Optical system and lidar

Abstract

This application provides an optical system and a lidar. The optical system includes: a light source comprising multiple light-emitting units; a microlens assembly comprising at least one microlens array, wherein the microlenses in the microlens array correspond to the light-emitting units, and the light-emitting units are located at the focal points of the microlenses; a microprism assembly comprising a light-transmitting substrate and a microprism array formed on the light-transmitting substrate, wherein the microprism array faces the microlens array, and the microprisms in the microprism array correspond to the microlenses in the microlens array; and an aperture stop, wherein light emitted by the light-emitting units is collimated by the microlenses and then incident on the microprisms, and exits from the aperture stop after being refracted by the microprisms. This optical system enables light spots at the edge of the field of view to have almost the same quality as the light spots in the central field of view, thereby improving the point cloud quality of the edge field of view.

Description

Technical Field

[0001] This application relates to the field of lidar technology, and more particularly to an optical system and lidar. Background Technology

[0002] With the development and application of LiDAR technology, the market demand for LiDAR with a large field of view is increasing. Currently, most LiDAR products on the market strive to achieve a large field of view to expand the detection range. However, the spot quality at the edges of the field of view is far worse than that at the center, which can affect the normal operation of the LiDAR to some extent.

[0003] Therefore, how to improve the spot quality at the edge of the field of view while increasing the field of view angle has become an urgent technical problem to be solved. Summary of the Invention

[0004] The main objective of this application is to provide an optical system and a lidar that enables the lidar using the optical system to have both a large field of view and high-quality light spots at the edge of the field of view.

[0005] In a first aspect, this application provides an optical system for use in lidar, the optical system comprising:

[0006] A light source, comprising multiple light-emitting units;

[0007] A microlens assembly, the microlens assembly including at least one microlens array, wherein the microlenses in the microlens array correspond to the light-emitting unit, and the light-emitting unit is located at the focal point of the microlens;

[0008] A microprism assembly, comprising a light-transmitting substrate and a microprism array formed on the light-transmitting substrate, wherein the microprism array is disposed facing the microlens array, and the microprisms in the microprism array correspond to the microlenses in the microlens array; and

[0009] An aperture is formed by light emitted from the light-emitting unit being collimated by the microlens and then incident on the microprism, and refracted by the microprism before exiting from the aperture.

[0010] In one embodiment, the optical system satisfies the following relationship:

[0011]

[0012] Wherein, d1 is the diameter of the microlens, d2 is the width of the microprism, the width being the width of the surface of the microprism in contact with the light-transmitting substrate, f is the focal length of the microlens, and θ is the divergence angle of the light-emitting unit.

[0013] In one embodiment, the number of light-emitting units, the number of microlenses in the microlens array, and the number of microprisms in the microprism array are the same and correspond one-to-one.

[0014] In one embodiment, in the microprism array, multiple microprisms have the same width, which is the width of the surface of the microprism in contact with the light-transmitting substrate.

[0015] In one embodiment, in the microprism array, the height of the microprisms closer to the center of the light-transmitting substrate is less than the height of the microprisms farther from the center, wherein the height is the distance between the vertex of the microprism and the surface of the light-transmitting substrate in contact with the microprism.

[0016] In one embodiment, the light-emitting unit is a vertical cavity surface-emitting laser, and the microlens array is a microspherical lens array or a microaspherical lens array.

[0017] In one embodiment, the light-emitting unit is a side-emitting laser, and at least one of the microlens arrays includes a fast-axis collimated microcylindrical lens array and a slow-axis collimated microcylindrical lens array.

[0018] In one embodiment, the microprism array is made of flint glass.

[0019] In one embodiment, the multiple microprisms in the microprism array are symmetrically arranged about the centerline of the light-transmitting substrate.

[0020] Secondly, embodiments of this application also provide a lidar, which includes the optical system provided in any embodiment of this application.

[0021] This application provides an optical system in which a microprism array is positioned facing a microlens array. This reduces the amplification effect of the microprism array on light, thereby reducing the divergence angle of the light emitted from the aperture. Consequently, the light spot at the edge of the field of view has almost the same quality as the light spot in the center of the field of view. The lidar using the optical system provided in this application not only has a large field of view, but also produces a high-quality light spot within the field of view, regardless of whether it is at the edge or the center. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the structure of an optical system provided in one embodiment of this application;

[0024] Figure 2 for Figure 1 The simulation results of the field of view of the optical system are shown in the figure.

[0025] Figure 3 This is a schematic diagram of the structure of an optical system in related technologies;

[0026] Figure 4 for Figure 3 The simulation results of the field of view of the optical system are shown in the figure.

[0027] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0028] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0029] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0030] Please refer to Figure 1 , Figure 1 This is a schematic diagram of an optical system according to an embodiment of this application. The optical system 100 can be applied to devices such as lidar, 3D SLAM scanners, and 3D spatial scanners. The optical system 100 includes a light source 10, a microlens assembly 20, a microprism assembly 30, and an aperture 40.

[0031] The light source 10 can be a laser light source, which includes multiple light-emitting units 11. Figure 1 The structural diagram shown only illustrates four light-emitting units 11. It can be understood that the number and arrangement of these light-emitting units 11 can be set according to actual needs, and no specific restrictions are imposed here.

[0032] In one embodiment, the light-emitting unit 11 can be a vertical-cavity surface-emitting laser (VCSEL), or other lasers, such as an edge-emitting laser (EEL). The specific type of the light-emitting unit 11 can be set according to actual needs, and no specific limitation is made here.

[0033] The microlens assembly 20 includes a first light-transmitting substrate 21 and at least one microlens array 22. Figure 1 In the schematic diagram shown, there is one microlens array 22, which is formed on a surface of the first light-transmitting substrate 21 away from the light-emitting unit 11, and is used to collimate the laser emitted by the light-emitting unit 11.

[0034] The microlenses in the microlens array 22 correspond to the light-emitting unit 11, which is located at the focal point of the microlens, thereby enabling the microlens to collimate the laser emitted by the corresponding light-emitting unit 11.

[0035] In one embodiment, when the light-emitting unit 11 is a vertical-cavity surface-emitting laser, the microlens array 22 can be a microspherical lens array or a microaspherical lens array. The microlenses in the microlens array 22 can correspond one-to-one with the light-emitting units 11, and the number of microlenses is the same as the number of light-emitting units 11. It is understood that the correspondence between the microlenses and the light-emitting units 11 is not limited to a one-to-one correspondence; other correspondences are also possible, and no specific limitations are imposed here.

[0036] In one embodiment, when the light-emitting unit 11 is a side-emitting laser, at least one of the microlens arrays 22 can be a combination of a fast-axis collimating microcylindrical lens array and a slow-axis collimating microcylindrical lens array. That is, the microlens assembly 20 includes two first transparent substrates 21, with the fast-axis collimating microcylindrical lens array and the slow-axis collimating microcylindrical lens array respectively formed on the surfaces of the two first transparent substrates 21 away from the light-emitting unit 11. Thus, after the laser is emitted from the light-emitting unit 11, it passes sequentially through the first transparent substrate 21, the fast-axis collimating microcylindrical lens array, the first transparent substrate 21, and the slow-axis collimating microcylindrical lens array. At this time, one microlens in the microlens array 22 can correspond to multiple light-emitting units 11.

[0037] The microprism assembly 30 includes a light-transmitting substrate 31 and a microprism array 32 formed on the light-transmitting substrate 31. For ease of understanding, the light-transmitting substrate 31 can be referred to as a second light-transmitting substrate. The microprism array 32 is disposed facing the microlens array 22, that is, the microprism array 32 is disposed on the light incident surface of the light-transmitting substrate 31. The microprisms in the microprism array 32 correspond to the microlenses in the microlens array 22 and are used to refract the light after it has been collimated by the microlenses.

[0038] In one embodiment, to further improve the quality of the center and edge light spots of the optical system 100, the diameter d1 of the microlens and the width d2 of the microprism can be set to satisfy the following relationship:

[0039]

[0040] The width of the microprism is the width of the surface of the microprism in contact with the light-transmitting substrate 31 (e.g., ...). Figure 1 (As shown), f is the focal length of the microlens, and θ is the divergence angle of the light-emitting unit 11.

[0041] In one embodiment, such as Figure 1 As shown, in the microprism array 32, multiple microprisms have the same width. The height h of the microprisms closer to the center of the light-transmitting substrate 31 is smaller than the height h of the microprisms farther from the center. The multiple microprisms are symmetrically arranged about the center line L of the light-transmitting substrate 31. The height of each microprism is the distance from its apex to the surface of the light-transmitting substrate 31 that contacts the microprism.

[0042] In one embodiment, the number of light-emitting units 11, the number of microlenses in the microlens array 22, and the number of microprisms in the microprism array 32 can be the same and correspond one-to-one. For example, when the light-emitting unit 11 is a vertical cavity surface-emitting laser and the microlens array 22 is a microspherical lens array, one light-emitting unit 11 corresponds to one microspherical lens and one microprism, so that the light emitted by the light-emitting unit 11 is collimated by the microspherical lens and then enters the microprism, and exits from the aperture 40 after being refracted by the microprism.

[0043] It is understandable that the number of light-emitting units 11, the number of microlenses in the microlens array 22, and the number of microprisms in the microprism array 32 may not be the same, and the correspondence is not limited to one-to-one correspondence. Both the number and the correspondence can be set according to actual needs, and no specific restrictions are imposed here.

[0044] In one embodiment, in order to improve imaging quality, the microprism array 32 can be made of a high refractive index material. For example, the material of the microprism array 32 can be flint glass, specifically, such as H-ZLAF92.

[0045] exist Figure 1 In the structure shown, the aperture 40 is an independent optical element. Of course, the aperture 40 can also be the light output window of the lidar, which can save space and reduce the size of the lidar.

[0046] To verify that the optical system in this embodiment can obtain high-quality edge spots, a specific experiment is given below.

[0047] In this experiment, such as Figure 1 As shown, the light-emitting unit 11 is a VCSEL with a wavelength of 905nm. The distance between two adjacent light-emitting units 11 is 2mm. The light-emitting size of the light-emitting unit 11 is 20μm, and the full width at half maximum (FWHM) divergence angle θ of the light-emitting unit 11 is 16°. After collimation by the microlens assembly 20, the divergence angle is required to be reduced to 0.2°. The focal length f of the microlens is 5.7mm, the diameter d1 of the microlens is 1.8mm, and the spacing between two adjacent microlenses is 0.2mm. In the microprism array 32, the material of the microprisms is H-ZLAF92, and the width d2 of all microprisms is 1.8mm. Figure 1 In the vertical direction shown, that is, the direction perpendicular to the center line L, the four microprisms from top to bottom have corresponding heights h of 0.99mm, 0.32mm, 0.32mm and 0.99mm, respectively. Their corresponding refracted beam angles are -30°, -10°, 10° and 30°, respectively, and their corresponding refracted beam divergence angles are all 0.2°.

[0048] The simulation results of the field of view of the optical system 100, based on the parameters set above, are as follows: Figure 2 As shown. From Figure 2 It can be seen that within the field of view, the quality of the edge spot is consistent with that of the center spot, exhibiting excellent edge field of view image quality, thus resulting in higher quality point cloud at the edge of the field of view.

[0049] like Figure 3 As shown, Figure 3 This is a schematic diagram of the structure of an optical system in related technologies. Figure 3In the optical system 200 shown, light emitted from the light source 10a is collimated by the microlens assembly 20a and then incident on the microprism assembly 30a. After refraction by the microprism assembly 30a, it exits from the aperture 40a. In the microprism assembly 30a, the microprism array 32a is located on the surface of the transparent substrate 31a away from the light source 10a. This magnifies the collimated light, increasing the divergence angle, resulting in severe divergence of the edge light spots in the field of view, with the quality of the edge light spots being far inferior to that of the central light spot. Specifically, Figure 4 As shown, Figure 4 for Figure 3 The simulation results of the field of view spot of the optical system are shown. With the parameters set the same as in the above experiment, from... Figure 4 The simulation results show that the edge light spots are severely diverged, resulting in very poor image quality.

[0050] In summary, the optical system provided in this application embodiment enables the edge light spots and the central light spot within the field of view to have essentially the same image quality, improving the point cloud quality in the edge field of view. Simultaneously, because the microlens array 22 and the microprism array 32 can be made very small and thin, the size of this optical system can be greatly simplified, achieving a large field of view while also reducing its size and exposed window. Furthermore, since the microprism array 32 is located on the surface of the light-transmitting substrate 31 facing the light source 10, this arrangement facilitates encapsulation and subsequent installation, reducing damage caused by the exposed microprism array 32. Finally, compared to other methods for improving the image quality of edge light spots, the microprism assembly 30 of this application has a lower manufacturing cost, reducing the manufacturing cost of optical systems with high-quality edge light spots.

[0051] One embodiment of this application also provides a lidar that utilizes the optical system described in any of the above embodiments. For the sake of brevity, the structure and working principle of the optical system used in this lidar can be referred to the foregoing embodiments, and will not be repeated here.

[0052] Because this lidar uses the optical system provided in this application, it can have a large field of view while also having high-quality edge spot, thus improving the image quality.

[0053] The foregoing disclosure provides many different implementations or examples for carrying out different structures of this application. To simplify the disclosure, the components and arrangements of specific examples are described above. Of course, these are merely examples and are not intended to limit the scope of this application. Any non-substantial changes and substitutions made by those skilled in the art based on this application are within the scope of protection claimed by this application.

[0054] Furthermore, reference numerals and / or reference letters may be repeated in different examples in this application. Such repetition is for simplification and clarity purposes and does not in itself indicate a relationship between the various embodiments and / or settings discussed. In addition, this application provides examples of various specific processes and materials; however, those skilled in the art will recognize the application of other processes and / or the use of other materials.

Claims

1. An optical system, characterized in that, The optical system, used in lidar, includes: A light source, comprising multiple light-emitting units; A microlens assembly, the microlens assembly including at least one microlens array, wherein the microlenses in the microlens array correspond to the light-emitting unit, and the light-emitting unit is located at the focal point of the microlens; A microprism assembly, comprising a light-transmitting substrate and a microprism array formed on the light-transmitting substrate, wherein the microprism array is disposed facing the microlens array, and the microprisms in the microprism array correspond to the microlenses in the microlens array; and An aperture is formed by light emitted from the light-emitting unit being collimated by the microlens and then incident on the microprism, and refracted by the microprism before exiting from the aperture. The optical system satisfies the following relationship: in, The diameter of the microlens is [missing information]. The width of the microprism is the width of the surface of the microprism that contacts the light-transmitting substrate. The focal length of the microlens is... The divergence angle of the light-emitting unit is given.

2. The optical system according to claim 1, characterized in that, The number of light-emitting units, the number of microlenses in the microlens array, and the number of microprisms in the microprism array are the same and correspond one-to-one.

3. The optical system according to claim 1, characterized in that, In the microprism array, multiple microprisms have the same width, which is the width of the surface of the microprism in contact with the light-transmitting substrate.

4. The optical system according to claim 3, characterized in that, In the microprism array, the height of the microprisms closer to the center of the light-transmitting substrate is less than the height of the microprisms farther from the center, wherein the height is the distance between the vertex of the microprism and the surface of the light-transmitting substrate in contact with the microprism.

5. The optical system according to claim 1, characterized in that, The light-emitting unit is a vertical cavity surface-emitting laser, and the microlens array is a microspherical lens array or a microaspherical lens array.

6. The optical system according to claim 1, characterized in that, The light-emitting unit is an edge-emitting laser, and at least one of the microlens arrays includes a fast-axis collimated microcylindrical lens array and a slow-axis collimated microcylindrical lens array.

7. The optical system according to claim 1, characterized in that, The microprism array is made of flint glass.

8. The optical system according to claim 1, characterized in that, The microprisms in the microprism array are symmetrically arranged about the center line of the light-transmitting substrate.

9. A lidar, characterized in that, The lidar includes the optical system described in any one of claims 1-8.

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