A cryogenic drift lidar receiving lens

Abstract

This invention discloses a cryogenic drift lidar receiving lens, characterized by consisting of a front aperture group with positive optical power and a rear aperture group with positive optical power from the object plane to the image plane, wherein the focal length f of the front aperture group is... f Satisfy: 15mm≤f f ≤22mm, the focal length f of the rear group of the aperture stop b Satisfies: 21mm≤f b The focal length f of the entire lens satisfies: 14mm≤f≤17mm, the working F-number F# of the entire lens satisfies: 1.4≤F#≤1.5, the total optical length TTL satisfies: 30mm≤TTL≤36mm, and the relationship between the total optical length TTL and the focal length f satisfies: 1.7≤|TTL / f|≤2.6. By reasonably allocating the curvature radius and optical power of the lens elements, higher-order aberrations can be eliminated, and high-definition imaging of distant targets can be achieved over a wide temperature range.

Description

Technical Field

[0001] This invention relates to a lidar receiving lens, and more particularly to a cryogenic lidar receiving lens. Background Technology

[0002] LiDAR has broad application prospects in the automotive field. The accuracy of its components, such as the light source, scanning device, and receiving lens, determines the accuracy of the LiDAR. Automotive LiDAR needs to identify distant targets, thus requiring high imaging resolution from the receiving lens. Meanwhile, the complex outdoor environment also affects the imaging quality of the receiving lens. Temperature changes affect the refractive index of optical components and the thickness of structural components, causing focal shift in the image plane and affecting lens assembly, leading to a decrease in image quality. Furthermore, various ambient lights can interfere with the accuracy of the receiving system.

[0003] Patent CN113419334A proposes a large aperture lidar receiving lens that achieves a large aperture of 0.75 through a five-element structure, thereby increasing the amount of light collected by the lens and providing a wider operating temperature range. However, this also increases aberrations and affects the image quality.

[0004] Patent CN211348622U proposes a four-piece structure lidar receiving lens, which is simple in design and effectively controls costs, but the imaging spot is large and the imaging quality is poor.

[0005] Patent CN115248496A proposes a high-definition optical lens that achieves high resolution through an eight-element structure, but it uses more cemented doublet lenses, which increases the cost.

[0006] Patent CN112462486A proposes an optical lens that uses a combination of four aspherical lenses to balance the relationship between distortion and relative illumination, expand the field of view, and correct wavefront aberration. However, in a preferred embodiment, the four lenses are made of plastic, resulting in poor thermal stability of the lens. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a cryogenic drift lidar receiving lens that can meet the requirements of high resolution and low distortion imaging in complex outdoor environments.

[0008] The technical solution adopted by the present invention to solve the above-mentioned technical problem is as follows: a low-temperature drift lidar receiving lens, characterized in that it consists of a front aperture group with positive optical power and a rear aperture group with positive optical power from the object plane to the image plane, wherein the focal length f of the front aperture group is... f Satisfy: 15mm≤f f ≤22mm, the focal length f of the rear group of the aperture stop b Satisfy: 21mm≤f bThe focal length f of the entire lens satisfies: 14mm≤f≤17mm, the working F-number F# of the entire lens satisfies: 1.4≤F#≤1.5, the total optical length TTL satisfies: 30mm≤TTL≤36mm, and the relationship between the total optical length TTL and the focal length f satisfies: 1.7≤|TTL / f|≤2.6.

[0009] Compared with the prior art, the advantage of the present invention is that by rationally allocating the curvature radius and optical power of the lenses, higher-order aberrations are eliminated, and high-definition imaging of distant targets can be achieved over a wide temperature range.

[0010] Preferably, the front group of the aperture stop, from the object side to the image side, consists of a first lens group with negative optical power and a second lens group with positive optical power; the rear group of the aperture stop, from the object side to the image side, consists of a third lens group with negative optical power and a fourth lens group with positive optical power; and the focal length f of the first lens group is... 110 Satisfies: -57mm≤f 110 ≤-22mm, the focal length f of the second lens group 120 Satisfy: 11mm≤f 120 ≤14mm, the focal length f of the third lens group 130 Satisfies: -37mm≤f 130 ≤-12mm, the focal length f of the fourth lens group 140 Satisfy: 10mm≤f 140 ≤19mm, the curvature radius R102 of the first lens group on the image side and the curvature radius R201 of the second lens group on the object side satisfy: |(R102-R201) / (R102+R201)|<0.4, and the curvature radius R301 of the third lens group on the object side and the curvature radius R302 on the image side can satisfy: 0.6<|R301 / R302|≤1.

[0011] In a further preferred embodiment, the first lens group is a biconcave lens; the second lens group, from the object side to the image side, consists of a biconvex lens with positive optical power and a cemented doublet lens with positive optical power; the cemented doublet lens, from the object side to the image side, is formed by cementing a meniscus lens with a convex object side and a concave image side and positive optical power, and a meniscus lens with a convex object side and a concave image side and negative optical power; the third lens group is a biconcave lens; and the fourth lens group, from the object side to the image side, consists of a spherical meniscus lens with a concave object side and a convex image side and positive optical power, and a spherical meniscus lens with a convex object side and a concave image side. The lens group consists of a spherical meniscus lens with a concave image side and positive optical power. The first lens group has a dispersion coefficient of VD101. The second lens group has dispersion coefficients of VD102, VD103, and VD104 from the object side to the image side, respectively. The third lens group has a dispersion coefficient of VD105. The fourth lens group has dispersion coefficients of VD106 and VD107 from the object side to the image side, respectively. The relationships between these components are: VD101 < 50; VD102 < 50; VD103 < 50; VD104 > 50; VD105 < 50; VD106 < 50; VD107 < 50.

[0012] In a further preferred embodiment, the first lens group is a meniscus lens with a convex object side and a concave image side; the second lens group consists of two meniscus lenses with a convex object side and a concave image side, both with positive optical power, from the object side to the image side; the third lens group is a biconcave lens; and the fourth lens group consists of a spherical meniscus lens with a concave object side and a convex image side, both with positive optical power, and an aspherical meniscus lens with a convex object side and a concave image side, both with positive optical power, from the object side to the image side. The first lens group has a dispersion coefficient of VD201, the second lens group has dispersion coefficients of VD202 and VD203 from the object side to the image side, the third lens group has a dispersion coefficient of VD204, and the fourth lens group has dispersion coefficients of VD205 and VD206 from the object side to the image side, respectively. The relationships between these dispersion coefficients are: VD201 < 50; VD202 < 50; VD203 < 50; VD204 < 50; VD205 < 50; VD206 < 50.

[0013] In a further preferred embodiment (third option), the first lens group is a meniscus lens with a convex object side and a concave image side; the second lens group is an aspherical biconvex lens; the third lens group is a biconcave lens; and the fourth lens group, from the object side to the image side, consists of a spherical meniscus lens with a concave object side, a convex image side, and positive optical power, and an aspherical meniscus lens with a convex object side, a concave image side, and positive optical power. The dispersion coefficient of the first lens group is VD301, the dispersion coefficient of the second lens group is VD302, the dispersion coefficient of the third lens group is VD303, and the dispersion coefficients of the fourth lens group from the object side to the image side are VD304 and VD305, respectively, satisfying the following relationships: VD301 < 50; VD302 < 50; VD303 < 50; VD304 < 50; VD305 < 50.

[0014] In a further preferred embodiment, the first lens group is a meniscus lens with a convex object side and a concave image side; the second lens group is an aspherical biconvex lens; the third lens group is an aspherical meniscus lens with a concave object side and a convex image side; and the fourth lens group is an aspherical meniscus lens with a convex object side and a concave image side. The dispersion coefficient of the first lens group is VD401, the dispersion coefficient of the second lens group is VD402, the dispersion coefficient of the third lens group is VD403, and the dispersion coefficient of the fourth lens group is VD404, and their relationships satisfy: VD401 < 50; VD402 < 50; VD403 < 50; VD404 < 50.

[0015] The above-mentioned further preferred solution, by reasonably selecting and matching lenses with different surface shapes, can maintain good working performance under conditions ranging from -40℃ to 100℃, and the MTF of the entire field of view is greater than 0.4 at 36lp / mm. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the lidar receiving lens in Embodiment 1 of the present invention;

[0017] Figure 2 The transfer function curve of the lidar receiving lens of Embodiment 1 of the present invention at 20°C;

[0018] Figure 3 The transfer function curve of the lidar receiving lens in Embodiment 1 of the present invention at -40℃ is shown.

[0019] Figure 4 The transfer function curve of the lidar receiving lens of Embodiment 1 of the present invention at 100°C is shown.

[0020] Figure 5 This is a distortion diagram of the laser radar receiving lens in Embodiment 1 of the present invention;

[0021] Figure 6 This is a schematic diagram of the structure of the lidar receiving lens in Embodiment 2 of the present invention;

[0022] Figure 7 The transfer function curve of the lidar receiving lens in Embodiment 2 of the present invention at 20°C;

[0023] Figure 8 This is a transfer function curve of the lidar receiving lens in Embodiment 2 of the present invention at -40℃;

[0024] Figure 9 The transfer function curve of the lidar receiving lens in Embodiment 2 of the present invention at 100°C is shown.

[0025] Figure 10 This is a distortion diagram of the lidar receiving lens in Embodiment 2 of the present invention;

[0026] Figure 11 This is a schematic diagram of the structure of the lidar receiving lens in Embodiment 3 of the present invention;

[0027] Figure 12 The transfer function curve of the lidar receiving lens in Embodiment 3 of the present invention at 20°C;

[0028] Figure 13 The transfer function curve of the lidar receiving lens in Embodiment 3 of the present invention at -40℃ is shown.

[0029] Figure 14 The transfer function curve of the lidar receiving lens in Embodiment 3 of the present invention at 100°C is shown.

[0030] Figure 15 This is a distortion diagram of the laser radar receiving lens in Embodiment 3 of the present invention;

[0031] Figure 16 This is a schematic diagram of the structure of the lidar receiving lens in Embodiment 4 of the present invention;

[0032] Figure 17 The transfer function curve of the lidar receiving lens in Embodiment 4 of the present invention at 20°C;

[0033] Figure 18 This is a transfer function curve of the lidar receiving lens in Embodiment 4 of the present invention at -40℃;

[0034] Figure 19 The transfer function curve of the lidar receiving lens in Embodiment 4 of the present invention at 100°C;

[0035] Figure 20 This is a distortion diagram of the lidar receiving lens in Embodiment 4 of the present invention. Detailed Implementation

[0036] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. The drawings are for reference and illustration only and do not constitute a limitation on the scope of protection of the present invention.

[0037] Example:

[0038] In an exemplary embodiment, the optical path from the object plane to the image plane includes, in sequence, a front aperture group 100 with positive optical power, an aperture STO, a rear aperture group 200 with positive optical power, a filter G1, and a protective glass G2.

[0039] The focal length f of the front aperture group 100 is... f Satisfy: 15mm≤f f ≤22mm.

[0040] The focal length f of the rear aperture group is 200mm. b Satisfy: 21mm≤f b ≤37mm.

[0041] The focal length f of the lens satisfies: 14mm≤f≤17mm.

[0042] The working F-number of the lens, F#, satisfies: 1.4 ≤ F# ≤ 1.5.

[0043] The total optical length (TTL) of the lens satisfies: 30mm≤TTL≤36mm, and the total optical length (TTL) and focal length (f) satisfy the relationship 1.7≤|TTL / f|≤2.6.

[0044] The front group 100 of the aperture stop, from the object side to the image side, consists of a first lens group 110 with negative optical power and a second lens group 120 with positive optical power. The rear group 200 of the aperture stop, from the object side to the image side, consists of a third lens group 130 with negative optical power and a fourth lens group 140 with positive optical power. The focal length f of the first lens group 110 is... 110 Satisfies: -57mm≤f 110 ≤-22mm, second lens group 120 focal length f 120 Satisfy: 11mm≤f 120 ≤14mm, third lens group 130 focal length f 130 Satisfies: -37mm≤f 130 ≤-12mm, fourth lens group with a focal length of 140mm. 140 Satisfy: 10mm≤f 140 ≤19mm.

[0045] The first mirror group has a negative optical power of 110, which can control the convergence and divergence of the beam in the central and peripheral fields of view, reducing field curvature. The image side of the first mirror group is concave, which can control the degree of beam divergence and reduce spherical aberration.

[0046] If the first lens group 110 is a biconcave lens, the object side is concave, which can reduce the front diameter of the lens and control the lens volume.

[0047] If the first lens group 110 is a meniscus lens with a convex object side, it will help improve the liquid adhesion in the outdoor environment and reduce the impact on imaging.

[0048] The second lens group 120 can be a three-element, two-element, or single-element structure. A three-element structure can be a biconvex lens or a cemented doublet; a two-element structure can be two meniscus lenses; and a single-element structure can be an aspherical biconvex lens. The object-side surface is convex, while the image-side surface can be either concave or convex.

[0049] If the second lens group 120 is composed of a biconvex lens and a cemented doublet, the biconvex lens can reduce coma and distortion, while the cemented doublet eliminates chromatic aberration by combining materials with high and low dispersion coefficients. The positive lens on the object side has a higher refractive index, while the negative lens on the image side has a lower refractive index. This allows the light rays on the object side to be quickly converged and then slightly diverged before transitioning to the image side, which can reduce the optical path, meet the requirements of a compact structure, facilitate the miniaturization of the lens design, and reduce the tolerance sensitivity of the lens elements.

[0050] If the second lens group 120 consists of two meniscus lenses, the image-side meniscus lens can reduce field curvature and distortion, while the object-side meniscus lens converges the beam to the next lens, reducing coma and distortion. Compared to the three-element structure, replacing the cemented doublet with a meniscus lens reduces costs while maintaining image quality.

[0051] If the second lens group 120 is a single aspherical biconvex lens, the object-side surface will have a smaller radius of curvature, which can reduce coma. Compared with the two-element structure, replacing the two meniscus lenses with a single aspherical lens reduces the difficulty of manufacturing and assembly, reduces lens sensitivity, and can control aberrations.

[0052] If the third lens group 130 is a biconcave lens, spherical aberration and distortion can be reduced.

[0053] If the third lens group 130 is an aspherical meniscus lens with a concave object side and a convex image side, coma can be reduced.

[0054] If the fourth lens group 140 consists of two spherical meniscus lenses, it can smoothly converge the diverging beam onto the image plane.

[0055] If the fourth lens group 140 consists of a spherical meniscus lens and an aspherical meniscus lens, compared with the combination of two spherical meniscus lenses, the control of the imaging beam is more flexible and can reduce astigmatism and spherical aberration.

[0056] If the fourth lens group 140 is an aspherical meniscus lens, compared with the two-element structure, it can control aberrations, reduce costs, and decrease distortion and coma.

[0057] The aperture STO is set between the front aperture group 100 and the rear aperture group 200, which helps to improve the thermal stability of the lens.

[0058] Filter G1 is positioned on the image side of the rear group 200 of the aperture to filter out excess wavelengths of light and reduce noise.

[0059] The protective glass G2 is placed between the filter G1 and the image plane IMA to prevent damage to the internal optical components of the lens.

[0060] In an exemplary embodiment, all lens elements are made of glass, maintaining stable optical performance within a temperature range of -40°C to 100°C, suppressing the problem of lens focal length drift with changes in ambient temperature, and expanding the operating temperature range.

[0061] In an exemplary embodiment, the radius of curvature R102 on the image side of the first lens group 110 and the radius of curvature R201 on the object side of the second lens group 120 satisfy |(R102-R201) / (R102+R201)|<0.4, ensuring that the light beam exits from the first lens group 110 and enters the object side of the second lens group 120 smoothly, thereby reducing the tolerance sensitivity of the lens.

[0062] In an exemplary embodiment, the focal length f of the second lens group 120 120 With the fourth lens group at a focal length of 140, f 140 Satisfy 1 < |f 120 / f 140 | <1.6, controls the degree of beam convergence and reduces lens size.

[0063] In an exemplary embodiment, a combination of aspherical lenses is used, which reduces the number of lenses compared to a combination of spherical lenses, thereby reducing manufacturing difficulty and cost while ensuring image quality.

[0064] In an exemplary embodiment, to improve lens image quality and reduce TTL, an aspherical lens is used, the surface shape of which satisfies the following equation:

[0065]

[0066] Where y represents the radial coordinate value of the lens perpendicular to the optical axis, Z is the sag of the aspherical lens at a height of y along the optical axis from the vertex of the aspherical surface, c = 1 / R, R represents the radius of curvature of the center of the aspherical lens surface, k represents the conic coefficient, and parameters A, B, C, D, E, and F are the coefficients of the 2nd, 4th, 6th, 8th, 10th, and 12th order terms of the higher-order aspherical polynomials.

[0067] The main design parameters for the four examples in this embodiment are shown in Table 1:

[0068] Table 1

[0069]

[0070]

[0071] Example 1:

[0072] The structure of Example 1 is as follows: Figure 1 As shown, from the object plane to the image plane, the following components are arranged in sequence: front aperture group 100 with positive optical power, aperture STO, rear aperture group 200 with positive optical power, filter G1, and protective glass G2.

[0073] The front group 100 of the aperture has a positive optical power. Along the optical axis from the object side to the image side, the elements are: the first lens group 110 with a negative optical power and the second lens group 120 with a positive optical power.

[0074] The rear group 200 has a positive optical power, and along the optical axis from the object side to the image side, the groups are: the third group 130 with a negative optical power, and the fourth group 140 with a positive optical power.

[0075] The first lens group 110 is a single-piece structure, consisting of a biconcave lens 101 with both the object-side and image-side surfaces being concave.

[0076] The second lens group 120 has a three-element structure, consisting of a biconvex lens 102 and a cemented doublet lens 108, with a convex object-side surface and a concave image-side surface. The biconvex lens 102 has positive optical power and is located near the object side. The cemented doublet lens 108 also has positive optical power and is located near the image side. The cemented doublet lens 108 is formed by cementing together a meniscus lens 103 with a convex object-side surface and a concave image-side surface and positive optical power, and a meniscus lens 104 with a convex object-side surface and a concave image-side surface and negative optical power. The meniscus lens 103 with positive optical power is located near the object side, and the meniscus lens 104 with negative optical power is located near the image side.

[0077] The third lens group 130 is a single-piece structure, consisting of a biconcave lens 105.

[0078] The fourth lens group 140 is a two-element structure, consisting of a spherical meniscus lens 106 with a concave object side and a convex image side and positive optical power, and a spherical meniscus lens 107 with a convex object side and a concave image side and positive optical power.

[0079] The dispersion coefficient of the first lens group 110 (single-element structure) is VD101. The dispersion coefficients of the second lens group 120 (three-element structure) from the object side to the image side are VD102, VD103, and VD104, respectively. The dispersion coefficient of the third lens group 130 (single-element structure) is VD105. The dispersion coefficients of the fourth lens group (two-element structure) from the object side to the image side are VD106 and VD107, respectively. The relationships satisfy: VD101 < 50; VD102 < 50; VD103 < 50; VD104 > 50; VD105 < 50; VD106 < 50; VD107 < 50.

[0080] The physical optical parameters of this Example 1 are shown in Table 2:

[0081] Table 2

[0082] surface radius of curvature R Thickness t Refractive index Nd Dispersion coefficient Vd 1 -82.2716 1.0005 1.62 36.65 2 16.0196 0.7360 3 36.2573 3.0016 1.90 31.42 4 -29.0096 0.1007 5 11.0125 3.0016 1.90 31.42 6 46.1159 1.0006 1.51 60.63 7 9.8243 1.3071 STO unlimited 1.6649 9 -17.0503 1.0006 1.58 40.75 10 17.0503 1.8898 11 -11557.6477 3.0015 1.91 35.28 12 -14.5216 1.4447 13 23.7963 3.0014 1.83 37.21 14 186.8875 1.1714 15 unlimited 0.5002 1.52 64.20 16 unlimited 7.0000 17 unlimited 0.1000 1.52 64.20 18 unlimited 0.2656 IMA unlimited

[0083] In Example 1, the lens transfer function curves at 20℃, -40℃, and 100℃ are shown below. Figure 2 , Figure 3 , Figure 4 As shown, the distortion curve is as follows Figure 5 As shown.

[0084] Figure 2 , Figure 3 , Figure 4 The transfer function graph shown illustrates that in Example 1 at 36 lp / mm, the MTF is >0.5 across the entire field of view, and the MTF can reach 0.6 at 90% of the field of view.

[0085] Figure 5 The distortion graph shown demonstrates that the distortion in Example 1 is controlled to within 0.6%.

[0086] Example 2:

[0087] The structure of Example 2 is as follows: Figure 6 As shown, from the object plane to the image plane, the following components are arranged in sequence: front aperture group 100 with positive optical power, aperture STO, rear aperture group 200 with positive optical power, filter G1, and protective glass G2.

[0088] The front group 100 of the aperture has a positive optical power. Along the optical axis from the object side to the image side, the elements are: the first lens group 110 with a negative optical power and the second lens group 120 with a positive optical power.

[0089] The rear group 200 has a positive optical power, and along the optical axis from the object side to the image side, the groups are: the third group 130 with a negative optical power, and the fourth group 140 with a positive optical power.

[0090] The first lens group 110 is a single-piece structure, which is a meniscus lens 201 with a convex object side and a concave image side.

[0091] The second lens group 120 consists of two meniscus lenses 202 and 203, which have a convex object side and a concave image side, and a positive optical power.

[0092] The third lens group 130 is a single-piece structure, consisting of a biconcave lens 204.

[0093] The fourth lens group 140 is a two-element structure, consisting of a spherical meniscus lens 205 with a concave object side and a convex image side and positive optical power, and an aspherical meniscus lens 206 with a convex object side and a concave image side and positive optical power. The spherical meniscus lens 205 is on the object side, and the aspherical meniscus lens 206 is on the image side.

[0094] The dispersion coefficient of the first lens group 110 (single-element structure) is VD201. The dispersion coefficients of the second lens group 120 (two-element structure) from the object side to the image side are VD202 and VD203, respectively. The dispersion coefficient of the third lens group 130 (single-element structure) is VD204. The dispersion coefficients of the fourth lens group 140 (two-element structure) from the object side to the image side are VD205 and VD206, respectively. The relationships satisfy: VD201 < 50; VD202 < 50; VD203 < 50; VD204 < 50; VD205 < 50; VD206 < 50.

[0095] The physical optical parameters of this Example 2 are shown in Table 3:

[0096] Table 3

[0097] surface radius of curvature R Thickness t Refractive index Nd Dispersion coefficient Vd 1 26.0537 2.0023 1.62 36.65 2 14.2052 2.5663 3 16.1071 2.6671 1.90 31.42 4 32.4782 0.2053 5 16.6694 2.7529 1.90 31.42 6 2551.3383 0.7510 STO unlimited 2.2579 8 -14.2126 1.0013 1.58 40.75 9 14.2126 2.1583 10 -799.5855 4.6293 1.91 35.28 11 -12.7380 0.2012 12 14.9284 4.9990 1.85 40.11 13 17.8492 1.1000 14 unlimited 0.5005 1.52 64.20 15 unlimited 4.0000 16 unlimited 0.1001 1.52 64.20 17 unlimited 0.3165 IMA unlimited -

[0098] In this example, the surface parameters of the aspherical meniscus lens 206 in the fourth lens group 140 are shown in Table 4:

[0099] Table 4

[0100]

[0101]

[0102] In Example 2, the lens transfer function curves at 20℃, -40℃, and 100℃ are shown below. Figure 7 , Figure 8 , Figure 9 As shown, the distortion curve is as follows Figure 10 As shown.

[0103] Figure 7 , Figure 8 , Figure 9 The transfer function curve shown in the figure indicates that in this embodiment 2, at 36 lp / mm, the MTF of the full field of view is >0.5, and the MTF of 90% field of view can reach 0.6.

[0104] Figure 10 The distortion graph shown demonstrates that the distortion in Example 2 is controlled to within 1.3%.

[0105] Example 3:

[0106] The structure of Example 3 is as follows: Figure 11 As shown, from the object plane to the image plane, the following components are arranged in sequence: front aperture group 100 with positive optical power, aperture STO, rear aperture group 200 with positive optical power, filter G1, and protective glass G2.

[0107] The front group 100 of the aperture has a positive optical power. Along the optical axis from the object side to the image side, the elements are: the first lens group 110 with a negative optical power and the second lens group 120 with a positive optical power.

[0108] The rear group 200 has a positive optical power, and along the optical axis from the object side to the image side, the groups are: the third group 130 with a negative optical power, and the fourth group 140 with a positive optical power.

[0109] The first lens group 110 is a single-piece structure, which is a meniscus lens 301 with a convex object side and a concave image side.

[0110] The second lens group 120 is a single-piece structure, which is an aspherical biconvex lens 302.

[0111] The third lens group 130 is a single-piece structure, consisting of a biconcave lens 303.

[0112] The fourth lens group 140 is a two-element structure, consisting of a spherical meniscus lens 304 with a concave object side and a convex image side and positive optical power, and an aspherical meniscus lens 305 with a convex object side and a concave image side and positive optical power. The spherical meniscus lens 304 is on the object side, and the aspherical meniscus lens 305 is on the image side.

[0113] The dispersion coefficient of the first lens group 110 single-element structure is VD301, the dispersion coefficient of the second lens group 120 single-element structure is VD302, the dispersion coefficient of the third lens group 130 single-element structure is VD303, and the dispersion coefficients of the fourth lens group 140 two-element structure from the object side to the image side are VD304 and VD305, respectively. The relationship between them is: VD301 < 50; VD302 < 50; VD303 < 50; VD304 < 50; VD305 < 50.

[0114] The physical optical parameters of this Example 3 are shown in Table 5:

[0115] Table 5

[0116]

[0117]

[0118] In this example, the surface parameters of the aspherical biconvex lens 302 in the second lens group 120 and the aspherical meniscus lens 305 in the fourth lens group 140 are shown in Table 6:

[0119] Table 6

[0120] k A B C D E F 302 side view -0.49 0 4.10E-6 4.64E-8 2.08E-9 -3.88E-11 3.67E-12 302 side view 4.02 0 4.16E-6 -1.48E-8 2.65E-9 2.58E-10 -6.81E-13 305 side view -7.45 0 3.04E-5 -2.96E-6 -4.19E-8 1.27E-9 -2.32E-11 305 side view 39.19 0 -1.01E-4 -5.49E-6 -5.33E-8 5.21E-9 -1.99E-10

[0121] In Example 3, the transfer function curves of the lens at 20℃, -40℃, and 100℃ are shown below. Figure 12 , Figure 13 , Figure 14 As shown, the distortion curve is as follows Figure 15 As shown.

[0122] Figure 12 , Figure 13 , Figure 14 The transfer function graph shown illustrates that in Example 3 at 36 lp / mm, the MTF > 0.4 across the entire field of view.

[0123] Figure 15 The distortion graph shown illustrates that the distortion in Example 3 is controlled to within 2.6%.

[0124] Example 4:

[0125] The structure of Example 4 is as follows: Figure 16 As shown, from the object plane to the image plane, the following components are arranged in sequence: front aperture group 100 with positive optical power, aperture STO, rear aperture group 200 with positive optical power, filter G1, and protective glass G2.

[0126] The front group 100 of the aperture has a positive optical power. Along the optical axis from the object side to the image side, the elements are: the first lens group 110 with a negative optical power and the second lens group 120 with a positive optical power.

[0127] The rear group 200 has a positive optical power, and along the optical axis from the object side to the image side, the groups are: the third group 130 with a negative optical power, and the fourth group 140 with a positive optical power.

[0128] The first lens group 110 is a single-piece structure, which is a meniscus lens 401 with a convex object side and a concave image side.

[0129] The second lens group 120 is a single-piece structure, which is an aspherical biconvex lens 402.

[0130] The third lens group 130 is a single-piece structure, an aspherical meniscus lens 403, with a concave object side and a convex image side.

[0131] The fourth lens group 140 is a single-piece structure, an aspherical meniscus lens 404, with a convex object side and a concave image side.

[0132] The dispersion coefficient of the first lens group (110 element-size) is VD401, the dispersion coefficient of the second lens group (120 element-size) is VD402, the dispersion coefficient of the third lens group (130 element-size) is VD403, and the dispersion coefficient of the fourth lens group (140 element-size) is VD404. The relationships satisfy: VD401 < 50; VD402 < 50; VD403 < 50; VD404 < 50.

[0133] The physical optical parameters of Example 4 are as follows:

[0134] Table 7

[0135] surface radius R Thickness t Refractive index Nd Dispersion coefficient Vd 1 16.6538 2.0008 1.62 36.65 2 9.8676 6.7335 3 12.7028 4.3465 1.85 40.11 4 -83.9435 1.7566 STO unlimited 4.0302 6 -6.2507 3.4000 1.85 40.11 7 -9.8357 1.3291 8 10.2591 6.0021 1.85 40.11 9 22.5324 1.3200 10 unlimited 0.5002 1.52 64.20 11 unlimited 3.1000 12 unlimited 0.1000 1.52 64.20 13 unlimited 0.3387 IMA unlimited -

[0136] In this example, the surface parameters of the aspherical biconvex lens 402 in the second lens group 120, the aspherical meniscus lens 403 in the third lens group 130, and the aspherical meniscus lens 404 in the fourth lens group 140 are shown in Table 8.

[0137] Table 8

[0138]

[0139]

[0140] In Example 4, the lens transfer function curves at 20℃, -40℃, and 100℃ are shown as follows: Figure 17 , Figure 18 , Figure 19 As shown, the distortion curve is as follows Figure 20 As shown.

[0141] Figure 17 , Figure 18 , Figure 19 The transfer function graph shown illustrates that in Example 4, the MTF > 0.4 across the entire field of view at 36 lp / mm.

[0142] Figure 20 The distortion graph shown demonstrates that the distortion in Example 4 is controlled within 7.5%.

[0143] The above examples are merely individual implementations of the present invention and do not limit the scope of protection of the present invention. Therefore, equivalent changes made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A cryogenic drift lidar receiving lens, characterized in that... The aperture group from the object plane to the image plane consists of a front aperture group and a rear aperture group with positive optical power. The front aperture group, from the object side to the image side, consists of a first lens group with negative optical power and a second lens group with positive optical power. The rear aperture group, from the object side to the image side, consists of a third lens group with negative optical power and a fourth lens group with positive optical power. The first lens group is a biconcave lens. The second lens group, from the object side to the image side, consists of a biconvex lens with positive optical power and a cemented doublet lens with positive optical power. The lens, from the object side to the image side, is cemented together with a meniscus lens whose object side is convex and image side is concave, and has positive optical power, and another meniscus lens whose object side is convex and image side is concave, and has negative optical power. The third lens group is a biconcave lens. The fourth lens group, from the object side to the image side, consists of a spherical meniscus lens whose object side is concave and image side is convex, and has positive optical power, and another spherical meniscus lens whose object side is convex and image side is concave, and has positive optical power. The focal length f of the front group of the aperture stop is... f Satisfy: 15mm≤f f ≤22mm, the focal length f of the rear group of the aperture stop b Satisfy: 21mm≤f b The focal length f of the entire lens satisfies: 14mm≤f≤17mm, the working F-number F# of the entire lens satisfies: 1.4≤F#≤1.5, the total optical length TTL satisfies: 30mm≤TTL≤36mm, and the relationship between the total optical length TTL and the focal length f satisfies: 1.7≤|TTL / f|≤2.

6.

2. The cryogenic drift lidar receiving lens as described in claim 1, characterized in that... The dispersion coefficient of the first lens group is VD101, the dispersion coefficients of the second lens group from the object side to the image side are VD102, VD103, and VD104, the dispersion coefficient of the third lens group is VD105, and the dispersion coefficients of the fourth lens group from the object side to the image side are VD106 and VD107, respectively. The relationships satisfy: VD101 < 50; VD102 < 50; VD103 < 50; VD104 > 50; VD105 < 50; VD106 < 50; VD107 < 50.

3. A cryogenic drift lidar receiving lens, characterized in that... The aperture assembly, from the object plane to the image plane, consists of a front aperture group and a rear aperture group with positive optical power. The front aperture group, from the object side to the image side, consists of a first lens group with negative optical power and a second lens group with positive optical power. The rear aperture group, from the object side to the image side, consists of a third lens group with negative optical power and a fourth lens group with positive optical power. The first lens group is a meniscus lens with a convex object side and a concave image side. The second lens group, from the object side to the image side, consists of two meniscus lenses with convex object sides and concave image sides, both with positive optical power. The third lens group is a biconcave lens. The fourth lens group, from the object side to the image side, consists of a spherical meniscus lens with a concave object side and a convex image side, both with positive optical power, and an aspherical meniscus lens with a convex object side and a concave image side, both with positive optical power. The focal length f of the front aperture group is... f Satisfy: 15mm≤f f ≤22mm, the focal length f of the rear group of the aperture stop b Satisfy: 21mm≤f b The focal length f of the entire lens satisfies: 14mm≤f≤17mm, the working F-number F# of the entire lens satisfies: 1.4≤F#≤1.5, the total optical length TTL satisfies: 30mm≤TTL≤36mm, and the relationship between the total optical length TTL and the focal length f satisfies: 1.7≤|TTL / f|≤2.

6.

4. A cryogenic drift lidar receiving lens as described in claim 3, characterized in that... The dispersion coefficient of the first lens group is VD201, the dispersion coefficients of the second lens group from the object side to the image side are VD202 and VD203, the dispersion coefficient of the third lens group is VD204, and the dispersion coefficients of the fourth lens group from the object side to the image side are VD205 and VD206, respectively, and their relationships satisfy: VD201 < 50; VD202 < 50; VD203 < 50; VD204 < 50; VD205 < 50; VD206 < 50.

5. A cryogenic drift lidar receiving lens, characterized in that... The aperture group from the object plane to the image plane consists of a front aperture group and a rear aperture group with positive optical power. The front aperture group, from the object side to the image side, consists of a first lens group with negative optical power and a second lens group with positive optical power. The rear aperture group, from the object side to the image side, consists of a third lens group with negative optical power and a fourth lens group with positive optical power. The first lens group is a meniscus lens with a convex object side and a concave image side. The second lens group is an aspherical biconvex lens. The third lens group is a biconcave lens. The fourth lens group, from the object side to the image side, consists of a spherical meniscus lens with a concave object side and a convex image side and positive optical power, and an aspherical meniscus lens with a convex object side and a concave image side and positive optical power. The focal length f of the front aperture group is... f Satisfy: 15mm≤f f ≤22mm, the focal length f of the rear group of the aperture stop b Satisfy: 21mm≤f b The focal length f of the entire lens satisfies: 14mm≤f≤17mm, the working F-number F# of the entire lens satisfies: 1.4≤F#≤1.5, the total optical length TTL satisfies: 30mm≤TTL≤36mm, and the relationship between the total optical length TTL and the focal length f satisfies: 1.7≤|TTL / f|≤2.

6.

6. A cryogenic drift lidar receiving lens as described in claim 5, characterized in that... The dispersion coefficient of the first lens group is VD301, the dispersion coefficient of the second lens group is VD302, the dispersion coefficient of the third lens group is VD303, and the dispersion coefficients of the fourth lens group from the object side to the image side are VD304 and VD305, respectively, and their relationships satisfy: VD301 < 50; VD302 < 50; VD303 < 50; VD304 < 50; VD305 < 50.

7. A cryogenic drift lidar receiving lens, characterized in that... The aperture assembly, from the object plane to the image plane, consists of a front aperture group and a rear aperture group with positive optical power. The front aperture group, from the object side to the image side, consists of a first lens group with negative optical power and a second lens group with positive optical power. The rear aperture group, from the object side to the image side, consists of a third lens group with negative optical power and a fourth lens group with positive optical power. The first lens group is a meniscus lens with a convex object side and a concave image side. The second lens group is an aspherical biconvex lens. The third lens group is an aspherical meniscus lens with a concave object side and a convex image side. The fourth lens group is an aspherical meniscus lens with a convex object side and a concave image side. The focal length f of the front aperture group is... f Satisfy: 15mm≤f f ≤22mm, the focal length f of the rear group of the aperture stop b Satisfy: 21mm≤f b The focal length f of the entire lens satisfies: 14mm≤f≤17mm, the working F-number F# of the entire lens satisfies: 1.4≤F#≤1.5, the total optical length TTL satisfies: 30mm≤TTL≤36mm, and the relationship between the total optical length TTL and the focal length f satisfies: 1.7≤|TTL / f|≤2.

6.

8. A cryogenic drift lidar receiving lens as described in claim 7, characterized in that... The dispersion coefficient of the first lens group is VD401, the dispersion coefficient of the second lens group is VD402, the dispersion coefficient of the third lens group is VD403, and the dispersion coefficient of the fourth lens group is VD404. The relationship between them is: VD401 < 50; VD402 < 50; VD403 < 50; VD404 < 50.

9. A cryogenic drift lidar receiving lens as described in any one of claims 1 to 8, characterized in that... The focal length f of the first lens group 110 Satisfies: -57mm≤f 110 ≤-22mm, the focal length f of the second lens group 120 Satisfy: 11mm≤f 120 ≤14mm, the focal length f of the third lens group 130 Satisfies: -37mm≤f 130 ≤-12mm, the focal length f of the fourth lens group 140 Satisfy: 10mm≤f 140 ≤19mm, the curvature radius R102 of the first lens group on the image side and the curvature radius R201 of the second lens group on the object side satisfy: |(R102-R201) / (R102+R201)|<0.4, and the curvature radius R301 of the third lens group on the object side and the curvature radius R302 on the image side can satisfy: 0.6<|R301 / R302|≤1.

Images