A symmetrical double telecentric lens and working method

Abstract

The present application relates to a symmetrical double telecentric lens and a working method, and relates to the technical field of measurement and control instruments in precision manufacturing. It includes an incident lens group, an imaging lens group and an aperture. The aperture is arranged between the incident lens group and the imaging lens group, and the incident lens group and the imaging lens group have the same focal length; the incident lens group and the imaging lens group on both sides of the aperture are each provided with the same number of seven lenses. The patent application uses a small number of lens groups to image an object at a 1:1 object-image ratio, making the vision more intuitive, reducing the illusion or image distortion caused by the way the image is magnified or reduced, and causing interpretation errors, thereby improving the authenticity and making it easy for people to distinguish the detailed features of the object on a sensor with a large target surface. It solves the problem that the existing lens has a large number of built-in lenses and is insufficient in terms of magnification and imaging stability, and cannot meet high-precision requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of measurement and control instruments in precision manufacturing, and in particular to a symmetrical double-telecentric lens and a working method thereof. Background Art

[0002] With the rapid development of industrial automation, the market's requirements for product inspection accuracy are constantly increasing. For example, in the fields of semiconductors and precision machinery manufacturing, higher standards are put forward for the detailed identification of tiny structures and complex workpieces.

[0003] However, many existing lenses on the market have a large number of built-in lenses and are insufficient in terms of magnification and imaging stability, and cannot meet high-precision requirements. In addition, the large number of built-in lenses in existing lenses causes the lenses to occupy a large space and increase manufacturing costs.

[0004] Regarding the above-mentioned related technologies, there are problems that the existing lenses have a large number of built-in lenses and are insufficient in magnification and imaging stability, and cannot meet high-precision requirements. Summary of the Invention

[0005] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a symmetrical bi-telecentric lens and a working method, aiming to solve the problem that the existing lens has a large number of built-in lenses and has deficiencies in magnification and imaging stability, and cannot meet high-precision requirements.

[0006] The present application provides a symmetrical bi-telecentric lens and a working method using the following technical solutions: A symmetrical bi-telecentric lens comprising:

[0007] Entrance mirror group;

[0008] Imaging lens assembly;

[0009] an aperture, arranged between the incident lens group and the imaging lens group, wherein the incident lens group and the imaging lens group have the same focal length;

[0010] The incident lens group includes a first convex lens, a second convex lens, a third convex lens, a fourth convex lens, a first concave lens, a second concave lens and a third concave lens;

[0011] The first convex lens, the second convex lens, the third convex lens, the first concave lens, the second concave lens, the third concave lens and the fourth convex lens are arranged in sequence, and the aperture is arranged close to the fourth convex lens;

[0012] The imaging lens group includes a fifth convex lens, a sixth convex lens, a seventh convex lens, an eighth convex lens, a fourth concave lens, a fifth concave lens and a sixth concave lens;

[0013] The fifth convex lens, the sixth convex lens, the seventh convex lens, the fourth concave lens, the fifth concave lens, the sixth concave lens and the eighth convex lens are arranged in sequence, and the aperture is arranged close to the eighth convex lens.

[0014] Optionally, the distance between the first convex lens and the second convex lens is 1-2 mm;

[0015] The distance between the second convex lens and the third convex lens is 6-7 mm;

[0016] The distance between the third convex lens and the first concave lens is 2-3 mm;

[0017] The distance between the first concave lens and the second concave lens is 9-10 mm;

[0018] The distance between the second concave lens and the third concave lens is 1-2 mm;

[0019] The distance between the third concave lens and the fourth convex lens is 1-2 mm;

[0020] The distance between the fourth convex lens and the aperture is 0.5-1 mm.

[0021] Optionally, the distance between the fifth convex lens and the sixth convex lens is 1-2 mm;

[0022] The distance between the sixth convex lens and the seventh convex lens is 6-7 mm;

[0023] The distance between the seventh convex lens and the fourth concave lens is 2-3 mm;

[0024] The distance between the fourth concave lens and the fifth concave lens is 9-10 mm;

[0025] The distance between the fifth concave lens and the sixth concave lens is 1-2 mm;

[0026] The distance between the sixth concave lens and the eighth convex lens is 1-2 mm;

[0027] The distance between the eighth convex lens and the aperture is 4-5 mm.

[0028] Optionally, the distance from the fifth convex lens to the image plane is 89-90 mm.

[0029] Optionally, a curvature radius of a side of the first convex lens facing away from the aperture is greater than or equal to 110 mm, and a curvature radius of a side of the first convex lens facing away from the aperture is less than or equal to 112 mm;

[0030] The curvature radius of the first convex lens on the side close to the aperture is greater than or equal to -215 mm, and the curvature radius of the first convex lens on the side close to the aperture is less than or equal to -214 mm;

[0031] The curvature radius of the second convex lens facing away from the aperture is greater than or equal to 61 mm, and the curvature radius of the second convex lens facing away from the aperture is less than or equal to 62 mm;

[0032] The curvature radius of the second convex lens on the side close to the aperture is greater than or equal to -235 mm, and the curvature radius of the second convex lens on the side close to the aperture is less than or equal to -234 mm;

[0033] The curvature radius of the third convex lens facing away from the aperture is greater than or equal to 25 mm, and the curvature radius of the third convex lens facing away from the aperture is less than or equal to 26 mm;

[0034] The curvature radius of the third convex lens near the aperture is greater than or equal to 752 mm, and the curvature radius of the third convex lens near the aperture is less than or equal to 753 mm;

[0035] The curvature radius of the fourth convex lens facing away from the aperture is greater than or equal to 32 mm, and the curvature radius of the fourth convex lens facing away from the aperture is less than or equal to 33 mm;

[0036] The curvature radius of the fourth convex lens near the aperture is greater than or equal to -25 mm, and the curvature radius of the fourth convex lens near the aperture is less than or equal to -24 mm;

[0037] The curvature radius of the first concave lens facing away from the aperture is greater than or equal to -247 mm, and the curvature radius of the first concave lens facing away from the aperture is less than or equal to -246 mm;

[0038] The curvature radius of the first concave lens on the side close to the aperture is greater than or equal to 20 mm, and the curvature radius of the first concave lens on the side close to the aperture is less than or equal to 21 mm;

[0039] The curvature radius of the second concave lens facing away from the aperture is greater than or equal to -31 mm, and the curvature radius of the second concave lens facing away from the aperture is less than or equal to -30 mm;

[0040] The curvature radius of the second concave lens on the side close to the aperture is greater than or equal to -92 mm, and the curvature radius of the second concave lens on the side close to the aperture is less than or equal to -91 mm;

[0041] The curvature radius of the third concave lens facing away from the aperture is greater than or equal to -55 mm, and the curvature radius of the third concave lens facing away from the aperture is less than or equal to -54 mm;

[0042] The curvature radius of the third concave lens close to the aperture is greater than or equal to 28 mm, and the curvature radius of the third concave lens close to the aperture is less than or equal to 29 mm.

[0043] Optionally, the curvature radius of the fifth convex lens facing away from the aperture is greater than or equal to -112 mm, and the curvature radius of the fifth convex lens facing away from the aperture is less than or equal to -111 mm;

[0044] The curvature radius of the fifth convex lens on the side close to the aperture is greater than or equal to 214 mm, and the curvature radius of the fifth convex lens on the side close to the aperture is less than or equal to 215 mm;

[0045] The curvature radius of the sixth convex lens facing away from the aperture is greater than or equal to -62 mm, and the curvature radius of the sixth convex lens facing away from the aperture is less than or equal to -61 mm;

[0046] The curvature radius of the sixth convex lens on the side close to the aperture is greater than or equal to 234 mm, and the curvature radius of the sixth convex lens on the side close to the aperture is less than or equal to 235 mm;

[0047] The curvature radius of the seventh convex lens facing away from the aperture is greater than or equal to -26 mm, and the curvature radius of the seventh convex lens facing away from the aperture is less than or equal to -25 mm;

[0048] The curvature radius of the seventh convex lens near the aperture is greater than or equal to -753 mm, and the curvature radius of the seventh convex lens near the aperture is less than or equal to -752 mm;

[0049] The curvature radius of the eighth convex lens facing away from the aperture is greater than or equal to -33 mm, and the curvature radius of the eighth convex lens facing away from the aperture is less than or equal to -32 mm;

[0050] The curvature radius of the eighth convex lens near the aperture is greater than or equal to 24 mm, and the curvature radius of the eighth convex lens near the aperture is less than or equal to 25 mm;

[0051] The curvature radius of the fourth concave lens facing away from the aperture is greater than or equal to 246 mm, and the curvature radius of the fourth concave lens facing away from the aperture is less than or equal to 247 mm;

[0052] The curvature radius of the fourth concave lens near the aperture is greater than or equal to -21 mm, and the curvature radius of the fourth concave lens near the aperture is less than or equal to -20 mm;

[0053] The curvature radius of the fifth concave lens facing away from the aperture is greater than or equal to 30 mm, and the curvature radius of the fifth concave lens facing away from the aperture is less than or equal to 31 mm;

[0054] The curvature radius of the fifth concave lens on the side close to the aperture is greater than or equal to 91 mm, and the curvature radius of the fifth concave lens on the side close to the aperture is less than or equal to 92 mm;

[0055] The curvature radius of the sixth concave lens facing away from the aperture is greater than or equal to 54 mm, and the curvature radius of the sixth concave lens facing away from the aperture is less than or equal to 55 mm;

[0056] The curvature radius of the sixth concave lens close to the aperture is greater than or equal to -29 mm, and the curvature radius of the sixth concave lens close to the aperture is less than or equal to -28 mm.

[0057] Optionally, the center thickness of the first convex lens is 5-6 mm;

[0058] The center thickness of the second convex lens is 7-8 mm;

[0059] The center thickness of the third convex lens is 7-8 mm;

[0060] The center thickness of the fourth convex lens is 7-8 mm;

[0061] The center thickness of the first concave lens is 2-3 mm;

[0062] The center thickness of the second concave lens is 1-2 mm;

[0063] The center thickness of the third concave lens is 1-2 mm.

[0064] Optionally, the center thickness of the fifth convex lens is 5-6 mm;

[0065] The center thickness of the sixth convex lens is 7-8 mm;

[0066] The center thickness of the seventh convex lens is 7-8 mm;

[0067] The center thickness of the eighth convex lens is 7-8 mm;

[0068] The center thickness of the fourth concave lens is 2-3 mm;

[0069] The center thickness of the fifth concave lens is 1-2 mm;

[0070] The center thickness of the sixth concave lens is 1-2 mm.

[0071] Optionally, the effective apertures of the lenses included in the incident lens group and the imaging lens group are both greater than 24 mm.

[0072] A method for operating a symmetrical bi-telecentric lens is applied to the symmetrical bi-telecentric lens as described in any one of the above items, the method comprising the steps of:

[0073] The light enters the incident lens group and is emitted from the imaging lens group, and passes through the first convex lens, the second convex lens, the third convex lens, the first concave lens, the second concave lens, the third concave lens, the fourth convex lens, the aperture, the eighth convex lens, the sixth concave lens, the fifth concave lens, the fourth concave lens, the seventh convex lens, the sixth convex lens and the fifth convex lens in sequence.

[0074] Compared with the prior art, the embodiments of the present invention have the following advantages:

[0075] The incident mirror group and imaging mirror group on both sides of the aperture are each provided with the same number of seven lenses. The incident mirror group and imaging mirror group on both sides of the aperture of this patent application adopt a symmetrical design. The distribution of the incident mirror group and the imaging mirror group makes the focal length on both sides of the aperture the same, achieving a magnification ratio of 1:1. The final image is consistent with the size of the object without any difference, which is particularly realistic.

[0076] This patent application uses a small number of lens elements to create an image at a 1:1 object-to-image ratio, making vision more intuitive and reducing the potential for misperceptions or image distortion caused by image magnification or reduction. This improves authenticity and makes it easier to discern detailed features on a large sensor surface. This solves the problem of existing lenses, which have a large number of built-in lenses and suffer from insufficient magnification and imaging stability, making them unable to meet high-precision requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0078] Figure 1 Schematic diagram of the structure of a symmetrical double telecentric lens configured with a coaxial optical system in an embodiment of the present application;

[0079] Figure 2 Schematic diagram of the structure of a symmetrical double telecentric lens in an embodiment of the present application without a coaxial optical system;

[0080] Figure 3 : is an MTF curve diagram of the symmetrical bi-telecentric lens in an embodiment of the present application;

[0081] Figure 4 is a point diagram of a symmetrical bi-telecentric lens in an embodiment of the present application;

[0082] Figure 5 : This is a diagram of field curvature and distortion of a symmetrical bi-telecentric lens in an embodiment of the present application;

[0083] Figure 6 is a relative illumination diagram of a symmetrical bi-telecentric lens in an embodiment of the present application;

[0084] Figure 7 This is a flow chart of the working method of the symmetrical bi-telecentric lens in an embodiment of the present application.

[0085] Description of reference numerals:

[0086] 1. Incident lens group; 11. First convex lens; 12. Second convex lens; 13. Third convex lens; 14. Fourth convex lens; 15. First concave lens; 16. Second concave lens; 17. Third concave lens; 2. Imaging lens group; 21. Fifth convex lens; 22. Sixth convex lens; 23. Seventh convex lens; 24. Eighth convex lens; 25. Fourth concave lens; 26. Fifth concave lens; 27. Sixth concave lens; 3. Aperture; 4. Coaxial optical system; 41. Coaxial light focusing lens; 42. Coaxial light emitting light source. DETAILED DESCRIPTION

[0087] In order to enable those skilled in the art to better understand the solutions of the present invention, the following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0088] The present application is further described in detail below with reference to the accompanying drawings.

[0089] The embodiments of the present application disclose a symmetrical bi-telecentric lens and a working method.

[0090] like Figure 1 and Figure 2As shown, a symmetrical bi-telecentric lens includes an incident lens group 1, an imaging lens group 2, and an aperture 3. The aperture 3 is arranged between the incident lens group 1 and the imaging lens group 2, and the focal lengths of the incident lens group 1 and the imaging lens group 2 are the same;

[0091] The incident lens assembly 1 includes a first convex lens 11 , a second convex lens 12 , a third convex lens 13 , a fourth convex lens 14 , a first concave lens 15 , a second concave lens 16 and a third concave lens 17 .

[0092] The first convex lens 11, the second convex lens 12, the third convex lens 13, the first concave lens 15, the second concave lens 16, the third concave lens 17 and the fourth convex lens 14 are arranged in sequence, and the aperture 3 is arranged close to the fourth convex lens 14; the imaging lens group 2 includes a fifth convex lens 21, a sixth convex lens 22, a seventh convex lens 23, an eighth convex lens 24, a fourth concave lens 25, a fifth concave lens 26 and a sixth concave lens 27.

[0093] The fifth convex lens 21 , the sixth convex lens 22 , the seventh convex lens 23 , the fourth concave lens 25 , the fifth concave lens 26 , the sixth concave lens 27 and the eighth convex lens 24 are arranged in sequence, and the aperture 3 is arranged close to the eighth convex lens 24 .

[0094] The incident lens group 1 and the imaging lens group 2 on both sides of the aperture 3 are each provided with the same number of seven lenses. The incident lens group 1 and the imaging lens group 2 on both sides of the aperture 3 of the present patent adopt a symmetrical design. The distribution of the incident lens group 1 and the imaging lens group 2 makes the focal length on both sides of the aperture 3 the same, achieving a magnification ratio of 1:1. The final image is consistent with the size of the object without any difference, which is particularly realistic.

[0095] This patent application uses a small number of lens elements to create an image at a 1:1 object-to-image ratio, making vision more intuitive and reducing the potential for misperceptions or image distortion caused by image magnification or reduction. This improves authenticity and makes it easier to discern detailed features on a large sensor surface. This solves the problem of existing lenses, which have a large number of built-in lenses and suffer from insufficient magnification and imaging stability, making them unable to meet high-precision requirements.

[0096] The radius of curvature of the first convex lens 11 facing away from the aperture 3 is greater than or equal to 110 mm, and the radius of curvature of the first convex lens 11 facing away from the aperture 3 is less than or equal to 112 mm (that is, 100≤R1 convex back≤112, where R1 convex back is the radius of curvature of the first convex lens 11 facing away from the aperture 3, and the unit of R1 convex back is millimeter).

[0097] The radius of curvature of the first convex lens 11 close to the aperture 3 is greater than or equal to -215 mm, and the radius of curvature of the first convex lens 11 close to the aperture 3 is less than or equal to -214 mm (that is, -215≤R1 convex ≤-214, where R1 convex is the radius of curvature of the first convex lens 11 close to the aperture 3, and the unit of R1 convex is millimeter).

[0098] The radius of curvature of the second convex lens 12 facing away from the aperture 3 is greater than or equal to 61 mm, and the radius of curvature of the second convex lens 12 facing away from the aperture 3 is less than or equal to 62 mm (that is, 61≤R2 convex back≤62, where R2 convex back is the radius of curvature of the second convex lens 12 facing away from the aperture 3, and the unit of R2 convex back is millimeter).

[0099] The radius of curvature of the second convex lens 12 close to the aperture 3 is greater than or equal to -235 mm, and the radius of curvature of the second convex lens 12 close to the aperture 3 is less than or equal to -234 mm (that is, -235≤R2 convex edge≤-234, where R2 convex edge is the radius of curvature of the second convex lens 12 close to the aperture 3, and the unit of R1 convex edge is millimeter).

[0100] The radius of curvature of the side of the third convex lens 13 away from the aperture 3 is greater than or equal to 25 mm, and the radius of curvature of the side of the third convex lens 13 away from the aperture 3 is less than or equal to 26 mm (that is, 25≤R3 convex back≤26, where R3 convex back is the radius of curvature of the side of the third convex lens 13 away from the aperture 3, and the unit of R3 convex back is millimeter).

[0101] The radius of curvature of the side of the third convex lens 13 close to the aperture 3 is greater than or equal to 752 mm, and the radius of curvature of the side of the third convex lens 13 close to the aperture 3 is less than or equal to 753 mm (that is, 752≤R3 convex ≤753, where R3 convex is the radius of curvature of the side of the third convex lens 13 close to the aperture 3, and the unit of R3 convex is millimeter).

[0102] The radius of curvature of the side of the fourth convex lens 14 facing away from the aperture 3 is greater than or equal to 32 mm, and the radius of curvature of the side of the fourth convex lens 14 facing away from the aperture 3 is less than or equal to 33 mm (i.e., 32≤R4 convex back≤33, where R4 convex back is the radius of curvature of the side of the fourth convex lens 14 facing away from the aperture 3, and the unit of R4 convex back is millimeters).

[0103] The radius of curvature of the surface of the fourth convex lens 14 close to the aperture 3 is greater than or equal to -25 mm, and the radius of curvature of the surface of the fourth convex lens 14 close to the aperture 3 is less than or equal to -24 mm (that is, -25≤R4 convex edge≤-24, where R4 convex edge is the radius of curvature of the surface of the fourth convex lens 14 close to the aperture 3, and the unit of R4 convex edge is millimeter).

[0104] The radius of curvature of the first concave lens 15 facing away from the aperture 3 is greater than or equal to -247 mm, and the radius of curvature of the first concave lens 15 facing away from the aperture 3 is less than or equal to -246 mm (that is, -247≤R1 concave back≤-246, where R1 concave back is the radius of curvature of the first concave lens 15 facing away from the aperture 3, and the unit of R1 concave back is millimeters).

[0105] The radius of curvature of the first concave lens 15 on the side close to the aperture 3 is greater than or equal to 20 mm, and the radius of curvature of the first concave lens 15 on the side close to the aperture 3 is less than or equal to 21 mm (i.e., 20≤R1 concave ≤21, where R1 concave is the radius of curvature of the first concave lens 15 on the side close to the aperture 3, and the unit of R1 concave is millimeters).

[0106] The radius of curvature of the side of the second concave lens 16 facing away from the aperture 3 is greater than or equal to -31 mm, and the radius of curvature of the side of the second concave lens 16 facing away from the aperture 3 is less than or equal to -30 mm (that is, -31≤R2 concave back≤-30, where R2 concave back is the radius of curvature of the side of the second concave lens 16 facing away from the aperture 3, and the unit of R2 concave back is millimeters).

[0107] The radius of curvature of the second concave lens 16 on the side close to the aperture 3 is greater than or equal to -92 mm, and the radius of curvature of the second concave lens 16 on the side close to the aperture 3 is less than or equal to -91 mm (that is, -92≤R2 concave ≤-91, where R2 concave is the radius of curvature of the second concave lens 16 on the side close to the aperture 3, and the unit of R2 concave is millimeters).

[0108] The radius of curvature of the side of the third concave lens 17 facing away from the aperture 3 is greater than or equal to -55 mm, and the radius of curvature of the side of the third concave lens 17 facing away from the aperture 3 is less than or equal to -54 mm (that is, -55≤R3 concave back≤-54, where R3 concave back is the radius of curvature of the side of the third concave lens 17 facing away from the aperture 3, and the unit of R3 concave back is millimeters).

[0109] The radius of curvature of the side of the third concave lens 17 close to the aperture 3 is greater than or equal to 28 mm, and the radius of curvature of the side of the third concave lens 17 close to the aperture 3 is less than or equal to 29 mm (that is, 28≤R3 concave back≤29, where R3 concave back is the radius of curvature of the side of the third concave lens 17 close to the aperture 3, and the unit of R3 concave back is millimeters).

[0110] The radius of curvature of the side of the fifth convex lens 21 facing away from the aperture 3 is greater than or equal to -112 mm, and the radius of curvature of the side of the fifth convex lens 21 facing away from the aperture 3 is less than or equal to -111 mm (that is, -112≤R5 convex back≤-111, where R5 convex back is the radius of curvature of the side of the fifth convex lens 21 facing away from the aperture 3, and the unit of R5 convex back is millimeters).

[0111] The radius of curvature of the fifth convex lens 21 on the side close to the diaphragm 3 is greater than or equal to 214 mm and less than or equal to 215 mm (i.e., 214 ≤ R5adjacent ≤ 215, where R5adjacent is the radius of curvature of the fifth convex lens 21 on the side close to the diaphragm 3, and the unit of R5adjacent is mm).

[0112] The radius of curvature of the sixth convex lens 22 on the side away from the diaphragm 3 is greater than or equal to -62 mm and less than or equal to -61 mm (i.e., -62 ≤ R6opposite ≤ -61, where R6opposite is the radius of curvature of the sixth convex lens 22 on the side away from the diaphragm 3, and the unit of R6opposite is mm).

[0113] The radius of curvature of the sixth convex lens 22 on the side close to the diaphragm 3 is greater than or equal to 234 mm and less than or equal to 235 mm (i.e., 234 ≤ R6adjacent ≤ 235, where R6adjacent is the radius of curvature of the sixth convex lens 22 on the side close to the diaphragm 3, and the unit of R6adjacent is mm).

[0114] The radius of curvature of the seventh convex lens 23 on the side away from the diaphragm 3 is greater than or equal to -26 mm and less than or equal to -25 mm (i.e., -26 ≤ R7opposite ≤ -25, where R7opposite is the radius of curvature of the seventh convex lens 23 on the side away from the diaphragm 3, and the unit of R7opposite is mm).

[0115] The radius of curvature of the seventh convex lens 23 on the side close to the diaphragm 3 is greater than or equal to -753 mm and less than or equal to -752 mm (i.e., -753 ≤ R7adjacent ≤ -752, where R7adjacent is the radius of curvature of the seventh convex lens 23 on the side close to the diaphragm 3, and the unit of R7adjacent is mm).

[0116] The radius of curvature of the eighth convex lens 24 on the side away from the diaphragm 3 is greater than or equal to -33 mm and less than or equal to -32 mm (i.e., -33 ≤ R8opposite ≤ -32, where R8opposite is the radius of curvature of the eighth convex lens 24 on the side away from the diaphragm 3, and the unit of R8opposite is mm). [[ID=第十六]] [[ID=第十七]]

[0117] [[ID=第十八]]The radius of curvature of the eighth convex lens 24 on the side close to the diaphragm 3 is greater than or equal to 24 mm and less than or equal to 25 mm (i.e., 24 ≤ R8adjacent ≤ 25, where R8adjacent is the radius of curvature of the eighth convex lens 24 on the side close to the diaphragm 3, and the unit of R8adjacent is mm). [[ID=第十九]] [[ID=第二十]]

[0118] The radius of curvature of the surface of the fourth concave lens 25 facing away from the diaphragm 3 is greater than or equal to 246 mm and less than or equal to 247 mm (i.e., 246 ≤ R_fourth_concave_back ≤ 247, where R_fourth_concave_back is the radius of curvature of the surface of the fourth concave lens 25 facing away from the diaphragm 3, and the unit of R_fourth_concave_back is mm).

[0119] The radius of curvature of the surface of the fourth concave lens 25 facing the diaphragm 3 is greater than or equal to -21 mm and less than or equal to -20 mm (i.e., -21 ≤ R_fourth_concave_near ≤ -20, where R_fourth_concave_near is the radius of curvature of the surface of the fourth concave lens 25 facing the diaphragm 3, and the unit of R_fourth_concave_near is mm).

[0120] The radius of curvature of the surface of the fifth concave lens 26 facing away from the diaphragm 3 is greater than or equal to 30 mm and less than or equal to 31 mm (i.e., 30 ≤ R_fifth_concave_back ≤ 31, where R_fifth_concave_back is the radius of curvature of the surface of the fifth concave lens 26 facing away from the diaphragm 3, and the unit of R_fifth_concave_back is mm).

[0121] The radius of curvature of the surface of the fifth concave lens 26 facing the diaphragm 3 is greater than or equal to 91 mm and less than or equal to 92 mm (i.e., 91 ≤ R_fifth_concave_near ≤ 92, where R_fifth_concave_near is the radius of curvature of the surface of the fifth concave lens 26 facing the diaphragm 3, and the unit of R_fifth_concave_near is mm).

[0122] The radius of curvature of the surface of the sixth concave lens 27 facing away from the diaphragm 3 is greater than or equal to 54 mm and less than or equal to 55 mm (i.e., 54 ≤ R_sixth_concave_back ≤ 55, where R_sixth_concave_back is the radius of curvature of the surface of the sixth concave lens 27 facing away from the diaphragm 3, and the unit of R_sixth_concave_back is mm).

[0123] The radius of curvature of the surface of the sixth concave lens 27 facing the diaphragm 3 is greater than or equal to -29 mm and less than or equal to -28 mm (i.e., -29 ≤ R_sixth_concave_near ≤ -28, where R_sixth_concave_near is the radius of curvature of the surface of the sixth concave lens 27 facing the diaphragm 3, and the unit of R_sixth_concave_near is mm).

[0124] Meanwhile, the center thickness of the first convex lens 11 is 5-6 mm. The center thickness of the second convex lens 12 is 7-8 mm. The center thickness of the third convex lens 13 is 7-8 mm. The center thickness of the fourth convex lens 14 is 7-8 mm. The center thickness of the first concave lens 15 is 2-3 mm. The center thickness of the second concave lens 16 is 1-2 mm. The center thickness of the third concave lens 17 is 1-2 mm. The center thickness of the fifth convex lens 21 is 5-6 mm. The center thickness of the sixth convex lens 22 is 7-8 mm. The center thickness of the seventh convex lens 23 is 7-8 mm. The center thickness of the eighth convex lens 24 is 7-8 mm. The center thickness of the fourth concave lens 25 is 2-3 mm. The center thickness of the fifth concave lens 26 is 1-2 mm. The center thickness of the sixth concave lens 27 is 1-2 mm.

[0125] The distance between the first convex lens 11 and the second convex lens 12 is 1-2 mm. The distance between the second convex lens 12 and the third convex lens 13 is 6-7 mm. The distance between the third convex lens 13 and the first concave lens 15 is 2-3 mm. The distance between the first concave lens 15 and the second concave lens 16 is 9-10 mm. The distance between the second concave lens 16 and the third concave lens 17 is 1-2 mm. The distance between the third concave lens 17 and the fourth convex lens 14 is 1-2 mm. The distance between the fourth convex lens 14 and the aperture 3 is 0.5-1 mm.

[0126] The distance between the fifth convex lens 21 and the sixth convex lens 22 is 1-2 mm. The distance between the sixth convex lens 22 and the seventh convex lens 23 is 6-7 mm. The distance between the seventh convex lens 23 and the fourth concave lens 25 is 2-3 mm. The distance between the fourth concave lens 25 and the fifth concave lens 26 is 9-10 mm. The distance between the fifth concave lens 26 and the sixth concave lens 27 is 1-2 mm. The distance between the sixth concave lens 27 and the eighth convex lens 24 is 1-2 mm. The distance between the eighth convex lens 24 and the aperture 3 is 4-5 mm.

[0127] Specifically, the incident lens group 1 is arranged on the left side of the aperture 3, and the imaging lens group 2 is arranged on the right side of the aperture 3. The symmetrical double telecentric lens of the present application is arranged in the direction of light transmission (the direction of light transmission is Figure 1 The incident lens group 1, the aperture 3 and the imaging lens group 2 are arranged in sequence (from left to right in the figure). The incident lens group 1 and the imaging lens group 2 are completely symmetrical systems.

[0128] Specifically, it is as follows: a first convex lens 11, a second convex lens 12, a third convex lens 13, a first concave lens 15, a second concave lens 16, a third concave lens 17, a fourth convex lens 14, an aperture 3, an eighth convex lens 24, a sixth concave lens 27, a fifth concave lens 26, a fourth concave lens 25, a seventh convex lens 23, a sixth convex lens 22 and a fifth convex lens 21.

[0129] In this embodiment, the side of the lens close to the incident light source is referred to as the front surface, and the side of the lens away from the incident light source is referred to as the rear surface.

[0130] The radius of curvature of the front surface of the first convex lens 11 is 111.162 mm, the radius of curvature of the rear surface is -214.124 mm, the center thickness of the first convex lens 11 is 5.18 mm, the material of the first convex lens 11 is H-FK61B, the refractive index of the material is 1.497, the dispersion coefficient is 81.60542, and the effective aperture of the first convex lens 11 is Φ48 mm.

[0131] The radius of curvature of the front surface of the second convex lens 12 is 61.228 mm, the radius of curvature of the rear surface is -234.467 mm, the center thickness of the second convex lens 12 is 7.363 mm, the material is H-ZPK7, the refractive index of the material is 1.56907, the dispersion coefficient is 71.30425, and the effective aperture of the second convex lens 12 is Φ47.2 mm. The distance between the front surface of the second convex lens 12 and the rear surface of the first convex lens 11 is 1.611 mm.

[0132] The radius of curvature of the front surface of the third convex lens 13 is 25.995 mm, the radius of curvature of the rear surface is 752.683 mm, the center thickness of the third convex lens 13 is 7.922 mm, the material is H-FK95N, the refractive index of the material is 1.43780, the dispersion coefficient is 94.523389, and the effective aperture of the third convex lens 13 is Φ35 mm. The distance between the front surface of the third convex lens 13 and the rear surface of the second convex lens 12 is 6.892 mm.

[0133] The radius of curvature of the front surface of the first concave lens 15 is -246.915 mm, the radius of curvature of the rear surface is 20.430 mm, the center thickness of the first concave lens 15 is 2.08 mm, the material is H-K51, the refractive index of the material is 1.523074, the dispersion coefficient is 58.608589, and the effective aperture of the first concave lens 15 is Φ32 mm. The distance between the front surface of the first concave lens 15 and the rear surface of the third convex lens 13 is 2.056 mm.

[0134] The second concave lens 16 has a front surface radius of curvature of -30.84 mm, a rear surface radius of curvature of -91.471 mm, a center thickness of 1.693 mm, and is made of H-TF3L, which has a refractive index of 1.6134 and an Abbe number of 44.107022. The effective aperture of the second concave lens 16 is Φ24 mm. The distance between the front surface of the second concave lens 16 and the rear surface of the first concave lens 15 is 9.376 mm.

[0135] The radius of curvature of the front surface of the third concave lens 17 is -54.915 mm, the radius of curvature of the rear surface is 28.149 mm, the center thickness of the third concave lens 17 is 1.684 mm, the material is H-LAK7A, the refractive index of the material is 1.713, the dispersion coefficient is 53.83297, and the effective aperture is Φ24 mm. The distance between the front surface of the third concave lens 17 and the rear surface of the second concave lens 16 is 1.906 mm.

[0136] The front surface curvature radius of the fourth convex lens 14 is 32.397 mm, the rear surface curvature radius is -24.1426 mm, the center thickness of the fourth convex lens 14 is 7.255 mm, the material is H-ZPK7, the refractive index of the material is 1.56907, the dispersion coefficient is 71.30425, and the effective aperture of the fourth convex lens 14 is Φ26 mm. The distance between the front surface of the fourth convex lens 14 and the rear surface of the third concave lens 17 is 1.491 mm.

[0137] The front surface of the aperture 3 is a plane, and the rear surface is also a plane. The center thickness of the aperture 3 is 25.4 mm. The material is H-K9L, the refractive index of the material is 1.516802, the dispersion coefficient is 64.230624, and the effective aperture of the aperture 3 is Φ25.4 mm. Among them, the front surface of the aperture 3 (that is, the side of the aperture 3 close to the fourth convex lens 14) is 0.629 mm away from the rear surface of the fourth convex lens 14.

[0138] It should be noted that if Figure 1 As shown, the aperture 3 can be made into a cylindrical lens or a quadrangular lens when the system does not need to be equipped with a coaxial optical system 4.

[0139] like Figure 2 As shown, when the system needs to be configured with a coaxial optical system 4 for illumination, the light stop 3 can be designed to be composed of two right-angle prisms glued together with an oblique surface, and the oblique surface of the single prism is coated with a semi-transparent and semi-reflective film for illuminating objects and participating in the imaging system to improve the illumination of the image surface.

[0140] In this case, the symmetrical bi-telecentric lens also includes a coaxial optical system 4, which is disposed above the aperture 3 and can emit parallel light toward the aperture 3. The coaxial optical system 4 includes a coaxial light condensing lens 41 and a coaxial light emitting light source 42. The coaxial light condensing lens 41 is disposed between the coaxial light emitting light source 42 and the aperture 3. The coaxial light emitting light source 42 can be emitted toward the aperture 3 in the form of parallel light through the coaxial light condensing lens 41.

[0141] like Figure 1 and Figure 2As shown, the radius of curvature of the front surface of the eighth convex lens 24 is 24.1426 mm, the radius of curvature of the rear surface is -32.397 mm, the center thickness of the eighth convex lens 24 is 7.255 mm, the material is H-ZPK7, the refractive index of the material is 1.56907, the dispersion coefficient is 71.30425, and the effective aperture of the eighth convex lens 24 is Φ26 mm. The distance between the front surface of the eighth convex lens 24 and the rear surface of the aperture 3 (that is, the side of the aperture 3 close to the eighth convex lens 24) is 4.199 mm.

[0142] The front surface curvature radius of the sixth concave lens 27 is -28.149 mm, and the rear surface curvature radius is 54.915 mm. The center thickness of the sixth concave lens 27 is 1.684 mm. The material is H-LAK7A, the refractive index of the material is 1.713, the dispersion coefficient is 53.83297, and the effective aperture of the sixth concave lens 27 is Φ24 mm. The distance between the front surface of the sixth concave lens 27 and the rear surface of the eighth convex lens 24 is 1.419 mm.

[0143] The front surface of the fifth concave lens 26 has a radius of curvature of 91.471 mm, the rear surface radius of curvature is 30.84 mm, the center thickness of the fifth concave lens 26 is 1.693 mm, the material is H-TF3L, the refractive index of the material is 1.6134, the Abbe number is 44.107022, the effective aperture of the fifth concave lens 26 is Φ24 mm, and the distance between the front surface of the fifth concave lens 26 and the rear surface of the sixth concave lens 27 is 1.906 mm.

[0144] The radius of curvature of the front surface of the fourth concave lens 25 is -20.430 mm, the radius of curvature of the rear surface is 246.915 mm, the center thickness of the fourth concave lens 25 is 2.08 mm, the material is H-K51, the refractive index of the material is 1.523074, the dispersion coefficient is 58.608589, and the effective aperture of the fourth concave lens 25 is Φ32 mm. The distance between the front surface of the fourth concave lens 25 and the rear surface of the fifth concave lens 26 is 9.376 mm.

[0145] The radius of curvature of the front surface of the seventh convex lens 23 is -752.683 mm, the radius of curvature of the rear surface is -25.995 mm, the center thickness of the seventh convex lens 23 is 7.922 mm, the material is H-FK95N, the refractive index of the material is 1.43780, the dispersion coefficient is 94.523389, and the effective aperture of the seventh convex lens 23 is Φ35 mm. The distance between the front surface of the seventh convex lens 23 and the rear surface of the fourth concave lens 25 is 2.056 mm.

[0146] The radius of curvature of the front surface of the sixth convex lens 22 is 234.467 mm, the radius of curvature of the rear surface is -61.228 mm, the center thickness of the sixth convex lens 22 is 7.363 mm, the material is H-ZPK7, the refractive index of the material is 1.56907, the dispersion coefficient is 71.30425, and the effective aperture of the sixth convex lens 22 is Φ47.2 mm. The distance between the front surface of the sixth convex lens 22 and the rear surface of the seventh convex lens 23 is 6.892 mm.

[0147] The front surface curvature of the fifth convex lens 21 is 214.1241 mm, the rear surface curvature radius is -111.162 mm, the center thickness of the fifth convex lens 21 is 5.18 mm, the lens material is H-FK61B, the refractive index of the material is 1.497, the dispersion coefficient is 81.60542, and the effective aperture of the fifth convex lens 21 is Φ48 mm. The distance between the front surface of the fifth convex lens 21 and the rear surface of the sixth convex lens 22 is 1.611 mm.

[0148] It should be noted that the distance between the fifth convex lens 21 and the image plane is 89-90 mm. In this embodiment, the distance between the rear surface of the fifth convex lens 21 and the image plane is 89.903 mm, and the diameter of the image plane is 29.72 mm.

[0149] The symmetrical bi-telecentric lens of the present application uses the above-mentioned lens design to obtain the following focal length values ​​of the incident lens group 1 and the imaging lens group 2: the focal length of the incident lens group 1 is 81.7605 mm, and the focal length of the imaging lens group 2 is also 81.7605 mm, achieving complete symmetry of the symmetrical bi-telecentric lens.

[0150] The focal length of the optical system is 285.896 mm, where the focal length of the optical system is the focal length obtained by combining the above 14 lenses.

[0151] After applying this symmetrical bi-telecentric lens to an optical system (the optical system includes a symmetrical bi-telecentric lens and all necessary components related thereto, such as a light source, an optical filter, an image processor, etc. These systems are typically used in applications requiring high-precision measurement, such as the measurement of precision mechanical components, the measurement of electronic components, etc., such as the use of a symmetrical bi-telecentric static head in conjunction with a camera in this application), the F value of the optical system (the F value is the FNo. value, which is a parameter indicating the light transmission capacity of the lens) can be adjusted to 5.4 through the aperture 3. The optical system can then combine a long focal length with a large aperture, and the image plane of the incident lens group 1 is at the position of the front focal plane of the imaging lens group 2. The optical system can achieve an imaging magnification of 1.

[0152] Specifically, such as Figure 1 、 Figure 3 、 Figure 4 、 Figure 5 and Figure 6 As shown in the figure, the actual numerical test of the symmetrical double telecentric lens is carried out, and its optical design indicators are displayed including: optical system diagram, modulation transfer function (MTF) curve diagram, point diagram, field curvature and distortion diagram, and relative illumination diagram.

[0153] Among them, such as Figure 1 and Figure 2 As shown, it can be seen from the optical system diagram that the optical structure design of the symmetrical double telecentric lens of the present application is completely symmetrical, achieving a magnification ratio of 1:1, and the image is consistent with the object size without any difference, which is particularly realistic.

[0154] like Figure 3 As shown in the MTF curve, the optical system, using a bi-telecentric lens and a diffraction-limited design, achieves an imaging resolution of MTF@0.3 = 180 (line pairs per millimeter (lp / mm)). The imaging resolution of different colors is very close to the diffraction limit, meeting the requirements of high-definition resolution. MTF@0.3 = 180 (lp / mm) indicates that the MTF value at 0.3 is 180 lp / mm.

[0155] like Figure 4 As shown in FIG, the three spot diagrams are the diffuse spot radius (RMS radius) under different image fields, where the RMS radius is an important optical parameter used to quantitatively reflect the size of the actual diffuse spot in the system.

[0156] The spot diagram shows that the spot size is less than 3μm within the inner field of view and only exceeds 7μm at the outer edges. Therefore, the symmetrical telecentric lens of this application has high imaging performance and quality. The 3μm pixels of existing sensors are sufficient to achieve full resolution.

[0157] like Figure 5 As shown, the left side is the field curvature diagram and the right side is the distortion diagram. It can be seen from the field curvature diagram that the field curvature changes of the meridian and sagittal lines in the entire field of view are within 0.05, which is a small field curvature optical system in the machine vision system.

[0158] Similarly, the distortion diagram shows that the distortion of the entire system in each field of view is less than 0.01%, which can be regarded as a distortion-free system. This has no effect or change on the imaging of the object, which can expand its application range or precision measurement.

[0159] like Figure 6As shown in the relative illumination diagram, it can be seen that the optical system of the symmetrical double telecentric lens of the present application has almost no difference in the relative illumination center and edge of the imaging surface, indicating that the illumination uniformity of the image surface is highly consistent, and there will be no situation where the center is bright and the edges are dark, thereby improving the accuracy of alignment and interpretation.

[0160] From the structure of the above symmetrical double telecentric lens and actual data detection, it can be seen that the structure of the present application has the following effects:

[0161] 1. The effective aperture of all lenses (i.e., 14 lenses) in the symmetrical double telecentric lens of this application is greater than Φ24 mm, meeting the requirements of large target surface imaging.

[0162] 2. The F-value (F-value, also known as FNo., a parameter indicating the light transmission capacity of a lens) of the optical system can be increased to 5.4 through aperture 3, and the focal length of the optical system can be increased to 285.896 mm. The focal length of the optical system is the focal length obtained by combining the aforementioned 14 lens elements. This is a typical long-focal-length, large-aperture optical system (long-focal-length, large-aperture optical systems require a larger focal length and a smaller F-number), achieving uniform brightness between the object and image surfaces.

[0163] 3. The symmetrical double telecentric lens of the present application is composed of 14 lenses and an aperture 3. The 14 lenses cooperate with each other to eliminate the influence of various aberrations on imaging, improve the imaging quality, and achieve high resolution.

[0164] 4. The optical design concept of the double telecentric lens enables the incident lens group 1 to image the object plane on the aperture 3 position plane. At the same time, the aperture 3 position is located at the front focal plane of the imaging lens group 2, sharing the advantages of object-space telecentricity and image-space telecentricity, improving the brightness uniformity of the object plane and the brightness uniformity of the image plane, while also improving the alignment accuracy of the object plane and the judgment accuracy of the image plane, further improving the monitoring level of precision testing and ultra-small components.

[0165] 5. Adopting a diffraction-limited design approach significantly improves the resolution of the optical system, enabling high-definition resolution lenses. The diffraction limit refers to the fact that due to the diffraction properties of light, traditional imaging, focusing, and transmission methods are limited by wavelength and aperture, resulting in the inability to achieve higher resolution and smaller spatial dimensions. The diffraction-limited design approach is the strategy designers employ to overcome this limitation.

[0166] 6. Use a larger aperture lens to improve the resolution of the image and obtain a wider range of object surface measurement or monitoring to expand the application range of the lens.

[0167] 7. A coaxial optical system 4 can be added to increase the brightness of the object plane and the image plane, thereby improving the uniformity of resolution, reducing alignment and reading errors, and adapting to applications in darker scenes.

[0168] The symmetrical bi-telecentric lens needs to be used with a camera. The camera sensor size can support up to 1.8 inches. The symmetrical bi-telecentric lens of this application is compatible with smaller-inch cameras.

[0169] That is, the symmetrical double telecentric lens of the present application can achieve a high resolution effect with a large target area and high magnification.

[0170] like Figure 7 As shown, a working method of a symmetrical bi-telecentric lens is applied to the symmetrical bi-telecentric lens as described in any one of the above items, and the method comprises the steps of:

[0171] S100. Light is incident from the incident lens group 1 and emitted from the imaging lens group 2, and passes through the first convex lens 11, the second convex lens 12, the third convex lens 13, the first concave lens 15, the second concave lens 16, the third concave lens 17, the fourth convex lens 14, the aperture 3, the eighth convex lens 24, the sixth concave lens 27, the fifth concave lens 26, the fourth concave lens 25, the seventh convex lens 23, the sixth convex lens 22 and the fifth convex lens 21 in sequence.

[0172] In summary, the structure of the symmetrical double telecentric lens of the present application can achieve a magnification of 1:1, that is, a true reflection of the actual situation of the object, without any illusion error caused by human factors; at the same time, by adopting a large-aperture objective lens, a long focal length, and a large aperture 3, the lens's ability to resolve object details is improved, and the lens is improved using the design ideas of the diffraction limit and telecentric lens, so that the brightness and resolution of the entire picture are uniform, the accuracy is improved so that the resolution meets the requirements of high definition, and the alignment accuracy is improved and the interpretation error is reduced. The auxiliary coaxial optical system 4 can improve the system's resolution and the brightness of the object image surface by a level, which can meet the shooting use of all sensors of any size camera below 1.8 inches, and has a wide range of applications; it adopts a completely symmetrical structural design, all of which are single lenses, simple to process and low cost.

[0173] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0174] It should be noted that the present invention uses a symmetrical bi-telecentric lens and a working method as an example to introduce the specific structure and working principle of the present invention, but the application of the present invention is not limited to a symmetrical bi-telecentric lens and a working method, and can also be applied to the production and use of other similar workpieces.

[0175] It should be understood that the present invention is not limited to the exact construction described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

[0176] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A symmetrical bi-telecentric lens, characterized in that: include: Entrance mirror group; Imaging lens assembly; an aperture, arranged between the incident lens group and the imaging lens group, the incident lens group and the imaging lens group having the same focal length, wherein the incident lens group and the imaging lens group on both sides of the aperture are each provided with an identical number of seven lenses; The incident lens group includes a first convex lens, a second convex lens, a third convex lens, a fourth convex lens, a first concave lens, a second concave lens and a third concave lens; The first convex lens, the second convex lens, the third convex lens, the first concave lens, the second concave lens, the third concave lens and the fourth convex lens are arranged in sequence, and the aperture is arranged close to the fourth convex lens; The imaging lens group includes a fifth convex lens, a sixth convex lens, a seventh convex lens, an eighth convex lens, a fourth concave lens, a fifth concave lens and a sixth concave lens; The fifth convex lens, the sixth convex lens, the seventh convex lens, the fourth concave lens, the fifth concave lens, the sixth concave lens and the eighth convex lens are arranged in sequence, and the aperture is arranged close to the eighth convex lens; The curvature radius of the first convex lens facing away from the aperture is greater than or equal to 110 mm, and the curvature radius of the first convex lens facing away from the aperture is less than or equal to 112 mm; The curvature radius of the first convex lens on the side close to the aperture is greater than or equal to -215 mm, and the curvature radius of the first convex lens on the side close to the aperture is less than or equal to -214 mm; The curvature radius of the second convex lens facing away from the aperture is greater than or equal to 61 mm, and the curvature radius of the second convex lens facing away from the aperture is less than or equal to 62 mm; The curvature radius of the second convex lens on the side close to the aperture is greater than or equal to -235 mm, and the curvature radius of the second convex lens on the side close to the aperture is less than or equal to -234 mm; The curvature radius of the third convex lens facing away from the aperture is greater than or equal to 25 mm, and the curvature radius of the third convex lens facing away from the aperture is less than or equal to 26 mm; The curvature radius of the third convex lens near the aperture is greater than or equal to 752 mm, and the curvature radius of the third convex lens near the aperture is less than or equal to 753 mm; The curvature radius of the fourth convex lens facing away from the aperture is greater than or equal to 32 mm, and the curvature radius of the fourth convex lens facing away from the aperture is less than or equal to 33 mm; The curvature radius of the fourth convex lens near the aperture is greater than or equal to -25 mm, and the curvature radius of the fourth convex lens near the aperture is less than or equal to -24 mm; The curvature radius of the first concave lens facing away from the aperture is greater than or equal to -247 mm, and the curvature radius of the first concave lens facing away from the aperture is less than or equal to -246 mm; The curvature radius of the first concave lens on the side close to the aperture is greater than or equal to 20 mm, and the curvature radius of the first concave lens on the side close to the aperture is less than or equal to 21 mm; The curvature radius of the second concave lens facing away from the aperture is greater than or equal to -31 mm, and the curvature radius of the second concave lens facing away from the aperture is less than or equal to -30 mm; The curvature radius of the second concave lens on the side close to the aperture is greater than or equal to -92 mm, and the curvature radius of the second concave lens on the side close to the aperture is less than or equal to -91 mm; The curvature radius of the third concave lens facing away from the aperture is greater than or equal to -55 mm, and the curvature radius of the third concave lens facing away from the aperture is less than or equal to -54 mm; The curvature radius of the third concave lens close to the aperture is greater than or equal to 28 mm, and the curvature radius of the third concave lens close to the aperture is less than or equal to 29 mm.

2. The symmetrical bi-telecentric lens according to claim 1, wherein: The distance between the first convex lens and the second convex lens is 1-2 mm; The distance between the second convex lens and the third convex lens is 6-7 mm; The distance between the third convex lens and the first concave lens is 2-3 mm; The distance between the first concave lens and the second concave lens is 9-10 mm; The distance between the second concave lens and the third concave lens is 1-2 mm; The distance between the third concave lens and the fourth convex lens is 1-2 mm; The distance between the fourth convex lens and the aperture is 0.5-1 mm.

3. The symmetrical bi-telecentric lens according to claim 2, wherein: The distance between the fifth convex lens and the sixth convex lens is 1-2 mm; The distance between the sixth convex lens and the seventh convex lens is 6-7 mm; The distance between the seventh convex lens and the fourth concave lens is 2-3 mm; The distance between the fourth concave lens and the fifth concave lens is 9-10 mm; The distance between the fifth concave lens and the sixth concave lens is 1-2 mm; The distance between the sixth concave lens and the eighth convex lens is 1-2 mm; The distance between the eighth convex lens and the aperture is 4-5 mm.

4. The symmetrical bi-telecentric lens according to claim 3, wherein: The distance between the fifth convex lens and the image plane is 89-90 mm.

5. The symmetrical bi-telecentric lens according to claim 4, wherein: The curvature radius of the fifth convex lens facing away from the aperture is greater than or equal to -112 mm, and the curvature radius of the fifth convex lens facing away from the aperture is less than or equal to -111 mm; The curvature radius of the fifth convex lens on the side close to the aperture is greater than or equal to 214 mm, and the curvature radius of the fifth convex lens on the side close to the aperture is less than or equal to 215 mm; The curvature radius of the sixth convex lens facing away from the aperture is greater than or equal to -62 mm, and the curvature radius of the sixth convex lens facing away from the aperture is less than or equal to -61 mm; The curvature radius of the sixth convex lens on the side close to the aperture is greater than or equal to 234 mm, and the curvature radius of the sixth convex lens on the side close to the aperture is less than or equal to 235 mm; The curvature radius of the seventh convex lens facing away from the aperture is greater than or equal to -26 mm, and the curvature radius of the seventh convex lens facing away from the aperture is less than or equal to -25 mm; The curvature radius of the seventh convex lens near the aperture is greater than or equal to -753 mm, and the curvature radius of the seventh convex lens near the aperture is less than or equal to -752 mm; The curvature radius of the eighth convex lens facing away from the aperture is greater than or equal to -33 mm, and the curvature radius of the eighth convex lens facing away from the aperture is less than or equal to -32 mm; The curvature radius of the eighth convex lens near the aperture is greater than or equal to 24 mm, and the curvature radius of the eighth convex lens near the aperture is less than or equal to 25 mm; The curvature radius of the fourth concave lens facing away from the aperture is greater than or equal to 246 mm, and the curvature radius of the fourth concave lens facing away from the aperture is less than or equal to 247 mm; The curvature radius of the fourth concave lens near the aperture is greater than or equal to -21 mm, and the curvature radius of the fourth concave lens near the aperture is less than or equal to -20 mm; The curvature radius of the fifth concave lens facing away from the aperture is greater than or equal to 30 mm, and the curvature radius of the fifth concave lens facing away from the aperture is less than or equal to 31 mm; The curvature radius of the fifth concave lens on the side close to the aperture is greater than or equal to 91 mm, and the curvature radius of the fifth concave lens on the side close to the aperture is less than or equal to 92 mm; The curvature radius of the sixth concave lens facing away from the aperture is greater than or equal to 54 mm, and the curvature radius of the sixth concave lens facing away from the aperture is less than or equal to 55 mm; The curvature radius of the sixth concave lens close to the aperture is greater than or equal to -29 mm, and the curvature radius of the sixth concave lens close to the aperture is less than or equal to -28 mm.

6. The symmetrical bi-telecentric lens according to claim 5, wherein: The center thickness of the first convex lens is 5-6 mm; The center thickness of the second convex lens is 7-8 mm; The center thickness of the third convex lens is 7-8 mm; The center thickness of the fourth convex lens is 7-8 mm; The center thickness of the first concave lens is 2-3 mm; The center thickness of the second concave lens is 1-2 mm; The center thickness of the third concave lens is 1-2 mm.

7. The symmetrical bi-telecentric lens according to claim 6, wherein: The center thickness of the fifth convex lens is 5-6 mm; The center thickness of the sixth convex lens is 7-8 mm; The center thickness of the seventh convex lens is 7-8 mm; The center thickness of the eighth convex lens is 7-8 mm; The center thickness of the fourth concave lens is 2-3 mm; The center thickness of the fifth concave lens is 1-2 mm; The center thickness of the sixth concave lens is 1-2 mm.

8. The symmetrical bi-telecentric lens according to claim 1, wherein: The effective apertures of the lenses included in the incident lens group and the imaging lens group are both greater than 24 mm.

9. A method for operating a symmetrical bi-telecentric lens, characterized in that: Applied to the symmetrical bi-telecentric lens according to any one of claims 1 to 8, the method comprises the steps of: The light enters the incident lens group and is emitted from the imaging lens group, and passes through the first convex lens, the second convex lens, the third convex lens, the first concave lens, the second concave lens, the third concave lens, the fourth convex lens, the aperture, the eighth convex lens, the sixth concave lens, the fifth concave lens, the fourth concave lens, the seventh convex lens, the sixth convex lens and the fifth convex lens in sequence.

Images