CN-120821052-B - Compact type long working distance fixed-magnification lens and optical system thereof

CN120821052BCN 120821052 BCN120821052 BCN 120821052BCN-120821052-B

Abstract

The invention relates to the technical field of optical imaging, and discloses a compact type long working distance fixed-magnification lens and an optical system thereof. The optical system comprises a front group with positive focal power, a middle group with negative focal power, a diaphragm and a rear group with positive focal power, wherein the focal length f of the optical system is BFL, the focal length of the front group is f S1 , the focal length of the middle group is f S2 , the focal length of the rear group is f S3 , the relation ：0.4<|f S1 /f|<0.75,1.1<|f S2 /f|<1.7,1.50<|f S3 /f|<8.00,0.05<|BFL/f|<0.35. is met respectively, the invention realizes a long working distance fixed-magnification lens with higher resolution, the lens magnification is 0.94X, the highest resolution can reach 100 lp/mm, the lens can be matched with a 5-micrometer pixel chip, the maximum target surface size is 1.2'', and the lens has low distortion performance.

Inventors

LIN JIAMIN
Zeng Zhenhuang
CHEN JIANWEI
LU SHENGLIN

Assignees

广东奥普特科技股份有限公司

Dates

Publication Date: 20260505
Application Date: 20250820

Claims (10)

1. An optical system of a compact type long working distance fixed-magnification lens is characterized by comprising a front group with positive focal power, a middle group with negative focal power, a diaphragm and a rear group with positive focal power, wherein the front group, the middle group and the diaphragm are sequentially arranged from an object side to an image side; The front group consists of a first lens with positive focal power, the middle group consists of a second lens with negative focal power, a third lens with positive focal power, a fourth lens with negative focal power, a fifth lens with positive focal power and a sixth lens with negative focal power, the rear group consists of a seventh lens with negative focal power, an eighth lens with positive focal power, a ninth lens with negative focal power and a tenth lens with positive focal power, the second lens, the third lens and the fourth lens are glued to form a first gluing lens group with negative focal power, and the fifth lens and the sixth lens are glued to form a second gluing lens group with positive focal power; The focal length f of the optical system, the optical back focal length of the optical system is BFL, the focal length of the front group is f S1 , the focal length of the middle group is f S2 , the focal length of the back group is f S3 , and the following relations are respectively satisfied: 0.4<|f S1 /f|<0.75,1.1<|f S2 /f|<1.7,1.50<|f S3 /f|<8.00,0.05<| BFL/f |<0.35.
2. A compact form as claimed in claim 1 an optical system with a long working distance and a fixed lens, the first lens is a biconvex lens; the distance from the front surface vertex of the first lens to the rear surface vertex of the rear group is L, and L and f satisfy the relation of 0.7< |L/f| <1.50.
3. The optical system of claim 2, wherein the focal length of the first cemented lens group is f U1 ,f U1 and f satisfies the relationship of 0.65< |f U1 /f| < 1.15. The focal lengths f U2 ,f U2 and f of the second cemented lens group satisfy the relation 1.8< |f U2 /f| <3.80.
4. A compact, long working distance, fixed magnification lens optical system as described in claim 3 wherein the second lens is a meniscus lens, the third lens and the fifth lens are both biconvex lenses, the fourth lens is a meniscus lens or biconcave lens, and the sixth lens is a biconcave lens.
5. The optical system of claim 3, wherein the focal length of the third cemented lens group is f U3 ,f U3 and f satisfies the relationship of 1.00< |f U3 /f| < 2.50. The focal length of the ninth lens is f G9 ,f G9 and f meets the relation of 0.18< |f G9 /f| <0.40; The tenth lens has a focal length f G10 ,f G10 and f satisfying the relation 0.25< |f G10 /f| <0.60.
6. The optical system of claim 5, wherein the seventh lens and the ninth lens are biconcave lenses, the eighth lens is biconvex lens, and the tenth lens is a meniscus lens or a plano-convex lens.
7. The optical system of claim 5, wherein the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens and the tenth lens are spherical mirrors, and the optical axes of all the spherical mirrors coincide with the predetermined optical axis.
8. The optical system of claim 1, wherein the half-image height of the optical system is y'; y 'and f satisfy the relation |y'/f| <0.12.
9. The optical system of the compact type long working distance fixed magnification lens of claim 7, wherein the aperture of the diaphragm is a round hole, the center of the round hole is on the preset optical axis, and the aperture value of the diaphragm is adjusted to be in the range of F2.8-F16.
10. A compact long working distance fixed magnification lens comprising an optical system of the compact long working distance fixed magnification lens according to any one of claims 1-9; the magnification of the compact long working distance fixed-magnification lens is 0.94X.

Description

Compact type long working distance fixed-magnification lens and optical system thereof Technical Field The invention relates to the technical field of optical imaging, in particular to a compact type long working distance fixed-magnification lens and an optical system thereof. Background Along with the rapid development of the fields of industrial detection, machine vision and precise instruments, the long-working-distance lens can realize long-distance high-precision imaging on the premise of not interfering a measured object or avoiding environmental interference, and is widely applied to an optical system of high-precision imaging. The fixed-magnification lens has remarkable advantages in standardized detection scenes due to the characteristics of simple structure, stable imaging and the like. However, the compatibility of the long working distance and the compact design in the prior art is insufficient, and the long working distance and the compact design become key bottlenecks for restricting the wide application of the lens. Especially, when the magnification is high (more than or equal to 0.9X), the long working distance often restricts the numerical aperture and resolution of the lens, and the micrometer detection requirement is difficult to meet. The existing industrial fixed magnification lens on the market has three major core contradictions, namely, the space conflict between a long working distance and a compact structure, the difficult problem of aberration correction under the fixed magnification constraint and the balanced dilemma of high resolution and low distortion, and the problems seriously restrict the improvement of the equipment integration level and the detection precision. Therefore, the development of the high-resolution low-distortion fixed-power optical lens with long working distance is more urgent. The above information is presented as background information only to aid in the understanding of the present disclosure and is not intended or admitted to be prior art relative to the present disclosure. Disclosure of Invention The invention aims to provide a compact long working distance fixed-magnification lens and an optical system thereof, which aim to solve or at least partially solve the technical problems existing in the prior art. To achieve the purpose, the invention adopts the following technical scheme: in a first aspect, the present invention provides an optical system of a compact type long working distance fixed magnification lens, comprising a front group with positive optical power, a middle group with negative optical power, a diaphragm and a rear group with positive optical power, which are sequentially arranged from an object side to an image side; The focal length f of the optical system, the optical back focal length of the optical system is BFL, the focal length of the front group is f S1, the focal length of the middle group is f S2, the focal length of the back group is f S3, and the following relations are respectively satisfied: 0.4<|fS1/f|<0.75,1.1<|fS2/f|<1.7,1.50<|fS3/f|<8.00,0.05<| BFL/f |<0.35. optionally, the front group includes a first lens having positive optical power, the first lens being a biconvex lens; the distance from the front surface vertex of the first lens to the rear surface vertex of the rear group is L, and L and f satisfy the relation of 0.7< |L/f| <1.50. Optionally, the middle group comprises a second lens with negative focal power, a third lens with positive focal power, a fourth lens with negative focal power, a fifth lens with positive focal power and a sixth lens with negative focal power, wherein the second lens, the third lens and the fourth lens are glued into a first gluing lens group with negative focal power, and the fifth lens and the sixth lens are glued into a second gluing lens group with positive focal power; the focal length of the first cemented lens group is f U1,fU1 and f satisfies the relation 0.65< |f U1/f| <1.15; the focal lengths f U2,fU2 and f of the second cemented lens group satisfy the relation 1.8< |f U2/f| <3.80. Optionally, the second lens is a meniscus lens, the third lens and the fifth lens are both biconvex lenses, the fourth lens is a meniscus lens or a biconcave lens, and the sixth lens is a biconcave lens. Optionally, the rear group comprises a seventh lens with negative focal power, an eighth lens with positive focal power, a ninth lens with negative focal power and a tenth lens with positive focal power, wherein the seventh lens and the eighth lens are glued into a third gluing lens group with positive focal power; The focal length of the third cemented lens group is f U3,fU3 and f satisfies the relation 1.00< |f U3/f| <2.50; The focal length of the ninth lens is f G9,fG9 and f meets the relation of 0.18< |f G9/f| <0.40; The tenth lens has a focal length f G10,fG10 and f satisfying the relation 0.25< |f G10/f| <0.60. Optionally, the seventh lens and the ninth lens are biconcave lenses, the eight