Optical system and laser radar

Abstract

The invention provides an optical system and a laser radar, and the optical system comprises a light source which comprises a plurality of light-emitting units; the micro-lens assembly comprises at least one micro-lens array, micro-lenses in the micro-lens array correspond to the light-emitting units, and the light-emitting units are located on focuses of the micro-lenses; the micro-prism assembly comprises a light-transmitting substrate and a micro-prism array formed on the light-transmitting substrate, the micro-prism array is arranged facing the micro-lens array, and micro-prisms in the micro-prism array correspond to micro-lenses in the micro-lens array; and the light emitted by the light emitting unit is collimated by the micro lens, then enters the micro prism, is refracted by the micro prism, and then exits from the diaphragm. According to the optical system, the quality of the light spots in the edge field of view in the field of view is almost the same as that of the light spots in the center field of view, and the point cloud quality of the edge field of view is improved.

Description

Technical Field

[0001] This application relates to the technical field of lidar, and particularly to an optical system and a lidar. Background Art

[0002] With the development and application of lidar technology, the market has an increasingly high demand for lidars with a large field of view. Currently, all lidars on the market are pursuing the effect of achieving a large field of view to expand the detection range. However, for such lidars, the spot quality in the edge field of view is much worse than that in the central field of view, which will to a certain extent affect the normal use of the lidar.

[0003] Therefore, how to improve the spot quality in the edge field of view while increasing the field of view has become a technical problem to be urgently solved. Summary of the Invention

[0004] The main purpose of this application is to provide an optical system and a lidar, such that the lidar applying this optical system has both a large field of view and high-quality spots in the edge field of view.

[0005] In a first aspect, this application provides an optical system, which is applied to a lidar. The optical system includes:

[0006] A light source, the light source includes a plurality of light-emitting units;

[0007] A microlens assembly, the microlens assembly includes at least one microlens array. Among them, the microlenses in the microlens array correspond to the light-emitting units, and the light-emitting units are located at the foci of the microlenses;

[0008] A microprism assembly, the microprism assembly includes a light-transmitting substrate and a microprism array formed on the light-transmitting substrate. Among them, the microprism array faces the microlens array, and the microprisms in the microprism array correspond to the microlenses in the microlens array; and

[0009] A diaphragm, the light emitted by the light-emitting units is collimated by the microlenses and then incident on the microprisms, and is refracted by the microprisms and then exits from the diaphragm.

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

[0011]

[0012] Among them, d1 is the diameter of the microlens, d2 is the width of the microprism, the width is the width of the surface where the microprism contacts 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 the light-emitting units, the number of microlenses of the microlens array, and the number of microprisms of the microprism array are the same and correspond to each other one by one.

[0014] In one embodiment, in the microprism array, the widths of a plurality of the microprisms are the same, and the width 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 microprism near the central position of the light-transmitting substrate is less than the height of the microprism far from the central position, where the height is the distance from the vertex of the microprism to 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 an edge-emitting laser, and at least one of the microlens arrays includes a fast-axis collimating microcylindrical lens array and a slow-axis collimating microcylindrical lens array.

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

[0019] In one embodiment, a plurality of microprisms in the microprism array are symmetrically arranged with respect to the center line of the light-transmitting substrate.

[0020] In a second aspect, an embodiment of the present application further provides a lidar, and the lidar includes the optical system provided in any embodiment of the present application.

[0021] An embodiment of the present application provides an optical system. The optical system arranges the microprism array on the side facing the microlens array, reduces the amplification effect of the microprism array on light, and further reduces the divergence angle of the light emitted from the aperture, so that the spot in the marginal field of view in the field of view has almost the same quality as the spot in the central field of view. The lidar using the optical system provided in the embodiment of the present application not only has a large field of view angle, but also has high-quality spots in the entire field of view, whether it is the marginal field of view or the central field of view. Description of the Drawings

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0023] Figure 1 Schematic structural diagram of an optical system provided by an embodiment of the present application;

[0024] Figure 2 is Figure 1 Simulation result diagram of the field spot of the optical system shown;

[0025] Figure 3 Schematic structural diagram of an optical system in the related art;

[0026] Figure 4 is Figure 3 Simulation result diagram of the field spot of the optical system shown.

[0027] The realization of the purpose of the present application, functional characteristics and advantages will be further described with reference to the embodiments and the accompanying drawings. Specific embodiments

[0028] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0029] Some embodiments of the present application will be described in detail below with reference to the accompanying drawings. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0030] Please refer to Figure 1 , Figure 1 Schematic structural diagram of an optical system provided by an embodiment of the present application. The optical system 100 can be applied to devices such as lidar, three-dimensional SLAM scanners, and three-dimensional space scanners. The optical system 100 includes a light source 10, a microlens assembly 20, a microprism assembly 30, and a diaphragm 40.

[0031] The light source 10 can be a laser light source, which includes a plurality of light-emitting units 11. In Figure 1 the schematic structural diagram shown, only four light-emitting units 11 are schematically shown. It can be understood that the number and arrangement of the light-emitting units 11 can be set according to actual needs and will not be specifically limited here.

[0032] In one embodiment, the light-emitting unit 11 may be a Vertical-Cavity Surface-Emitting Laser (VCSEL), or may be other lasers. For example, it may also be an Edge-Emitting Laser (EEL). The specific type of the light-emitting unit 11 may be set according to actual requirements and will not be specifically limited herein.

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

[0034] The microlenses in the microlens array 22 correspond to the light-emitting unit 11, and the light-emitting unit 11 is located at the focal point of the microlens, so that the microlens collimates 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 may be a micro-spherical lens array or a micro-asphere lens array. The microlenses in the microlens array 22 may correspond to the light-emitting unit 11 one by one, and at this time, the number of microlenses is the same as the number of light-emitting units 11. It can be understood that the correspondence between the microlenses and the light-emitting unit 11 is not limited to one-to-one correspondence, and may also be other correspondence relationships, which will not be specifically limited herein.

[0036] In one embodiment, when the light-emitting unit 11 is an edge-emitting laser, at least one of the microlens arrays 22 may be a combination of a fast-axis collimating micro-cylindrical lens array and a slow-axis collimating micro-cylindrical lens array. That is to say, two first light-transmitting substrates 21 are included in the microlens assembly 20, and the fast-axis collimating micro-cylindrical lens array and the slow-axis collimating micro-cylindrical lens array are respectively formed on the surfaces of the two first light-transmitting substrates 21 away from the light-emitting unit 11. In this way, after the laser is emitted from the light-emitting unit 11, it passes through the first light-transmitting substrate 21, the fast-axis collimating micro-cylindrical lens array, the first light-transmitting substrate 21, and the slow-axis collimating micro-cylindrical lens array in sequence. At this time, one microlens in the microlens array 22 may correspond to multiple light-emitting units 11.

[0037] The micro prism assembly 30 includes a light-transmitting substrate 31 and a micro prism array 32 formed on the light-transmitting substrate 31. For the convenience of understanding, the light-transmitting substrate 31 may be referred to as the second light-transmitting substrate. The micro prism array 32 is arranged facing the micro lens array 22, that is, the micro prism array 32 is arranged on the light incident surface of the light-transmitting substrate 31. The micro prisms in the micro prism array 32 correspond to the micro lenses in the micro lens array 22 and are used for refracting the light collimated by the micro lenses.

[0038] In one embodiment, in order to further improve the quality of the central spot and the edge spot of the optical system 100, the diameter d1 of the micro lens and the width d2 of the micro prism may satisfy the following relational expression:

[0039]

[0040] wherein, the width of the micro prism is the width of the surface of the micro prism in contact with the light-transmitting substrate 31 (as Figure 1 shown), f is the focal length of the micro lens, and θ is the divergence angle of the light-emitting unit 11.

[0041] In one embodiment, as Figure 1 shown, in the micro prism array 32, the widths of multiple micro prisms are the same, the height h of the micro prism near the center position of the light-transmitting substrate 31 is less than the height h of the micro prism far from the center position, and multiple micro prisms are symmetrically arranged with respect to the center line L of the light-transmitting substrate 31. Wherein, the height of the micro prism is the distance between the vertex of the micro prism and the surface of the light-transmitting substrate 31 in contact with the micro prism.

[0042] In one embodiment, the number of the light-emitting units 11, the number of the micro lenses in the micro lens array 22 and the number of the micro prisms in the micro prism array 32 may be the same and correspond one by one. For example, when the light-emitting unit 11 is a vertical cavity surface emitting laser and the micro lens array 22 is a micro spherical lens array, one light-emitting unit 11 corresponds to one micro spherical lens and one micro prism, so that the light emitted by the light-emitting unit 11 is collimated by the micro spherical lens and then enters the micro prism, and is refracted by the micro prism and exits from the aperture 40.

[0043] It can be understood that the number of the light-emitting units 11, the number of the micro lenses in the micro lens array 22 and the number of the micro prisms in the micro prism array 32 may also be different, and the corresponding manner is not limited to one-to-one correspondence. Both the number and the corresponding manner can be set according to actual needs and are not specifically limited herein.

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

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

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

[0047] In this test, as Figure 1 shown, the light - emitting unit 11 is a VCSEL, the optical wavelength is 905 nm, the distance between two adjacent light - emitting units 11 is 2 mm, the light - emitting size of the light - emitting unit 11 is 20 μm, the full - width at half - maximum divergence angle θ of the light - emitting unit 11 is 16°. After being collimated by the microlens assembly 20, the divergence angle is required to be reduced to 0.2°; the focal length f of the microlens is 5.7 mm, the diameter d1 of the microlens is 1.8 mm, and the interval between two adjacent microlenses is 0.2 mm; in the micro - prism array 32, the material of the micro - prism is H - ZLAF92, the width d2 of all micro - prisms is 1.8 mm, in Figure 1 the vertical direction shown, that is, in the direction perpendicular to the center line L, for the four micro - prisms from top to bottom, their corresponding heights h are 0.99 mm, 0.32 mm, 0.32 mm, and 0.99 mm 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] For the optical system 100 set according to the above parameters, the simulation result of the field - of - view spot is as Figure 2 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 central spot, having good image quality in the edge field of view, so that the point - cloud quality of the edge field of view is higher.

[0049] As Figure 3 shown, Figure 3 is a schematic structural diagram of an optical system in the related art. In Figure 3In the optical system 200 shown, the light rays emitted by the light source 10a are collimated by the microlens assembly 20a and then incident on the microprism assembly 30a, and after passing through the refraction of the microprism assembly 30a, they exit from the aperture 40a. In this microprism assembly 30a, the microprism array 32a is located on the surface of the light-transmitting substrate 31a away from the light source 10a. In this way, the microprism assembly 30a amplifies the collimated light rays, enlarging the divergence angle, resulting in serious divergence of the edge spots in the field of view, and the quality of the edge spots is much worse than that of the central spots. Specifically, Figure 4 as shown Figure 4 is Figure 3 the simulation result of the field-of-view spots of the optical system shown. When the set parameters are the same as those of the above experiment, from Figure 4 the shown simulation result, it can be seen that the divergence of the edge spots is serious and the image quality is very poor.

[0050] In summary, the optical system provided by the embodiment of the present application can make the edge spots and the central spots in the field of view have basically the same image quality, improving the point cloud quality at the edge of the field of view. At the same time, since 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. While achieving a large field of view angle, its size and the exposed window are also smaller. In addition, since the microprism array 32 is located on the surface of the light-transmitting substrate 31 facing the light source 10, such a setting is also more conducive to packaging and subsequent installation, reducing the damage caused by the exposure of the microprism array 32. Finally, compared with other methods for improving the image quality of edge spots, the manufacturing cost of the microprism assembly 30 of the present application is lower, reducing the manufacturing cost of the optical system with high-quality edge spots.

[0051] An embodiment of the present application further provides a lidar, which applies the optical system described in any of the above embodiments. For the sake of simplicity of the description, the structure and working principle of the optical system adopted by this lidar can refer to the foregoing embodiments and will not be elaborated herein.

[0052] Since this lidar applies the optical system provided by the present application, it can have a large field of view angle and at the same time can also have high-quality edge spots, improving the quality of the image quality.

[0053] The above disclosure provides many different embodiments or examples to implement different structures of the present application. To simplify the disclosure of the present application, the components and settings of specific examples are described above. Of course, they are only examples and are not intended to limit the present application. Any non-substantive changes and substitutions made by those skilled in the art based on the present application fall within the scope claimed by the present application.

[0054] In addition, the present application may repeat reference numerals and / or reference letters in different instances. This repetition is for the purpose of simplicity and clarity and does not in itself indicate a relationship between the various embodiments and / or configurations discussed. Further, the present application provides examples of various specific processes and materials, but one of ordinary skill in the art will recognize the applicability of other processes and / or the use of other materials.

Claims

1. An optical system, characterized in that, Applied to a lidar, the optical system includes: A light source, the light source including a plurality of 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 units, and the light-emitting units are located at the focal points of the microlenses; A microprism assembly, the microprism assembly including a light-transmitting substrate and a microprism array formed on the light-transmitting substrate, wherein the microprism array is arranged facing the microlens array, and the microprisms in the microprism array correspond to the microlenses in the microlens array; and An aperture, the light emitted by the light-emitting units is collimated by the microlenses and then incident on the microprisms, and is refracted by the microprisms and then exits from the aperture.

2. The optical system according to claim 1, wherein The optical system satisfies the following relationship: 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.

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

4. The optical system according to claim 1, wherein In the microprism array, the widths of a plurality of the microprisms are the same, the width being the width of the surface of the microprism in contact with the light-transmitting substrate.

5. The optical system according to claim 4, wherein In the microprism array, the height of the microprism near the central position of the light-transmitting substrate is less than the height of the microprism far from the central position, 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.

6. The optical system according to claim 1, wherein The light-emitting unit is a vertical-cavity surface-emitting laser, and the microlens array is a micro-spherical lens array or a micro-asphere lens array.

7. 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 collimating microcylindrical lens array and a slow-axis collimating microcylindrical lens array.

8. The optical system according to claim 1, wherein The material of the microprism array is flint glass.

9. The optical system according to claim 1, wherein A plurality of the microprisms in the microprism array are symmetrically arranged with respect to the center line of the light-transmitting substrate.

10. A lidar, characterized in that, The lidar includes the optical system according to any one of claims 1-9.

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