Optical system

Abstract

The application discloses an optical system and a laser radar detection system comprising the optical system. The optical system comprises: a transmitting front end comprising: a light source configured to emit a detection light; at least one collimating lens configured to collimate the detection light; and at least one microlens array comprising a plurality of microlens units, configured to divide the collimated detection light to form a plurality of light beams as a surface array light source, wherein the number of the plurality of light beams is the same as the number of the plurality of microlens units; and a lens assembly comprising at least one imaging lens configured to diverge the surface array light source formed after the microlens array.

Description

Technical Field

[0001] This application relates to the field of optical components, and more specifically, to an optical system. Background Technology

[0002] In recent years, the rapid development of automotive driver assistance systems has led to the widespread application of lenses in automobiles. For some specialized applications, such as lidar detection systems, to improve resolution and increase the detection field of view, a large-area point light source, such as a VCSEL array light source, is typically used at the transmitting end in conjunction with the lens. However, large-area light sources have very large luminous areas and are expensive. Moreover, some large-area light sources are composed of multiple small point light sources, such as VCSEL array light sources. The larger the luminous area of ​​the light source, the more severely it is affected by manufacturing processes and other factors, resulting in more small, non-emitting point light sources within the light source, which can even seriously affect the detection function and effect. Summary of the Invention

[0003] This application provides an optical system comprising: a transmitting front end including a light source for emitting a probe ray; at least one collimating lens for collimating the probe ray; and at least one microlens array including multiple microlens units for dividing the collimated probe ray into multiple beams as an area array light source, the number of multiple beams being the same as the number of multiple microlens units; and a lens assembly including at least one imaging lens for emitting the area array light source formed after passing through the microlens array.

[0004] In one embodiment, the transmitting front end further includes a homogenizer located between the light source and the collimating lens. The homogenizer includes multiple lens units to homogenize and shape the Gaussian-like beam emitted by the light source into a flat-top distribution.

[0005] In one embodiment, the light source includes at least one of LD and VCSEL.

[0006] In one embodiment, the collimating lens has a surface shape of at least one of a spherical surface, an aspherical surface, or a freeform surface.

[0007] In one implementation, for each microlens unit, the aperture D3 of the microlens unit and the focal length F3 of the microlens unit satisfy: D3 / F3≥0.1.

[0008] In one embodiment, the effective aperture D2 of the collimating lens facing the microlens array and the distance L2 from the light source to the collimating lens facing the light source on the optical axis satisfy: 0.5≤D2 / L2≤2.

[0009] In one embodiment, the effective aperture D2 of the collimating lens facing the microlens array and the emission diameter W of the light source satisfy: D2 / W≥3.

[0010] In one embodiment, the distance L1 from the light source to the side of the homogenizer facing the light source on the optical axis and the distance L2 from the light source to the side of the collimating lens facing the light source on the optical axis satisfy: L1 / L2≤0.5.

[0011] In one embodiment, the aperture D3 of the microlens unit and the effective aperture D2 of the collimating lens facing the microlens array satisfy: D3 / D2≤0.7.

[0012] In one embodiment, the distance L2 from the light source to the side of the collimating lens facing the light source on the optical axis and the distance TTL1 from the light source to the side of the microlens array facing the light source on the optical axis satisfy: L2 / TTL1≤1.

[0013] In one embodiment, the light-emitting diameter W of the light source and the focal length F2 of the collimating lens satisfy the condition: W / F2≤0.5.

[0014] In one embodiment, the light-emitting diameter W of the light source, the overall divergence angle θ of the light source, and the effective aperture D2 of the collimating lens facing the microlens array satisfy: W×θ / D2≤5.

[0015] In one embodiment, the light-emitting diameter W of the light source, the overall divergence angle θ of the light source, and the focal length F2 of the collimating lens satisfy: W×θ / F2≤5.

[0016] In one embodiment, the effective aperture D2 of the collimating lens facing the microlens array and the distance TTL1 between the light source and the side of the microlens array facing the light source on the optical axis satisfy: 0.2≤D2 / TTL1≤3.

[0017] In one embodiment, the focal length F2 of the collimating lens and the focal length F3 of the microlens unit satisfy: F2 / F3≥1.

[0018] In one embodiment, the focal length F3 of the microlens unit and the focal length F1 of the lens unit of the light homogenizer satisfy: F3 / F1≥1.

[0019] In one embodiment, the aperture D3 of the microlens unit and the effective aperture D1 of the lens unit of the light homogenizer satisfy: D3 / D1≥1.

[0020] In one embodiment, the effective aperture D2 of the collimating lens facing the microlens array satisfies the following condition with the full FOV of the optical system: D2 / (2×tan(FOV / 2)≤10.

[0021] In one embodiment, the air gap TTL2 between the microlens array and the imaging lens closest to the microlens array in the lens assembly, the focal length F3 of the microlens unit, and the aperture D3 of the microlens unit satisfy: 0.1≤(TTL2-F3)×D3 / (2×F3)≤10.

[0022] In one embodiment, the air gap TTL2 between the microlens array and the imaging lens closest to the microlens array on the optical axis and the distance TTL1 between the light source and the side of the microlens array facing the light source on the optical axis satisfy: 0.1≤TTL2 / TTL1≤1.5.

[0023] In one implementation, for each microlens unit, the aperture D3 of the microlens unit and the focal length F3 of the microlens unit satisfy: 1 / (2×sin(arctan(D3 / (2×F3))))≤2.5.

[0024] This application also provides a lidar detection system. The lidar detection system includes an optical system and a receiver according to this application. The optical system emits detection rays towards a target scene, and the receiver receives the portion of the detection rays reflected back by the target scene.

[0025] The optical system of this application, through the reasonable setting of the shape and optical power of the transmitting front end, adopts a small area light source, which is first homogenized and diverged to a certain size, then collimated by a collimating lens, and the light source is cut into the desired number of point light sources by a microlens array, so as to realize a large area array of point light sources. The optical system has at least one beneficial effect such as miniaturization, high resolution, high collimation, high uniformity, and large field of view. Attached Figure Description

[0026] Other features, objects, and advantages of this utility application will become more apparent from the following detailed description of the embodiments, taken in conjunction with the accompanying drawings. In the drawings:

[0027] Figure 1 A schematic diagram of an LD light source according to an embodiment of this application is shown;

[0028] Figure 2 A schematic diagram of the structure of the optical system according to Embodiment 1 of this application is shown;

[0029] Figure 3 A partial structural schematic diagram of the light-diffusing plate of the optical system according to Embodiment 1 of this application is shown;

[0030] Figure 4 A schematic diagram of the structure of the microlens array of the optical system according to Embodiment 1 of this application is shown;

[0031] Figure 5A schematic diagram showing the full range of emission angles of the optical system according to Embodiment 1 of this application is shown; and

[0032] Figure 6 A schematic diagram of the structure of an optical system according to Embodiment 2 of this application is shown. Detailed Implementation

[0033] To facilitate understanding of this application, a more complete description of the application will be provided below with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of exemplary embodiments of the application and are not intended to limit the scope of the application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0034] It should be noted that in this specification, the terms "first," "second," etc., are used only to distinguish one feature from another and do not imply any limitation on the features. Therefore, without departing from the teachings of this application, the first aspect discussed below may also be referred to as the second aspect, and vice versa.

[0035] In the accompanying drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are illustrated by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustrative purposes only and are not strictly to scale.

[0036] In this paper, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the location of the convexity is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the location of the concaveness is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each element closest to the first side is called the first side surface of the element, and the surface of each element closest to the second side is called the second side surface of the element.

[0037] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprising," when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. Furthermore, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire list of features, not individual elements in the list. Additionally, when describing embodiments of this application, the word "may" is used to mean "one or more embodiments of this application." And the term "exemplary" is intended to refer to an example or illustration.

[0038] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms (e.g., those defined in common dictionaries) shall be interpreted as having a meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formalized sense, unless expressly so specified herein.

[0039] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0040] The features, principles and other aspects of this application are described in detail below.

[0041] In an exemplary embodiment, the optical system sequentially includes an emitting front end and a lens assembly along the optical axis from the first side to the second side. The emitting front end includes a light source, a homogenizer, at least one collimating lens, and at least one microlens array. The light source emits probe rays. After being homogenized and shaped by the homogenizer, the probe rays form a near-flat-top distribution. After being collimated by the collimating lens, they enter the microlens array. The microlens array cuts the collimated beam into segments, the number of segments being the same as the number of microlens units in the array, forming a planar light source similar to a VCSEL array. Because the beam has a near-flat-top distribution before cutting, the edge divergence angle energy and the center divergence angle energy are relatively uniform. Therefore, the edge divergence angle energy and the center divergence angle energy are also relatively uniform after cutting. The homogenizer ensures that the energy within the beam at each position of the subsequent microlens array segmentation is the same, ensuring that the same detection distance can be achieved at different field-of-view angles. Without this beam homogenizer, since semiconductor light sources are all Gaussian-like distributed, the edge energy is weak. Therefore, after the beam is split by the microlens array, the edge energy is weak and the middle energy is strong. During detection, this can easily lead to unequal detection distances in different fields of view.

[0042] In an exemplary embodiment, the light source can be a single or combined area array light source such as an LD or VCSEL, whose divergence angle-energy distribution is a Gaussian-like distribution with weaker edge energy. Figure 1 The LD light source of this application is illustrated by way of example. From left to right, they are LD point light source, LD line light source and LD area array light source. However, this application does not limit the specific form of the light source. The light source of this application can also be any other suitable light source.

[0043] In an exemplary embodiment, the lens assembly includes at least one imaging lens for emitting a surface light source formed by the microlens array, the surface light source being used to detect a target object.

[0044] The optical system provided in this application can be used as a transmitter in, for example, a lidar system. It employs a small-area emission light source, which is first homogenized and diverged to a certain size. Then, it is collimated by a collimating lens, and a microlens array is used to cut the light source into the required number of point light sources, thereby achieving the effect of a large-area point light source. This improves the resolution of the lidar system and expands the detectable field of view.

[0045] In an exemplary embodiment, the optical system provided in this application can be used as, for example, a vehicle-mounted lens. In this case, the second side of the optical system can be the object side, and the first side can be the image side. Light rays from the object side can form an image on the image side. The first side of the optical system is the imaging surface of the optical system.

[0046] In exemplary embodiments, the collimating lens in the optical system according to this application may have a surface shape including, but not limited to, at least one of a spherical, aspherical, or freeform surface. The surface shape of the collimating lens may be, for example, a rotationally symmetric structure, a biconical structure, etc., but this application does not limit the structural type of the collimating lens.

[0047] In an exemplary embodiment, the optical system according to this application satisfies: D3 / F3 ≥ 0.1, where D3 is the aperture of the microlens unit and F3 is the focal length of the microlens unit. More specifically, D3 and F3 may further satisfy: D3 / F3 ≥ 0.2. Satisfying D3 / F3 ≥ 0.1, while determining the aperture of the microlens unit, controls its focal length within a certain range, which is beneficial for matching lens assemblies.

[0048] In an exemplary embodiment, the optical system according to this application satisfies: 0.5 ≤ D² / L² ≤ 2, where D² is the effective aperture of the collimating lens facing the microlens array, and L² is the distance along the optical axis from the light source to the side of the collimating lens facing the light source. More specifically, D² and L² can further satisfy: 1 ​​≤ D² / L² ≤ 1.5. Satisfying 0.5 ≤ D² / L² ≤ 2 helps to limit the length of the optical system and achieve miniaturization of the optical system.

[0049] In an exemplary embodiment, the optical system according to this application satisfies: D² / W ≥ 3, where D² is the effective aperture of the collimating lens facing the microlens array, and W is the emission diameter of the light source. More specifically, D² and W can further satisfy: D² / W ≥ 5. Satisfying D² / W ≥ 3 makes the effective aperture of the collimating lens much larger than the emission diameter of the light source, which is beneficial for improving collimation.

[0050] In an exemplary embodiment, the optical system according to this application satisfies the following condition: L1 / L2 ≤ 0.5, where L1 is the distance on the optical axis from the light source to the side of the homogenizer facing the light source, and L2 is the distance on the optical axis from the light source to the side of the collimating lens facing the light source. More specifically, L1 and L2 can further satisfy: L1 / L2 ≤ 0.2. Satisfying L1 / L2 ≤ 0.5 means the homogenizer is closer to the light source, which helps to improve the collimation of the collimating lens.

[0051] In an exemplary embodiment, the optical system according to this application satisfies the following condition: D3 / D2 ≤ 0.7, where D3 is the aperture of the microlens unit and D2 is the effective aperture of the collimating lens facing the microlens array. More specifically, D3 and D2 can further satisfy: D3 / D2 ≤ 0.5. Satisfying D3 / D2 ≤ 0.7 means that the aperture of the microlens unit in the microlens array is smaller than the aperture of the collimating lens, forming multiple point light sources, which helps to increase the number of light-emitting points at the emitting end, thereby improving resolution.

[0052] In an exemplary embodiment, the optical system according to this application satisfies: L2 / TTL1≤1, where L2 is the distance on the optical axis from the light source to the side of the collimating lens facing the light source, and TTL1 is the distance on the optical axis from the light source to the side of the microlens array facing the light source. More specifically, L2 and TTL1 can further satisfy: L2 / TTL1≤0.8. Satisfying L2 / TTL1≤1 is beneficial for achieving lens miniaturization.

[0053] In an exemplary embodiment, the optical system according to this application satisfies: W / F2 ≤ 0.5, where W is the emission diameter of the light source and F2 is the focal length of the collimating lens. More specifically, W and F2 can further satisfy: W / F2 ≤ 0.2. Satisfying W / F2 ≤ 0.5 means that the focal length of the collimating lens is much larger than the emission diameter of the light source, which is beneficial for improving collimation.

[0054] In an exemplary embodiment, the optical system according to this application satisfies: W×θ / D2≤5, where W is the emission diameter of the light source, θ is the overall divergence angle of the light source, and D2 is the effective aperture of the collimating lens facing the microlens array. More specifically, W, θ, and D2 can further satisfy: W×θ / D2≤3. Satisfying W×θ / D2≤5, given a fixed emission diameter and divergence angle of the light source, the collimating lens has a larger effective aperture, which is beneficial for improving collimation.

[0055] In an exemplary embodiment, the optical system according to this application satisfies: W×θ / F2≤5, where W is the emission diameter of the light source, θ is the total divergence angle of the light source, and F2 is the focal length of the collimating lens. More specifically, W, θ, and F2 can further satisfy: W×θ / F2≤3. Satisfying W×θ / F2≤5, when the emission diameter and divergence angle of the light source are determined, the collimating lens exhibits long focal length characteristics, which is beneficial for improving collimation.

[0056] In an exemplary embodiment, the optical system according to this application satisfies: 0.2 ≤ D2 / TTL1 ≤ 3, where D2 is the effective aperture of the collimating lens facing the microlens array, and TTL1 is the distance on the optical axis between the light source and the side of the microlens array facing the light source. More specifically, D2 and TTL1 can further satisfy: 0.5 ≤ D2 / TTL1 ≤ 2. Satisfying 0.2 ≤ D2 / TTL1 ≤ 3 helps to achieve miniaturization.

[0057] In an exemplary embodiment, the optical system according to this application satisfies: F2 / F3≥1, where F2 is the focal length of the collimating lens and F3 is the focal length of the microlens unit. More specifically, F2 and F3 may further satisfy: F2 / F3≥1.5. Satisfying F2 / F3≥1 means that the focal length of the collimating lens is greater than the focal length of the microlens unit of the microlens array, which helps the microlens array to divide a larger number of lenses, thereby achieving high resolution.

[0058] In an exemplary embodiment, the optical system according to this application satisfies: F3 / F1≥1, where F3 is the focal length of the microlens unit and F1 is the focal length of the lens unit of the light homogenizer. More specifically, F3 and F1 may further satisfy: F3 / F1≥1.5. Satisfying F3 / F1≥1 means that the focal length of the microlens unit of the microlens array is greater than the focal length of the lens unit of the light homogenizer, which helps to arrange a larger number of lenses in the light homogenizer and achieve high light homogenization.

[0059] In an exemplary embodiment, the optical system according to this application satisfies: D3 / D1≥1, where D3 is the aperture of the microlens unit and D1 is the effective aperture of the lens unit of the light homogenizer. More specifically, D3 and D1 may further satisfy: D3 / D1≥2. Satisfying D3 / D1≥1 means that the aperture of the microlens unit of the microlens array is larger than the aperture of the lens unit of the light homogenizer, which helps the light homogenizer to arrange a larger number of lenses and achieve high light homogenization.

[0060] In an exemplary embodiment, the optical system according to this application satisfies: D2 / (2×tan(FOV / 2)≤10, where D2 is the effective aperture of the collimating lens facing the microlens array, and FOV is the total exit angle of the optical system. More specifically, D2 and FOV can further satisfy: D2 / (2×tan(FOV / 2)≤5. Satisfying D2 / (2×tan(FOV / 2)≤10 is beneficial for achieving a large exit angle.

[0061] In an exemplary embodiment, the optical system according to this application satisfies: 0.1 ≤ (TTL2 - F3) × D3 / (2 × F3) ≤ 10, where TTL2 is the air gap on the optical axis between the microlens array and the imaging lens closest to the microlens array in the lens assembly, F3 is the focal length of the microlens unit, and D3 is the aperture of the microlens unit. More specifically, TTL2, F3, and D3 can further satisfy: 0.3 ≤ (TTL2 - F3) × D3 / (2 × F3) ≤ 8. Satisfying 0.1 ≤ (TTL2 - F3) × D3 / (2 × F3) ≤ 10 facilitates the cooperation between the imaging lens assembly and the transmitting front end, reduces the distance between the lens assembly and the transmitting front end, and achieves miniaturization.

[0062] In an exemplary embodiment, the optical system according to this application satisfies: 0.1 ≤ TTL2 / TTL1 ≤ 1.5, where TTL2 is the air gap on the optical axis between the microlens array and the imaging lens closest to the microlens array in the lens assembly, and TTL1 is the distance on the optical axis between the light source and the side of the microlens array facing the light source. More specifically, TTL2 and TTL1 can further satisfy: 0.3 ≤ TTL2 / TTL1 ≤ 1. Satisfying 0.1 ≤ TTL2 / TTL1 ≤ 1.5 is beneficial for miniaturization.

[0063] In an exemplary embodiment, the optical system according to this application satisfies: 1 / (2×sin(arctan(D3 / (2×F3))))≤2.5, where D3 is the aperture of the microlens unit and F3 is the focal length of the microlens unit. More specifically, D3 and F3 further satisfy: 1 / (2×sin(arctan(D3 / (2×F3))))≤2. Satisfying 1 / (2×sin(arctan(D3 / (2×F3))))≤2.5 is beneficial for the coordination between the transmitting front end and the lens assembly.

[0064] In an exemplary embodiment, the lens assembly of the optical system of this application may include multiple imaging lenses as needed, and the number of imaging lenses is not specifically limited. As needed, the lens assembly may also include a filter and / or protective glass and an imaging surface, wherein the filter and / or protective glass filters light of different wavelengths and prevents damage to the image-side elements (e.g., chips) of the optical system.

[0065] In exemplary embodiments, the lenses in the lens assembly can be spherical lenses or aspherical lenses. This application does not specifically limit the number of spherical and aspherical lenses; when image quality is paramount, the number of aspherical lenses can be increased, and even all lenses can be aspherical. Aspherical lenses are characterized by a continuously changing curvature from the lens center to the periphery. Unlike spherical lenses, which have a constant curvature from the lens center to the periphery, aspherical lenses have better radius of curvature characteristics, offering advantages in improving distortion and astigmatism. Using aspherical lenses can eliminate aberrations that occur during imaging as much as possible, thereby improving the lens's image quality. The inclusion of aspherical lenses helps correct system aberrations and improves resolving power.

[0066] Optical lenses made of glass can suppress the shift of the back focus of an optical system due to temperature changes, thereby improving system stability. At the same time, using glass avoids lens blurring caused by high and low temperature variations in the operating environment, thus preventing interference with normal lens use. For example, an all-glass optical system has a wider temperature range, maintaining stable optical performance from -40℃ to 105℃. Specifically, when image quality and reliability are paramount, all lenses in the lens assembly can be glass. Of course, in applications with lower temperature stability requirements, all lenses in the lens assembly can be made of plastic. Using plastic to make optical lenses effectively reduces manufacturing costs. Alternatively, lenses in the lens assembly can be made from a combination of plastic and glass.

[0067] The optical system according to the above embodiments of this application, through the reasonable setting of the shape and optical power of the transmitting front end, adopts a small area light source, first homogenizes it, diverges it to a certain size, then collimates it through a collimating lens, and uses a microlens array to cut the light source into the desired number of point light sources, thereby realizing a large area array of point light sources. The optical system achieves at least one beneficial effect such as miniaturization, high resolution, high collimation, high uniformity, and large field of view.

[0068] Specific embodiments of the optical system applicable to the above-described embodiments are further described below with reference to the accompanying drawings.

[0069] Example 1

[0070] The following is for reference Figures 2 to 5 An optical system 1000 according to Embodiment 1 of this application is described. Figure 2 A schematic diagram of the structure of an optical system 1000 according to Embodiment 1 of this application is shown. Figure 3 A partial structural schematic diagram of the light-diffusing plate 2 of the optical system 1000 according to Embodiment 1 of this application is shown. Figure 4 A schematic diagram of the structure of the microlens array 4 of the optical system 1000 according to Embodiment 1 of this application is shown. Figure 5A schematic diagram of the outgoing full-angle FOV of the optical system 1000 according to Embodiment 1 of this application is shown.

[0071] like Figure 2 As shown, the optical system 1000 includes an emission front end 100 and a lens assembly 200 sequentially from the first side to the second side along the optical axis. The emission front end 100 includes a light source 1, a light homogenizer 2, a collimating lens 3, and a microlens array 4. Figure 2 The image only shows one collimating lens 3 and one microlens array 4 by way of example. This application does not limit the specific number of collimating lenses 3 and microlens array 4.

[0072] Light source 1 can be a semiconductor light source used to emit probe light. Light source 1 can be a single or combined area array light source such as an LD or VCSEL. In this embodiment, the overall divergence angle θ of light source 1 is 35°.

[0073] The homogenizer 2 homogenizes and shapes the Gaussian-like beam emitted from the light source 1, forming a flat-top distribution. This ensures that the energy at each position is uniform after the subsequent microlens array 4 divides the beam. Without the homogenizer 2, since the light source 1 is typically a semiconductor light source with a Gaussian-like divergence angle-energy distribution, the edge energy is weaker. Therefore, after the microlens array 4 divides the beam, the edge energy is weaker and the center energy is stronger, which can easily lead to unequal detection distances in different fields of view during detection. Figure 2 As shown, the homogenizer 2 is closer to the light source 1, and the distance L1 between the side of the light source 1 and the homogenizer 2 facing the light source 1 on the optical axis is 0.400 mm. Figure 3 As shown, the light homogenizer 2 can be a regular or irregular ultra-micro lens array, that is, the light homogenizer 2 includes multiple lens units 20. The effective aperture D1 of the lens unit 20 of the light homogenizer 2 is 0.02 mm.

[0074] Collimating lens 3 collimates the probe light rays homogenized and shaped by homogenizer 2, such as... Figure 2 As shown, the effective aperture D2 of the collimating lens 3 facing the microlens array 4 is 10.000 mm.

[0075] In Example 1, as Figure 2 As shown, one side of the collimating lens 3 is a plane, and the other side is a convex surface. The surface shape of the collimating lens 3 in the optical system 1000 according to this application may include, but is not limited to, at least one of a spherical, aspherical, or freeform surface. The structural type of the collimating lens 3 may be, for example, a rotationally symmetric structure, a biconical structure, etc., but this application does not limit the structural type of the collimating lens 3. This application also does not limit the surface shape of the collimating lens 3; the object-side and image-side surfaces of the collimating lens 3 can be any combination of convex, concave, and plane surfaces.

[0076] The microlens array 4 can be a regular or irregular array of microlenses, such as... Figure 2 and Figure 4 As shown, the microlens array 4 includes multiple microlens units 40. The number of microlens units 40 in the XZ direction and the YZ direction may be different. The focal length of the microlens units 40 in the XZ direction and the YZ direction may be different. Exemplarily, the microlens array 4 may have one side convex and the other side planar. Alternatively, in other embodiments, the microlens array 4 may have both sides convex. However, this application does not specifically limit the surface shape of the microlens array 4, including but not limited to... Figure 4 The surface shape in the image. In this embodiment, the aperture D3 of the microlens unit 40 is 1.1 mm.

[0077] The lens assembly 200 includes at least one lens (not shown), and the number of lenses can be set as needed.

[0078] like Figure 2 As shown, the distance L2 on the optical axis from the side of the collimating lens 3 facing the light source 1 is 8.020 mm; the emission diameter W of the light source 1 is 0.500 mm; the focal length F1 of the lens unit 20 of the homogenizer 2 is 0.047 mm; the focal length F2 of the collimating lens 3 is 8.67 mm; and the focal length F3 of the microlens unit 40 is 1.965 mm. The distance TTL1 on the optical axis between the side of the light source 1 and the side of the microlens array 4 facing the light source 1 is 12.800 mm; the air gap TTL2 on the optical axis between the microlens array 4 and the imaging lens closest to the microlens array 4 in the lens assembly 200 is 9.22 mm. The outgoing full-angle FOV of the optical system 1000 is... Figure 5 The angle is 120°.

[0079] The optical system 1000 provided in this application can be used as, for example, a projection lens or a lidar transmitter lens. In this case, light from the transmitting front end 100 passes through the lens assembly 200 and is ultimately projected onto a projection surface (not shown) or a target object (not shown) disposed on the second side. It should be understood that the optical system 1000 provided in this application can also be used as, for example, a vehicle-mounted lens. In this case, light from an object (not shown) passes through the lens assembly 200 and is ultimately imaged onto an imaging surface (not shown) disposed on the first side.

[0080] Example 2

[0081] The following is for reference Figure 6 An optical system 2000 according to Embodiment 2 of this application is described. In this embodiment and the following embodiments, for the sake of brevity, descriptions similar to those in Embodiment 1 will be omitted. Figure 6 A schematic diagram of the structure of an optical system 2000 according to Embodiment 2 of this application is shown.

[0082] like Figure 6 As shown, the optical system 2000 includes a transmitting front end 100 and a lens assembly 200 sequentially from the first side to the second side along the optical axis. The transmitting front end 100 includes a light source 1, a light homogenizer 2, a collimating lens 3, and a microlens array 4. Figure 6 The image only shows one collimating lens 3 and one microlens array 4 by way of example. This application does not limit the specific number of collimating lenses 3 and microlens array 4.

[0083] By way of example, referring to embodiment 1 Figure 4 The microlens array 4 may have one convex surface and the other flat surface. Alternatively, in other embodiments, the microlens array 4 may have both convex surfaces. However, this application does not specifically limit the surface shape of the microlens array 4, including but not limited to... Figure 4 The face shape in the middle.

[0084] In Example 2, as Figure 6 As shown, one side of the collimating lens 3 is convex, and the other side is also convex. The surface shape of the collimating lens 3 in the optical system 2000 according to this application may include, but is not limited to, at least one of a spherical, aspherical, or freeform surface. The structural type of the collimating lens 3 may be, for example, a rotationally symmetric structure, a biconical structure, etc., but this application does not limit the structural type of the collimating lens 3. This application also does not limit the surface shape of the collimating lens 3; the object-side and image-side surfaces of the collimating lens 3 can be any combination of convex, concave, and planar surfaces.

[0085] In Example 2, the overall divergence angle θ of the light source 1 is 35°, the distance L1 between the light source 1 and the side of the light homogenizer 2 facing the light source 1 on the optical axis is 0.400 mm, and the lens unit 20 of the light homogenizer 2 (reference) Figure 3 The effective aperture D1 of the optical system 2000 is 0.02 mm; the effective aperture D2 of the collimating lens 3 facing the microlens array 4 is 10.000 mm; the aperture D3 of the microlens unit 40 is 1.1 mm; the distance L2 on the optical axis from the light source 1 to the collimating lens 3 facing the light source 1 is 7.908 mm; the emission diameter W of the light source 1 is 0.500 mm; the focal length F1 of the lens unit 20 of the homogenizer 2 is 0.0481 mm; the focal length F2 of the collimating lens is 8.1402 mm; the focal length F3 of the microlens unit 40 is 2.063 mm; the distance TTL1 on the optical axis between the light source 1 and the microlens array 4 facing the light source 1 is 13.670 mm; the air gap TTL2 on the optical axis between the microlens array 4 and the imaging lens closest to the microlens array 4 in the lens assembly 200 is 8.8216 mm; the exit full-angle FOV of the optical system 2000 (reference) Figure 5 The angle is 120°.

[0086] The optical system 2000 provided in this application can be used as, for example, a projection lens or a lidar transmitter lens. In this case, light from the transmitting front end 100 passes through the lens assembly 200 and is ultimately projected onto a projection surface (not shown) or a target object (not shown) disposed on the second side. It should be understood that the optical system 2000 provided in this application can also be used as, for example, a vehicle-mounted lens. In this case, light from an object (not shown) passes through the lens assembly 200 and is ultimately imaged onto an imaging surface (not shown) disposed on the first side.

[0087] In summary, Examples 1 to 2 satisfy the relationships in Table 1 below. In Table 1, the units of F1, D1, F2, F3, D3, TTL1, W, D2, L1, L2 and TTL2 are millimeters (mm), and the units of θ and FOV are degrees (°).

[0088]

[0089]

[0090] Table 1

[0091] The optical system provided in this application forms an array of point light sources at the emitting end, and combines the array of point light sources with a lens assembly to form an object-side telecentric optical system, which collimates the array of point light sources into parallel beams with different field of view angles, thereby achieving long-distance detection.

[0092] This application also provides a lidar detection system. The lidar detection system includes an optical system and a receiver according to this application. The optical system emits detection light rays towards a target scene, and the receiver receives the portion of the detection light rays reflected back by the target scene.

[0093] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. An optical system, characterized in that, include: The launch front end includes: A light source used to emit detection rays; At least one collimating lens is used to collimate the probe light; and At least one microlens array, comprising multiple microlens units, divides the collimated probe light into multiple beams as an area array light source, wherein the number of the multiple beams is the same as the number of the multiple microlens units; and The lens assembly includes at least one imaging lens for emitting an area array light source formed after passing through the microlens array.

2. The optical system according to claim 1, wherein, The transmitting front end also includes a homogenizer, located between the light source and the collimating lens. The homogenizer includes multiple lens units to homogenize and shape the Gaussian-like beam emitted by the light source into a flat-top distribution.

3. The optical system according to claim 1, wherein, The light source includes at least one of LD and VCSEL.

4. The optical system according to claim 1, wherein, The collimating lens has a surface shape of at least one of spherical, aspherical, or freeform surface.

5. The optical system according to any one of claims 1-4, wherein, For each of the microlens units, the aperture D3 of the microlens unit and the focal length F3 of the microlens unit satisfy: D3 / F3≥0.

1.

6. The optical system according to any one of claims 1-4, wherein, The effective aperture D2 of the collimating lens facing the microlens array and the distance L2 on the optical axis from the light source to the side of the collimating lens facing the light source satisfy: 0.5≤D2 / L2≤2.

7. The optical system according to any one of claims 1-4, wherein, The effective aperture D2 of the collimating lens facing the microlens array and the emission diameter W of the light source satisfy: D2 / W≥3.

8. The optical system according to claim 2, wherein, The distance L1 from the light source to the side of the light homogenizer facing the light source on the optical axis and the distance L2 from the light source to the side of the collimating lens facing the light source on the optical axis satisfy: L1 / L2≤0.

5.

9. The optical system according to any one of claims 1-4, wherein, The aperture D3 of the microlens unit and the effective aperture D2 of the collimating lens facing the microlens array satisfy the following condition: D3 / D2≤0.

7.

10. The optical system according to any one of claims 1-4, wherein, The distance L2 from the light source to the side of the collimating lens facing the light source on the optical axis and the distance TTL1 from the light source to the side of the microlens array facing the light source on the optical axis satisfy: L2 / TTL1≤1.

11. The optical system according to any one of claims 1-4, wherein, The light-emitting diameter W of the light source and the focal length F2 of the collimating lens satisfy the condition: W / F2≤0.

5.

12. The optical system according to any one of claims 1-4, wherein, The light-emitting diameter W of the light source, the overall divergence angle θ of the light source, and the effective aperture D2 of the collimating lens facing the microlens array satisfy: W×θ / D2≤5.

13. The optical system according to any one of claims 1-4, wherein, The light-emitting diameter W of the light source, the overall divergence angle θ of the light source, and the focal length F2 of the collimating lens satisfy: W×θ / F2≤5.

14. The optical system according to any one of claims 1-4, wherein, The effective aperture D2 of the collimating lens facing the microlens array and the distance TTL1 between the light source and the side of the microlens array facing the light source on the optical axis satisfy: 0.2≤D2 / TTL1≤3.

15. The optical system according to any one of claims 1-4, wherein, The focal length F2 of the collimating lens and the focal length F3 of the microlens unit satisfy: F2 / F3≥1.

16. The optical system according to claim 2, wherein, The focal length F3 of the microlens unit and the focal length F1 of the lens unit of the light homogenizer satisfy the following condition: F3 / F1≥1.

17. The optical system according to claim 2, wherein, The aperture D3 of the microlens unit and the effective aperture D1 of the lens unit of the light homogenizer satisfy the condition: D3 / D1≥1.

18. The optical system according to any one of claims 1-4, wherein, The effective aperture D2 of the collimating lens facing the microlens array satisfies the following condition with the full FOV of the optical system: D2 / (2×tan(FOV / 2)≤10.

19. The optical system according to any one of claims 1-5, wherein, The air gap TTL2 between the microlens array and the imaging lens closest to the microlens array in the lens assembly, the focal length F3 of the microlens unit and the aperture D3 of the microlens unit satisfy: 0.1≤(TTL2-F3)×D3 / (2×F3)≤10.

20. The optical system according to any one of claims 1-4, wherein, The air gap TTL2 between the microlens array and the imaging lens closest to the microlens array in the lens assembly on the optical axis and the distance TTL1 between the light source and the side of the microlens array facing the light source on the optical axis satisfy: 0.1≤TTL2 / TTL1≤1.

5.

21. The optical system according to any one of claims 1-4, wherein, For each of the microlens units, the aperture D3 of the microlens unit and the focal length F3 of the microlens unit satisfy: 1 / (2×sin(arctan(D3 / (2×F3))))≤2.

5.

22. The optical system according to any one of claims 1-4, wherein, The optical system satisfies at least one of the following: D3 / F3≥0.2; 1≤D2 / L2≤1.5; D2 / W≥5; L1 / L2≤0.2; D3 / D2≤0.5; L2 / TTL1≤0.8; W / F2≤0.2; W×θ / D2≤3; W×θ / F2≤3; 0.5≤D2 / TTL1≤2; F2 / F3≥1.5; F3 / F1≥1.5; D3 / D1≥2; D2 / (2×tan(FOV / 2)≤5; 0.3≤(TTL2-F3)×D3 / (2×F3)≤8; 0.3≤TTL2 / TTL1≤1; 1 / (2×sin(arctan(D3 / (2×F3))))≤2; Wherein, D3 is the aperture of the microlens unit, F3 is the focal length of the microlens unit, D2 is the effective aperture of the collimating lens facing the microlens array, L2 is the distance on the optical axis from the light source to the collimating lens facing the light source, W is the emission diameter of the light source, L1 is the distance on the optical axis from the light source to the homogenizer facing the light source, TTL1 is the distance on the optical axis between the light source and the microlens array facing the light source, F2 is the focal length of the collimating lens, θ is the total divergence angle of the light source, F1 is the focal length of the lens unit of the homogenizer, D1 is the effective aperture of the lens unit of the homogenizer, FOV is the total emission angle of the optical system, and TTL2 is the air gap on the optical axis between the microlens array and the imaging lens closest to the microlens array in the lens assembly.

23. The optical system according to any one of claims 1-4, wherein, The optical system satisfies at least one of the following: 0.5598≥D3 / F3≥0.2; 1.2469≤D2 / L2≤1.2645; 20.0000≥D2 / W≥5; 0.0499≤L1 / L2≤0.2; 0.1100≤D3 / D2≤0.5; 0.5785≤L2 / TTL1≤0.8; 0.0577≤W / F2≤0.2; 1.7500≤W×θ / D2≤3; 2.0185≤W×θ / F2≤3; 0.7315≤D2 / TTL1≤0.7813; 4.4122≥F2 / F3≥1.5; 42.88981289≥F3 / F1≥1.5; 55.0000≥D3 / D1≥2; 2.8868≤D2 / (2×tan(FOV / 2)≤5; 1.8019≤(TTL2-F3)×D3 / (2×F3)≤2.0307; 0.6453≤TTL2 / TTL1≤0.7203; 1.855018879≤1 / (2×sin(arctan(D3 / (2×F3))))≤2; Wherein, D3 is the aperture of the microlens unit, F3 is the focal length of the microlens unit, D2 is the effective aperture of the collimating lens facing the microlens array, L2 is the distance on the optical axis from the light source to the collimating lens facing the light source, W is the emission diameter of the light source, L1 is the distance on the optical axis from the light source to the homogenizer facing the light source, TTL1 is the distance on the optical axis between the light source and the microlens array facing the light source, F2 is the focal length of the collimating lens, θ is the total divergence angle of the light source, F1 is the focal length of the lens unit of the homogenizer, D1 is the effective aperture of the lens unit of the homogenizer, FOV is the total emission angle of the optical system, and TTL2 is the air gap on the optical axis between the microlens array and the imaging lens closest to the microlens array in the lens assembly.

24. A lidar detection system, comprising: The optical system as described in any one of claims 1-23 emits a probe beam toward the target scene; as well as The receiving end receives the portion of the probe light that is reflected back by the target scene.

Images