A laser slow axis collimation lens and a laser radar

Abstract

The application provides an optical lens applied to a laser radar, in particular to a laser slow-axis collimation lens applied to a laser radar, which comprises a first lens and a second lens arranged in sequence from an object side to an image side, the first lens is a meniscus cylindrical lens with positive optical power, and the second lens is a meniscus cylindrical lens with positive optical power. Through reasonable optical design, the point light source is converted into a line light source, and the structure is compact in the case of realizing the function, and has good collimation effect in the direction perpendicular to the line light source.

Description

Technical Field

[0001] This invention relates to an optical lens for use in lidar, and more particularly to a laser slow-axis collimating lens. Background Technology

[0002] With the development of the automotive industry and the popularization of smart devices, autonomous driving technology has gradually become a hot topic. Autonomous vehicles need the ability to perceive surrounding obstacles and the environment, and currently, various perception devices exist, such as cameras, millimeter-wave radar, and lidar. Among them, lidar is favored due to its long-range recognition advantage and is widely used in autonomous driving technology.

[0003] Currently, the field of automotive LiDAR technology is flourishing, with multiple technical approaches coexisting. Based on the number of laser beams emitted, LiDAR can be divided into single-line LiDAR and multi-line LiDAR. Currently, the mainstream technology, aiming for higher detection efficiency, primarily uses multi-line LiDAR. For multi-line LiDAR, if a rotationally symmetric optical system is used to collimate the beam, the imaging effect of the light source in different fields of view will vary due to aberration interference. To solve this problem, cylindrical mirrors can be used to process the horizontal and vertical directions separately.

[0004] There are currently few laser collimating lens products on the market, and existing products often use single spherical lenses for collimation, which is not very effective for lidar applications. Summary of the Invention

[0005] (I) Problems to be solved

[0006] This invention addresses the problems of limited product variety and poor collimation performance in existing lidar systems by proposing a slow-axis collimating lens for use in lidar. This lens, composed of cylindrical mirrors, can project a point light source as a line light source. Furthermore, this lens collimates the light rays, effectively reducing light divergence and significantly extending the working range of the lidar system.

[0007] (II) Technical Solution

[0008] To achieve the above objectives, this product uses the following technical solution.

[0009] A laser slow-axis collimating lens is composed of a first cylindrical mirror and a second cylindrical mirror. The refractive power meridians of the two cylindrical mirrors are parallel. The plane perpendicular to the cylindrical mirrors and parallel to the refractive power meridians is defined as the y-plane, and the plane perpendicular to the y-plane and passing through the optical axis is defined as the x-plane. The lens collimates the light incident on the y-plane and acts as an equivalent parallel plate for the light incident on the x-plane, thereby transforming the laser from a point source to a line source and collimating it on the y-plane.

[0010] The laser slow-axis collimating lens has a first cylindrical lens and a second cylindrical lens, both of which are meniscus cylindrical lenses.

[0011] The laser slow-axis collimating lens has a focal length of f1 in the y-direction of the first cylindrical mirror, a focal length of f2 in the y-direction of the second cylindrical mirror, and a focal length of f in the y-direction of the optical system, the proportions of which satisfy:

[0012] (1) 1.5 < f1 / f < 1.8;

[0013] (2) 2.1 < f2 / f < 2.4.

[0014] The laser slow-axis collimating lens: the materials used to construct the first and second cylindrical mirrors have the following optical properties:

[0015] (3)N d ≥1.9, V d ≤30;

[0016] Where N d V is the refractive index of the material. d Let be Abbe's constant.

[0017] The laser slow-axis collimating lens described above is suitable for a wavelength of 905nm.

[0018] The present invention also provides a lidar, including a laser and a laser slow-axis collimating lens.

[0019] (III) Beneficial Effects

[0020] This invention can project a point light source into a line light source. Furthermore, this lens also collimates the light, effectively reducing light divergence and greatly extending the working range of the lidar, allowing it to operate effectively at distances exceeding 100 meters. Attached Figure Description

[0021] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0022] Figure 1 This is a front view of the optical system of the present invention;

[0023] Figure 2 This is a 45-degree angle view of the optical system of the present invention;

[0024] Figure 3 This is a three-dimensional structural diagram of the cylindrical mirror in the laser slow-axis collimating lens of the present invention;

[0025] Figure 4 This is a front view of the cylindrical mirror in the laser slow-axis collimating lens of the present invention;

[0026] Figure 5 This is a schematic diagram of the y-plane of one of the meniscus cylindrical mirrors of the present invention;

[0027] Figure 6 This is a schematic diagram of the x-plane of one of the meniscus cylindrical mirrors of the present invention;

[0028] Figure 7 This is a collimation effect diagram of Embodiment 1 of the present invention;

[0029] Figure 8 This is a collimation effect diagram of Embodiment 2 of the present invention;

[0030] Figure 9 This is a collimation effect diagram of Embodiment 3 of the present invention. Detailed Implementation

[0031] In the description of this invention, it should be noted that the terms "first", "second", "y-plane", "x-plane", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the position or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention.

[0032] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0033] The laser collimation system consists of a first cylindrical mirror L1 and a second cylindrical mirror L2. A front view of the optical system is shown below. Figure 1 As shown, Figure 2 A schematic diagram of the optical system at a 45-degree angle is shown. The refractive power meridians of the two cylindrical mirrors are parallel, as shown... Figure 5 , 6 As shown, the plane perpendicular to the lens and parallel to the refractive power meridian is defined as the y-plane, and the plane perpendicular to the y-plane and passing through the optical axis is defined as the x-plane. The lens collimates the incident light on the y-plane and is equivalent to a parallel plate for the incident light on the x-plane, thus transforming the laser from a point source to a line source and collimating it on the y-plane.

[0034] Both the first cylindrical mirror L1 and the second cylindrical mirror L2 are meniscus cylindrical mirrors.

[0035] The use of cylindrical mirrors is not only to convert divergent point light sources into line light sources, but also because of the characteristics of cylindrical mirrors, they are equivalent to parallel plates in the x-direction. Therefore, multiple point light sources can be collimated with the same effect at the same time. This characteristic is very important for microchip technology solutions in lidar, as it can increase the integration of light sources and thus achieve a high number of lidar threads in a small volume.

[0036] In this embodiment, the focal length of the first cylindrical mirror L1 in the y-direction is f1, the focal length of the second cylindrical mirror L2 in the y-direction is f2, and the focal length of the optical system in the y-direction is f, the proportions of which satisfy:

[0037] (1) 1.5 < f1 / f < 1.8;

[0038] (2) 2.1 < f2 / f < 2.4.

[0039] A cylindrical mirror that meets this range can effectively collimate the laser beam in the y-direction, preventing the laser power reflected back from distant objects from being too low and drowned out by noise, thus greatly increasing the application range of lidar.

[0040] In this embodiment, the materials used to constitute the first cylindrical mirror L1 and the second cylindrical mirror L2 have the following optical properties:

[0041] (3)N d ≥1.9, V d ≤30;

[0042] Where N d V is the refractive index of the material. d This is Abbe's constant. Using high-refractive-index materials allows for better collimation of the light beam, thus requiring fewer lenses and reducing lens thickness.

[0043] In this embodiment, the lens is used for 905nm wavelength laser.

[0044] Example 1

[0045] A laser slow-axis collimating lens consists of a first cylindrical mirror L1 and a second cylindrical mirror L2. The refractive power meridians of the two cylindrical mirrors are parallel, as shown below. Figure 5 , 6 As shown, the plane perpendicular to the lens and parallel to the refractive power meridian is defined as the y-plane, and the plane perpendicular to the y-plane and passing through the optical axis is defined as the x-plane. The lens collimates the incident light on the y-plane and is equivalent to a parallel plate for the incident light on the x-plane, thus transforming the laser from a point source to a line source and collimating it on the y-plane.

[0046] Both the first cylindrical mirror L1 and the second cylindrical mirror L2 are meniscus cylindrical mirrors.

[0047] In this embodiment, the focal length of the first cylindrical mirror L1 in the y-direction is f1, the focal length of the second cylindrical mirror L2 in the y-direction is f2, and the focal length of the optical system in the y-direction is f, the proportions of which satisfy:

[0048] (1) f1 / f is 1.551;

[0049] (2) f2 / f is 2.384.

[0050] The optical data of the cylindrical mirror in the laser slow-axis collimating lens are shown in Table 1:

[0051]

[0052] like Figure 1 As shown in Table 1, the surface numbers represent the surface numbers of each cylindrical mirror from the object side to the image side.

[0053] In this embodiment, the lens is used for 905nm wavelength laser.

[0054] The collimation effect of the laser slow-axis collimating lens in this embodiment is as follows: Figure 7 As shown in the figure, OBJ and IMA represent the object-side field of view and the image-side field of view, respectively, indicating that the light is incident perpendicularly and observed in the vertical direction.

[0055] The collimation data of the laser slow-axis collimating lens described in this embodiment is shown in Table 2:

[0056] Rms size(mr) 25.4822534 0.087493102

[0057] Where α represents the divergence angle in the direction without collimation in the x-plane, and β represents the divergence angle in the y-direction of the beam after collimation in the y-plane. A comparison of the two shows that the collimation effect in the y-direction is better.

[0058] The cylindrical mirror described above can effectively collimate the laser beam in the y-direction, preventing the laser power reflected back from distant objects from being too low and drowned out by noise, thus greatly increasing the application range of lidar.

[0059] Example 2

[0060] In this embodiment of a laser slow-axis collimating lens, the focal length of the first cylindrical mirror L1 in the y-direction is f1, the focal length of the second cylindrical mirror L2 in the y-direction is f2, and the focal length of the optical system in the y-direction is f, the proportions of which satisfy:

[0061] (1) f1 / f is 1.593;

[0062] (2) f2 / f is 2.284.

[0063] The optical data of the cylindrical mirror in the laser slow-axis collimating lens are shown in Table 3:

[0064]

[0065] like Figure 1 As shown in Table 3, the surface numbers represent the surface numbers of each cylindrical mirror from the object side to the image side.

[0066] The rest is the same as in Example 1.

[0067] The collimation effect of the laser slow-axis collimating lens in this embodiment is as follows: Figure 8 As shown in the figure, OBJ and IMA represent the object-side field of view and the image-side field of view, respectively, indicating that the light is incident perpendicularly and observed in the vertical direction.

[0068] The collimation data of the laser slow-axis collimating lens described in this embodiment is shown in Table 4:

[0069]

[0070]

[0071] Where α represents the divergence angle in the direction without collimation in the x-plane, and β represents the divergence angle in the y-direction of the beam after collimation in the y-plane. A comparison of the two shows that the collimation effect in the y-direction is better.

[0072] The cylindrical mirror described above can effectively collimate the laser beam in the y-direction, preventing the laser power reflected back from distant objects from being too low and drowned out by noise, thus greatly increasing the application range of lidar.

[0073] Example 3

[0074] In this embodiment of a laser slow-axis collimating lens, the focal length of the first cylindrical mirror L1 in the y-direction is f1, the focal length of the second cylindrical mirror L2 in the y-direction is f2, and the focal length of the optical system in the y-direction is f, the proportions of which satisfy:

[0075] (1) f1 / f is 1.757;

[0076] (2) f2 / f is 2.165.

[0077] The optical data of the cylindrical lens in the laser slow-axis collimating lens are shown in Table 5:

[0078]

[0079] like Figure 1 As shown in Table 5, the surface numbers represent the surface numbers of each cylindrical mirror from the object side to the image side.

[0080] The rest is the same as in Example 1.

[0081] The collimation effect of the laser slow-axis collimating lens in this embodiment is as follows: Figure 9 As shown in the figure, OBJ and IMA represent the object-side field of view and the image-side field of view, respectively, indicating that the light is incident perpendicularly and observed in the vertical direction.

[0082] The collimation data of the laser slow-axis collimating lens described in this embodiment is shown in Table 6:

[0083] Rms size(mr) 27.1849988 0.0140947416

[0084] Where α represents the divergence angle in the direction without collimation in the x-plane, and β represents the divergence angle in the y-direction of the beam after collimation in the y-plane.

[0085] The cylindrical mirror described above can effectively collimate the laser beam in the y-direction, preventing the laser power reflected back from distant objects from being too low and drowned out by noise, thus greatly increasing the application range of lidar.

[0086] Example 4

[0087] This embodiment provides a lidar, which includes a laser and the laser slow-axis collimating lens provided in embodiments 1-3 above. Therefore, when collimating the laser light generated by the laser using this lidar, the laser slow-axis collimating lens, employing a cylindrical lens group, can achieve collimation of the laser light generated by the laser. Thus, the lidar of this embodiment can achieve collimation of the lidar's emitted light. Furthermore, since a first cylindrical lens and a second cylindrical lens are used to collimate the emitted light generated by the laser, the manufacturing process of these cylindrical lenses is simpler and easier to assemble and adjust than that of spherical lenses, graded-index optical fibers, etc. Therefore, by using a lidar including this laser slow-axis collimating lens, collimation of the laser's emitted light can be achieved while reducing the overall cost of the lidar.

[0088] The above description, in conjunction with the embodiments, provides a further detailed explanation of the present invention, but it should not be construed as limiting the specific implementation of the invention to these descriptions. For those skilled in the art, simple deductions and substitutions can be made without departing from the concept of the invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A laser slow-axis collimating lens, characterized in that: The laser slow-axis collimating lens consists of a first cylindrical lens and a second cylindrical lens. The refractive power meridians of the two cylindrical lenses are parallel. A plane perpendicular to the lens and parallel to the refractive power meridian is defined as the y-plane, and a plane perpendicular to the y-plane and passing through the optical axis is defined as the x-plane. The lens collimates the incident light on the y-plane, and the incident light on the x-plane is equivalent to a parallel plate, thus transforming the laser from a point source to a line source and collimating it on the y-plane. The focal length of the first cylindrical lens in the y-direction is f1, the focal length of the second cylindrical lens in the y-direction is f2, and the focal length of the optical system in the y-direction is f, with the following ratio: 1.5 < f1 / f < 1.8; 2.1 < f2 / f < 2.

4.

2. The laser slow-axis collimating lens according to claim 1, characterized in that: Both the first cylindrical mirror and the second cylindrical mirror are meniscus cylindrical mirrors.

3. The laser slow-axis collimating lens according to claim 1, characterized in that: The first and second cylindrical mirrors are made of the same material, and their optical properties satisfy the following: N d ≥1.9,V d ≤30, Where N d V is the refractive index of the material. d Let be Abbe's constant.

4. The laser slow-axis collimating lens according to claim 1, characterized in that: The wavelength applicable to the laser slow-axis collimating lens is 905nm.

5. A lidar, characterized in that, Includes a laser and a laser slow-axis collimating lens as described in any one of claims 1-4.

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