Laser radar transmitting lens

Abstract

The application provides a laser radar emitting lens, the number of lenses with optical power is four, and the lenses sequentially include a first lens, a second lens, a third lens and a fourth lens along an optical axis from an object side to a light source emitting surface; the first lens, the second lens, the third lens and the fourth lens each include an incident surface close to the light source emitting surface and an emitting surface close to the object side; the first lens has negative optical power, the emitting surface is a convex surface, and the incident surface is a concave surface; the second lens has negative optical power, the emitting surface is a convex surface, and the incident surface is a concave surface; the third lens has positive optical power, the emitting surface is a convex surface, and the incident surface is a convex surface near the optical axis; and the fourth lens has positive optical power, the emitting surface is a convex surface, and the incident surface is a convex 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 field of view, 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 laser radar transmitting lens. Background Technology

[0002] Today, lidar is widely used for detecting the three-dimensional coordinates and ranging of objects. A lidar system consists of 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 uses the information from both the emitted and reflected beams to determine 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 the incompatibility between a large field of view, high emission quality, and high collimation performance, failing to meet market demands. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a laser radar transmitting lens that has 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 has four lenses with optical power, which are arranged sequentially along the optical axis from the object side to the light source emitting surface, including a first lens, a second lens, a third lens, and a fourth lens; each of the first lens, the second lens, the third lens, and the fourth 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 negative optical power, its light-emitting surface is convex, and its light-incident surface is concave. The second lens has negative optical power, its light-emitting surface is convex, and its light-incident surface is concave. The third lens has positive optical power, its light-emitting surface is convex, and its light-incident surface is convex near the optical axis. The fourth lens has positive optical power, and its light-emitting surface is convex, as is its light-incident surface. wherein, a focal length f3 of the third lens and an effective focal length f of the lidar transmitting lens satisfy: 6<f3 / f<11; a maximum field of view FOV of the lidar transmitting lens and an aperture value Fno of the lidar transmitting lens satisfy: 63°<FOV / Fno<100°.

[0006] further preferably, a real image height IH corresponding to the maximum field of view of the lidar transmitting lens and the aperture value Fno of the lidar transmitting lens satisfy: 1.5mm<IH / Fno<2.2mm.

[0007] further preferably, the focal length f3 of the third lens and a focal length f4 of the fourth lens satisfy: 2.1<f3 / f4<3.2.

[0008] further preferably, a curvature radius R7 of a light exit surface of the fourth lens and a curvature radius R8 of a light incident surface of the fourth lens satisfy: -2.2<R7 / R8<-1.3.

[0009] further preferably, a curvature radius R6 of a light incident surface of the third lens and the effective focal length f of the lidar transmitting lens satisfy: -110<R6 / f<-11.

[0010] further preferably, the curvature radius R7 of the light exit surface of the fourth lens and the effective focal length f of the lidar transmitting lens satisfy: 5.4<R7 / f<10.4.

[0011] further preferably, a spacing CT23 between the second lens and the third lens on an optical axis and the focal length f3 of the third lens satisfy: 0.28<CT23 / f3<0.37.

[0012] further preferably, a sag SAG41 of a clear semi-diameter of the light exit surface of the fourth lens, a sag SAG42 of a clear semi-diameter of the light incident surface of the fourth lens, and a clear semi-diameter DM41 of the light exit surface of the fourth lens satisfy: -0.44<(SAG42-SAG41) / DM41<-0.3.

[0013] further preferably, a sag SAG21 of a clear semi-diameter of a light exit surface of the second lens, a sag SAG22 of a clear semi-diameter of a light incident surface of the second lens, and a central thickness CT2 of the second lens satisfy: 0.53<(SAG22-SAG21) / CT2<1.75.

[0014] further preferably, a clear semi-diameter DM32 of the light incident surface of the third lens and a clear semi-diameter DM42 of the light incident surface of the fourth lens satisfy: 0.7<DM32 / DM42<0.95.

[0015] The laser radar transmitting lens provided by this invention uses four lenses with specific optical power. Through specific surface shape matching and reasonable optical power distribution, it can improve the transmission quality of the lens, reduce aberrations, and enhance the transmission quality of the lens, giving the lens one or more advantages such as miniaturization, small CRA, large field of view, high transmission quality, and high collimation performance. Attached Figure Description

[0016] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the structure of the lidar transmitting lens in Embodiment 1 of the present invention.

[0017] Figure 2 This is a field curvature curve diagram of the laser radar transmitting lens in Embodiment 1 of the present invention.

[0018] Figure 3 This is the F-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 chromatic aberration curve of the laser radar transmitting lens in Embodiment 1 of the present invention.

[0021] Figure 6 This is a relative illumination curve of the laser radar transmitting lens in Embodiment 1 of the present invention.

[0022] Figure 7 This is a schematic diagram of the structure of the lidar transmitting lens in Embodiment 2 of the present invention.

[0023] Figure 8 This is a field curvature curve diagram of the laser radar transmitting lens in Embodiment 2 of the present invention.

[0024] Figure 9 This is the F-Theta distortion curve of the laser radar transmitting lens in Embodiment 2 of the present invention.

[0025] Figure 10 This is an axial aberration curve of the laser radar transmitting lens in Embodiment 2 of the present invention.

[0026] Figure 11 This is a chromatic aberration curve of the laser radar transmitting lens in Embodiment 2 of the present invention.

[0027] Figure 12 This is a relative illumination curve of the laser radar transmitting lens in Embodiment 2 of the present invention.

[0028] Figure 13 This is a schematic diagram of the structure of the lidar transmitting lens in Embodiment 3 of the present invention.

[0029] Figure 14 This is a field curvature curve diagram of the laser radar transmitting lens in Embodiment 3 of the present invention.

[0030] Figure 15 This is the F-Theta distortion curve of the laser radar transmitting lens in Embodiment 3 of the present invention.

[0031] Figure 16 This is an axial aberration curve of the laser radar transmitting lens in Embodiment 3 of the present invention.

[0032] Figure 17 This is a chromatic aberration curve of the laser radar transmitting lens in Embodiment 3 of the present invention.

[0033] Figure 18 This is a relative illumination curve of the laser radar transmitting lens in Embodiment 3 of the present invention.

[0034] Figure 19 This is a schematic diagram of the structure of the lidar transmitting lens in Embodiment 4 of the present invention.

[0035] Figure 20 This is a field curvature curve diagram of the laser radar transmitting lens in Embodiment 4 of the present invention.

[0036] Figure 21 This is the F-Theta distortion curve of the laser radar transmitting lens in Embodiment 4 of the present invention.

[0037] Figure 22 This is an axial aberration curve of the laser radar transmitting lens in Embodiment 4 of the present invention.

[0038] Figure 23 This is a chromatic aberration curve of the laser radar transmitting lens in Embodiment 4 of the present invention.

[0039] Figure 24 This is a relative illumination curve of the laser radar transmitting lens in Embodiment 4 of the present invention.

[0040] Figure 25 This is a schematic diagram of the structure of the laser radar transmitting lens in Embodiment 5 of the present invention.

[0041] Figure 26 This is a field curvature curve diagram of the laser radar transmitting lens in Embodiment 5 of the present invention.

[0042] Figure 27 This is the F-Theta distortion curve of the laser radar transmitting lens in Embodiment 5 of the present invention.

[0043] Figure 28This is an axial aberration curve of the laser radar transmitting lens in Embodiment 5 of the present invention.

[0044] Figure 29 This is a chromatic aberration curve of the laser radar transmitting lens in Embodiment 5 of the present invention.

[0045] Figure 30 This is a relative illumination curve of the laser radar transmitting lens in Embodiment 5 of the present invention.

[0046] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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 has four lenses with optical power, sequentially comprising a first lens, a second lens, a third lens, and a fourth lens along the optical axis from the object side to the light source emitting surface (in the opposite direction of light transmission). Each of the first, second, third, and fourth lenses includes an incident surface near the light source emitting surface and an exit surface near the object side. It is 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 exit surface of that lens.

[0055] In some embodiments, the first lens may have negative optical power, with a convex exit surface and a concave entrance surface. The second lens may have negative optical power, with a convex exit surface and a concave entrance surface. The third lens may have positive optical power, with a convex exit surface and a convex entrance surface near the optical axis. The fourth lens may have positive optical power, with a convex exit surface and a convex entrance surface.

[0056] In some implementations, the lidar transmitting lens may also include an aperture stop, which may be located between the second lens and the third lens. It is understood that the aperture stop can control beam transmission and correct aberrations.

[0057] In some embodiments, the focal length f3 of the third lens and the effective focal length f of the lidar emission lens satisfy: 6<f3 / f<11. When the above condition is satisfied, the third lens facilitates light convergence, which can improve the collimation effect on laser light and reduce the exit angle of the lens.

[0058] In some embodiments, the maximum field of view FOV of the lidar emission lens and the aperture value Fno of the lidar emission lens satisfy: 63°<FOV / Fno<100°. When the above condition is satisfied, it is beneficial to expand the field of view of the lens and increase the aperture of the lens, realizing the characteristics of wide angle and large aperture of the lens. The wide-angle characteristic can meet the demand for large-range detection.

[0059] In some embodiments, the real image height IH corresponding to the maximum field of view of the lidar emission lens and the aperture value Fno of the lidar emission lens satisfy: 1.5mm<IH / Fno<2.2mm. Satisfying the above range can improve the brightness at the edge of the lens image and enhance the relative illuminance of the entire optical system.

[0060] In some embodiments, the focal length f3 of the third lens and the focal length f4 of the fourth lens satisfy: 2.1<f3 / f4<3.2. When the above condition is satisfied, it facilitates the smooth transition of incident light beams between the third lens and the fourth lens, and reduces the manufacturing cost of the lens.

[0061] In some embodiments, the curvature radius R7 of the light exit surface of the fourth lens and the curvature radius R8 of the light incident surface of the fourth lens satisfy: -2.2<R7 / R8<-1.3. When the above condition is satisfied, it facilitates light convergence, so as to adjust the propagation trend of edge beams and ensure the lens has high collimation performance.

[0062] In some embodiments, 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: -110<R6 / f<-11. When the above condition is satisfied, the third lens enables the light beam to converge, reduces the divergence angle of the light beam, further improves the convergence efficiency, and reduces the light exit angle of the lens.

[0063] In some embodiments, the curvature radius R7 of the light exit surface of the fourth lens and the effective focal length f of the lidar emission lens satisfy: 5.4<R7 / f<10.4. When the above condition is satisfied, the converged light beam can be effectively gathered and converged, and the path of light after passing through the third lens can also be softened, which helps to realize small CRA and high emission quality of the lens.

[0064] In some embodiments, the spacing CT23 between the second lens and the third lens on the optical axis and the focal length f3 of the third lens satisfy: 0.28 < CT23 / f3 < 0.37. When the above condition is satisfied, by reasonably setting the relationship between the air gap of the second and third lenses and the focal length of the third lens, the deflection degree of light can be effectively moderated, the field curvature and distortion of the system can be effectively reduced, and the emission quality can be improved.

[0065] In some embodiments, the sag SAG41 of the clear semi-aperture on the light exit surface of the fourth lens, the sag SAG42 of the clear semi-aperture on the light incident surface of the fourth lens, and the clear semi-aperture DM41 of the light exit surface of the fourth lens satisfy: -0.44 < (SAG42 - SAG41) / DM41 < -0.3. When the above condition is satisfied, by controlling the relationship between the sag height difference between the light incident surface and the light exit surface of the fourth lens and the aperture of the light exit surface of the fourth lens, it is beneficial to correct the coma of off-axis field of view and improve the collimation effect of laser beams.

[0066] In some embodiments, the sag SAG21 of the clear semi-aperture on the light exit surface of the second lens, the sag SAG22 of the clear semi-aperture on the light incident surface of the second lens, and the central thickness CT2 of the second lens satisfy: 0.53 < (SAG22 - SAG21) / CT2 < 1.75. When the above condition is satisfied, by controlling the relationship between the sag height difference between the light incident surface and the light exit surface of the second lens and the central thickness of the second lens, it is beneficial to correct the coma of off-axis field of view.

[0067] In some embodiments, the clear semi-aperture DM32 of the light incident surface of the third lens and the clear semi-aperture DM42 of the light incident surface of the fourth lens satisfy: 0.7 < DM32 / DM42 < 0.95. When the above condition is satisfied, by reasonably setting the aperture relationship between the third lens and the fourth lens, the emitted light can exit at a relatively parallel and wide viewing angle, reducing CRA.

[0068] In some embodiments, the distance BL from the light incident surface of the fourth lens to the light emitting surface of the light source on the optical axis and the total optical length TTL of the lidar emission lens satisfy: 0.15 < BL / TTL < 0.22. When the above condition is satisfied, it is beneficial to achieve a short back focal length of the lens, and it is conducive to realizing the miniaturization of the lens while ensuring sufficient space for the installation of optical elements.

[0069] 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: 12 < TTL / f < 19. When the above condition is satisfied, the length of the lens can be effectively limited, which is conducive to realizing the miniaturization of the lidar emission lens.

[0070] In some embodiments, the real image height IH corresponding to the maximum field of view of the lidar emission lens, the effective focal length f of the lidar emission lens, and the maximum field of view FOV of the lidar emission lens satisfy: 52°<f×FOV / IH<80°. When the above range is satisfied, the relationship among the focal length, field of view and image height of the lens is reasonably limited, so that the lens has good optical performance.

[0071] In some embodiments, the real image height IH corresponding to the maximum field of view of the lidar emission lens and the effective focal length f of the lidar emission lens satisfy: 2.1<IH / f<3. When the above range is satisfied, the ratio of the image height to the focal length of the lens is reasonably controlled, so that the ultra-wide-angle characteristic is realized.

[0072] In some embodiments, the total optical length TTL of the lidar emission lens and the real image height IH corresponding to the maximum field of view of the lidar emission lens satisfy: 5.3<TTL / IH<7. When the above range is satisfied, the total length of the optical system is relatively short, the lens structure is compact, and thus miniaturization is realized.

[0073] In some embodiments, the focal length f1 of the first lens and the effective focal length f of the lidar emission lens satisfy: -8.8<f1 / f<-4.5. When the above range is satisfied, the first lens receives light entering the lens at a large angle, expands the field of view range of the lens, and at the same time is beneficial to reducing the sensitivity of the lens and realizing the miniaturization design of the lens.

[0074] In some embodiments, the focal length f2 of the second lens and the effective focal length f of the lidar emission lens satisfy: -5.7<f2 / f<-2.8. When the above range is satisfied, the second lens has a negative focal length, can perform secondary adjustment on the full-field-of-view light beam, perform secondary deflection on the large-field-of-view light beam, and steer the light beam to the transition lens group, which is beneficial to realizing a large field of view of the lens.

[0075] In some embodiments, the focal length f4 of the fourth lens and the effective focal length f of the lidar emission lens satisfy: 2.6<f4 / f<4. When the above range is satisfied, the fourth lens is a positive lens and is complementary to the preceding lenses, so that the outgoing light beam can be collimated into collimated light with lower divergence to realize long-distance projection.

[0076] In some embodiments, the total optical length TTL of the lidar emission lens, the real image height IH corresponding to the maximum field of view of the lidar emission lens, and the maximum field of view FOV of the lidar emission lens satisfy: 0.03<1°×TTL / IH / FOV<0.05. When the above range is satisfied, it is beneficial to balance the relationship among the total length, image height and field of view of the lens.

[0077] In some embodiments, the real image height IH corresponding to the maximum field of view of the LiDAR emission lens and the entrance pupil diameter EPD of the LiDAR emission lens satisfy: 3.7<IH / EPD<6. Satisfying the above condition balances the field of view and luminous flux, and improves laser emission efficiency.

[0078] In some embodiments, the maximum field of view FOV of the LiDAR emission lens and the real image height IH corresponding to the maximum field of view of the LiDAR emission lens satisfy: 40° / mm<FOV / IH<50° / mm. Satisfying the above condition can ensure that the lens has a large field-of-view characteristic on the premise of meeting the image height requirement, thereby enabling the lens to have good optical performance.

[0079] In some embodiments, the curvature radius R5 of the light exit surface of the third lens and the curvature radius R6 of the light entrance surface of the third lens satisfy: -0.95<(R5+R6) / (R5-R6)<-0.43. Satisfying the above range can improve the emission quality of the lens.

[0080] In some embodiments, the curvature radius R7 of the light exit surface of the fourth lens and the curvature radius R8 of the light entrance surface of the fourth lens satisfy: 0.18<(R7+R8) / (R7-R8)<0.37. Satisfying the above range allows reasonable control of the curvature radius of the fourth lens, which is conducive to controlling the shape of the fourth lens and correcting aberrations generated by the lens itself.

[0081] In some embodiments, the curvature radius R1 of the light exit surface of the first lens and the effective focal length f of the LiDAR emission lens satisfy: 6<R1 / f<9.5; the curvature radius R2 of the light entrance surface of the first lens and the effective focal length f of the LiDAR emission lens satisfy: 2.5<R2 / f<3.5. Satisfying the above range, the first lens is generally meniscus-shaped with its concave surface facing the second side, which allows light to gently enter the rear optical system, thus slowing down the trend of edge light, helping to reduce the incident angle of the chief ray in each field of view, and improving the emission quality of the lens.

[0082] In some embodiments, the curvature radius R3 of the light exit surface of the second lens and the effective focal length f of the LiDAR emission lens satisfy: 5.7<R3 / f<18; the curvature radius R4 of the light entrance surface of the second lens and the effective focal length f of the LiDAR emission lens satisfy: 1.6<R4 / f<2.8. Satisfying the above condition, the second lens causes the laser beam to diverge to a certain extent, avoids concentrated energy loss caused by excessively rapid direct convergence of light, and improves the emission quality of the lens.

[0083] In some embodiments, the radius of curvature R1 of the light exit surface of the first lens, the radius of curvature R2 of the light incident surface of the first lens, and the central thickness CT1 of the first lens satisfy: 1.3 < R1 / (R2+CT1) < 2.45. Satisfying the above range can reduce the difficulty of correcting edge field of view distortion, and control the distortion within a reasonable range.

[0084] In some embodiments, the focal length f1 of the first lens and the focal length f2 of the second lens satisfy: 0.9 < f1 / f2 < 2.8. When the above range is satisfied, both the first lens and the second lens are negative lenses. The combination of negative focal lengths enables large-field-of-view beams to be quickly collected and adjusted in the optical path at the front end of the lens, thereby ensuring that subsequent lenses such as the third lens have a smaller caliber, and at the same time realizing the large-field-of-view characteristic and small-volume advantage of the lens.

[0085] In some embodiments, the focal length f2 of the second lens and the focal length f3 of the third lens satisfy: -0.58 < f2 / f3 < -0.45. Satisfying the above condition enables further compensation and adjustment of the aberration of the lidar emission lens, so as to achieve high imaging performance of the lidar emission lens.

[0086] In some embodiments, the central thickness CT1 of the first lens and the central thickness CT2 of the second lens satisfy: 1.2 < CT1 / CT2 < 2.8. Satisfying the above condition can improve the stability of the lens and also reduce temperature drift.

[0087] In some embodiments, the total optical length TTL of the lidar emission lens and the sum ΣCT of the central thicknesses of the first lens, the second lens, the third lens and the fourth lens along the optical axis respectively satisfy: 0.4 < ΣCT / 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.

[0088] In some embodiments, the sag SAG41 of the clear half-aperture of the light exit surface of the fourth lens and the clear half-aperture DM41 of the light exit surface of the fourth lens satisfy: 0.09 < SAG41 / DM41 < 0.15. Satisfying the above range, the sag and aperture of the light exit surface of the fourth lens are reasonably controlled, the beam trend is controlled and final imaging is performed, which ensures that the opening angle of the fourth lens is within a certain range, is conducive to realizing high resolution of the lidar emission lens, and endows the lidar emission lens with high imaging quality.

[0089] In some embodiments, the clear half-aperture DM11 of the light exit surface of the first lens and the clear half-aperture DM42 of the light incident surface of the fourth lens satisfy: 1.9 < DM11 / DM42 < 2.6. Satisfying the above range, by reasonably setting the relationship between the focal lengths and apertures 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, so as to realize high relative illumination of the lens.

[0090] In some embodiments, the clear half-aperture DM11 of the light exit surface of the first lens and the real image height IH corresponding to the maximum field of view of the lidar emission lens satisfy: 1.5 < DM11 / IH < 2.2. Satisfying the above condition can ensure that the lens has a large field of view while maintaining a moderate overall size of the lens.

[0091] In some embodiments, the clear half-aperture DM11 of the light exit surface of the first lens and the focal length f1 of the first lens satisfy: -1.1 < DM11 / f1 < -0.5. Satisfying the above condition, by controlling the ratio of the clear half-aperture of the light exit surface of the first lens to the focal length of the first lens, the shape of the first lens is reasonably controlled, so that light is incident on the object-side surface of the first lens at the maximum incident angle, realizing wide-angle of the optical system.

[0092] In some embodiments, the clear half-aperture DM11 of the light exit surface of the first lens and the curvature radius R1 of the light exit surface of the first lens satisfy: 1 < 2×DM11 / R1 < 1.4. Satisfying the above condition avoids the lens from being super-hemispherical, greatly reducing the processing difficulty of the first lens.

[0093] In some embodiments, the clear half-aperture DM42 of the light incident surface of the fourth lens and the real image height IH corresponding to the maximum field of view of the lidar emission lens satisfy: 0.65 < DM42 / IH < 0.88. Satisfying the above condition is conducive to allowing the chief ray of the marginal field of view to exit to the imaging surface in parallel, which is beneficial to realizing a small CRA.

[0094] In some embodiments, the chief ray exit angle CRA of the maximum field of view of the lidar emission lens and the distance BL between the light incident surface of the fourth lens and the light emitting surface of the light source on the optical axis satisfy: 0.07mm < tan(CRA)×BL < 0.23mm. Satisfying the above condition, the chief ray exit angle of the maximum field of view of the lidar emission lens is small, which is beneficial for the laser to emit high energy, improves the light output efficiency when applied to the optical emission lens for lidar.

[0095] In some embodiments, the real image height IH corresponding to the maximum field of view of the lidar emission lens, the effective focal length f of the lidar emission lens, and the radian value θ of the maximum half field of view of the lidar emission lens satisfy: 0.75 < (IH / 2) / (f×θ) < 1. Satisfying the above condition can better achieve small distortion and obtain more accurate ranging data.

[0096] In some embodiments, the LiDAR emission lens satisfies the following conditional expressions: 19 mm < TTL < 24 mm; 1.1 mm < f < 1.8 mm; 140° < FOV < 180°; 3.1 mm < IH < 4 mm; 1.7 < Fno < 2.3; 0.9° < CRA < 3.3°. 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 angle of the LiDAR emission lens, IH represents the real image height corresponding to the maximum field angle of the LiDAR emission lens, Fno represents the aperture value of the LiDAR emission lens; CRA represents the chief ray exit angle at the maximum field of view of the LiDAR emission lens. Satisfying the above ranges, the LiDAR emission lens has at least one or more advantages such as miniaturization, small CRA, and large field angle.

[0097] In some embodiments, the lens material of the LiDAR emission lens provided by the present invention may be glass or plastic. When the lens is made of plastic, the production cost can be effectively reduced. On the other hand, when the lens is made of glass, the low dispersion property of glass itself can be used to effectively correct the geometric chromatic aberration of the optical system. 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 emission quality.

[0098] In some embodiments, the first lens, the second lens, the third lens, and the fourth lens may be 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 lens, and better realizing the miniaturization of the lens. More specifically, the first lens of the present invention is a spherical lens, and the second lens, the third lens, and the fourth lens may be spherical lenses or aspherical lenses.

[0099] In various embodiments of the present invention, when the lenses are aspherical lenses, the shape of each aspherical surface of the LiDAR emission lens satisfies the following equation: ; Wherein, z is the distance between the curved surface and the vertex of the curved surface in the optical axis direction, h is the distance from the optical axis to the curved surface, c is the curvature of the curved surface vertex, K is the conic constant, and B, C, D, E, F are the 4th-order, 6th-order, 8th-order, 10th-order, and 12th-order surface coefficients respectively.

[0100] 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.

[0101] Example 1

[0102] 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 includes, along the optical axis from the object side to the light source emitting surface S9 (in the opposite direction of light transmission): a first lens L1, a second lens L2, an aperture ST, a third lens L3, and a fourth lens L4. Each of the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 includes an incident light surface and an emitting light 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 light surface of the lens, and the surface of each lens near the object side is called the emitting light surface of the lens.

[0103] Among them, the first lens L1 has negative optical power, its light-emitting surface S1 is convex, and its light-incident surface S2 is concave. The second lens L2 has negative optical power, its light-exiting surface S3 is convex, and its light-incident surface S4 is concave. The third lens L3 has positive optical power, its light-exiting surface S5 is convex, and its light-incident surface S6 is convex near the optical axis. The fourth lens L4 has positive optical power, its light-exiting surface S7 is convex, and its light-incident surface S8 is convex. The first lens L1, the second lens L2, and the fourth lens L4 are glass spherical lenses; the third lens L3 is a glass aspherical lens.

[0104] The relevant parameters of each lens in the lidar transmitting lens 100 in Example 1 are shown in Table 1-1.

[0105] Table 1-1 The surface parameters of the aspherical lens of the lidar transmitting lens 100 in Example 1 are shown in Table 1-2.

[0106] Table 1-2 In this embodiment, the field curvature curve, F-Theta distortion curve, axial aberration curve, transverse chromatic aberration curve, and relative illumination curve of the lidar emitting lens 100 are respectively as follows: Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 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 -0.06 mm to 0, indicating that the lidar transmitting lens can effectively correct the field curvature.

[0108] Figure 3 The F-Theta distortion curve of Example 1 is shown, which represents the F-Theta distortion of light in each field of view. 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 figure, the F-Theta distortion is controlled within -1% to 0, indicating that the lidar transmitting lens can correct the distortion well.

[0109] 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. As can be seen from the diagram, the axial aberration offset is controlled within -0.05 mm to 0.01 mm, indicating that the lidar transmitting 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 (0.940 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. The diagram shows that the transverse chromatic aberration of the longest and shortest wavelengths is controlled within ±2 μm, indicating that the lidar transmitting lens can effectively correct chromatic aberration.

[0111] Figure 6 The relative illumination curves for Example 1 are shown, representing the relative illumination values ​​at different field-of-view angles on the imaging plane. The horizontal axis represents the half-field-of-view angle (unit: °), and the vertical axis represents the relative illumination (unit: %). As can be seen from the figure, the relative illumination value of the lidar transmitting lens is still greater than 90% at the maximum half-field-of-view angle, indicating that the lidar transmitting lens has good relative illumination.

[0112] Example 2

[0113] Please see Figure 7 The figure 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 third lens L3 is a glass spherical lens; the second lens L2 and the fourth lens L4 are glass aspherical lenses; and the optical parameters such as the radius of curvature and lens thickness of each lens surface are different.

[0114] The relevant parameters of each lens in the lidar transmitting lens 200 in Example 2 are shown in Table 2-1.

[0115] Table 2-1 The surface profile parameters of the aspherical lens of the lidar transmitting lens 200 in Example 2 are shown in Table 2-2.

[0116] Table 2-2 In this embodiment, the field curvature curve, F-Theta distortion curve, axial aberration curve, transverse chromatic aberration curve, and relative illumination curve of the lidar emitting lens 200 are respectively as follows: Figure 8 , Figure 9 , Figure 10 , Figure 11 , Figure 12 As shown.

[0117] from Figure 8 As can be seen, the field curvature of the meridional and sagittal image planes is controlled within -0.06mm to 0, indicating that the lidar transmitting lens can effectively correct the field curvature.

[0118] from Figure 9 As can be seen, the F-Theta distortion is controlled within -25% to 0, indicating that the lidar transmitting lens can effectively correct distortion.

[0119] from Figure 10 As can be seen, the axial aberration offset is controlled within -0.05mm to 0.02mm, indicating that the lidar transmitting lens can effectively correct axial aberration.

[0120] from Figure 11 As can be seen, the chromatic difference between the longest and shortest wavelengths is controlled within ±2μm, indicating that the lidar transmitting lens can effectively correct chromatic difference.

[0121] from Figure 12 As can be seen, the relative illumination value of the lidar transmitting lens is still greater than 98% at the maximum half field of view, indicating that the lidar transmitting lens has good relative illumination.

[0122] Example 3

[0123] Please see Figure 13 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 third lens L3 is a glass spherical lens; the second lens L2 and the fourth lens L4 are glass aspherical lenses; and the optical parameters such as the radius of curvature and lens thickness of each lens surface are different.

[0124] The relevant parameters of each lens in the lidar transmitting lens 300 in Example 3 are shown in Table 3-1.

[0125] Table 3-1 The surface profile parameters of the aspherical lens of the lidar transmitting lens 300 in Example 3 are shown in Table 3-2.

[0126] Table 3-2 In this embodiment, the field curvature curve, F-Theta distortion curve, axial aberration curve, transverse chromatic aberration curve, and relative illumination curve of the lidar emitting lens 300 are respectively as follows: Figure 14 , Figure 15 , Figure 16 , Figure 17 , Figure 18 As shown.

[0127] from Figure 14 As can be seen, the field curvature of the meridional and sagittal image planes is controlled within -0.04mm to 0, indicating that the lidar transmitting lens can effectively correct the field curvature.

[0128] from Figure 15 As can be seen, the F-Theta distortion is controlled within -2% to 0, indicating that the lidar transmitting lens can effectively correct distortion.

[0129] from Figure 16 As can be seen, the axial aberration offset is controlled within -0.04mm to 0.02mm, indicating that the lidar transmitting lens can effectively correct axial aberration.

[0130] from Figure 17 As can be seen, the chromatic difference between the longest and shortest wavelengths is controlled within ±2μm, indicating that the lidar transmitting lens can effectively correct chromatic difference.

[0131] from Figure 18As can be seen, the relative illumination value of the lidar transmitting lens is still greater than 95% at the maximum half field of view, indicating that the lidar transmitting lens has good relative illumination.

[0132] Example 4

[0133] Please see Figure 19 The diagram shown is a schematic diagram of the structure of the laser radar transmitting lens 400 provided in Embodiment 4 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.

[0134] The relevant parameters of each lens in the lidar transmitting lens 400 in Example 4 are shown in Table 4-1.

[0135] Table 4-1 The surface profile parameters of the aspherical lens of the lidar transmitting lens 400 in Example 4 are shown in Table 4-2.

[0136] Table 4-2 In this embodiment, the field curvature curve, F-Theta distortion curve, axial aberration curve, transverse chromatic aberration curve, and relative illumination curve of the lidar emitting lens 400 are respectively as follows: Figure 20 , Figure 21 , Figure 22 , Figure 23 , Figure 24 As shown.

[0137] from Figure 20 As can be seen, the field curvature of the meridional and sagittal image planes is controlled within -0.06mm to 0, indicating that the lidar transmitting lens can effectively correct the field curvature.

[0138] from Figure 21 As can be seen, the F-Theta distortion is controlled within -2% to 0, indicating that the lidar transmitting lens can effectively correct distortion.

[0139] from Figure 22 As can be seen, the axial aberration offset is controlled within -0.05mm to 0.01mm, indicating that the lidar transmitting lens can effectively correct axial aberration.

[0140] from Figure 23 As can be seen, the chromatic difference between the longest and shortest wavelengths is controlled within ±2μm, indicating that the lidar transmitting lens can effectively correct chromatic difference.

[0141] from Figure 24As can be seen, the relative illumination value of the lidar transmitting lens is still greater than 95% at the maximum half field of view, indicating that the lidar transmitting lens has good relative illumination.

[0142] Example 5

[0143] Please see Figure 25 The diagram shown is a schematic diagram of the structure of the laser radar transmitting lens 500 provided in Embodiment 5 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.

[0144] The relevant parameters of each lens in the lidar transmitting lens 500 in Example 5 are shown in Table 5-1.

[0145] Table 5-1 The surface profile parameters of the aspherical lens of the lidar transmitting lens 500 in Example 5 are shown in Table 5-2.

[0146] Table 5-2 In this embodiment, the field curvature curve, F-Theta distortion curve, axial aberration curve, transverse chromatic aberration curve, and relative illumination curve of the lidar emitting lens 500 are respectively as follows: Figure 26 , Figure 27 , Figure 28 , Figure 29 , Figure 30 As shown.

[0147] from Figure 26 As can be seen, the field curvature of the meridional and sagittal image planes is controlled within -0.06mm to 0, indicating that the lidar transmitting lens can effectively correct the field curvature.

[0148] from Figure 27 As can be seen, the F-Theta distortion is controlled within -1% to 0, indicating that the lidar transmitting lens can effectively correct distortion.

[0149] from Figure 28 As can be seen, the axial aberration offset is controlled within -0.05mm to 0.01mm, indicating that the lidar transmitting lens can effectively correct axial aberration.

[0150] from Figure 29 As can be seen, the chromatic difference between the longest and shortest wavelengths is controlled within ±2μm, indicating that the lidar transmitting lens can effectively correct chromatic difference.

[0151] from Figure 30As can be seen, the relative illumination value of the lidar transmitting lens is still greater than 95% at the maximum half field of view, indicating that the lidar transmitting lens has good relative illumination.

[0152] 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 emitting 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 incident surface of the fourth lens to the emitting surface of the light source on the optical axis, and the values ​​corresponding to each conditional expression in each embodiment.

[0153] Table 5 In summary, the lidar transmitting lens provided by the present invention uses four lenses with specific optical power. Through specific surface shape matching and reasonable optical power distribution, it can improve the transmission quality of the lens, reduce aberrations, and enhance the transmission quality of the lens, giving the lens one or more advantages such as miniaturization, small CRA, large field of view, high transmission quality, and high collimation performance.

[0154] 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.

[0155] 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, comprising four lenses with optical power, characterized in that, Comprises a first lens, a second lens, a third lens and a fourth lens in sequence along the optical axis from the object side to the light source emitting surface; each of the first lens, the second lens, the third lens and the fourth lens comprises a light incident surface close to the light source emitting surface and a light exit surface close to the object side; The first lens has negative refractive power, the light exit surface thereof is a convex surface, and the light incident surface thereof is a concave surface; The second lens has negative refractive power, the light exit surface thereof is a convex surface, and the light incident surface thereof is a concave surface; The third lens has positive refractive power, the light exit surface thereof is a convex surface, and the light incident surface thereof is a convex surface near the optical axis; The fourth lens has positive refractive power, the light exit surface thereof is a convex surface, and the light incident surface thereof is a convex surface; Wherein, the focal length f3 of the third lens and the effective focal length f of the lidar emission lens satisfy: 6<f3 / f<11; the maximum field of view FOV of the lidar emission lens and the aperture value Fno of the lidar emission lens satisfy: 63°<FOV / Fno<100°; 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: -110<R6 / f<-11.

2. The lidar transmitting lens according to claim 1, characterized in that, The real image height IH corresponding to the maximum field of view of the lidar emission lens and the aperture value Fno of the lidar emission lens satisfy: 1.5mm<IH / Fno<2.2mm.

3. The lidar transmitting lens according to claim 1, characterized in that, The focal length f3 of the third lens and the focal length f4 of the fourth lens satisfy: 2.1<f3 / f4<3.

2.

4. The lidar transmitting lens according to claim 1, characterized in that, The curvature radius R7 of the light exit surface of the fourth lens and the curvature radius R8 of the light incident surface of the fourth lens satisfy: -2.2<R7 / R8<-1.

3.

5. The lidar transmitting lens according to claim 1, characterized in that, The curvature radius R7 of the light exit surface of the fourth lens and the effective focal length f of the lidar emission lens satisfy: 5.4<R7 / f<10.

4.

6. The lidar transmitting lens according to claim 1, characterized in that, The spacing CT23 between the second lens and the third lens on the optical axis and the focal length f3 of the third lens satisfy: 0.28<CT23 / f3<0.

37.

7. The lidar transmitting lens according to claim 1, characterized in that, The sag SAG41 of the clear semi-aperture of the light exit surface of the fourth lens, the sag SAG42 of the clear semi-aperture of the light incident surface of the fourth lens and the clear semi-aperture DM41 of the light exit surface of the fourth lens satisfy: -0.44<(SAG42-SAG41) / DM41<-0.

3.

8. The lidar transmitting lens according to claim 1, characterized in that, The sag SAG21 of the clear semi-aperture of the light exit surface of the second lens, the sag SAG22 of the clear semi-aperture of the light incident surface of the second lens and the central thickness CT2 of the second lens satisfy: 0.53<(SAG22-SAG21) / CT2<1.

75.

9. The lidar transmitting lens according to claim 1, characterized in that, The clear semi-aperture DM32 of the light incident surface of the third lens and the clear semi-aperture DM42 of the light incident surface of the fourth lens satisfy: 0.7<DM32 / DM42<0.95.

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