Transmission system of multi-line lidar and multi-line lidar

Abstract

The present invention provides a transmitting system for a multi-line lidar and a multi-line lidar. The transmitting system includes a plurality of chip-lens combinations. Each chip-lens combination includes a transmitting chip and its corresponding wedge-shaped lens. The transmitting chip includes one or more light-emitting units. Each wedge-shaped lens is configured to shift the virtual image formed by the light-emitting units of its corresponding transmitting chip in a preset direction, so that the field-of-view distributions of the light-emitting units of all the transmitting chips do not overlap. Wherein, the preset direction is the x direction and / or the y direction in a preset coordinate system, and the z direction of the preset coordinate system is the direction where the optical axis of the wedge-shaped lens is located. The present invention can implement a multi-line lidar with a general transmitting chip, solving the problems of high cost, long development cycle and low yield caused by chip customization.

Description

Technical Field

[0001] The present invention relates to the technical field of lidar, and in particular, to a transmitting system of a multi-line lidar and a multi-line lidar. Background Art

[0002] A lidar is a radar system that detects targets by emitting laser beams. According to the number of detected beam lines, lidars can be divided into single-line lidars and multi-line lidars. Compared with single-line lidars, multi-line lidars can provide more dense and rich point cloud information, and have significant advantages in environmental perception and target recognition, thus attracting much attention.

[0003] A multi-line lidar forms a detection channel by arranging multiple laser transmitting units and corresponding receiving units vertically, and the laser beam is horizontally rotated by a motor or a rotating mirror to achieve scanning detection. Currently, multi-line lidars usually adopt the integrated transceiver array chip method, that is, using an optical lens to match the field of view of an array unit in the transmitting chip with an array unit in the receiving array chip to form a detection channel. The more array units the chip has, the greater the number of detected beam lines, and the system volume will not increase significantly, and the difficulty of transceiver calibration and alignment is also relatively low.

[0004] However, the integrated transceiver array chip method requires the chip supplier to provide customized and dedicated array chips. For this reason, the chip supplier needs to invest a large amount of development costs and batch wafer tests and validations in the early stage of research and development. At the same time, the yield rate of array chips is lower than that of single chips, and the higher the number of arrays, the lower the yield rate, and the corresponding development cycle and development cost are also higher. Summary of the Invention

[0005] Embodiments of the present invention provide a transmitting system of a multi-line lidar and a multi-line lidar to solve the problems of high cost, long development cycle, and low yield rate caused by the need for chip customization in existing multi-line lidars.

[0006] In a first aspect, embodiments of the present invention provide a transmitting system of a multi-line lidar, including a plurality of chip-lens combinations. Each chip-lens combination includes a transmitting chip and its corresponding wedge-shaped lens, and the transmitting chip includes one or more light-emitting units;

[0007] Each wedge-shaped lens is used to shift the virtual image formed by the light-emitting unit of its corresponding transmitting chip in a preset direction, so that the field of view distributions of the light-emitting units of all transmitting chips do not overlap; wherein, the preset direction is the x direction and / or the y direction in a preset coordinate system, and the z direction of the preset coordinate system is the direction where the optical axis of the wedge-shaped lens is located.

[0008] In a possible implementation, the rear surface of the wedge-shaped lens is an inclined plane, and the rear surface is located on the side of the light-emitting point of its corresponding light-emitting unit. The angle α between the rear surface and the section plane of the wedge-shaped lens satisfies the following condition:

[0009]

[0010] where n is the refractive index of the material of the wedge-shaped lens, y F is the distance between the light-emitting point and the optical axis of the wedge-shaped lens, and z F is the distance between the light-emitting point and the rear surface in the direction of the optical axis. The section plane is perpendicular to the optical axis;

[0011] The front surface of the wedge-shaped lens is a curved surface, and the surface shape of the curved surface satisfies the following condition:

[0012] L1 + nL2 - L3 = L 10 + nL 20 - L 30 ;

[0013] where L1 is the distance between the light-emitting point and the incident point where any-angle light emitted by it enters the rear surface, L2 is the distance between the incident point and the exit point where any-angle light leaves the front surface, L3 is the distance between the exit point and the virtual image point formed by the wedge-shaped lens for the light-emitting point, L 10 is the distance between the light-emitting point and the first intersection point, the first intersection point is the point where the optical axis intersects the rear surface, and L 20 is the distance between the first intersection point and the second intersection point, the second intersection point is the point where the optical axis intersects the front surface, and L 30 is the distance between the second intersection point and the virtual image point.

[0014] In a possible implementation, the surface shape of the front surface is obtained by fitting a polynomial fitting equation set of the front surface through a preset fitting algorithm, and the polynomial fitting equation set is based on a plurality of rear surface coordinate points discretely selected on the rear surface.

[0015] In a possible implementation, the vertical magnification b near the chief ray of the light-emitting unit satisfies the following condition:

[0016]

[0017]

[0018]

[0019] where y is the object height of the light-emitting point of the light-emitting unit, y' is the image height of the light-emitting point of the light-emitting unit, the incident angle of the chief ray relative to the rear surface normal on the rear surface is u, the refraction angle is u', the incident angle of the chief ray relative to the front surface normal on the front surface is v', and the refraction angle is v.

[0020] In a possible implementation, the arrangement of multiple chips and lenses is an extended arrangement, and the extended arrangement is an arrangement in which the emission angles of all light-emitting units do not overlap with each other.

[0021] In a possible implementation, the arrangement of multiple chips and lenses is a staggered arrangement, and the staggered arrangement is as follows: a first preset ratio of multiple chips and lenses are arranged as a first emission system in which the emission angles of the light-emitting units gradually increase and do not overlap with each other, and a second preset ratio of multiple chips and lenses are arranged as a second emission system in which the emission angles of the light-emitting units gradually increase and do not overlap with each other, and the emission angles of the light-emitting units in the first emission system and the second emission system are complementary and overlapping; wherein, the sum of the first preset ratio and the second preset ratio is one.

[0022] In a possible implementation, the model relationships of the emission chips in the multiple chip and lens combinations are different from each other, all the same, or partially the same.

[0023] In a possible implementation, the emission chip is a vertical cavity surface emitting laser or an edge emitting laser.

[0024] In a possible implementation, when the light-emitting unit is a vertical cavity surface emitting laser, the arrangement of the multiple chips and lenses is a square arrangement, and the square arrangement is to arrange the light-emitting units in the multiple chips and lenses according to a square.

[0025] In a second aspect, an embodiment of the present invention provides a multi-line lidar, including the emission system described in the first aspect or any possible implementation of the first aspect.

[0026] An embodiment of the present invention provides an emission system of a multi-line lidar and a multi-line lidar. The emission system includes multiple chip and lens combinations. Each chip and lens combination includes an emission chip and its corresponding wedge-shaped lens. The emission chip includes one or more light-emitting units. Since each wedge-shaped lens in the emission system is used to shift the virtual image formed by the light-emitting unit of its corresponding emission chip in a preset direction, so that the field of view distributions of the light-emitting units of all emission chips do not overlap, therefore, by changing the parameters of the wedge-shaped lens group, the multi-line emission field of view distribution can be changed without adjusting the chip arrangement, so that multiple general emission chips can be combined, for example, multiple emission chips used in the emission system of a single-line lidar can be combined to implement the emission system of a multi-line lidar, and the emission system has good flexibility and adaptability. In this way, a multi-line lidar can be realized with general emission chips or array chips, which not only greatly expands the selection range of emission chips, reduces the chip cost, but also avoids the problems of long development cycle and low yield caused by custom chips. Description of the Drawings

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the accompanying drawings required for use in the embodiments or the description of the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0028] Figure 1 is a schematic diagram of the principle of a multi-line lidar based on a 1×4 linear array emission chip provided by an embodiment of the present invention;

[0029] Figure 2 is a schematic diagram of the principle of image shift of a wedge lens provided by an embodiment of the present invention;

[0030] Figure 3 is a schematic diagram of the vertical magnification of a wedge lens provided by an embodiment of the present invention;

[0031] Figure 4 is a schematic diagram of the principle of generating lateral and lateral image shifts of a wedge lens provided by an embodiment of the present invention;

[0032] Figure 5 is a schematic diagram of the ray tracing of lateral and lateral image shifts provided by an embodiment of the present invention;

[0033] Figure 6 is a schematic diagram of a 16-line emission system formed by combining the emission beams of 4 1×4 linear array emission chips in an extended manner using a wedge lens provided by an embodiment of the present invention;

[0034] Figure 7 is a schematic diagram of a 16-line emission system formed by combining the emission beams of 4 1×4 linear array emission chips in an interleaved manner using a wedge lens provided by an embodiment of the present invention;

[0035] Figure 8 is a schematic diagram of converting an N×N square arrangement of VCSEL emission arrays into an N×N multi-line laser emission system using a wedge lens group provided by an embodiment of the present invention;

[0036] Figure 9 is a schematic diagram of a multi-line lidar provided by an embodiment of the present invention. Specific Embodiments

[0037] In the following description, specific details such as specific system architectures and technologies are presented for the purpose of illustration rather than limitation, so as to thoroughly understand the embodiments of the present invention. However, those skilled in the art should clearly understand that the present invention can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid unnecessary details from interfering with the description of the present invention.

[0038] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will be described through specific embodiments in conjunction with the accompanying drawings.

[0039] In existing multi-line lidars based on array chips, the transmitting chip is usually placed at the focal plane of the transmitting lens, and the receiving array chip is placed at the focal plane of the receiving lens. The field of view of the transmitting chip array unit and the receiving chip array unit are made to correspond one by one, and then the beam is horizontally scanned through a beam scanning component to achieve multi-line laser detection.

[0040] As Figure 1 shown, it shows a schematic diagram of the principle of a multi-line lidar based on a 1×4 linear array transmitting chip. The array units of this transmitting chip form an equally spaced and uniform field-of-view angle distribution, and its chip center is set on the optical axis of the transmitting lens. Assuming the focal length of the transmitting lens is f, the size of the light-emitting unit area is d, and the gap is c, then the field-of-view angle corresponding to the transmitting chip array unit 1 is The field-of-view angle corresponding to the chip array unit 2 is The field-of-view angle corresponding to the chip array unit 3 is The field-of-view angle corresponding to the chip array unit 4 is Similarly, assuming the focal length of the receiving lens is f’, the size of the receiving unit area is d’, and the gap is c’, then the field-of-view angle corresponding to the receiving chip array unit 1 is The field-of-view angle corresponding to the chip array unit 2 is The field-of-view angle corresponding to the chip array unit 3 is The field-of-view angle corresponding to the chip array unit 4 is

[0041] It can be seen that in order to make the field of view of the transmitting chip array unit and the receiving chip array unit correspond one by one, the manufactured transmitting chip needs to satisfy the following parameter relationships:

[0042]

[0043] However, after the general chip is packaged, the distance a between the light-emitting unit and the chip edge is usually greater than the gap c between the light-emitting units. In order to enable the emission lens to detect more equally spaced beam bundles, it is necessary to increase the emission chip array units in a customized manner according to the above parameter relationship. Therefore, the integrated transceiver array chip method has problems of high cost, long development cycle, and low yield.

[0044] To solve the problems of the prior art, an embodiment of the present invention provides a transmitting system of a multi-line lidar and a multi-line lidar. First, the transmitting system of the multi-line lidar provided by the embodiment of the present invention will be introduced below.

[0045] A transmitting system of a multi-line lidar provided by an embodiment of the present invention includes a plurality of chip-lens combinations. Each chip-lens combination includes a transmitting chip and its corresponding wedge-shaped lens. The transmitting chip includes one or more light-emitting units, such as an edge-emitting laser (EEL) or a vertical-cavity surface-emitting laser (VCSEL). Specifically, each wedge-shaped lens is used to shift the virtual image formed by the light-emitting unit of its corresponding transmitting chip in a preset direction, so that the field-of-view distributions of the light-emitting units of all transmitting chips do not overlap; wherein, the preset direction is the x direction and / or the y direction in a preset coordinate system, and the z direction of the preset coordinate system is the direction where the optical axis of the wedge-shaped lens is located.

[0046] It should be noted that for the transmitting system provided by the embodiment of the present invention, there is no need to customize the transmitting chips. The transmitting chips in the transmitting system can use general transmitting chips, such as Figure 1 the 1×4 linear array transmitting chip shown in, or other general 1×8 linear array transmitting chips, etc. The transmitting system shifts the virtual image formed by the light-emitting unit of its corresponding transmitting chip in a preset direction through the wedge-shaped lens, which can make the field-of-view distributions of the light-emitting units of all transmitting chips not overlap, achieving the effect of superimposing the beam bundles of multiple transmitting chips. For example, 4 1×4 linear array transmitting chips can be superimposed into a 16-line transmitting system, and 16 1×4 linear array transmitting chips can be superimposed into a 64-line transmitting system. In this way, the multi-line emission field-of-view distribution can be adjusted by changing the parameters of the wedge-shaped lens group, so that a multi-line laser transmitting system with doubled detection beam bundles can be realized without customizing the transmitting chips.

[0047] It is worth mentioning that since only the parameters of the wedge-shaped lens need to be changed, the transmitting chips in the plurality of chip-lens combinations can use all the same models, or different models from each other, or some of the same models. In this way, the selection range of the transmitting chips is greatly expanded, which can not only reduce the chip cost, but also avoid the problems of long development cycle and low yield caused by customizing chips.

[0048] In some embodiments, the rear surface of the above-mentioned wedge-shaped lens is an inclined plane, and the rear surface is located on the side of the light-emitting point of its corresponding light-emitting unit. The included angle α between the rear surface and the section plane of the wedge-shaped lens satisfies the following conditions:

[0049]

[0050] where n is the refractive index of the material of the wedge-shaped lens, y F is the distance between the light-emitting point and the optical axis of the wedge-shaped lens, and z F is the distance between the light-emitting point and the rear surface in the direction of the optical axis. The section plane is perpendicular to the optical axis;

[0051] The front surface of the wedge-shaped lens is a curved surface, and the surface shape of the curved surface satisfies the following conditions:

[0052] L1 + nL2 - L3 = L 10 + nL 20 - L30;

[0053] where L1 is the distance between the light-emitting point and the incident point where any angle of the emitted light enters the rear surface, L2 is the distance between the incident point and the exit point where any angle of the light leaves the front surface, L3 is the distance between the exit point and the virtual image point formed by the wedge-shaped lens for the light-emitting point, L 10 is the distance between the light-emitting point and the first intersection point, the first intersection point is the point where the optical axis intersects the rear surface, L 20 is the distance between the first intersection point and the second intersection point, the second intersection point is the point where the optical axis intersects the front surface, L 30 is the distance between the second intersection point and the virtual image point.

[0054] As Figure 2 shown, it shows the principle of image shift of the wedge-shaped lens. Specifically, the light emitted from the light-emitting point F enters the wedge-shaped lens after being refracted by the rear surface of the wedge-shaped lens, and then is refracted out from the front surface of the wedge-shaped lens. The extended reverse of the emitted light intersects at point F', that is, the virtual image point of point F. Assume that the z-axis is the optical axis of the wedge-shaped lens, which is perpendicular to the light-emitting surface. The included angle between the rear surface and the y-axis is α, the x-axis is on the rear surface, the origin is o', the distance between point F and the origin in the z direction is z F , the distance between point F and the origin in the y direction (transverse) is y F , the distance between point F' and the origin on the z-axis is z' F , to make point F form a virtual image point at F' after passing through the lens, the parameter α of the rear surface can be obtained through the refraction law, that is:

[0055]

[0056] According to the above formula, it can be seen that to make the lateral offset of the virtual image point y F larger, the inclination angle α of the wedge surface is also larger. When y FWhen δ = 0, the virtual image point has no lateral offset. At this time, the inclination angle α of the wedge surface is 0°, that is, the lens will be a conventional plano-convex lens.

[0057] For the front surface of the wedge lens, its surface shape parameters can be determined by the following conditions according to Fermat's principle of equal optical path and in combination with the law of refraction:

[0058] L1 + nL2 - L3 = L 10 + nL 20 - L 30 .

[0059] In some embodiments, the surface shape of the front surface is obtained by fitting a polynomial fitting equation set of the front surface through a preset fitting algorithm, and the polynomial fitting equation set is based on a plurality of rear surface coordinate points discretely selected on the rear surface.

[0060] Specifically, let the point G(x G , y G , z G ) be a point on the rear surface of the wedge lens, and its coordinates satisfy the following relationship:

[0061] y G sinα - z G cosα = 0;

[0062] Since the optical path L = L 10 + nL 20 - L 30 is determined by the positions of points F and F' and L 20 , therefore, each point G(x G , y G , z G ) on the rear surface can calculate the corresponding point H(x G , y G , z G ) of point G(x H , y H , z H ) through Fermat's principle of equal optical path and the law of refraction. In this way, the surface shape parameters of the front surface can be determined according to the rear surface parameters.

[0063] It should be noted that although each point H(x H , y H , z H ) on the front surface corresponds one-to-one with the corresponding point G(x G , y G , z G ) on the rear surface, considering the huge amount of calculation, it is difficult to obtain an accurate free-form surface expression z H = f(x H , y H), for this, it can be considered to take N G(x Gi , y Gi , z Gi ) from the surface point coordinates after discretization, i = 1, …, N, and then determine the N coordinate values H(x Hi , y Hi , z Hi ) of the front surface through calculation. After that, a polynomial fitting equation system for the front surface is established, that is:

[0064]

[0065] Next, polynomial fitting is performed on the polynomial fitting equation system. For example, the least squares method is used for fitting. By minimizing the error term ∑ i |δz Hi |, the free-form surface equation is obtained.

[0066] For example, for the equation system that needs to perform 4th-order high-order fitting:

[0067]

[0068] The coefficient matrix of the least squares method used can be:

[0069]

[0070] Among them, the column vector is:

[0071] Z N×1 = [z H1 , z Hi , …, z HN T ;

[0072] Thus, the fitted coefficient vector can be obtained as:

[0073]

[0074] Among them, [] T represents the transpose operation of the matrix. In this way, according to different calculation accuracy requirements, different numbers of discretization points N and the fitting order of the polynomial can be selected to approximate the surface shape of the front surface for design verification and processing.

[0075] In some embodiments, in order to determine the angular relationship between the introduced wedge lens and the vertical direction of the outgoing light beam, it is necessary to calculate the lateral magnification near the chief ray.

[0076] ​Specifically, assume that the object height of the light-emitting point F is y, the image height of its corresponding image point F′ is y′, the incident angle of the chief ray on the rear surface of the wedge-shaped lens with respect to the surface normal N1 is u, the refraction angle is u′, the incident angle on the front surface with respect to the surface normal N2 after transmission is v′, the refraction angle is v, and the reverse extension line of the light ray emerging from the front surface intersects the z-axis at the image point F′. Consider a light ray at the object height y that is refracted through the rear surface of the lens and transmitted to the same point on the front surface as the chief ray. The incident angle with respect to the surface normal N1 is u + du, the refraction angle is u′ + du′, the incident angle on the front surface with respect to the surface normal N2 after transmission is v′ + dv′, the refraction angle is v + dv, the included angle between the emerging ray and the emerging ray of the chief ray is dv, and its reverse extension line intersects the image plane to form an image point with an image height of y′, as Figure 3 shown, which shows a schematic diagram of the vertical magnification of the wedge-shaped lens. According to the law of refraction, we can obtain:

[0077]

[0078] The rear surface normal vector N1 is calculated from α. From the geometric relationship, it can be known that the incident angle of the chief ray u = α. Using the vector relationship of the law of refraction, the rear surface normal vector N2 can be obtained. Differentiating the above formula (1), we can get:

[0079] cos u du = n cos u′du′, cos v dv = n cos v′dv′;

[0080] Combined with the above (1) and sorted out, the vertical magnification b is calculated as:

[0081]

[0082]

[0083]

[0084] In this way, by using the characteristics of the above wedge-shaped lens and combining with a common collimating lens, the beam bundles of multiple emission chips can be superimposed to increase the detection beam bundles of the emission system of the multi-line lidar.

[0085] Taking the example of superimposing the emission light beams of two general array chips, first, the image points formed by the light-emitting units of the array chips can be placed at the focal plane of the collimating lens in the axial direction, the lateral position of the image points is offset to a preset position, and according to the calculated transverse magnification, the angular range of the multi-line emission light beam after combining the wedge lens and the collimating lens can be determined. For a general packaged chip with the distance a from the light-emitting unit to the chip edge and the lateral dimension e, the chip is placed at the lateral position of the light-emitting center y = e / 2. A wedge lens is introduced on the side of y>0 to offset the virtual image point downward by e / 2, and another chip is placed at the lateral position of the light-emitting center y = -e / 2. A wedge lens is introduced on the side of y<0 to offset the virtual image point upward by e / 2. In this way, the virtual image points of the light-emitting centers of the two chips can be moved to the z-axis, which is equivalent to offsetting and combining two light-emitting points with different lateral positions to the same position. The virtual image point is at the focal plane of the collimating lens with a focal length of f, so that the light beams of the two light-emitting units can be superimposed and the output power can be doubled.

[0086] Still taking Figure 1 the 1×4 linear array emission chip shown as an example, if a wedge lens is introduced on the side of y>0 to offset the virtual image point downward by e / 2, and then the light-emitting unit in the emission chip and the wedge lens are translated upward by ε as a whole, that is, the lateral position of the light-emitting center is y = e / 2 + ε, while a wedge lens is introduced on the side of y<0 to offset the virtual image point of the other chip upward by e / 2, and then the light-emitting unit and the wedge lens are translated downward by ε as a whole, and the lateral position of the light-emitting center is y = -e / 2 - ε, then the light beams of the two light-emitting units can be combined, and the output central fields of view are respectively offset and Specifically as follows:

[0087] For array chip 1, the field of view angle corresponding to the emission chip array unit 1 is:

[0088]

[0089] The field of view angle corresponding to the emission chip array unit 2 is:

[0090]

[0091] The field of view angle corresponding to the emission chip array unit 3 is:

[0092]

[0093] The field of view angle corresponding to the emission chip array unit 4 is:

[0094]

[0095] For array chip 2, the field of view angle corresponding to the emission chip array unit 1 is:

[0096]

[0097] The field of view angle corresponding to the chip array unit 2 is:

[0098]

[0099] The field of view angle corresponding to the chip array unit 3 is:

[0100]

[0101] The field of view angle corresponding to the chip array unit 4 is:

[0102]

[0103] It should be noted that the downward offset of the virtual image point is not limited to e / 2, as long as the offset value is greater than a.

[0104] It can be seen that according to the general array chip parameters, by introducing a wedge lens and a collimating lens with appropriate parameters, a multi-line lidar emission system can be combinedly realized, and two 1×4 linear array emission chips can be combined into an 8-line lidar.

[0105] To facilitate the understanding of the scheme of combining multiple linear array emission chips through a wedge lens to obtain a multi-line lidar, taking a linear array chip as an example, the principle of combining the light emission beams of the linear array chips through a wedge lens is elaborated below.

[0106] The linear array emission chip can adopt an array light-emitting unit composed of an edge-emitting laser or a vertical-cavity surface-emitting laser. The arrangement direction of the chip linear array unit is parallel to the horizontal direction (y-axis). For the light-emitting unit adopting a vertical-cavity surface-emitting laser, the emitted light spot is circular, that is, σ x = σ y , while for the light-emitting unit adopting an edge-emitting laser, its divergence angle σ x in the fast axis direction (perpendicular to the junction plane, x-axis) is greater than the divergence angle σ y in the slow axis direction (parallel to the junction plane, y-axis), and the emitted light spot is elliptical. For the linear array chip composed of edge-emitting lasers, by combining the light emissions of two general linear array chips through a wedge lens and a collimating lens, the virtual image points of the light-emitting units 1, 2, 3, 4 of the array chip 1 and the light-emitting units 1', 2', 3', 4' of the array chip 2 are located on the focal plane of the collimating lens. The distances from the centers of the array chip 1 and the array chip 2 to the optical axis of the collimating lens are h a and h b . If the array chip 1 and the array chip 2 are of the same model, then h a and h b are the same, and the horizontal center position of the virtual image points formed by the light-emitting units 1, 2, 3, 4 of the array chip 1 is:

[0107]

[0108] When ∈ = 2(c + d)b, a 8-line lidar with a uniform pitch angle distribution φ1, φ2, φ3, φ4, φ5, φ6, φ7, φ8 at the centers of each wire harness can be realized, and its parameters satisfy the following relationship:

[0109]

[0110] It should be noted that the above-mentioned lateral offset y of the virtual image point F and the overall downward translation ε of the light-emitting unit and the wedge lens to realize the parameter selection of the field of view angle combination of the multi-line lidar are not unique, and different y F and ε can be selected according to the actual application to form a multi-line laser emission system.

[0111] In some embodiments, the above-mentioned principle of image shift of the wedge lens can be extended to have image shifts in both the lateral (y-axis) and lateral (x-axis) directions, that is, the virtual image point is made to have image shifts in both the lateral and lateral directions through the wedge lens, and the multi-line lidar emission system can be further combined and extended, so that the system obtains a more compact and higher space utilization emission system.

[0112] As Figure 4 and Figure 5 shown, Figure 4 it shows a schematic diagram of the principle of the wedge lens generating lateral and lateral image shifts, Figure 5 and shows a ray tracing schematic diagram of the lateral and lateral image shifts. Specifically, the rear surface of the wedge lens is still an inclined plane. Any ray emitted from point F is refracted by the rear surface G of the lens and then enters the lens and is refracted out from the front surface H. The extended outgoing ray intersects at point F′, that is, the virtual image point of point F, and its coordinates are (x' F , 0, z' F ). Similarly, it is assumed that the z-axis is perpendicular to the light-emitting surface, and the inclination angle of the inclined plane is determined by the lateral offset position of the virtual image point. The angle parameter is the same as that of the above Figure 2 , the angle between the rear surface and the y-axis is α, the x-axis is on the rear surface, the origin is o', the distance of point F from the origin in the z direction is z F , the distance of point F from the origin in the y direction (lateral) is y F , that is, the coordinates of point F are (0, y F , z F ), the distance of point F′ from the origin on the z-axis is z' F , and the parameter α of the rear surface can be obtained through the law of refraction:

[0113]

[0114] The front surface of the lens is also a curved surface, and the determination process can refer to the above polynomial fitting part, which will not be elaborated here.

[0115] Specifically, in order to achieve lateral and lateral image shift generated by the wedge lens, the emission chip and lens combination can be arranged in an extended manner or a staggered manner. Among them, the extended manner is an arrangement method in which the emission angles of all light-emitting units do not overlap; the staggered manner is as follows: a plurality of chips and lens combinations with a first preset ratio are arranged as a first emission system in which the emission angles of the light-emitting units gradually increase and do not overlap, and a plurality of chips and lens combinations with a second preset ratio are arranged as a second emission system in which the emission angles of the light-emitting units gradually increase and do not overlap, and the emission angles of the light-emitting units in the first emission system and the second emission system are complementary and overlap; among them, the sum of the first preset ratio and the second preset ratio is one. For example, the first preset ratio and the second preset ratio can be one-half, or the first preset ratio is one-fourth and the second preset ratio is three-fourths.

[0116] As Figure 6 and Figure 7 shown, Figure 6 shows a schematic diagram of combining the emission beams of 4 1×4 linear array emission chips into a 16-line emission system using a wedge lens in the extended manner, Figure 7 shows a schematic diagram of combining the emission beams of 4 1×4 linear array emission chips into a 16-line emission system using a wedge lens in the staggered manner.

[0117] For the extended manner, it means that each light-emitting array unit of the 4 linear array emission chips corresponds to a determined field-of-view angle range, and there is no superposition of the emission angles of the light-emitting array units. The detection pitch angle range of the system is doubled, and the pitch angle resolution remains unchanged.

[0118] Specifically, the detection beam field-of-view ranges corresponding to the light-emitting units 1, 2, 3, and 4 of the 1×4 linear array emission chip 1 at the chip center position F1 are φ 16 、φ 15 、φ 14 、φ 13 , the detection beam field-of-view ranges corresponding to the light-emitting units 1″′, 2″′, 3″′, and 4″′ of the 1×4 linear array emission chip 2 at the chip center position F2 are φ4, φ3, φ2, φ1, the detection beam field-of-view ranges corresponding to the light-emitting units 1″, 2″, 3″, and 4″ of the 1×4 linear array emission chip 3 at the chip center position F3 are φ8, φ7, φ6, φ5, and the detection beam field-of-view ranges corresponding to the light-emitting units 1′, 2′, 3′, and 4′ of the 1×4 linear array emission chip 4 at the chip center position F4 are φ 12 、φ 11 、φ 10 、φ9, and the field-of-view angle ranges from φ1 to φ 16Gradually decrease, and the field of view angles do not overlap.

[0119] For this, by placing the linear array emission chip 1 on the side where y > 0, with the chip center in the yz plane, introducing a wedge-shaped lens 1 that only makes the virtual image point of the chip's light emission shift horizontally downward can make the linear array chip generate φ 16 、φ 15 、φ 14 、φ 13 field of view distribution. Similarly, by placing the linear array emission chip 2 on the side where y < 0, with the chip center in the yz plane, introducing a wedge-shaped lens 2 that only makes the virtual image point of the chip's light emission shift horizontally upward can make the linear array chip generate φ4, φ3, φ2, φ1 field of view distribution. By placing the linear array emission chip 3 on the side where x < 0, with the chip center in the xz plane, limited by the chip package size, the chip center is greater than or equal to w / 2 away from the yz plane. Introducing a wedge-shaped lens 3 that makes the virtual image point of the chip's light emission shift horizontally downward and laterally inward by w / 2 can make the linear array chip generate φ8, φ7, φ6, φ5 field of view distribution. Similarly, by placing the linear array emission chip 4 on the side where x > 0, with the chip center in the xz plane, limited by the chip package size, the chip center is greater than or equal to w / 2 away from the yz plane. Introducing a wedge-shaped lens 4 that makes the virtual image point of the chip's light emission shift horizontally upward and laterally inward by w / 2 can make the linear array chip generate φ 12 、φ 11 、φ 10 、φ9 field of view distribution. The light-emitting units of the linear array emission chips 1, 2, 3, and 4 are in the same z F plane, and the centers of F1, F2, F3, and F4 are distributed in four different directions. The virtual images formed by the light-emitting units of the linear array emission chips 1, 2, 3, and 4 through the wedge-shaped lens sheets 1, 2, 3, and 4 are in the same z’ F plane, and the distribution of the centers of F’1, F’2, F’3, and F’4 becomes a linear array distribution along the y-axis direction.

[0120] For the interleaved mode, it means forming a group of 8-line emission systems with gradually increasing and non-overlapping emission angles by combining each light-emitting array unit of 2 linear array emission chips, and forming another group of 8-line emission systems with gradually increasing and non-overlapping emission angles by combining each light-emitting array unit of the remaining 2 linear array emission chips. The emitted beams between the two groups of 8-line emission systems are staggered to form a 16-line emission system, and the detection pitch angle range of the system remains unchanged, and the pitch angle resolution is doubled.

[0121] Specifically, the arrangement of the four linear array chips can be the same as the above-mentioned staggered arrangement, that is, the linear array transmitting chip 1 is placed on the side where y>0, and the chip center is located in the yz plane. The linear array transmitting chip 2 is placed on the side where y<0, and the chip center is located in the yz plane. The linear array transmitting chip 3 is placed on the side where x<0, and the chip center is located in the xz plane, and the chip center is more than or equal to w / 2 away from the yz plane. The linear array transmitting chip 4 is placed on the side where x>0, and the chip center is located in the xz plane, and the chip center is more than or equal to w / 2 away from the yz plane. The field of view ranges of the detection beam bundles corresponding to the light-emitting units 1, 2, 3, and 4 of the 1×4 linear array transmitting chip 1 at the chip center position F1 are φ8, φ7, φ6, and φ5. The field of view ranges of the detection beam bundles corresponding to the light-emitting units 1″′, 2″′, 3″′, and 4″′ of the 1×4 linear array transmitting chip 2 at the chip center position F2 are φ4, φ3, φ2, and φ1. The field of view ranges of the detection beam bundles corresponding to the light-emitting units 1″, 2″, 3″, and 4″ of the 1×4 linear array transmitting chip 3 at the chip center position F3 are φ 12 、φ 11 、φ 10 、φ9. The field of view ranges of the detection beam bundles corresponding to the light-emitting units 1′, 2′, 3′, and 4′ of the 1×4 linear array transmitting chip 4 at the chip center position F4 are φ 16 、φ 15 、φ 14 、φ 13 ,and the fields of view are divided into two groups, φ1,…,φ8 and φ9,…,φ 16 ,and the field of view angles decrease gradually from φ1 to φ8 and from φ9 to φ 16 ,and there is no overlap in the field of view angles from φ1 to φ8 and from φ9 to φ 16 ,while the fields of view φ1,…,φ8 and φ9,…,φ 16 are staggered and separated from each other.

[0122] For the distribution of the fields of view, it can be achieved in the following way:

[0123] Introducing the wedge lens 1 that only makes the virtual image point of the chip's light emission shift horizontally downward can make the linear array chip produce the field of view distribution of φ8, φ7, φ6, and φ5. Introducing the wedge lens 2 that only makes the virtual image point of the chip's light emission shift horizontally upward can make the linear array chip produce the field of view distribution of φ4, φ3, φ2, and φ1. Introducing the wedge lens 3 that makes the virtual image point of the chip's light emission shift horizontally downward and laterally inward by w / 2 can make the linear array chip produce φ 12 、φ 11 、φ 10 、φ9 field of view distribution. Introducing the wedge lens 4 that makes the virtual image point of the chip's light emission shift horizontally upward and laterally inward by w / 2 can make the linear array chip produce φ 16 、φ 15 、φ 14 、φ 13Field of view distribution. The light-emitting units of the linear array emission chips 1, 2, 3, and 4 are in the same z F plane, and the centers of F1, F2, F3, and F4 are distributed in four different directions respectively. The virtual images formed by the light-emitting units of the linear array emission chips 1, 2, 3, and 4 through the wedge-shaped lens sheets 1, 2, 3, and 4 are located in the same z’ F plane, and the distribution of the centers of F’1, F’2, F’3, and F’4 becomes a 16-line array distribution along the y-axis direction or forms two groups of 8-line arrays that are horizontally staggered and longitudinally alternating.

[0124] In this way, in actual production, 4 linear array emission chips can be arranged on the same circuit board, and 4 corresponding wedge-shaped lenses can be made to obtain a 16-line emission system with different field of view distributions. In this way, by changing the parameters of the wedge-shaped lens group, the field of view distribution of the multi-line emission can be changed without adjusting the chip arrangement, and the system has better flexibility and adaptability.

[0125] In a possible implementation manner, when the light-emitting unit is a vertical cavity surface emitting laser, the arrangement manner of multiple chips and lenses is a square arrangement manner, and the square arrangement manner is to arrange the light-emitting units in the multiple chips and lens combinations according to a square.

[0126] Specifically, for the array light-emitting units of the vertical cavity surface emitting laser type, the emitted light spot is circular, that is, σ x = σ y = σ. A wedge-shaped lens group can be used to convert the VCSEL emission array arranged in an N×N square into an N×N multi-line laser emission system, as Figure 8 shown. Assuming that the light-emitting diameter of the VCSEL array is q and the array element pitch is p, a wedge-shaped lens with an aperture of p is introduced for each light-emitting array element to cause the virtual image point of the center of the light-emitting unit to have lateral and lateral offsets, and then a multi-line laser emission system is realized through a collimating lens with a focal length of f. In this way:

[0127] When N = 2k + 1, the center F1 coordinate of the light-emitting unit 1 is (kp, kp, z F ), the center F2 coordinate of the light-emitting unit 2 is (kp - p, kp, z F ), ……, the center F of the light-emitting unit N N coordinate is (-kp, kp, z F ), the center F of the light-emitting unit N + 1 N+1 coordinate is (kp, kp - p, z F ), the center F of the light-emitting unit 2N 2N coordinate is (-kp, kp - p, z F ), the center F of the light-emitting unit NN NN coordinate is (-kp, -kp, z F), that is, wedge-shaped lenses 1, 2, …, N are respectively introduced at the centers of the light-emitting units 1, 2, …, N. Among them, the wedge-shaped lens 1 causes the virtual image point F’1 of the center F1 of the light-emitting unit 1 to be laterally offset by bp / 2 and laterally offset by -kp, that is, the coordinates of the virtual image point F’1 are (0, kp + bp / 2, z′ F ), the wedge-shaped lens 2 causes the virtual image point F’2 of the center F2 of the light-emitting unit 2 to be laterally offset by bp / 2 - bp / N and laterally offset by -kp + p, that is, the coordinates of the virtual image point F’2 are (0, kp + bp / 2 - bp / N, z′ F ), the wedge-shaped lens N causes the virtual image point F N of the center F N to be laterally offset by -bp / 2 and laterally offset by kp, that is, the virtual image point F’ N has coordinates (0, kp - bp / 2, z′ F ), the wedge-shaped lens N + 1 causes the virtual image point F N+1 of the center F of the next-row light-emitting unit N + 1 N+1 to be laterally offset by bp / 2 and laterally offset by -kp, that is, the virtual image point F’ N+1 has coordinates (0, kp - p + bp / 2, z′ F ), the wedge-shaped lens 2N causes the virtual image point F’2N of the center F of the light-emitting unit 2N 2N to be laterally offset by -bp / 2 and laterally offset by kp, that is, the virtual image point F’ N+1 has coordinates (0, kp - p - bp / 2, z′ F ), and so on. The wedge-shaped lens NN causes the virtual image point F NN of the center F of the light-emitting unit NN NN to be laterally offset by bp / 2 and laterally offset by kp, that is, the virtual image point F’ N+1 has coordinates (0, -kp - bp / 2, z′ F ), where b is the longitudinal magnification of each wedge-shaped lens.

[0128] In this way, a multi-line laser emission system with the following field-of-view distribution can be realized by arranging the wedge-shaped lens array in the above manner for the VCSEL array light-emitting units arranged in an N×N square and then adding a collimating lens with a focal length of f:

[0129] When N = 2k, the coordinates of the center F1 of the light-emitting unit 1 are (kp - p / 2, kp - p / 2, z F ), the coordinates of the center F2 of the light-emitting unit 2 are (kp - p / 2 - p, kp - p / 2, z F ), the coordinates of the center F of the light-emitting unit N N are (-kp + p / 2, kp - p / 2, z F ), the coordinates of the center F of the light-emitting unit N + 1N+1 The coordinates are (kp - p / 2, kp - p / 2 - p, z F ), and the center F of the light-emitting unit 2N 2N The coordinates are (-kp + p / 2, kp - p / 2 - p, z F ), and the center F of the light-emitting unit NN NN The coordinates are (-kp + p / 2, -kp + p / 2, z F ), respectively, wedge-shaped lenses 1, 2, …, N are introduced at the centers of the light-emitting units 1, 2, …, N. Among them, the wedge-shaped lens 1 makes the virtual image point F’1 of the center F1 of the light-emitting unit 1 laterally offset by bp / 2 and laterally offset by -kp + p / 2, that is, the coordinates of the virtual image point F’1 are (0, kp - p / 2 + bp / 2, z′ F ), the wedge-shaped lens 2 makes the virtual image point F’2 of the center F2 of the light-emitting unit 2 laterally offset by bp / 2 - bp / N and laterally offset by -kp + p + p / 2, that is, the coordinates of the virtual image point F’2 are (0, kp - p / 2 + bp / 2 - bp / N, z′ F ), the wedge-shaped lens N makes the virtual image point F N of the center F of the light-emitting unit N N laterally offset by -bp / 2 and laterally offset by kp - p / 2, that is, the virtual image point F’ N The coordinates are (0, kp - p / 2 - bp / 2, z′ F ), the wedge-shaped lens N + 1 makes the virtual image point F N+1 of the center F of the next row of light-emitting unit N + 1 N+1 laterally offset by bp / 2 and laterally offset by -kp + p / 2, that is, the virtual image point F’ N+1 The coordinates are (0, kp - p / 2 + bp / 2, z′ F ), the wedge-shaped lens 2N makes the virtual image point F’2N of the center F of the light-emitting unit 2N laterally offset by -bp / 2 and laterally offset by kp - p / 2, that is, the virtual image point F’ 2N The coordinates are (0, kp - 3p / 2 - bp / 2, z′ N+1 ), and so on. The wedge-shaped lens NN makes the virtual image point F’NN of the center F of the light-emitting unit NN laterally offset by bp / 2 and laterally offset by kp - p / 2, that is, the virtual image point F’ F The coordinates are (0, -kp + p / 2 - bp / 2, z′ NN ), where b is the longitudinal magnification of each wedge-shaped lens. N+1 ), where b is the longitudinal magnification of each wedge-shaped lens. F )

[0130] In this way, a multi-line laser emission system with the following field-of-view distribution can be realized by arranging the wedge-shaped lens array in the above manner for the VCSEL array light-emitting units arranged in an N×N square and then adding a collimating lens with a focal length of f:

[0131] When b = 1, a multi-line laser emission system with a uniform field of view interval can be obtained through a VCSEL array arranged in a square. For example, the light-emitting units of an 8×8 square-arranged VCSEL array can realize a 64-line laser emission system with a uniform field of view distribution: The above arrangements and field of view distributions are only exemplary, and actual designs can be made according to different required parameters.

[0132] In an embodiment of the present invention, a multi-line lidar emission system is provided, which includes a combination of multiple chips and lenses. Each chip and lens combination includes a transmitting chip and its corresponding wedge-shaped lens, and the transmitting chip includes one or more light-emitting units. Since each wedge-shaped lens in the emission system is used to offset the virtual image formed by the light-emitting units of its corresponding transmitting chip in a preset direction, so that the field of view distributions of the light-emitting units of all transmitting chips do not overlap. Therefore, by changing the parameters of the wedge-shaped lens group, the multi-line emission field of view distribution can be changed without adjusting the chip arrangement. Thus, multiple general-purpose transmitting chips can be combined to realize a multi-line lidar emission system, and this emission system has good flexibility and adaptability. In this way, a multi-line lidar can be realized with general-purpose transmitting chips or array chips, which not only greatly expands the selection range of transmitting chips, reduces the chip cost, but also avoids the problems of long development cycle and low yield rate caused by customized chips.

[0133] It should be understood that the magnitudes of the sequence numbers of the steps in the above embodiments do not mean the order of execution. The execution order of each process should be determined according to its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.

[0134] An embodiment of the present invention also provides a multi-line lidar, as Figure 9 shown. This multi-line lidar includes the aforementioned emission system.

[0135] In the above embodiments, the descriptions of each embodiment have their own emphases. For parts not detailed or recorded in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0136] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A transmitting system of a multi-line lidar, characterized in that, Comprising a plurality of chip and lens combinations, each of the chip and lens combinations includes a transmitting chip and its corresponding wedge-shaped lens, and the transmitting chip includes one or more light-emitting units; Each of the wedge-shaped lenses is configured to shift the virtual image formed by the light-emitting units of its corresponding transmitting chip in a preset direction, so that the field-of-view distributions of the light-emitting units of all the transmitting chips do not overlap; wherein, the preset direction is the x direction and / or the y direction in a preset coordinate system, and the z direction of the preset coordinate system is the direction where the optical axis of the wedge-shaped lens is located; The rear surface of the wedge-shaped lens is an inclined plane, the rear surface is located on the side of the light-emitting point of its corresponding light-emitting unit, and the included angle α between the rear surface and the tangent plane of the wedge-shaped lens satisfies the following condition: where n is the refractive index of the material of the wedge-shaped lens, y F is the distance between the light-emitting point and the optical axis of the wedge-shaped lens, z F is the distance between the light-emitting point and the rear surface in the direction of the optical axis, and the section plane is perpendicular to the optical axis; The front surface of the wedge-shaped lens is a curved surface, and the surface shape of the curved surface satisfies the following condition: L1 + nL2 - L3 = L 10 + nL 20 - L 30 ; Wherein, L1 is the distance between the light-emitting point and the incident point where any ray emitted therefrom enters the rear surface, L2 is the distance between the incident point and the exit point where the ray at any angle leaves the front surface, L3 is the distance between the exit point and the virtual image point formed by the wedge-shaped lens for the light-emitting point, and L 10 is the distance between the light-emitting point and the first intersection point, where the first intersection point is the point where the optical axis intersects the rear surface, and L 20 is the distance between the first intersection point and the second intersection point, where the second intersection point is the point where the optical axis intersects the front surface, and L 30 is the distance between the second intersection point and the virtual image point; The vertical magnification b near the chief ray of the light-emitting unit satisfies the following condition: Wherein, y is the object height of the light-emitting point of the light-emitting unit, y′ is the image height of the light-emitting point of the light-emitting unit, the incident angle of the chief ray on the rear surface relative to the rear surface normal is u, the refraction angle is u′, the incident angle of the chief ray transmitted to the front surface relative to the front surface normal is v′, and the refraction angle is v.

2. The emission system of the multi-line lidar according to claim 1, characterized in that The surface shape of the front surface is obtained by fitting a polynomial fitting equation set of the front surface through a preset fitting algorithm, and the polynomial fitting equation set is based on a plurality of rear surface coordinate points discretely selected on the rear surface.

3. The emission system of the multi-line lidar according to claim 1, characterized in that The arrangement mode of the plurality of chip and lens combinations is an extended mode, and the extended mode is an arrangement mode in which the emission angles of all the light-emitting units do not overlap.

4. The emission system of the multi-line lidar according to claim 1, characterized in that, The arrangement mode of the plurality of chip and lens combinations is an interleaved mode, and the interleaved mode is: Arranging a first preset proportion of the plurality of chip and lens combinations as a first emission system in which the emission angles of the light-emitting units gradually increase and do not overlap, and arranging a second preset proportion of the plurality of chip and lens combinations as a second emission system in which the emission angles of the light-emitting units gradually increase and do not overlap, and the emission angles of the light-emitting units in the first emission system and the second emission system are complementary and overlapping; wherein, the sum of the first preset proportion and the second preset proportion is one.

5. The emission system of the multi-line lidar according to claim 1, wherein The model relationships of the transmitting chips in the plurality of chip and lens combinations are different from each other, all the same, or partially the same.

6. The emission system of the multi-line lidar according to claim 1, characterized in that The light-emitting unit is a vertical-cavity surface-emitting laser or an edge-emitting laser.

7. The emission system of the multi-line lidar according to claim 6, characterized in that, In the case where the light-emitting unit is a vertical-cavity surface-emitting laser, the arrangement mode of the plurality of chip and lens combinations is a square arrangement mode, and the square arrangement mode is to arrange the light-emitting units in the plurality of chip and lens combinations according to a square.

8. A multi-line lidar, characterized in that, The multi-line lidar includes the emission system according to any one of claims 1 to 7.

Images