A laser radar optical system applied to automobile auxiliary driving

Abstract

The application discloses a laser radar optical system applied to automobile auxiliary driving and relates to the technical field of optical systems.The technical scheme points of the laser radar optical system are as follows: a first lens, a second lens, a third lens, a diaphragm, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a filter and an image plane are arranged in sequence along the direction from an object side to an image side;the first lens is a concave-convex lens with positive optical power;the second lens is a meniscus lens with positive optical power;the third lens is a meniscus lens with negative optical power;the fourth lens is a double-concave lens with negative optical power;the fifth lens is a concave-convex lens with negative optical power;the sixth lens is a double-convex lens with positive optical power;the seventh lens is a concave-convex lens with positive optical power;and the eighth lens is a concave-convex lens with negative optical power.The system has the characteristics of long focal length, a large target surface, short total optical length, a large aperture, stable thermal drift and the like.

Description

Technical Field

[0001] This invention relates to the field of optical system technology, specifically to a lidar optical system for automotive driver assistance. Background Technology

[0002] With the continuous advancement of technology and the standardization of automotive safety equipment, LiDAR, as a key sensor in the field of autonomous driving, is receiving increasing attention. The principle of LiDAR is to emit a detection signal towards the target, and then use a receiving lens group in front of the LiDAR detector to focus the reflected light onto the detector. By comparing and processing the reflected and emitted signals, relevant information about the target can be obtained, such as the target's distance, altitude, and speed, thereby enabling target detection, tracking, and identification. However, existing LiDAR lenses generally suffer from the following problems: excessively short focal length, excessively long total optical length, excessively small aperture, excessively low holographic height, and inability to adapt to large target surfaces; and poor stability due to thermal drift at high and low temperatures under extreme environmental conditions. Summary of the Invention

[0003] To address the problems mentioned in the background section, this invention designs a lidar optical system for automotive driver assistance, which features a long focal length, large target surface, short overall optical length, large aperture, and stable thermal drift.

[0004] The above-mentioned technical objective of the present invention is achieved through the following technical solution: a lidar optical system for automotive driver assistance, comprising a first lens, a second lens, a third lens, an aperture, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a filter, and an image plane arranged sequentially along the direction from the object side to the image side; The first lens is a concave-convex lens with positive optical power, the second lens is a meniscus lens with positive optical power, the third lens is a meniscus lens with negative optical power, the fourth lens is a biconcave lens with negative optical power, the fifth lens is a concave-convex lens with negative optical power, the sixth lens is a biconvex lens with positive optical power, the seventh lens is a concave-convex lens with positive optical power, and the eighth lens is a concave-convex lens with negative optical power. The second lens and the third lens are bonded together to form a second cemented lens group, and the optical power of the second cemented lens group is positive. The refractive indices of the first to eighth lenses satisfy the following condition: 1.5 <n1<2.0;1.2<n2<1.7;1.3<n3<1.8;1.5<n4<2.0;1.3<n5<1.8;1.2<n6<1.9;1.5<n7<2.2;1.3<n8<1.8; Wherein, n1 is the refractive index of the first lens, n2 is the refractive index of the second lens, n3 is the refractive index of the third lens, n4 is the refractive index of the fourth lens, n5 is the refractive index of the fifth lens, n6 is the refractive index of the sixth lens, n7 is the refractive index of the seventh lens, and n8 is the refractive index of the eighth lens.

[0005] In some embodiments, the ratio of the focal length of the first to eighth lenses to the focal length of the lens satisfies the following set relationship: 0.7<|f1 / f|<1.4, 0.8<|f2 / f|<1.2, 8.1<|f3 / f|<8.9, 0.2<|f4 / f|<0.7, 1.0<|f5 / f|<1.8, 0.3<|f6 / f|<0.9, 0.4<|f7 / f|<1.1, 0.6<|f8 / f|<1.3; Where f1 represents the effective focal length of the first lens, f2 represents the effective focal length of the second lens, f3 represents the effective focal length of the third lens, f4 represents the effective focal length of the fourth lens, f5 represents the effective focal length of the fifth lens, f6 represents the effective focal length of the sixth lens, f7 represents the effective focal length of the seventh lens, f8 represents the effective focal length of the eighth lens, and f represents the effective focal length of the optical system.

[0006] In some embodiments, the refractive index of both the second lens and the fifth lens is 1.49, and the Abbe number is greater than 68 and less than 74. The refractive indices of the third and sixth lenses are both greater than 1.35 and less than 1.75, and the Abbe coefficients are both greater than 60 and less than 77.

[0007] In some embodiments, the lidar optical system for automotive driver assistance as described in claim 1 is characterized in that: the relative aperture of the optical system is F1.2.

[0008] In some embodiments, the holographic height IH of the optical system satisfies the following condition: IH ≥ 15.4 mm.

[0009] In some embodiments, the effective focal length f of the optical system satisfies the following condition: 35.9mm ≤ f ≤ 39.8mm.

[0010] In some embodiments, the first lens has a convex surface facing the object side and a slightly concave surface facing the image side; the second lens has a convex surface facing the object side and a concave surface facing the image side; the third lens has a convex surface facing the object side and a concave surface facing the image side; the fourth lens has a slightly concave surface facing the object side and a concave surface facing the image side; the fifth lens has a concave surface facing the object side and a slightly convex surface facing the image side; the sixth lens has a large convex surface facing the object side and a small convex surface facing the image side; the seventh lens has a large convex surface facing the object side and a slightly concave surface facing the image side; and the eighth lens has a concave surface facing the object side and a slightly convex surface facing the image side.

[0011] In some embodiments, the first to eighth lenses are all spherical glass lenses, and their imaging wavelength range is concentrated in the range of 1315-1345nm.

[0012] In some embodiments, the optical system is matched with a 1 / 1.16” large target chip.

[0013] In some embodiments, the total optical length (TTL) of the optical system is 48 mm.

[0014] In summary, the present invention has the following beneficial effects: The first to eighth lenses used in this invention are all spherical glass lenses. By adopting reasonable glass materials and combinations, the imaging band is different from the traditional visible light range of 400-700nm. The imaging band range can be concentrated in the range of 1315-1345nm, and at the same time, it is designed to have relatively excellent imaging quality. With a focal length of 37.87mm and a full-image height of 15.4mm, it can capture distant objects. Matched with a 1 / 1.16” large-area chip, it features low optical distortion, with overall distortion controlled within 1.5%, preventing edge distortion. The aperture reaches a large F1.2, effectively improving the energy transfer ratio of the LiDAR, increasing obstacle resolution efficiency, and shortening recognition time. The total optical length (TTL) is 48mm, resulting in a smaller size and more space-saving design. The rational use of cemented glass lenses and limiting the optical power of each lens effectively reduces spherical aberration, coma, astigmatism, field curvature, positional chromatic aberration, and magnification chromatic aberration throughout the lens system. This improves product resolution and effectively avoids ghosting and stray light effects. It also perfectly achieves thermal drift compensation, with a temperature range of -40℃ to 125℃, ensuring use in extreme environmental conditions. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a lens according to an embodiment of the present invention; Figure 2 This is an analytical plot of 60 lp / mm MTF at 20°C according to an embodiment of the present invention; Figure 3 This is a defocusing curve at 20°C with a radius of 60 lp / mm, according to an embodiment of the present invention. Figure 4 This is a defocusing curve at 85°C and 60 lp / mm, according to an embodiment of the present invention. Figure 5 This is a defocusing curve at -40℃ with a depth of 60 lp / mm, according to an embodiment of the present invention. Figure 6 This is a field curvature diagram of an embodiment of the present invention; Figure 7 This is an optical distortion diagram of an embodiment of the present invention; Figure 8 This is a dot diagram of an embodiment of the present invention.

[0016] In the diagram: E1: First lens; E2: Second lens; E3: Third lens; STO (Stop): Aperture stop; E4: Fourth lens; E5: Fifth lens; E6: Sixth lens; E7: Seventh lens; E8: Eighth lens; IR (Infrared Filter): Filter; IMA (Image Surface): Image plane; S1: The object-side side of the first lens; S2: The image-side side of the first lens; S3: The object-side side of the second lens; S4: The side where the second and third lenses are in contact with each other; S5: The image-side side of the third lens; S7: The object-side side of the fourth lens; S8: The image-side side of the fourth lens; S9: The object-side side of the fifth lens; S10: The image-side side of the fifth lens; S11: The object-side side of the sixth lens; S12: The image-side side of the sixth lens; S13: The object-side side of the seventh lens; S14: The image-side side of the seventh lens; S15: The object-side side of the eighth lens; S16: The image-side side of the eighth lens. Detailed Implementation

[0017] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0018] In the description of this invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0019] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0020] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0021] In this embodiment, the parameters of the lens group are listed in Table 1:

[0022] Table 1 The optical system provided in Table 1 has an effective focal length of 37.87 mm, a full-image height of 15.4 mm, a light-transmitting aperture of F1.2, and a total optical length (TTL) of 48 mm. In Table 1, mirror numbers 1 and 2 represent the two mirrors of the first lens E1 along the direction of light incidence, mirror number 3 represents the object-side mirror of the second lens E2, mirror number 4 represents the cemented surface of the second lens E2 and the third lens E3 (i.e., the side where the two are bonded together), mirror number 5 represents the image-side mirror of the third lens E3, mirror numbers 7 and 8 represent the two mirrors of the fourth lens E4 along the direction of light incidence, mirror numbers 9 and 10 represent the two mirrors of the fifth lens E5 along the direction of light incidence, mirror numbers 11 and 12 represent the two mirrors of the sixth lens E6 along the direction of light incidence, mirror numbers 13 and 14 represent the two mirrors of the seventh lens E7 along the direction of light incidence, and mirror numbers 15 and 16 represent the two mirrors of the eighth lens E8 along the direction of light incidence.

[0023] like Figure 1 As shown in the embodiment of the present invention, a lidar optical system for automotive driver assistance includes a first lens E1, a second lens E2, a third lens E3, an aperture stop STO, a fourth lens E4, a fifth lens E5, a sixth lens E6, a seventh lens E7, an eighth lens E8, a filter IR, and an image plane IMA arranged sequentially along the direction from the object side to the image side. The first lens E1 is a concave-convex lens with positive optical power, the second lens E2 is a meniscus lens with positive optical power, the third lens E3 is a meniscus lens with negative optical power, the fourth lens E4 is a biconcave lens with negative optical power, the fifth lens E5 is a concave-convex lens with negative optical power, the sixth lens E6 is a biconvex lens with positive optical power, the seventh lens E7 is a concave-convex lens with positive optical power, and the eighth lens E8 is a concave-convex lens with negative optical power. The second lens E2 and the third lens E3 are bonded together to form a second cemented lens group, and the optical power of the second cemented lens group is positive. The refractive indices of the first lens E1 to the eighth lens E8 satisfy the following condition: 1.5 <n1<2.0;1.2<n2<1.7;1.3<n3<1.8;1.5<n4<2.0;1.3<n5<1.8;1.2<n6<1.9;1.5<n7<2.2;1.3<n8<1.8; Wherein, n1 is the refractive index of the first lens E1, n2 is the refractive index of the second lens E2, n3 is the refractive index of the third lens E3, n4 is the refractive index of the fourth lens E4, n5 is the refractive index of the fifth lens E5, n6 is the refractive index of the sixth lens E6, n7 is the refractive index of the seventh lens E7, and n8 is the refractive index of the eighth lens E8.

[0024] In some embodiments, the ratio of the focal length of the first lens E1 to the eighth lens E8 to the focal length of the lens satisfies the following set relationship: 0.7<|f1 / f|<1.4, 0.8<|f2 / f|<1.2, 8.1<|f3 / f|<8.9, 0.2<|f4 / f|<0.7, 1.0<|f5 / f|<1.8, 0.3<|f6 / f|<0.9, 0.4<|f7 / f|<1.1, 0.6<|f8 / f|<1.3; Where f1 represents the effective focal length of the first lens E1, f2 represents the effective focal length of the second lens E2, f3 represents the effective focal length of the third lens E3, f4 represents the effective focal length of the fourth lens E4, f5 represents the effective focal length of the fifth lens E5, f6 represents the effective focal length of the sixth lens E6, f7 represents the effective focal length of the seventh lens E7, f8 represents the effective focal length of the eighth lens E8, and f represents the effective focal length of the optical system.

[0025] In some embodiments, the refractive index of the second lens E2 and the fifth lens E5 are both equal to 1.49, and the Abbe coefficients are both greater than 68 and less than 74. The refractive indices of the third lens E3 and the sixth lens E6 are both greater than 1.35 and less than 1.75, and the Abbe coefficients are both greater than 60 and less than 77.

[0026] In some embodiments, the lidar optical system for automotive driver assistance as described in claim 1 is characterized in that: the relative aperture of the optical system is F1.2.

[0027] In some embodiments, the holographic height IH of the optical system satisfies the following condition: IH ≥ 15.4 mm.

[0028] In some embodiments, the effective focal length f of the optical system satisfies the following condition: 35.9mm ≤ f ≤ 39.8mm.

[0029] In some embodiments, the first lens E1 has a convex surface facing the object side and a slightly concave surface facing the image side; the second lens E2 has a convex surface facing the object side and a concave surface facing the image side; the third lens E3 has a convex surface facing the object side and a concave surface facing the image side; the fourth lens E4 has a slightly concave surface facing the object side and a concave surface facing the image side; the fifth lens E5 has a concave surface facing the object side and a slightly convex surface facing the image side; the sixth lens E6 has a highly convex surface facing the object side and a slightly convex surface facing the image side; the seventh lens E7 has a highly convex surface facing the object side and a slightly concave surface facing the image side; and the eighth lens E8 has a concave surface facing the object side and a slightly convex surface facing the image side.

[0030] In some embodiments, the first lens E1 to the eighth lens E8 are all spherical glass lenses, and their imaging wavelength range is concentrated in the range of 1315-1345nm.

[0031] In some embodiments, the optical system is matched with a 1 / 1.16” large target chip.

[0032] In some embodiments, the total optical length (TTL) of the optical system is 48 mm.

[0033] The first lens E1 to the eighth lens E8 used in this invention are all spherical glass lenses. By adopting reasonable glass materials and combinations, the imaging band is different from the traditional visible light part of 400-700nm. The imaging band range can be concentrated in the range of 1315-1345nm, and at the same time, it is designed to have relatively excellent imaging quality. With a focal length of 37.87mm and a full-image height of 15.4mm, it can capture distant objects. Matched with a 1 / 1.16” large-area chip, it features low optical distortion, with overall distortion controlled within 1.5%, preventing edge distortion. The aperture reaches a large F1.2, effectively improving the energy transfer ratio of the LiDAR, increasing obstacle resolution efficiency, and shortening recognition time. The total optical length (TTL) is 48mm, resulting in a smaller size and more space-saving design. The rational use of cemented glass lenses and limiting the optical power of each lens effectively reduces spherical aberration, coma, astigmatism, field curvature, positional chromatic aberration, and magnification chromatic aberration throughout the lens system. This improves product resolution and effectively avoids ghosting and stray light effects. It also perfectly achieves thermal drift compensation, with a temperature range of -40℃ to 125℃, ensuring use in extreme environmental conditions.

[0034] In an embodiment of the present invention, Figure 2 This is a modulation transfer function (MTF) curve for the visible light band, representing the overall resolving power of an optical system. The horizontal axis represents spatial frequency, in cycles per millimeter (mm), and the vertical axis represents the MTF value. The MTF value is used to evaluate the image quality of a lens, ranging from 0 to 1. It is worth noting that the optical transfer function is a relatively accurate, intuitive, and common way to evaluate the image quality of an optical system. The higher and smoother the curve, the better the image quality and the stronger the ability to reproduce the true image. Figure 2 It can be seen that in the visible light band, at a spatial frequency of 60 lp / mm, the MTF in the imaging region near the center is >0.6, indicating good imaging quality. Figures 3 to 5 It can be seen that the defocus curves at both high and low temperatures meet the requirements of high resolution, with small changes in focus and stable thermal drift effect; Figure 6 Representing the field curve diagram, by Figure 6 It can be seen that the field curvature value should be controlled between -0.1mm and 0.1mm. The smaller the field curvature value, the better the image quality of the lens. Figure 7 Represents optical distortion diagrams, by Figure 7 It can be seen that the optical distortion is small, with the overall distortion controlled within -1.5%, which will not cause distortion at the edges of the image.

[0035] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A lidar optical system for automotive driver assistance, characterized in that: It includes a first lens, a second lens, a third lens, an aperture stop, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a filter, and an image plane arranged sequentially from the object side to the image side; The optical system has 8 lenses; The first lens is a concave-convex lens with positive optical power, the second lens is a meniscus lens with negative optical power, the third lens is a meniscus lens with positive optical power, the fourth lens is a biconcave lens with negative optical power, the fifth lens is a concave-convex lens with negative optical power, the sixth lens is a biconvex lens with positive optical power, the seventh lens is a concave-convex lens with positive optical power, and the eighth lens is a concave-convex lens with negative optical power. The second lens and the third lens are bonded together to form a second cemented lens group, and the optical power of the second cemented lens group is positive. The refractive indices of the first to eighth lenses satisfy the following condition: 1.5 <n1<2.0;1.2<n2<1.7;1.3<n3<1.8;1.5<n4<2.0;1.3<n5<1.8;1.2<n6<1.9;1.5<n7<2.2;1.3<n8<1.8; Wherein, n1 is the refractive index of the first lens, n2 is the refractive index of the second lens, n3 is the refractive index of the third lens, n4 is the refractive index of the fourth lens, n5 is the refractive index of the fifth lens, n6 is the refractive index of the sixth lens, n7 is the refractive index of the seventh lens, and n8 is the refractive index of the eighth lens. The ratio of the focal length of the first lens, the fourth to the eighth lenses to the focal length of the optical system satisfies the following set relationship: 0.7<|f1 / f|<1.4, 0.2<|f4 / f|<0.7, 1.0<|f5 / f|<1.8, 0.3<|f6 / f|<0.9, 0.4<|f7 / f|<1.1, 0.6<|f8 / f|<1.3; Where f1 represents the effective focal length of the first lens, f4 represents the effective focal length of the fourth lens, f5 represents the effective focal length of the fifth lens, f6 represents the effective focal length of the sixth lens, f7 represents the effective focal length of the seventh lens, f8 represents the effective focal length of the eighth lens, and f represents the effective focal length of the optical system.

2. The lidar optical system for automotive driver assistance as described in claim 1, characterized in that: The refractive index of both the second and fifth lenses is 1.49, and the Abbe number is greater than 68 and less than 74. The refractive indices of the third and sixth lenses are both greater than 1.35 and less than 1.75, and the Abbe coefficients are both greater than 60 and less than 77.

3. The lidar optical system for automotive driver assistance as described in claim 1, characterized in that: The relative aperture of the optical system is F1.

2.

4. The lidar optical system for automotive driver assistance as described in claim 1, characterized in that: The hologram height IH of the optical system satisfies the following condition: IH ≥ 15.4 mm.

5. A lidar optical system for automotive driver assistance as described in claim 2, characterized in that: The effective focal length f of the optical system satisfies the following condition: 35.9mm≤f≤39.8mm.

6. The lidar optical system for automotive driver assistance as described in claim 1, characterized in that: The first lens has a convex surface facing the object side and a concave surface facing the image side; the second lens has a convex surface facing the object side and a concave surface facing the image side; the third lens has a convex surface facing the object side and a concave surface facing the image side; the fourth lens has a concave surface facing the object side and a concave surface facing the image side; the fifth lens has a concave surface facing the object side and a convex surface facing the image side; the sixth lens has a convex surface facing the object side and a convex surface facing the image side; the seventh lens has a convex surface facing the object side and a concave surface facing the image side; and the eighth lens has a concave surface facing the object side and a convex surface facing the image side.

7. A lidar optical system for automotive driver assistance as described in claim 1, characterized in that: The first to the eighth lenses are all spherical glass lenses, and their imaging wavelength range is concentrated in the range of 1315-1345nm.

8. The lidar optical system for automotive driver assistance as described in claim 1, characterized in that: The optical system is matched with a 1 / 1.16” large target chip.

9. A lidar optical system for automotive driver assistance as described in claim 1, characterized in that: The total optical length (TTL) of the optical system is 48 mm.

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