Laser radar transmitting lens and laser radar device

Abstract

The application provides a laser radar emitting lens and a laser radar device, which are composed of three lenses with optical power and a reflecting element, and sequentially include a first lens, the reflecting element, a second lens and a third lens along an optical axis from an object side to a light source emitting surface; the first lens has positive optical power, an emitting surface thereof is a convex surface, and an incident surface thereof is a concave surface; the reflecting element is used for turning light; light emitted from the light source emitting surface sequentially passes through the third lens, the second lens, and is emitted after passing through the reflecting element, so that the optical axis is turned by 90 degrees and then passes through the first lens to reach the object side; the second lens has positive optical power, and an emitting surface thereof is a convex surface; and the third lens has negative optical power, an emitting surface thereof is a concave surface, and an incident surface thereof is a concave surface. The application can improve the emission quality of the lens, and the lens has one or more advantages such as miniaturization, small CRA, a large image surface, high emission quality, high collimation performance and the like.

Description

Technical Field

[0001] This invention relates to the technical field of lenses, and in particular to a lidar transmitting lens and lidar device. Background Technology

[0002] Today, lidar is widely used for detecting the three-dimensional coordinates and ranging of objects. A lidar system includes a controller, a light source, and a receiver. The controller controls the light source to emit a light beam. When the beam encounters a target object, it undergoes diffuse reflection. The receiver receives the reflected beam and, based on the information from the emitted and reflected beams, determines relevant information about the target object, such as its distance, azimuth, altitude, speed, attitude, and even shape. LiDAR is widely used in autonomous vehicles, drones, autonomous robots, satellites, and rockets.

[0003] As a key component of lidar, the optical lens processes the emitted beam and the reflected light. With the ever-increasing performance requirements of lidar applications, optical lens parameters need to evolve towards larger apertures, wider fields of view, and miniaturization to meet the growing demands for high-precision, wide-coverage detection. Current lidar optical lenses suffer from difficulties in achieving a balance between miniaturization, high emission quality, and high collimation performance, thus failing to meet market demands. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a lidar transmitting lens and lidar device that have the advantages of high transmission quality and high collimation performance.

[0005] The technical solution adopted in this invention is as follows: A lidar transmitting lens comprises three lenses with optical power and a reflective element. Along the optical axis from the object side to the light source emitting surface, it includes a first lens, a reflective element, a second lens, and a third lens in sequence. Each of the first lens, the second lens, and the third lens includes an incident light surface near the light source emitting surface and an exit light surface near the object side. The first lens has positive optical power, its light-emitting surface is convex, and its light-incident surface is concave. The reflective element is used to deflect light. The light emitted from the light source surface passes through the third lens and the second lens in sequence, and then passes through the reflective element to be emitted, so that the optical axis is deflected by 90° before passing through the first lens to reach the object side. The second lens has positive optical power and its light-emitting surface is convex. The third lens has negative optical power, and its light-emitting surface is concave, as is its light-incident surface. Among them, the clear aperture semi-diameter d6 of the incident light surface of the third lens and the true image height IH corresponding to the maximum field angle of the lidar emission lens satisfy: 1 < 2×d6 / IH < 1.25; the principal ray exit angle CRA of the maximum field of the lidar emission lens and the distance BL on the optical axis from the incident light surface of the third lens to the light source emission surface satisfy: 0.01 mm < tan(CRA)×BL < 0.1 mm.

[0006] Further preferably, the clear aperture semi-diameter d1 of the light-emitting surface of the first lens and the clear aperture semi-diameter d3 of the light-emitting surface of the second lens satisfy: 0.75 < d1 / d3 < 1.1; the clear aperture semi-diameter d1 of the light-emitting surface of the first lens and the true image height IH corresponding to the maximum field angle of the lidar emission lens satisfy: 0.52 < d1 / IH < 0.7.

[0007] Further preferably, the sagittal height SAG1 of the clear aperture semi-diameter of the light-emitting surface of the first lens, the sagittal height SAG2 of the clear aperture semi-diameter of the incident light surface of the first lens, and the central thickness CT1 of the first lens satisfy: 0.1 < (SAG2 - SAG1) / CT1 < 0.42; the sagittal height SAG5 of the clear aperture semi-diameter of the light-emitting surface of the third lens, the sagittal height SAG6 of the clear aperture semi-diameter of the incident light surface of the third lens, and the central thickness CT3 of the third lens satisfy: 0.6 < (SAG6 - SAG5) / CT3 < 0.8.

[0008] Further preferably, the true image height IH corresponding to the maximum field angle of the lidar emission lens and the entrance pupil diameter EPD of the lidar emission lens satisfy: 1.4 < IH / EPD < 1.7; the true image height IH corresponding to the maximum field angle of the lidar emission lens and the effective focal length f of the lidar emission lens satisfy: 0.42 < IH / f < 0.5.

[0009] Further preferably, the true image height IH corresponding to the maximum field angle of the lidar emission lens, the effective focal length f of the lidar emission lens, and the maximum field angle FOV of the lidar emission lens satisfy: 55° < f×FOV / IH < 60°; the true image height IH corresponding to the maximum field angle of the lidar emission lens and the f-number Fno of the lidar emission lens satisfy: 4.5 mm < IH / Fno < 5.2 mm.

[0010] Further preferably, the focal length f1 of the first lens and the effective focal length f of the lidar emission lens satisfy: 1.3 < f1 / f < 1.8; the radius of curvature R1 of the light-emitting surface of the first lens and the effective focal length f of the lidar emission lens satisfy: 0.9 < R1 / f < 1.4; the radius of curvature R2 of the incident light surface of the first lens and the effective focal length f of the lidar emission lens satisfy: 2.6 < R2 / f < 6.6.

[0011] More preferably, the focal length f3 of the third lens and the effective focal length f of the lidar emission lens satisfy: -1.6 < f3 / f < -0.95; the radius of curvature R5 of the light-emitting surface of the third lens and the effective focal length f of the lidar emission lens satisfy: -1.2 < R5 / f < -0.95; the radius of curvature R6 of the light-incident surface of the third lens and the effective focal length f of the lidar emission lens satisfy: 0.85 < R6 / f < 2.1.

[0012] More preferably, the radius of curvature R1 of the light-emitting surface of the first lens and the radius of curvature R2 of the light-incident surface of the first lens satisfy: 0.2 < R1 / R2 < 0.37; the radius of curvature R1 of the light-emitting surface of the first lens and the radius of curvature R2 of the light-incident surface of the first lens satisfy: -0.7 < (R1 - R2) / (R1 + R2) < -0.45.

[0013] More preferably, the radius of curvature R5 of the light-emitting surface of the third lens and the radius of curvature R6 of the light-incident surface of the third lens satisfy: -1.3 < R5 / R6 < -0.5; the radius of curvature R5 of the light-emitting surface of the third lens and the radius of curvature R6 of the light-incident surface of the third lens satisfy: -20 < (R5 - R6) / (R5 + R6) < 10.5.

[0014] A lidar device includes a beam splitter, a lidar receiving lens, and the above-mentioned lidar emission lens, and the lidar emission lens and the lidar receiving lens share the beam splitter for light transmission or reflection.

[0015] The lidar emission lens and the lidar device provided by the present invention adopt three lenses with specific optical powers and one reflection element. Through specific surface shape combinations and reasonable optical power distributions, the emission quality of the lens can be improved, aberrations can be reduced, the emission quality of the lens can be enhanced, and the lens has one or more advantages such as miniaturization, small CRA, large image plane, high emission quality, and high collimation performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, in which: Figure 1 It is a schematic structural diagram of the lidar emission lens in Embodiment 1 of the present invention.

[0017] Figure 2 It is a field curvature curve diagram of the lidar emission lens in Embodiment 1 of the present invention.

[0018] Figure 3This is the F-TAN (Theta) distortion curve of the laser radar transmitting lens in Embodiment 1 of the present invention.

[0019] Figure 4 This is an axial aberration curve of the laser radar transmitting lens in Embodiment 1 of the present invention.

[0020] Figure 5 This is a schematic diagram of the structure of the lidar transmitting lens in Embodiment 2 of the present invention.

[0021] Figure 6 This is a field curvature curve diagram of the laser radar transmitting lens in Embodiment 2 of the present invention.

[0022] Figure 7 This is the F-TAN (Theta) distortion curve of the laser radar transmitting lens in Embodiment 2 of the present invention.

[0023] Figure 8 This is an axial aberration curve of the laser radar transmitting lens in Embodiment 2 of the present invention.

[0024] Figure 9 This is a schematic diagram of the structure of the lidar transmitting lens in Embodiment 3 of the present invention.

[0025] Figure 10 This is a field curvature curve diagram of the laser radar transmitting lens in Embodiment 3 of the present invention.

[0026] Figure 11 This is the F-TAN (Theta) distortion curve of the laser radar transmitting lens in Embodiment 3 of the present invention.

[0027] Figure 12 This is an axial aberration curve of the laser radar transmitting lens in Embodiment 3 of the present invention.

[0028] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0029] To better understand this application, various aspects of this application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of embodiments of this application and are not intended to limit the scope of this 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.

[0030] It should be noted that in this specification, the terms "first," "second," "third," 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 the invention, the first lens discussed below may also be referred to as the second lens or the third lens.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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 the meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formal sense unless expressly so specified herein.

[0035] 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.

[0036] This invention provides a lidar transmitting lens that transmits the emitted light beam to the object side. The lidar transmitting lens is positioned in the light-emitting direction of the light source, meaning the emitting surface of the light source is the light-emitting side. The lidar transmitting lens consists of three lenses with optical power and one reflective element. Along the optical axis from the object side to the light source emitting surface (in the opposite direction of light transmission), it sequentially includes a first lens, a reflective element, a second lens, and a third lens. Each of the first, second, and third lenses includes an incident surface near the light source emitting surface and an emitting surface near the object side. It can be understood that the surface of each lens near the light source emitting surface is called the incident surface of that lens, and the surface of each lens near the object side is called the emitting surface of that lens.

[0037] In some embodiments, the first lens may have positive optical power, with a convex light-emitting surface and a concave light-incident surface. The second lens may have positive optical power, with a convex light-emitting surface and a concave or convex light-incident surface. The third lens may have negative optical power, with a concave light-emitting surface and a concave light-incident surface.

[0038] In some embodiments, the reflective element is used to deflect light rays. Light rays emitted from the light source's emitting surface pass sequentially through a third lens and a second lens before being reflected by the reflective element, causing the optical axis to bend by 90° before passing through the first lens to reach the object side. The reflective element can be a flat glass plate and is positioned at a 45° angle relative to the light source's emitting surface. The reflective element can also be other elements capable of reflection.

[0039] In some embodiments, an aperture stop may be provided between the first lens and the object side, and the aperture stop is arranged parallel to the reflecting element. The aperture stop can be controlled by a beam splitter to control beam transmission. Specifically, after passing through the first lens, the light passes through the beam splitter to reach the object surface, and the light reflected by the object surface returns to the beam splitter. The beam splitter reflects the reflected light, causing the optical axis to bend by 90°, and then passes through receiving devices such as the lidar receiving lens to determine relevant information about the target object. It can be understood that the beam splitter can be used for the lidar transmitting lens to transmit light, or it can reflect the reflected light into the lidar receiving lens. That is, the lidar transmitting lens and the lidar receiving lens use the beam splitter to achieve light transmission and reflection functions in different areas.

[0040] In some implementations, the half-aperture d6 of the incident surface of the third lens and the true image height IH corresponding to the maximum field of view of the lidar transmitting lens satisfy the condition: 1 < 2 × d6 / IH < 1.25. Satisfying this condition is beneficial for the parallel emission of the principal rays from the edge field of view, which is conducive to achieving a small CRA.

[0041] In some embodiments, the distance BL from the incident light surface of the third lens to the light source emission surface on the optical axis and the chief ray angle CRA of the maximum field of view of the lidar emission lens satisfy: 0.01 mm < tan(CRA) × BL < 0.1 mm. Meeting the above conditions, the chief ray angle of the maximum field of view of the lidar emission lens is small. For an optical lens applied to lidar emission, it is beneficial to the high-energy emission of the laser and improves the light emission efficiency.

[0042] In some embodiments, the clear aperture semi-diameter d1 of the light-emitting surface of the first lens and the clear aperture semi-diameter d3 of the light-emitting surface of the second lens satisfy: 0.75 < d1 / d3 < 1.1. Meeting the above conditions can ensure that light enters the lens within a large range and ensure that the lens has a large field of view angle.

[0043] In some embodiments, the clear aperture semi-diameter d1 of the light-emitting surface of the first lens and the true image height IH corresponding to the maximum field of view angle of the lidar emission lens satisfy: 0.52 < d1 / IH < 0.7. Meeting the above conditions can ensure that the lens has a large field of view angle while ensuring that the overall size of the lens is moderate.

[0044] In some embodiments, the sagittal height SAG1 of the clear aperture of the light-emitting surface of the first lens, the sagittal height SAG2 of the clear aperture of the incident light surface of the first lens, and the central thickness CT1 of the first lens satisfy: 0.1 < (SAG2 - SAG1) / CT1 < 0.42. Meeting the above conditions can limit the degree of central depression of the first lens and reduce the difficulty of off-axis field aberration correction.

[0045] In some embodiments, the sagittal height SAG5 of the clear aperture of the light-emitting surface of the third lens, the sagittal height SAG6 of the clear aperture of the incident light surface of the third lens, and the central thickness CT3 of the third lens satisfy: 0.6 < (SAG6 - SAG5) / CT3 < 0.8. Meeting the above conditions, by controlling the relationship between the height difference of the sagittal heights of the incident light surface and the light-emitting surface of the third lens and the central thickness of the third lens, it is beneficial to correct the coma of the off-axis field and is beneficial to the collimation effect of the laser beam.

[0046] In some embodiments, the true image height IH corresponding to the maximum field of view angle of the lidar emission lens and the entrance pupil diameter EPD of the lidar emission lens satisfy: 1.4 < IH / EPD < 1.7. Meeting the above conditions makes the field of view and light flux balanced and improves the laser emission efficiency.

[0047] In some embodiments, the true image height IH corresponding to the maximum field of view angle of the lidar emission lens and the effective focal length f of the lidar emission lens satisfy: 0.42 < IH / f < 0.5. Meeting the above range, by reasonably controlling the ratio of the image height to the focal length of the lidar emission lens, a large field of view is achieved.

[0048] In some embodiments, the true image height IH corresponding to the maximum field angle of the lidar emission lens, the effective focal length f of the lidar emission lens, and the maximum field angle FOV of the lidar emission lens satisfy: 55° < f×FOV / IH < 60°. By satisfying the above range, by reasonably restricting the relationship between the focal length, field angle, and image height of the lidar emission lens, the lidar emission lens has good optical performance.

[0049] In some embodiments, the true image height IH corresponding to the maximum field angle of the lidar emission lens and the aperture value Fno of the lidar emission lens satisfy: 4.5mm < IH / Fno < 5.2mm. By satisfying the above range, the brightness of the edge of the lens picture can be improved, and the relative illuminance of the entire optical system can be enhanced.

[0050] In some embodiments, the focal length f1 of the first lens and the effective focal length f of the lidar emission lens satisfy: 1.3 < f1 / f < 1.8. By satisfying the above conditions, the first lens is beneficial to light convergence, can improve the collimation effect on the laser, and for a laser light source with a main wavelength of 905nm, reduce the exit angle of the lens.

[0051] In some embodiments, the curvature radius R1 of the light-emitting surface of the first lens and the effective focal length f of the lidar emission lens satisfy: 0.9 < R1 / f < 1.4; the curvature radius R2 of the light-incident surface of the first lens and the effective focal length f of the lidar emission lens satisfy: 2.6 < R2 / f < 6.6. When the above conditions are satisfied, the first lens makes the light beam have a converging effect, reduces the divergence angle of the light beam, further improves the convergence efficiency, and reduces the light exit angle of the lens.

[0052] In some embodiments, the focal length f3 of the third lens and the effective focal length f of the lidar emission lens satisfy: -1.6 < f3 / f < -0.95. By satisfying the above range, the third lens can have an appropriate negative optical power, enabling the light emitted by the laser to have a smooth transition in its trend, and improving the emission quality of the emission lens.

[0053] In some embodiments, the curvature radius R5 of the light-emitting surface of the third lens and the effective focal length f of the lidar emission lens satisfy: -1.2 < R5 / f < -0.95; the curvature radius R6 of the light-incident surface of the third lens and the effective focal length f of the lidar emission lens satisfy: 0.85 < R6 / f < 2.1. By satisfying the above conditions, the third lens makes the laser beam diverge to a certain extent, avoiding excessive direct convergence of light and resulting in concentrated energy loss, and improving the emission quality of the emission lens.

[0054] In some embodiments, the curvature radius R1 of the light-emitting surface of the first lens and the curvature radius R2 of the light-incident surface of the first lens satisfy: 0.2 < R1 / R2 < 0.37; the curvature radius R1 of the light-emitting surface of the first lens and the curvature radius R2 of the light-incident surface of the first lens satisfy: -0.7 < (R1 - R2) / (R1 + R2) < -0.45. Meeting the above conditions is beneficial to light beam convergence, thereby adjusting the trend of marginal beams and ensuring that the lens has high collimation performance.

[0055] In some embodiments, the curvature radius R5 of the light-emitting surface of the third lens and the curvature radius R6 of the light-incident surface of the third lens satisfy: -1.3 < R5 / R6 < -0.5; the curvature radius R5 of the light-emitting surface of the third lens and the curvature radius R6 of the light-incident surface of the third lens satisfy: -20 < (R5 - R6) / (R5 + R6) < 10.5. Meeting the above range can improve the emission quality of the emission lens.

[0056] In some embodiments, the combined focal length f12 of the first lens and the second lens and the effective focal length f of the lidar emission lens satisfy: -0.9 < f12 / f < -0.75. Meeting the above requirements, by reasonably distributing the combined optical power of the first lens and the second lens, the light deflection angle at the front end of the lens is reduced, and the generation of various off-axis aberrations is reduced.

[0057] In some embodiments, the combined focal length f23 of the second lens and the third lens and the effective focal length f of the lidar emission lens satisfy: -2 < f23 / f < -1.3. Meeting the above requirements, by reasonably distributing the combined optical power of the second lens and the third lens, the focal length of the lens is balanced, the aberration correction ability of various parts at the rear end of the lens is improved, and the light beam emission quality of the lens is enhanced.

[0058] In some embodiments, the clear aperture semi-diameter d1 of the light-emitting surface of the first lens and the clear aperture semi-diameter d6 of the light-incident surface of the third lens satisfy: 0.9 < d1 / d6 < 1.2. By reasonably setting the ratio of the apertures of the first and last lenses, the lens can have a smaller head size, a compact structure, and can improve the space utilization rate inside the lidar.

[0059] In some embodiments, the clear aperture semi-diameter d4 of the light-incident surface of the second lens and the curvature radius R4 of the light-incident surface of the second lens satisfy: -0.24 < 2×d4 / R4 < 0.15. Avoiding the lens being super hemispherical greatly reduces the processing difficulty of the second lens.

[0060] In some embodiments, the clear aperture semi-diameter d1 of the light-emitting surface of the first lens and the focal length f1 of the first lens satisfy: 0.25 < d1 / f1 < 0.33. By controlling the ratio of the clear aperture semi-diameter of the light-emitting surface of the first lens to the focal length of the first lens, the lens shape of the first lens is reasonably controlled, and the field angle of the optical system is expanded.

[0061] In some embodiments, the total optical length TTL of the lidar emission lens and the effective focal length f of the lidar emission lens satisfy: 1.8 < TTL / f < 2.1. This can effectively limit the length of the lens and is conducive to the miniaturization of the lidar emission lens. The total optical length TTL is the distance from the aperture to the light source emission surface on the optical axis.

[0062] In some embodiments, the total optical length TTL of the lidar emission lens and the true image height IH corresponding to the maximum field of view angle of the lidar emission lens satisfy: 3.8 < TTL / IH < 4.5. This can better achieve the miniaturization of the lens and, while ensuring the same total length of the lens, have a larger image plane.

[0063] In some embodiments, the true image height IH corresponding to the maximum field of view angle of the lidar emission lens, the effective focal length f of the lidar emission lens, and the maximum field of view angle FOV of the lidar emission lens satisfy: 0.9 < (IH / 2) / (f × tan(FOV / 2)) < 1.05. Meeting the above requirements indicates that the optical distortion of the lidar emission lens is well controlled.

[0064] In some embodiments, the maximum field of view angle FOV of the lidar emission lens and the f-number Fno of the lidar emission lens satisfy: 7.5° < FOV / Fno < 8.8°. This is conducive to expanding the field of view angle of the lens and increasing the aperture of the lens, achieving the characteristics of a large field of view angle and a large aperture of the lens. The large field of view angle can meet the requirements of large-range detection.

[0065] In some embodiments, the distance BL from the light incident surface of the third lens to the light source emission surface on the optical axis and the effective focal length f of the lidar emission lens satisfy: 0.2 < BL / f < 0.25. Meeting the above range is conducive to achieving a balance between good emission quality and easy assembly, ensuring the emission quality of the lens while avoiding interference between the lens and other components and reducing the assembly process difficulty of the lens module.

[0066] In some embodiments, the total optical length TTL of the lidar emission lens, the true image height IH corresponding to the maximum field of view angle of the lidar emission lens, and the maximum field of view angle FOV of the lidar emission lens satisfy: 0.15 / ° < TTL / IH / FOV < 0.16 / °. Meeting the above range can achieve a balance among a large image height, a long focal length, and miniaturization, and improve the emission quality of the laser lens.

[0067] In some embodiments, the total optical length TTL of the lidar emission lens and the sum ∑CT of the central thicknesses of the first lens, the second lens, and the third lens along the optical axis satisfy: 0.14 < ∑CT / TTL < 0.22. Meeting the above range can effectively compress the total length of the lens while being beneficial to the structural design and production process of the lens.

[0068] In some embodiments, the clear aperture semi-diameter d1 of the light-emitting surface of the first lens, the true image height IH corresponding to the maximum field angle of the lidar emission lens, and the maximum field angle FOV of the lidar emission lens satisfy: 2.2 < d1 / IH / tan(FOV / 2) < 3. Meeting the above range can ensure the balance among the size of the lens, the field angle, and the image plane.

[0069] In some embodiments, the distance BL on the optical axis from the light-incident surface of the third lens to the light-source emission surface and the total optical length TTL of the lidar emission lens satisfy: 0.1 < BL / TTL < 0.13. While ensuring sufficient space for the installation of optical elements, it is beneficial to achieve miniaturization of the lens.

[0070] In some embodiments, the focal length f2 of the second lens and the effective focal length f of the lidar emission lens satisfy: 0.6 < f2 / f < 1. The second lens is a positive lens, which complements the front and rear lenses, thereby collimating the outgoing light beam into a collimated light with a lower divergence degree to achieve emission at a relatively long distance.

[0071] In some embodiments, the focal length f1 of the first lens and the focal length f2 of the second lens satisfy: 1.5 < f1 / f2 < 2.6. Meeting the above conditions is beneficial to the smooth transition of the incident light beam between the first lens and the second lens and reduces the manufacturing cost of the lens.

[0072] In some embodiments, the focal length f2 of the second lens and the focal length f3 of the third lens satisfy: -0.7 < f2 / f3 < -0.55. Meeting the above range is beneficial to moderately expand the width of the laser beam while taking into account the beam quality and collimation characteristics.

[0073] In some embodiments, the lidar emission lens satisfies the following conditional expressions: 66 mm < TTL < 67 mm; 34 mm < f < 35 mm; 26° < FOV < 27°; 15 mm < IH < 16 mm; 3.2 < Fno < 3.4; 0.3° < CRA < 0.5°. In the above conditional expressions, TTL represents the total optical length of the lidar emission lens, f represents the effective focal length of the lidar emission lens, FOV represents the maximum field of view angle of the lidar emission lens, IH represents the true image height corresponding to the maximum field of view angle of the lidar emission lens, Fno represents the aperture value of the lidar emission lens; CRA represents the principal ray exit angle of the maximum field of view of the lidar emission lens. Meeting the above ranges, the lidar emission lens has at least one or more advantages such as miniaturization, small CRA, and large image plane.

[0074] In some embodiments, the lens material of the lidar emission lens provided by the present invention can be glass or plastic. When the lens material is plastic, the production cost can be effectively reduced. On the other hand, when the lens material is glass, the geometric chromatic aberration of the optical system can be effectively corrected by the low dispersion characteristic of the glass itself. The lens provided by the present invention can adopt an all-glass lens structure, which can reduce dispersion, effectively correct the chromatic aberration of the lens, and improve the emission quality.

[0075] In some embodiments, the first lens, the second lens, and the third lens can adopt spherical lenses or aspherical lenses. Compared with the spherical structure, the aspherical structure can effectively reduce the aberration of the optical system, thereby reducing the number of lenses and the size of the lenses, and better realizing the miniaturization of the lens. More specifically, the first lens, the second lens, and the third lens of the present invention adopt spherical lenses.

[0076] The present invention also provides a lidar device, including a beam splitter, a lidar receiving lens, and the above-mentioned lidar emission lens. The lidar emission lens and the lidar receiving lens share the beam splitter for light transmission or reflection. Sharing the beam splitter can reduce the use of optical elements and is beneficial to the miniaturization of the lidar device. Specifically, light passes through the beam splitter and reaches the object surface, and the light reflected from the surface of the target object returns to the beam splitter. The beam splitter reflects the reflected light, turning the optical axis by 90°, and then passes through receiving devices such as the lidar receiving lens to determine relevant information about the target object. It can be understood that the beam splitter can be used for the lidar emission lens to transmit light and can also reflect the reflected light into the lidar receiving lens.

[0077] The present invention will be further described below with reference to several embodiments. In each embodiment, the thickness, radius of curvature, and material selection of each lens in the lens are different; for specific differences, please refer to the parameter tables of each embodiment. The following embodiments are merely preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the following embodiments. Any changes, substitutions, combinations, or simplifications made without departing from the innovative points of the present invention should be considered equivalent substitutions and are included within the protection scope of the present invention.

[0078] Example 1 Please see Figure 1 The diagram shows a schematic of the structure of a lidar emitting lens 100 provided in Embodiment 1 of the present invention. The lidar emitting lens 100 transmits the emitted light beam to the object side. The lidar emitting lens 100 is located in the light-emitting direction of the light source, that is, the emitting surface of the light source is the light-emitting side. The lidar emitting lens 100, along the optical axis from the object side to the light source emitting surface S7 (in the opposite direction of light transmission), sequentially includes: an aperture ST, a first lens L1, a reflective element Pr, a second lens L2, and a third lens L3. Each of the first lens L1, second lens L2, and third lens L3 includes an incident surface and an emitting surface, which are disposed opposite to each other on the surface of each lens. It can be understood that the surface of each lens near the light source emitting surface is called the incident surface of that lens, and the surface of each lens near the object side is called the emitting surface of that lens.

[0079] Among them, the first lens L1 has positive optical power, its light-emitting surface S1 is convex, and its light-incident surface S2 is concave. The second lens L2 has positive optical power, its light-exiting surface S3 is convex, and its light-incident surface S4 is convex. The third lens L3 has negative optical power, its light-exiting surface S5 is concave, and its light-incident surface S6 is concave. The reflecting element Pr is used to deflect light rays. The light beam emitted from the light source passes sequentially through the third lens L3 and the second lens L2, and is reflected when it reaches the reflecting element Pr, causing the optical axis to deflect by 90°. It then passes sequentially through the first lens L1 and the aperture ST, finally reaching the object surface. The reflecting element Pr can be a flat glass plate and is positioned at a 45° angle relative to the light source's emitting surface. The reflecting element Pr can also be any other element capable of reflection.

[0080] The beam splitter ST can be used to control beam transmission, and the beam splitter ST is set parallel to the reflective element Pr. More specifically, the light passes through the beam splitter to reach the object surface, and the light reflected by the object surface returns to the beam splitter. The beam splitter reflects the reflected light, causing the optical axis to bend by 90°. Then, it passes through receiving devices such as the lidar receiving lens to determine the relevant information of the target object.

[0081] The first lens L1, the second lens L2, and the third lens L3 are glass spherical lenses.

[0082] The relevant parameters of each lens in the lidar transmitting lens 100 in Example 1 are shown in Table 1.

[0083] Table 1 In this embodiment, the field curvature curve, F-TAN (Theta) distortion curve, and axial aberration curve of the lidar transmitting lens 100 are respectively as follows: Figure 2 , Figure 3 , Figure 4 As shown.

[0084] Figure 2 The field curvature curve of Example 1 is shown, which represents the degree of curvature of light in the meridional and sagittal image planes. The horizontal axis represents the offset (unit: mm), and the vertical axis represents the half field of view (unit: °). As can be seen from the figure, the field curvature of the meridional and sagittal image planes is controlled within -0.2 mm to 0.3 mm, indicating that the lidar transmitting lens can effectively correct the field curvature.

[0085] Figure 3 The diagram shows the F-TAN (Theta) distortion curves for Example 1, representing the F-TAN (Theta) distortion of light of different wavelengths at different image heights. The horizontal axis represents the distortion value (unit: %), and the vertical axis represents the half field of view (unit: °). The diagram shows that the F-TAN (Theta) distortion is controlled within -5% to 0, indicating that the lidar transmitting lens can effectively correct distortion.

[0086] Figure 4 The diagram shows the axial aberration curves for Example 1, representing the aberrations of each wavelength along the optical axis. The horizontal axis represents the axial aberration value (unit: mm), and the vertical axis represents the normalized pupil radius. The diagram shows that the axial aberration offset is controlled within 0~0.3 mm, indicating that the lidar transmitting lens can effectively correct axial aberrations.

[0087] Example 2 Please see Figure 5 The diagram shown is a schematic diagram of the structure of the laser radar transmitting lens 200 provided in Embodiment 2 of the present invention. The main difference between this embodiment and Embodiment 1 is that the optical parameters such as the radius of curvature and lens thickness of each lens surface are different.

[0088] The relevant parameters of each lens in the lidar transmitting lens 200 in Example 2 are shown in Table 2.

[0089] Table 2 In this embodiment, the field curvature curve, F-TAN (Theta) distortion curve, and axial aberration curve of the lidar transmitting lens 200 are respectively as follows: Figure 6 , Figure 7 , Figure 8 As shown.

[0090] from Figure 6 As can be seen, the field curvature of the meridional and sagittal image planes is controlled within -0.1mm to 0.3mm, indicating that the lidar transmitting lens can effectively correct the field curvature.

[0091] from Figure 7 As can be seen, the F-TAN (Theta) distortion is controlled within -5% to 0, indicating that the lidar transmitting lens can effectively correct distortion.

[0092] from Figure 8 As can be seen, the axial aberration offset is controlled within 0~0.3mm, indicating that the lidar transmitting lens can effectively correct axial aberration.

[0093] Example 3 Please see Figure 9 The figure shown is a schematic diagram of the structure of the laser radar transmitting lens 300 provided in Embodiment 3 of the present invention. The main difference between this embodiment and Embodiment 1 is that the light incident surface S4 of the second lens L2 is concave; the optical parameters such as the radius of curvature and lens thickness of each lens surface are different.

[0094] The relevant parameters of each lens in the lidar transmitting lens 300 in Example 3 are shown in Table 3.

[0095] Table 3 In this embodiment, the field curvature curve, F-TAN (Theta) distortion curve, and axial aberration curve of the lidar transmitting lens 300 are respectively as follows: Figure 10 , Figure 11 , Figure 12 As shown.

[0096] from Figure 10 As can be seen, the field curvature of the meridional and sagittal image planes is controlled within -0.1mm to 0.3mm, indicating that the lidar transmitting lens can effectively correct the field curvature.

[0097] from Figure 11 As can be seen, the F-TAN (Theta) distortion is controlled within -5% to 0, indicating that the lidar transmitting lens can effectively correct distortion.

[0098] from Figure 12As can be seen, the axial aberration offset is controlled within 0~0.3mm, indicating that the lidar transmitting lens can effectively correct axial aberration.

[0099] Please refer to Table 4 for the optical characteristics corresponding to each of the above embodiments, including the effective focal length f of the lidar emitting lens, the total optical length TTL (distance from the aperture to the light source emitting surface on the optical axis), the aperture value Fno, the true image height IH corresponding to the maximum field of view, the maximum field of view FOV, the distance BL from the light incident surface of the third lens to the light source emitting surface on the optical axis, and the values ​​corresponding to each conditional expression in each embodiment.

[0100] Table 4 In summary, the lidar transmitting lens and lidar device provided by the present invention employ three lenses with specific optical power and one reflective element. Through specific surface shape matching and reasonable optical power distribution, the emission quality of the lens can be improved, aberrations reduced, and the emission quality of the lens enhanced, giving the lens one or more advantages such as miniaturization, small CRA, large image plane, high emission quality, and high collimation performance.

[0101] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0102] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A lidar transmitting lens, characterized in that, It consists of three lenses with optical power and a reflecting element, and successively includes a first lens, a reflecting element, a second lens, and a third lens along the optical axis from the object side to the light source emission surface; the first lens, the second lens, and the third lens each include an incident light surface close to the light source emission surface and an outgoing light surface close to the object side; The first lens has a positive optical power, its outgoing light surface is convex, and its incident light surface is concave; The reflecting element is used to deflect light. The light emitted from the light source emission surface passes through the third lens and the second lens successively and then is reflected by the reflecting element, so that the optical axis is deflected by 90° and then passes through the first lens to reach the object side; The second lens has a positive optical power, and its outgoing light surface is convex; The third lens has a negative optical power, its outgoing light surface is concave, and its incident light surface is concave; Wherein, the clear aperture semi-diameter d6 of the incident light surface of the third lens and the true image height IH corresponding to the maximum field angle of the lidar emission lens satisfy: 1 < 2×d6 / IH < 1.25; the main ray exit angle CRA of the maximum field of the lidar emission lens and the distance BL on the optical axis from the incident light surface of the third lens to the light source emission surface satisfy: 0.01mm < tan(CRA)×BL < 0.1mm.

2. The lidar transmitting lens according to claim 1, characterized in that, The clear aperture semi-diameter d1 of the outgoing light surface of the first lens and the clear aperture semi-diameter d3 of the outgoing light surface of the second lens satisfy: 0.75 < d1 / d3 < 1.1; the clear aperture semi-diameter d1 of the outgoing light surface of the first lens and the true image height IH corresponding to the maximum field angle of the lidar emission lens satisfy: 0.52 < d1 / IH < 0.

7.

3. The lidar transmitting lens according to claim 1, characterized in that, The sagittal height SAG1 of the clear aperture semi-diameter of the outgoing light surface of the first lens, the sagittal height SAG2 of the clear aperture semi-diameter of the incident light surface of the first lens, and the central thickness CT1 of the first lens satisfy: 0.1 < (SAG2-SAG1) / CT1 < 0.42; the sagittal height SAG5 of the clear aperture semi-diameter of the outgoing light surface of the third lens, the sagittal height SAG6 of the clear aperture semi-diameter of the incident light surface of the third lens, and the central thickness CT3 of the third lens satisfy: 0.6 < (SAG6-SAG5) / CT3 < 0.

8.

4. The lidar transmitting lens according to claim 1, characterized in that, The true image height IH corresponding to the maximum field angle of the lidar emission lens and the entrance pupil diameter EPD of the lidar emission lens satisfy: 1.4 < IH / EPD < 1.7; the true image height IH corresponding to the maximum field angle of the lidar emission lens and the effective focal length f of the lidar emission lens satisfy: 0.42 < IH / f < 0.

5.

5. The lidar transmitting lens according to claim 1, characterized in that, The true image height IH corresponding to the maximum field angle of the lidar emission lens, the effective focal length f of the lidar emission lens, and the maximum field angle FOV of the lidar emission lens satisfy: 55° < f×FOV / IH < 60°; the true image height IH corresponding to the maximum field angle of the lidar emission lens and the f-number Fno of the lidar emission lens satisfy: 4.5mm < IH / Fno < 5.2mm.

6. The lidar transmitting lens according to claim 1, characterized in that, The focal length f1 of the first lens and the effective focal length f of the lidar emission lens satisfy: 1.3 < f1 / f < 1.8; the radius of curvature R1 of the light-emitting surface of the first lens and the effective focal length f of the lidar emission lens satisfy: 0.9 < R1 / f < 1.4; the radius of curvature R2 of the light-incident surface of the first lens and the effective focal length f of the lidar emission lens satisfy: 2.6 < R2 / f < 6.

6.

7. The lidar transmitting lens according to claim 1, characterized in that, The focal length f3 of the third lens and the effective focal length f of the lidar emission lens satisfy: -1.6 < f3 / f < -0.95; the radius of curvature R5 of the light-emitting surface of the third lens and the effective focal length f of the lidar emission lens satisfy: -1.2 < R5 / f < -0.95; the radius of curvature R6 of the light-incident surface of the third lens and the effective focal length f of the lidar emission lens satisfy: 0.85 < R6 / f < 2.

1.

8. The lidar transmitting lens according to claim 1, characterized in that, The radius of curvature R1 of the light-emitting surface of the first lens and the radius of curvature R2 of the light-incident surface of the first lens satisfy: 0.2 < R1 / R2 < 0.37; the radius of curvature R1 of the light-emitting surface of the first lens and the radius of curvature R2 of the light-incident surface of the first lens satisfy: -0.7 < (R1 - R2) / (R1 + R2) < -0.

45.

9. The lidar transmitting lens according to claim 1, characterized in that, The radius of curvature R5 of the light-emitting surface of the third lens and the radius of curvature R6 of the light-incident surface of the third lens satisfy: -1.3 < R5 / R6 < -0.5; the radius of curvature R5 of the light-emitting surface of the third lens and the radius of curvature R6 of the light-incident surface of the third lens satisfy: -20 < (R5 - R6) / (R5 + R6) < 10.

5.

10. A lidar device, characterized in that, It includes a beam splitter, a lidar receiving lens, and the lidar emission lens according to any one of claims 1-9, and the lidar emission lens and the lidar receiving lens share the beam splitter for light transmission or reflection.

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