Lidar receiving lens and lidar device

Abstract

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

[0005] The technical solution adopted in this invention is as follows:

[0006] A lidar receiving lens consists of three lenses with optical power and a reflective element, and along the optical axis from the object side to the imaging surface, it includes a reflective element, a first lens, a second lens, and a third lens in sequence.

[0007] The reflective element is used to deflect light so that the optical axis is deflected by 90° and then passes through the first lens, the second lens and the third lens in sequence before reaching the imaging surface;

[0008] The first lens has positive optical power and its object side is convex.

[0009] The second lens has negative optical power, and its object side is concave, as is its image side;

[0010] The third lens has positive optical power, and its object side is convex, and its image side is convex.

[0011] Among them, the chief ray angle (CRA) of the main light ray of the maximum field of view of the lidar receiving lens and the distance BL on the optical axis from the image side of the third lens to the imaging surface satisfy: 0.85 mm < tan(CRA) × BL < 2.5 mm.

[0012] Further preferably, the distance BL on the optical axis from the image side of the third lens to the imaging surface and the total optical length TTL of the lidar receiving lens satisfy: 0.18 < BL / TTL < 0.33; the total optical length TTL of the lidar receiving lens and the effective focal length f of the lidar receiving lens satisfy: 1.5 < TTL / f < 1.95.

[0013] Further preferably, the true image height IH corresponding to the maximum field of view angle of the lidar receiving lens, the effective focal length f of the lidar receiving lens and the maximum field of view angle FOV of the lidar receiving lens satisfy: 52° < f × FOV / IH < 63°; the true image height IH corresponding to the maximum field of view angle of the lidar receiving lens and the effective focal length f of the lidar receiving lens satisfy: 0.4 < IH / f < 0.5.

[0014] Further preferably, the focal length f3 of the third lens and the effective focal length f of the lidar receiving lens satisfy: 0.55 < f3 / f < 0.7; the curvature radius R5 of the object side of the third lens and the curvature radius R6 of the image side of the third lens satisfy: -1 < (R5 + R6) / (R5 - R6) < -0.5.

[0015] Further preferably, the total optical length TTL of the lidar receiving lens, the true image height IH corresponding to the maximum field of view angle of the lidar receiving lens and the maximum field of view angle FOV of the lidar receiving lens satisfy: 0.13 / ° < TTL / IH / FOV < 0.16 / °; the true image height IH corresponding to the maximum field of view angle of the lidar receiving lens and the entrance pupil diameter EPD of the lidar receiving lens satisfy: 0.7 < IH / EPD < 0.9.

[0016] Further preferably, the true image height IH corresponding to the maximum field of view angle of the lidar receiving lens and the maximum field of view angle FOV of the lidar receiving lens satisfy: 1.5° / mm < FOV / IH < 1.8° / mm; the true image height IH corresponding to the maximum field of view angle of the lidar receiving lens and the f-number Fno of the lidar receiving lens satisfy: 8 mm < IH / Fno < 10 mm.

[0017] Further preferably, the central thickness CT1 of the first lens, the central thickness CT2 of the second lens and the focal length f1 of the first lens satisfy: 0.5 < (CT1 + CT2) / f1 < 1.

[0018] More preferably, the sagittal height SAG11 of the clear aperture on the object side of the first lens, the sagittal height SAG12 of the clear aperture on the image side of the first lens, and the clear aperture diameter DM11 on the object side of the first lens satisfy: -0.45 < (SAG12 - SAG11) / DM11 < 0.22; the sagittal height SAG21 of the clear aperture on the object side of the second lens, the sagittal height SAG22 of the clear aperture on the image side of the second lens, and the central thickness CT2 of the second lens satisfy: -0.3 < (SAG22 - SAG21) / CT2 < 0.45.

[0019] More preferably, the clear aperture diameter DM11 on the object side of the first lens and the clear aperture diameter DM32 on the image side of the third lens satisfy: 0.85 < DM11 / DM32 < 1.55; the clear aperture diameter DM11 on the object side of the first lens and the focal length f1 of the first lens satisfy: 0.2 < DM11 / f1 < 0.5.

[0020] A lidar device includes a lidar transmitting lens and the above-mentioned lidar receiving lens, and the lidar receiving lens and the lidar transmitting lens share the reflection element for reflection or light transmission.

[0021] The lidar receiving 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 receiving quality of the lens can be improved, aberration can be reduced, the receiving quality of the lens can be enhanced, and the lens has one or more advantages such as miniaturization, small CRA, large image plane, high telecentricity, and high collimation performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the following description of the embodiments in conjunction with the accompanying drawings, where:

[0023] Figure 1 is a schematic structural diagram of the lidar receiving lens in Embodiment 1 of the present invention.

[0024] Figure 2 is the field curvature curve graph of the lidar receiving lens in Embodiment 1 of the present invention.

[0025] Figure 3 is the F-TAN(Theta) distortion curve of the lidar receiving lens in Embodiment 1 of the present invention.

[0026] Figure 4 is the axial aberration curve graph of the lidar receiving lens in Embodiment 1 of the present invention.

[0027] Figure 5 This is a chromatic aberration curve of the laser radar receiving lens in Embodiment 1 of the present invention.

[0028] Figure 6 This is a schematic diagram of the structure of the lidar receiving lens in Embodiment 2 of the present invention.

[0029] Figure 7 This is a field curvature curve diagram of the lidar receiving lens in Embodiment 2 of the present invention.

[0030] Figure 8 This is the F-TAN (Theta) distortion curve of the lidar receiving lens in Embodiment 2 of the present invention.

[0031] Figure 9 This is an axial aberration curve of the lidar receiving lens in Embodiment 2 of the present invention.

[0032] Figure 10 This is a chromatic aberration curve of the laser radar receiving lens in Embodiment 2 of the present invention.

[0033] Figure 11 This is a schematic diagram of the structure of the lidar receiving lens in Embodiment 3 of the present invention.

[0034] Figure 12 This is a field curvature curve diagram of the lidar receiving lens in Embodiment 3 of the present invention.

[0035] Figure 13 This is the F-TAN (Theta) distortion curve of the lidar receiving lens in Embodiment 3 of the present invention.

[0036] Figure 14 This is an axial aberration curve of the lidar receiving lens in Embodiment 3 of the present invention.

[0037] Figure 15 This is a chromatic aberration curve of the laser radar receiving lens in Embodiment 3 of the present invention.

[0038] Figure 16 This is a schematic diagram of the structure of the lidar receiving lens in Embodiment 4 of the present invention.

[0039] Figure 17 This is a field curvature curve diagram of the lidar receiving lens in Embodiment 4 of the present invention.

[0040] Figure 18 This is the F-TAN (Theta) distortion curve of the lidar receiving lens in Embodiment 4 of the present invention.

[0041] Figure 19 This is an axial aberration curve of the laser radar receiving lens in Embodiment 4 of the present invention.

[0042] Figure 20This is a chromatic aberration curve of the laser radar receiving lens in Embodiment 4 of the present invention.

[0043] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0044] 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.

[0045] 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.

[0046] 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.

[0047] In this article, 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 lens closest to the subject is called the object-side surface of the lens, and the surface of each lens closest to the imaging plane is called the image-side surface of the lens.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] This invention provides a lidar receiving lens that transmits light reflected from an object's surface to an imaging surface. The lidar receiving lens consists of three lenses with optical power and a reflective element, and sequentially includes, along the optical axis from the object side to the imaging surface: a reflective element, a first lens, a second lens, and a third lens.

[0052] The reflective element is used to deflect light, causing the optical axis to bend by 90°. The reflective element can be a beam splitter, achieving both transmission and reflection in specific areas. After the light beam is emitted, it passes through the lidar transmitting lens, then through the beam splitter to reach the object surface. The light reflected from the object surface returns to the beam splitter, which reflects the reflected light back, causing the optical axis to bend by 90°. The light then passes through a first lens, a second lens, and a third lens to reach the imaging surface. The reflective element can be tilted at 45° relative to the imaging surface. The reflective element can also be any other element that can achieve both transmission and reflection. It can be understood that the beam splitter can be used by the lidar transmitting lens to transmit light, or it can reflect the reflected light back into the lidar receiving lens; that is, the lidar transmitting lens and the lidar receiving lens use a beam splitter for transmission and reflection respectively.

[0053] Specifically, the first lens may have positive optical power, with its object-side surface being convex and its image-side surface being concave, convex, or flat. The second lens may have negative optical power, with its object-side surface being concave and its image-side surface being concave. The third lens may have positive optical power, with its object-side surface being convex and its image-side surface being convex.

[0054] In some embodiments, the lidar receiving lens may further include an aperture stop and a filter. The aperture stop may be disposed between the reflecting element and the first lens, or the object-side or image-side of the first lens may be used as the aperture stop, or the object-side of the filter may be used as the aperture stop. The aperture stop is used to limit the amount of light entering the lens, thereby changing the brightness of the image. The filter may be disposed between the reflecting element and the first lens, or between the third lens and the imaging surface. The filter is used to filter out interference light, preventing interference light from reaching the imaging surface of the lidar receiving lens and affecting the reception of normal light.

[0055] In some embodiments, the distance BL on the optical axis from the image side of the third lens to the imaging surface of the lidar receiving lens satisfies: 0.85 mm < tan(CRA) × BL < 2.5 mm. Meeting the above conditions, the lens can achieve a high telecentricity, making the chief ray nearly parallel to the optical axis in the object space, which is beneficial to ensuring a high receiving efficiency of the imaging chip.

[0056] In some embodiments, the distance BL on the optical axis from the image side of the third lens to the imaging surface and the total optical length TTL of the lidar receiving lens satisfy: 0.18 < BL / TTL < 0.33. This is beneficial to achieving a short back focal length of the lidar receiving lens. When ensuring sufficient space for the installation of optical elements, it is beneficial to miniaturize the lidar receiving lens.

[0057] In some embodiments, the total optical length TTL of the lidar receiving lens and the effective focal length f of the lidar receiving lens satisfy: 1.5 < TTL / f < 1.95. This can effectively limit the length of the lens, which is beneficial to miniaturizing the lidar receiving lens.

[0058] In some embodiments, the true image height IH corresponding to the maximum field angle of the lidar receiving lens, the effective focal length f of the lidar receiving lens, and the maximum field angle FOV of the lidar receiving lens satisfy: 52° < f × FOV / IH < 63°. Meeting the above range, by reasonably restricting the relationship between the focal length, field angle, and image height of the lidar receiving lens, the lidar receiving lens has good optical performance.

[0059] In some embodiments, the true image height IH corresponding to the maximum field angle of the lidar receiving lens and the effective focal length f of the lidar receiving lens satisfy: 0.4 < IH / f < 0.5. Meeting the above range can reasonably control the ratio of the image height to the focal length of the lidar receiving lens.

[0060] In some embodiments, the focal length f3 of the third lens and the effective focal length f of the lidar receiving lens satisfy: 0.55 < f3 / f < 0.7. The third lens is a positive lens, which transmits the light beam to the final imaging lens group, compensates for aberrations with the front and rear optical systems, thereby achieving high imaging quality of the lidar receiving lens and enabling high-quality collimation performance.

[0061] In some embodiments, the radius of curvature R5 of the object side surface of the third lens and the radius of curvature R6 of the image side surface of the third lens satisfy: -1 < (R5 + R6) / (R5 - R6) < -0.5. By satisfying the above range and reasonably defining the shapes of the object side surface and the image side surface of the third lens, the third lens can have an appropriate surface shape, which helps to control the light trend in the marginal field of view, improve the imaging quality of the marginal field of view, and achieve high-quality collimation performance.

[0062] In some embodiments, the total optical length TTL of the lidar receiving lens, the true image height IH corresponding to the maximum field of view angle of the lidar receiving lens, and the maximum field of view angle FOV of the lidar receiving lens satisfy: 0.13 / ° < TTL / IH / FOV < 0.16 / °. By satisfying the above range, it is beneficial to balance the relationship among the total length, image height, and field of view angle of the lidar receiving lens.

[0063] In some embodiments, the true image height IH corresponding to the maximum field of view angle of the lidar receiving lens and the entrance pupil diameter EPD of the lidar receiving lens satisfy: 0.7 < IH / EPD < 0.9. By satisfying the above conditions, the field of view and light flux are balanced, the imaging quality of the lens is improved, and high-quality collimation performance can be achieved.

[0064] In some embodiments, the true image height IH corresponding to the maximum field of view angle of the lidar receiving lens and the maximum field of view angle FOV of the lidar receiving lens satisfy: 1.5° / mm < FOV / IH < 1.8° / mm. By satisfying the above conditions, on the premise of meeting the requirements of the image height, the field of view characteristics of the lidar receiving lens can be guaranteed, so that the lidar receiving lens has good optical performance.

[0065] In some embodiments, the true image height IH corresponding to the maximum field of view angle of the lidar receiving lens and the f-number Fno of the lidar receiving lens satisfy: 8mm < IH / Fno < 10mm. By satisfying the above range, the brightness at the edge of the lens picture can be increased, the relative illumination of the entire optical system can be improved, and the imaging quality can be optimized. Optionally, for an optical lens applied to lidar reception, high-quality collimation performance can be achieved.

[0066] In some embodiments, the central thickness CT1 of the first lens, the central thickness CT2 of the second lens, and the focal length f1 of the first lens satisfy: 0.5 < (CT1 + CT2) / f1 < 1. The first lens and the second lens form a thick lens group and form a positive refractive power, so that the light converges moderately.

[0067] In some embodiments, the sagittal height SAG11 of the clear aperture semi-diameter on the object side of the first lens, the sagittal height SAG12 of the clear aperture semi-diameter on the image side of the first lens, and the clear aperture semi-diameter DM11 on the object side of the first lens satisfy: -0.45 < (SAG12 - SAG11) / DM11 < 0.22. By satisfying the above conditions, the shape of the first lens can be controlled, the forming difficulty of the first lens can be reduced, thereby reducing the processing sensitivity, which is beneficial to improving the production yield of the wide-angle lens.

[0068] In some embodiments, the sagittal height SAG21 of the clear aperture semi-diameter on the object side of the second lens, the sagittal height SAG22 of the clear aperture semi-diameter on the image side of the second lens, and the central thickness CT2 of the second lens satisfy: -0.3 < (SAG22 - SAG21) / CT2 < 0.45. By controlling the relationship between the height difference of the sagittal heights of the image side and the object side of the second lens and the central thickness of the second lens, it is beneficial to correct the coma of the off-axis field, beneficial to improving the imaging quality of the off-axis field of the lidar receiving lens, and can achieve high-quality collimation performance.

[0069] In some embodiments, the clear aperture semi-diameter DM11 on the object side of the first lens and the clear aperture semi-diameter DM32 on the image side of the third lens satisfy: 0.85 < DM11 / DM32 < 1.55. By satisfying the above range, by reasonably setting the aperture relationship of the first and last lenses, while ensuring that as much light as possible enters the system, the area of light entering the image plane is increased, and high relative illuminance of the lens is achieved.

[0070] In some embodiments, the clear aperture semi-diameter DM11 on the object side of the first lens and the focal length f1 of the first lens satisfy: 0.2 < DM11 / f1 < 0.5. By controlling the ratio of the semi-aperture on the object side of the first lens to the focal length of the first lens, the lens shape of the first lens is reasonably controlled, so that light enters the object-side surface of the first lens at the maximum incident angle, and the field angle of the optical system is expanded.

[0071] In some embodiments, the total optical length TTL of the lidar receiving lens and the true image height IH corresponding to the maximum field angle of the lidar receiving lens satisfy: 3.3 < TTL / IH < 4.4. By controlling the ratio between the distance from the object-side surface of the first lens on the optical axis to the image plane of the optical system and the image height of the optical system, the total optical length of the optical system is shorter, the lens structure is compact, and miniaturization is thus achieved.

[0072] In some embodiments, the focal length f1 of the first lens and the effective focal length f of the lidar receiving lens satisfy: 0.6 < f1 / f < 0.8. The first lens receives light rays that enter the lidar receiving lens at large angles, expands the field angle range of the lidar receiving lens, and is also beneficial to reducing the sensitivity of the lidar receiving lens, achieving a miniaturized design of the lidar receiving lens.

[0073] In some embodiments, the focal length f2 of the second lens and the effective focal length f of the lidar receiving lens satisfy: -0.55 < f2 / f < -0.4. The second lens has a negative focal length and a relatively small focal length, which can perform a second adjustment on the full-field beam, deflect the large-field beam a second time, and turn the beam to the transition lens group, thus facilitating the realization of a large image plane of the lidar receiving lens.

[0074] 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 receiving lens satisfy: 3.1 < f12 / f < 7.7. Meeting the above conditions is beneficial for the first lens and the second lens to gently transmit light to the third lens and reduce the CRA of the lens.

[0075] In some embodiments, the maximum field of view FOV of the lidar receiving lens and the aperture value Fno of the lidar receiving lens satisfy: 14° < FOV / Fno < 16°. This is beneficial for expanding the field of view of the lidar receiving lens and increasing the aperture of the lens, realizing the characteristics of a large aperture.

[0076] In some embodiments, the curvature radius R1 of the object side surface of the first lens and the curvature radius R2 of the image side surface of the first lens satisfy: -0.2 < R1 / R2 < 0.2. Meeting the above conditions helps the first lens better receive light.

[0077] In some embodiments, the curvature radius R1 of the object side surface of the first lens and the curvature radius R2 of the image side surface of the first lens satisfy: -1.5 < (R1 + R2) / (R1 - R2) < -0.7. Reasonably controlling the curvature radii of the object side surface and the image side surface of the first lens is beneficial for controlling the shape of the first lens, correcting the aberration generated by itself, improving the imaging quality, and realizing high-quality collimation performance.

[0078] In some embodiments, the curvature radius R1 of the object side surface of the first lens and the effective focal length f of the lidar receiving lens satisfy: 0.6 < R1 / f < 0.8. Meeting the above conditions can make light enter the rear optical system gently, thus slowing down the trend of marginal light, being beneficial for reducing the incident angle of the chief ray of each field of view, improving the imaging quality of the lidar receiving lens, and realizing high-quality collimation performance.

[0079] In some embodiments, the curvature radius R3 of the object side surface of the second lens and the effective focal length f of the lidar receiving lens satisfy: -2.2 < R3 / f < -1.5; the curvature radius R4 of the image side surface of the second lens and the effective focal length f of the lidar receiving lens satisfy: 0.32 < R4 / f < 0.42. Meeting the above conditions enables the second lens to adjust the trend of light and also helps to reduce the aperture of the subsequent lens, thus realizing cost reduction.

[0080] In some embodiments, the radius of curvature R5 of the object side surface of the third lens and the effective focal length f of the lidar receiving lens satisfy: 0.52 < R5 / f < 0.85; the radius of curvature R6 of the image side surface of the third lens and the effective focal length f of the lidar receiving lens satisfy: -17.5 < R6 / f < -2.2. The third lens satisfying the above conditions is a biconvex lens, which is beneficial to gently converge and converge the front beam, is beneficial to improving the imaging quality of the lidar receiving lens, and can achieve high-quality collimation performance.

[0081] In some embodiments, the focal length f1 of the first lens and the focal length f2 of the second lens satisfy: -1.7 < f1 / f2 < -1.4. Satisfying the above, the combination of a weaker positive focal length and a stronger negative focal length can quickly collect and adjust the light path of the large field-of-view beam at the front end of the lidar receiving lens, so as to ensure that subsequent lenses such as the third lens have a smaller aperture, and at the same time realize the large field-of-view angle characteristic and small volume advantage of the lidar receiving lens.

[0082] In some embodiments, the focal length f2 of the second lens and the focal length f3 of the third lens satisfy: -0.9 < f2 / f3 < -0.6. Satisfying the above conditions can further compensate and adjust the aberration of the lidar receiving lens, realize the high imaging performance of the lidar receiving lens, and can achieve high-quality collimation performance.

[0083] In some embodiments, the central thickness CT2 of the second lens and the central thickness CT3 of the third lens satisfy: 1.1 < CT2 / CT3 < 1.8. Satisfying the above conditions can improve the stability of the lens and reduce the temperature drift.

[0084] In some embodiments, the total optical length TTL of the lidar receiving 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: 0.3 < ∑CT / TTL < 0.5. Satisfying the above range can effectively compress the total length of the lens, and is beneficial to the structural design and production process of the lens.

[0085] In some embodiments, the sagittal height SAG31 of the object side surface clear aperture of the third lens and the object side surface clear aperture DM31 of the third lens satisfy: -0.26 < SAG31 / DM31 < 1.1. Reasonably controlling the sagittal height and aperture of the object side surface of the third lens, controlling the beam trend and performing final imaging, ensuring that the opening angle of the third lens is within a certain range, is beneficial to the lidar receiving lens to achieve high resolution, making the lidar receiving lens have high imaging quality, and can achieve high-quality collimation performance.

[0086] In some embodiments, the clear aperture radius DM11 of the object side surface of the first lens and the clear aperture radius DM21 of the object side surface of the second lens satisfy: 0.6 < DM11 / DM21 < 1.2. This ensures that light enters the lens within a relatively large range, guaranteeing that the lens has a large field of view angle.

[0087] In some embodiments, the clear aperture radius DM11 of the object side surface of the first lens and the true image height IH corresponding to the maximum field of view angle of the lidar receiving lens satisfy: 0.33 < DM11 / IH < 0.8. Meeting the above conditions can ensure that the lens has a large field of view angle while keeping the overall size of the lens moderate.

[0088] In some embodiments, the clear aperture radius DM22 of the image side surface of the second lens and the radius of curvature R4 of the image side surface of the second lens satisfy: 0.9 < 2×DM22 / R4 < 1.45. This avoids the lens being super hemispherical and greatly reduces the processing difficulty of the second lens.

[0089] In some embodiments, the clear aperture radius DM32 of the image side surface of the third lens and the true image height IH corresponding to the maximum field of view angle of the lidar receiving lens satisfy: 0.23 < DM32 / IH < 0.85. Meeting the above conditions is beneficial for the chief ray of the edge field of view to emerge parallel to the imaging surface, which is beneficial for achieving a small CRA.

[0090] In some embodiments, the lidar receiving lens satisfies the following conditional expressions: 57mm < TTL < 63.5mm; 34mm < f < 35.5mm; 26° < FOV < 27°; 15mm < IH < 16mm; 1.6 < Fno < 1.9; 3.5° < CRA < 8°. In the above conditional expressions, TTL represents the total optical length of the lidar receiving lens, f represents the effective focal length of the lidar receiving lens, FOV represents the maximum field of view angle of the lidar receiving lens, IH represents the true image height corresponding to the maximum field of view angle of the lidar receiving lens, Fno represents the aperture value of the lidar receiving lens; CRA represents the chief ray incident angle of the maximum field of view of the lidar receiving lens. Meeting the above ranges, the lidar receiving lens has at least one or more advantages such as a large aperture, miniaturization, a small CRA, and a large image plane.

[0091] In some embodiments, the lens material of the lidar receiving 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, due to the low dispersion characteristics of the glass itself, the geometric chromatic aberration of the optical system can be effectively corrected. 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 lidar receiving lens, and improve the imaging quality.

[0092] In some embodiments, the first lens, second lens, and third lens can be spherical lenses or aspherical lenses. Compared to spherical structures, aspherical structures can effectively reduce the aberrations of the optical system, thereby reducing the number of lenses and the size of the lenses, and better achieving lens miniaturization. More specifically, the first lens, second lens, and third lens of the present invention are spherical lenses.

[0093] This invention also provides a lidar device, including a lidar transmitting lens and the aforementioned lidar receiving lens. The lidar receiving lens and the lidar transmitting lens share a reflective element for reflection or transmission. The reflective element can be a beam splitter. Using a beam splitter reduces the number of optical elements used, which is beneficial for miniaturizing the lidar device. Specifically, light passes through the lidar transmitting lens, passes through the beam splitter, and reaches the object surface. The light reflected from the target object surface returns to the beam splitter, which reflects the reflected light back, causing the optical axis to bend by 90°. The light then passes through the lenses of the lidar receiving lens to reach the imaging surface. It can be understood that a beam splitter can be used for transmitting light through the lidar receiving lens, or for reflecting back light into the lidar receiving lens.

[0094] 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.

[0095] Example 1

[0096] Please see Figure 1 The diagram shows a schematic of the structure of a lidar receiving lens 100 provided in Embodiment 1 of the present invention. The lidar receiving lens 100 transmits the light reflected from the surface of an object to the imaging surface. The lidar receiving lens 100 includes, along the optical axis from the object side to the imaging surface S9, the following components in sequence: a reflecting element Pr, a first lens L1, a second lens L2, a third lens L3, and a filter G1.

[0097] The reflective element Pr is used to deflect light, causing the optical axis to bend by 90°. The reflective element Pr can be a beam splitter, achieving both transmission and reflection in specific areas. After the light beam is emitted, it passes through the lidar's transmitting lens, then through the beam splitter to reach the object surface. The light reflected from the object surface returns to the beam splitter, which reflects the reflected light back, causing the optical axis to bend by 90°. The light then passes through the first lens L1, the second lens L2, the third lens L3, and the filter G1 to reach the imaging surface. The reflective element Pr can be tilted at 45° relative to the imaging surface. The reflective element Pr can also be any other element that can achieve both transmission and reflection.

[0098] The first lens L1 has positive optical power, its object side S1 is convex, its image side S2 is flat, and its object side S1 can be used as an aperture stop ST to limit the beam. That is, the object side S1 of the first lens and the aperture stop ST are coplanar.

[0099] The second lens L2 has negative optical power, its object side S3 is concave, and its image side S4 is concave.

[0100] The third lens L3 has positive optical power, its object side S5 is convex, and its image side S6 is convex.

[0101] The object-side surface S7 and the image-side surface S8 of filter G1 are both planar.

[0102] The first lens L1, the second lens L2, and the third lens L3 are glass spherical lenses.

[0103] The relevant parameters of each lens in the lidar receiving lens 100 in Example 1 are shown in Table 1.

[0104] Table 1

[0105]

[0106] In this embodiment, the field curvature curve, F-TAN (Theta) distortion curve, axial aberration curve, and transverse chromatic aberration curve of the lidar receiving lens 100 are respectively as follows: Figure 2 , Figure 3 , Figure 4 , Figure 5 As shown.

[0107] 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, indicating that the lidar receiving lens can effectively correct the field curvature.

[0108] Figure 3The 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: °). As can be seen from the diagram, the F-TAN (Theta) distortion is controlled within -5% to 0, indicating that the lidar receiving lens can effectively correct distortion.

[0109] Figure 4 The diagram shows the axial aberration curves for Example 1, representing the aberrations of each wavelength along the optical axis at the imaging plane. 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 -0.2 mm to 0 mm, indicating that the lidar receiving lens can effectively correct axial aberrations.

[0110] Figure 5 The diagram shows the transverse chromatic aberration curves for Example 1, representing the chromatic aberration of each wavelength relative to the center wavelength (0.905 μm) at different image heights on the imaging plane. The horizontal axis represents the transverse chromatic aberration value of each wavelength relative to the center wavelength (unit: μm), and the vertical axis represents the normalized field of view. As can be seen from the diagram, the transverse chromatic aberration of the longest and shortest wavelengths is controlled within ±2 μm, indicating that the optical lens can excellently correct chromatic aberration at the edges of the field of view.

[0111] Example 2

[0112] Please see Figure 6 The diagram shown is a schematic diagram of the structure of the lidar receiving lens 200 provided in Embodiment 2 of the present invention. The lidar receiving lens 200 includes, along the optical axis from the object side to the imaging surface S9, the following components in sequence: a reflective element Pr, a filter G1, a first lens L1, a second lens L2, and a third lens L3.

[0113] The reflective element Pr is used to deflect light, causing the optical axis to bend by 90°. The reflective element Pr can be a beam splitter, achieving both transmission and reflection in specific areas. After the light beam is emitted, it passes through the laser radar receiving lens, then through the beam splitter to reach the object surface. The light reflected from the object surface returns to the beam splitter, which reflects the reflected light back, causing the optical axis to bend by 90°. Afterward, it passes through the filter G1, the first lens L1, the second lens L2, and the third lens L3 to reach the imaging surface. The reflective element Pr can be tilted at 45° relative to the imaging surface. The reflective element Pr can also be any other element that can achieve both transmission and reflection.

[0114] The object side surface S1 and the image side surface S2 of the filter G1 are both planes. The object side surface S1 can be used as the aperture ST to limit the beam, that is, the object side surface S1 of the filter and the aperture ST are coplanar.

[0115] The first lens L1 has positive optical power, its object side S3 is convex, and its image side S4 is convex.

[0116] The second lens L2 has negative optical power, its object side S5 is concave, and its image side S6 is concave.

[0117] The third lens L3 has positive optical power, its object side S7 is convex, and its image side S8 is convex.

[0118] The first lens L1, the second lens L2, and the third lens L3 are glass spherical lenses.

[0119] The relevant parameters of each lens in the lidar receiving lens 200 in Example 2 are shown in Table 2.

[0120] Table 2

[0121]

[0122] In this embodiment, the field curvature curve, F-TAN (Theta) distortion curve, axial aberration curve, and transverse chromatic aberration curve of the lidar receiving lens 200 are respectively as follows: Figure 7 , Figure 8 , Figure 9 , Figure 10 As shown.

[0123] from Figure 7 As can be seen, the field curvature of the meridional and sagittal image planes is controlled within -0.3mm to -0.1mm, indicating that the lidar receiving lens can effectively correct the field curvature.

[0124] from Figure 8 As can be seen, the F-TAN (Theta) distortion is controlled within -5% to 0, indicating that the lidar receiving lens can effectively correct distortion.

[0125] from Figure 9 As can be seen, the axial aberration offset is controlled within -0.3mm to 0.1mm, indicating that the lidar receiving lens can effectively correct axial aberration.

[0126] from Figure 10 As can be seen, the chromatic aberration of the longest and shortest wavelengths is controlled within ±2μm, indicating that the laser radar receiving lens can correct the chromatic aberration at the edge of the field of view very well.

[0127] Example 3

[0128] Please see Figure 11The diagram shown is a schematic diagram of the structure of the lidar receiving lens 300 provided in Embodiment 3 of the present invention. The lidar receiving lens 300 includes, along the optical axis from the object side to the imaging surface S9, the following components in sequence: a reflective element Pr, an aperture ST, a filter G1, a first lens L1, a second lens L2, and a third lens L3.

[0129] The reflective element Pr is used to deflect light, causing the optical axis to bend by 90°. The reflective element Pr can be a beam splitter, achieving both transmission and reflection in specific areas. After the light beam is emitted, it passes through the laser radar receiving lens, then through the beam splitter to reach the object surface. The light reflected from the object surface returns to the beam splitter, which reflects the reflected light back, causing the optical axis to bend by 90°. The light then passes through the aperture ST, filter G1, first lens L1, second lens L2, and third lens L3 to reach the imaging surface. The reflective element Pr can be tilted at 45° relative to the imaging surface. The reflective element Pr can also be any other element that can achieve both transmission and reflection.

[0130] The object-side surface S1 and the image-side surface S2 of filter G1 are both planar.

[0131] The first lens L1 has positive optical power, its object side S3 is convex, and its image side S4 is flat.

[0132] The second lens L2 has negative optical power, its object side S5 is concave, and its image side S6 is concave.

[0133] The third lens L3 has positive optical power, its object side S7 is convex, and its image side S8 is convex.

[0134] The first lens L1, the second lens L2, and the third lens L3 are glass spherical lenses.

[0135] The relevant parameters of each lens in the lidar receiving lens 300 in Example 3 are shown in Table 3.

[0136] Table 3

[0137]

[0138] In this embodiment, the field curvature curve, F-TAN (Theta) distortion curve, axial aberration curve, and transverse chromatic aberration curve of the lidar receiving lens 300 are respectively as follows: Figure 12 , Figure 13 , Figure 14 , Figure 15 As shown.

[0139] from Figure 12 As can be seen, the field curvature of the meridional and sagittal image planes is controlled within -0.3mm to 0mm, indicating that the lidar receiving lens can effectively correct the field curvature.

[0140] from Figure 13 As can be seen, the F-TAN (Theta) distortion is controlled within -5% to 0, indicating that the lidar receiving lens can effectively correct distortion.

[0141] from Figure 14 As can be seen, the axial aberration offset is controlled within -0.3mm to 0.1mm, indicating that the lidar receiving lens can effectively correct axial aberration.

[0142] from Figure 15 As can be seen, the chromatic aberration of the longest and shortest wavelengths is controlled within ±2μm, indicating that the laser radar receiving lens can correct the chromatic aberration at the edge of the field of view very well.

[0143] Example 4

[0144] Please see Figure 16 The diagram shows a schematic of the structure of the lidar receiving lens 400 provided in Embodiment 4 of the present invention. The lidar receiving lens 400 includes, along the optical axis from the object side to the imaging surface S9, the following components in sequence: a reflecting element Pr, a first lens L1, a second lens L2, a third lens L3, and a filter G1.

[0145] The reflective element Pr is used to deflect light, causing the optical axis to bend by 90°. The reflective element Pr can be a beam splitter, achieving both transmission and reflection in specific areas. After the light beam is emitted, it passes through the laser radar receiving lens, then through the beam splitter to reach the object surface. The light reflected from the object surface returns to the beam splitter, which reflects the reflected light back, causing the optical axis to bend by 90°. The light then passes through the first lens L1, the second lens L2, the third lens L3, and the filter G1 to reach the imaging surface. The reflective element Pr can be tilted at 45° relative to the imaging surface. The reflective element Pr can also be any other element that can achieve both transmission and reflection.

[0146] The first lens L1 has positive optical power. Its object side S1 is convex, and its image side S2 is concave. The image side S2 can be used as an aperture stop ST to limit the beam. That is, the image side S2 of the first lens and the aperture stop ST are coplanar.

[0147] The second lens L2 has negative optical power, its object side S3 is concave, and its image side S4 is concave.

[0148] The third lens L3 has positive optical power, its object side S5 is convex, and its image side S6 is convex.

[0149] The object-side surface S7 and the image-side surface S8 of filter G1 are both planar.

[0150] The first lens L1, the second lens L2, and the third lens L3 are glass spherical lenses.

[0151] The relevant parameters of each lens in the lidar receiving lens 400 in Example 4 are shown in Table 4.

[0152] Table 4

[0153]

[0154] In this embodiment, the field curvature curve, F-TAN (Theta) distortion curve, axial aberration curve, and transverse chromatic aberration curve of the lidar receiving lens 400 are respectively as follows: Figure 17 , Figure 18 , Figure 19 , Figure 20 As shown.

[0155] from Figure 17 As can be seen, the field curvature of the meridional and sagittal image planes is controlled within -0.3mm to 0mm, indicating that the lidar receiving lens can effectively correct the field curvature.

[0156] from Figure 18 As can be seen, the F-TAN (Theta) distortion is controlled within -5% to 0, indicating that the lidar receiving lens can effectively correct distortion.

[0157] from Figure 19 As can be seen, the axial aberration offset is controlled within -0.3mm to 0.1mm, indicating that the lidar receiving lens can effectively correct axial aberration.

[0158] from Figure 20 As can be seen, the chromatic aberration of the longest and shortest wavelengths is controlled within ±1μm, indicating that the laser radar receiving lens can correct the chromatic aberration at the edge of the field of view very well.

[0159] Please refer to Table 5 for the optical characteristics corresponding to each of the above embodiments, including the effective focal length f of the lidar receiving lens, the total optical length TTL, 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 image side of the third lens to the imaging plane on the optical axis, and the values ​​corresponding to each conditional expression in each embodiment.

[0160] Table 5

[0161]

[0162]

[0163] In summary, the lidar receiving 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 receiving quality of the lens can be improved, aberrations reduced, and the receiving quality of the lens enhanced, giving the lens one or more advantages such as miniaturization, small CRA, large image plane, high telecentricity, and high collimation performance.

[0164] 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.

[0165] 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 laser radar receiving lens, characterized in that, It consists of three lenses with optical power and one reflecting element, and successively includes a reflecting element, a first lens, a second lens, and a third lens along the optical axis from the object side to the imaging plane; The reflecting element is used to deflect light rays, so that the optical axis is deflected by 90° and then passes through the first lens, the second lens, and the third lens in sequence and reaches the imaging plane; The first lens has a positive optical power, and its object side is a convex surface; The second lens has a negative optical power, its object side is a concave surface, and its image side is a concave surface; The third lens has a positive optical power, its object side is a convex surface, and its image side is a convex surface; Wherein, the main ray incident angle CRA of the maximum field of view of the lidar receiving lens and the distance BL on the optical axis from the image side of the third lens to the imaging plane satisfy: 0.85mm < tan(CRA) × BL < 2.5mm.

2. The lidar receiving lens according to claim 1, characterized in that, The distance BL on the optical axis from the image side of the third lens to the imaging plane and the total optical length TTL of the lidar receiving lens satisfy: 0.18 < BL / TTL < 0.33; the total optical length TTL of the lidar receiving lens and the effective focal length f of the lidar receiving lens satisfy: 1.5 < TTL / f < 1.

95.

3. The lidar receiving lens according to claim 1, characterized in that, The true image height IH corresponding to the maximum field of view angle of the lidar receiving lens, the effective focal length f of the lidar receiving lens, and the maximum field of view angle FOV of the lidar receiving lens satisfy: 52° < f × FOV / IH < 63°; the true image height IH corresponding to the maximum field of view angle of the lidar receiving lens and the effective focal length f of the lidar receiving lens satisfy: 0.4 < IH / f < 0.

5.

4. The lidar receiving 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 receiving lens satisfy: 0.55 < f3 / f < 0.7; the curvature radius R5 of the object side of the third lens and the curvature radius R6 of the image side of the third lens satisfy: -1 < (R5 + R6) / (R5 - R6) < -0.

5.

5. The lidar receiving lens according to claim 1, characterized in that, The total optical length TTL of the lidar receiving lens, the true image height IH corresponding to the maximum field of view angle of the lidar receiving lens, and the maximum field of view angle FOV of the lidar receiving lens satisfy: 0.13 / ° < TTL / IH / FOV < 0.16 / °; the true image height IH corresponding to the maximum field of view angle of the lidar receiving lens and the entrance pupil diameter EPD of the lidar receiving lens satisfy: 0.7 < IH / EPD < 0.

9.

6. The lidar receiving lens according to claim 1, characterized in that, The true image height IH corresponding to the maximum field of view angle of the lidar receiving lens and the maximum field of view angle FOV of the lidar receiving lens satisfy: 1.5° / mm < FOV / IH < 1.8° / mm; the true image height IH corresponding to the maximum field of view angle of the lidar receiving lens and the aperture value Fno of the lidar receiving lens satisfy: 8mm < IH / Fno < 10mm.

7. The lidar receiving lens according to claim 1, characterized in that, The central thickness CT1 of the first lens, the central thickness CT2 of the second lens, and the focal length f1 of the first lens satisfy: 0.5 < (CT1 + CT2) / f1 < 1.

8. The lidar receiving lens according to claim 1, characterized in that, The sagittal height SAG11 of the clear aperture semi-diameter on the object side of the first lens, the sagittal height SAG12 of the clear aperture semi-diameter on the image side of the first lens, and the clear aperture semi-diameter DM11 on the object side of the first lens satisfy: -0.45 < (SAG12 - SAG11) / DM11 < 0.22; the sagittal height SAG21 of the clear aperture semi-diameter on the object side of the second lens, the sagittal height SAG22 of the clear aperture semi-diameter on the image side of the second lens, and the central thickness CT2 of the second lens satisfy: -0.3 < (SAG22 - SAG21) / CT2 < 0.

45.

9. The lidar receiving lens according to claim 1, characterized in that, The clear aperture semi-diameter DM11 on the object side of the first lens and the clear aperture semi-diameter DM32 on the image side of the third lens satisfy: 0.85 < DM11 / DM32 < 1.55; the clear aperture semi-diameter DM11 on the object side of the first lens and the focal length f1 of the first lens satisfy: 0.2 < DM11 / f1 < 0.

5.

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

Images