emitting region and a second sub-light-emitting region; The first sub-light-emitting area is located near the first end and is used to detect distant targets; The second sub-light-emitting area is located near the second end and is used to detect targets at close range; The areas of the first sub-light-emitting area and the second sub-light-emitting area are different, and the echo spots generated by the distant target and the echo spots generated by the near target both cover the detection surface of the receiving device.

2. The laser unit as described in claim 1, characterized in that, The light-emitting point distribution density of the second sub-light-emitting region is less than that of the first sub-light-emitting region.

3. The laser unit as described in claim 1, characterized in that, The size of the second sub-light-emitting region in the second direction is smaller than the size of the first sub-light-emitting region in the second direction.

4. The laser unit as described in claim 1, characterized in that, All light-emitting points in the effective light-emitting area emit light simultaneously, and / or select sub-light-emitting areas corresponding to different target distances to emit light.

5. The laser unit as described in claim 1, characterized in that, The distance between each sub-luminescent region and the target object along the first direction gradually decreases.

6. The laser unit as described in claim 1, characterized in that, The first sub-luminescent area is used to detect targets at a distance greater than a first distance; The second sub-luminescent area is used to detect targets at a second distance or less than the first distance.

7. The laser unit as described in claim 6, characterized in that, One or more third sub-luminescent areas are located between the first sub-luminescent area and the second sub-luminescent area for detecting targets between the second distance and the first distance.

8. The laser unit as described in claim 7, characterized in that, The first and second sub-light-emitting areas are rectangular, and the third sub-light-emitting area is trapezoidal or rectangular.

9. The laser unit as described in claim 7, characterized in that, The portion of the one or more third sub-light-emitting regions near the first end is a reference portion, and the spacing between the reference portions of adjacent third sub-light-emitting regions gradually increases along the first direction.

10. The laser unit as claimed in claim 1, characterized in that, The effective light-emitting area is larger in the first direction than in the second direction.

11. The laser unit as claimed in claim 1, characterized in that, The light-emitting points in the sub-light-emitting region are arranged alternately along the first direction and / or the second direction; or, The light-emitting points in the sub-light-emitting region are arranged in a matrix.

12. The laser unit as described in any one of claims 1-11, characterized in that, The light-emitting point is a vertical cavity surface-emitting laser.

13. A lidar, comprising: The laser unit as described in any one of claims 1-12 is used to provide emitted light projected toward a target, wherein the emitted light forms an echo beam after passing through the target; A light receiving device is disposed near the first end of the laser unit for detecting the echo beam.

14. The lidar as described in claim 13, characterized in that, Also includes: The control unit is used to control all light-emitting points in the effective light-emitting area to emit light, and to control the light receiving device to receive detection signals.

15. The lidar as described in claim 14, characterized in that, The control unit obtains the distance information of the target object based on the detection signal, and controls the light-emitting points in the sub-light-emitting area corresponding to the distance information to emit light.

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