CN213934371U

CN213934371U - Telecentric lens

Info

Publication number: CN213934371U
Application number: CN202022338152.6U
Authority: CN
Inventors: 贾睿; 关文武; 王舒颖; 王溪; 吴垚; 张纯济; 姚远峰; 刘晓波; 杨振华; 高云峰
Original assignee: Han s Laser Technology Industry Group Co Ltd
Current assignee: Han s Laser Technology Industry Group Co Ltd
Priority date: 2020-10-19
Filing date: 2020-10-19
Publication date: 2021-08-10
Anticipated expiration: 2030-10-19

Abstract

The utility model aims at providing a telecentric lens, include the first mirror group, the second mirror group, prism and the third mirror group that arrange in proper order from the object space to the image space, the first mirror group is including the first lens that has positive focal power and falcate structure, the second lens that has positive focal power and falcate structure, the third lens that has positive focal power and biconvex structure; the second lens group comprises a fourth lens with positive focal power and a meniscus structure; the third lens group comprises a fifth lens with negative focal power and a meniscus structure, a sixth lens with positive focal power and a meniscus structure and a seventh lens with positive focal power and a meniscus structure. The technical scheme of the utility model the telecentric mirror head cost of having solved the well resolution ratio among the prior art is high, the problem that the structure is complicated effectively.

Description

Telecentric lens

Technical Field

The utility model relates to a machine vision technical field, concretely relates to telecentric lens.

Background

In the precision machining and manufacturing process, the product is necessarily positioned and detected, and if a common industrial lens is used, aberrations such as large distortion, parallax and the like exist, so that the positioning and detection precision is influenced. The problems are greatly reduced by using a telecentric lens and a special parallel light path design, and the magnification of the obtained image cannot be changed within a certain object distance range. Therefore, the telecentric lens is very suitable for the field of precision machining.

However, the design difficulty is limited, the high-resolution telecentric lens in the current market has high manufacturing cost and complex structure, and if the design is not reasonable, the tolerance sensitivity is high, which is not beneficial to production.

SUMMERY OF THE UTILITY MODEL

The utility model discloses aim at solving the problem that the telecentric mirror head cost of the well resolution ratio of prior art is high, the structure is complicated. In order to solve the above problems, the present invention provides a telecentric lens comprising a first lens group, a second lens group, a prism and a third lens group sequentially arranged from an object space to an image space, wherein the first lens group comprises a first lens having a positive focal power and a meniscus structure, a second lens having a positive focal power and a meniscus structure, and a third lens having a positive focal power and a biconvex structure; the second lens group comprises a fourth lens with positive focal power and a meniscus structure; the third lens group comprises a fifth lens with negative focal power and a meniscus structure, a sixth lens with positive focal power and a meniscus structure and a seventh lens with positive focal power and a meniscus structure.

Further, the telecentric lens further comprises a diaphragm, and the diaphragm is arranged between the fourth lens and the prism.

Further, the sixth lens and the seventh lens are cemented together.

Further, the telecentric lens further comprises a point light source interface, and the point light source interface is arranged at the prism.

Further, the refractive index n1 of the first lens satisfies: 1.742 is not less than n1 is not less than 1.765, and the Abbe number v1 of the first lens satisfies: v1 is more than or equal to 23 and less than or equal to 27; the refractive index n2 of the second lens satisfies: 1.735 is not less than n2 is not less than 1.753, and Abbe number v2 of the second lens meets the following conditions: 27 is less than or equal to v2 is less than or equal to 29; the refractive index n3 of the third lens satisfies: 1.526 is not less than n3 is not less than 1.714, and the Abbe number v3 of the third lens meets the following requirements: 59 is less than or equal to v3 is less than or equal to 62.

Further, the refractive index n1 of the first lens is 1.750, and the abbe number v1 of the first lens is 25.51; the refractive index n2 of the second lens is 1.742, and the Abbe number v2 of the second lens is 28.34; the refractive index n3 of the third lens is 1.602, and the abbe number v3 of the third lens is 60.26.

Further, the refractive index n4 of the fourth lens satisfies: 1.401 is not less than n4 is not less than 1.588; the abbe number v4 of the fourth lens satisfies: 69 is less than or equal to v4 is less than or equal to 72.

Further, the refractive index n4 of the fourth lens is 1.499; the abbe number v4 of the fourth lens was 70.46.

Further, the refractive index n5 of the fifth lens satisfies: 1.587 is not less than n5 is not less than 1.714, and Abbe number v5 of the fifth lens meets the following requirements: v5 is more than or equal to 47 and less than or equal to 50; the refractive index n6 of the sixth lens satisfies: 1.685 and n6 and 1.823, and the Abbe number v6 of the sixth lens meets the following requirements: v6 is more than or equal to 25 and less than or equal to 28; the refractive index n7 of the seventh lens satisfies: 1.583 is not less than n7 is not less than 1.725, and Abbe number v7 of the seventh lens meets the following requirements: 34 is less than or equal to v7 is less than or equal to 38.

Further, the refractive index n5 of the fifth lens is 1.647, and the abbe number v5 of the fifth lens is 48.07; the refractive index n6 of the sixth lens is 1.758, and the abbe number v6 of the sixth lens is 27.04; the refractive index n7 of the seventh lens is 1.636, and the abbe number v7 of the seventh lens is 36.83.

Implement the utility model discloses an embodiment will have following beneficial effect:

the utility model discloses a telecentric lens passes through optical element combination and material selection to and optimal design has reached 1 times magnification, and F/# is 9, and object space working distance is 110mm, and image space image circle 11 mm's high resolution, high magnification, the high brightness formation of image, and have lower tolerance sensitivity, greatly provide the quality of camera lens production.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Wherein:

fig. 1 shows a schematic diagram of an optical path system of an embodiment of a telecentric lens according to the present invention;

FIG. 2 illustrates a field curvature distortion plot of the telecentric lens of FIG. 1;

FIG. 3 shows an MTF plot for the telecentric lens of FIG. 1; and

fig. 4 shows a relative illumination diagram for the telecentric lens of fig. 1.

The above figures contain the following reference numerals:

g1, first lens; g2, second lens; g3, third lens; g4, fourth lens; g5, fifth lens; g6, sixth lens; g7, seventh lens; 1. a diaphragm; 2. and a prism.

Detailed Description

In order to facilitate understanding of the present invention, the present invention will be described more fully hereinafter with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

As shown in fig. 1, the left side of the drawing is an object side, and the right side is an image side, the telecentric lens of the embodiment includes three lens groups arranged in sequence from the object side to the image side, wherein the first lens group includes a first lens G1 having positive focal power and a meniscus structure, a second lens G2 having positive focal power and a meniscus structure, and a third lens G3 having positive focal power and a double convex structure; the second lens group comprises a fourth lens G4 with positive focal power and a meniscus structure; the third lens group includes a fifth lens G5 having a negative power and a meniscus configuration, a sixth lens G6 having a positive power and a meniscus configuration, and a seventh lens G7 having a positive power and a meniscus configuration. A prism 2 is arranged between the second lens group and the third lens group.

The telecentric lens of the embodiment has the advantages that 1 time of magnification is achieved through optical element combination and material selection and optimized design, the F/# is 9, the object space working distance is 110mm, the image space image circle is 11mm in high resolution, high magnification and high brightness, the telecentric lens has lower tolerance sensitivity, and the quality of lens production is greatly improved.

As shown in fig. 1, the telecentric lens of the present embodiment further includes a diaphragm 1 and a point light source interface, wherein the diaphragm 1 is disposed between the fourth lens G4 and the prism 2, and the point light source interface is disposed at the prism 2.

As a preferable range, in the telecentric lens of the present embodiment, the first lens group: the refractive index n1 of the first lens G1 satisfies: 1.742 is not less than n1 is not less than 1.765, and the Abbe number v1 of the first lens G1 satisfies: v1 is more than or equal to 23 and less than or equal to 27; the refractive index n2 of the second lens G2 satisfies: 1.735 is not less than n2 is not less than 1.753, and Abbe number v2 of the second lens G2 satisfies: 27 is less than or equal to v2 is less than or equal to 29; the refractive index n3 of the third lens G3 satisfies: 1.526 is not less than n3 is not less than 1.714, and Abbe number v3 of the third lens G3 satisfies: 59 is less than or equal to v3 is less than or equal to 62. A second lens group: the refractive index n4 of the fourth lens G4 satisfies: 1.401 is not less than n4 is not less than 1.588; the abbe number v4 of the fourth lens G4 satisfies: 69 is less than or equal to v4 is less than or equal to 72. A third lens group: the refractive index n5 of the fifth lens G5 satisfies: 1.587 is not less than n5 is not less than 1.714, and Abbe number v5 of the fifth lens G5 satisfies: v5 is more than or equal to 47 and less than or equal to 50; the refractive index n6 of the sixth lens G6 satisfies: 1.685 and n6 and 1.823, and the Abbe number v6 of the sixth lens G6 satisfy: v6 is more than or equal to 25 and less than or equal to 28; the refractive index n7 of the seventh lens G7 satisfies: 1.583 is not less than n7 is not less than 1.725, and Abbe number v7 of the seventh lens G7 satisfies: 34 is less than or equal to v7 is less than or equal to 38.

According to the order of passing through the lenses from the object side to the image side, each lens is divided into a front surface and a rear surface, and the specific parameters of each lens of the telecentric lens of the embodiment are as follows:

the "radius" in the above table is the radius of curvature of the respective lens surface, and referring to fig. 1, the image side is positive and the object side is negative. For example, the center of the sphere of the front surface of G1 is on the right side (positive direction) of its sphere surface, with a radius of curvature of 22.831 mm; the center of the rear surface of G3 is on the left side (negative) of its sphere, and its radius of curvature is-106.875 mm. The "thickness" in the above table is the distance from each lens surface to the next lens surface in the object-to-image direction, for example, the distance between the front surface of G1 and the rear surface of G1 (i.e., the thickness of the first lens G1) in fig. 1 is 5.587 mm; the distance between the rear surface of G1 and the front surface of G2 in fig. 1 (i.e., the distance between the first lens G1 and the second lens G2) is 1.565 mm; the distance from the back surface of G7 to the image formation site was 20.000 mm.

"refractive index" and "Abbe number" are the refractive index and Abbe number of the corresponding lens. As shown in the above table, in the first lens group of this embodiment, the refractive index n1 of the first lens element G1 is 1.750, and the abbe number v1 of the first lens element G1 is 25.51; the refractive index n2 of the second lens G2 is 1.742, and the Abbe number v2 of the second lens G2 is 28.34; the refractive index n3 of the third lens G3 was 1.602, and the abbe number v3 of the third lens G3 was 60.26. The refractive index n4 of the fourth lens element G4 in the second lens group of the present embodiment is 1.499; the abbe number v4 of the fourth lens G4 is 70.46. In the third lens group of this embodiment, the refractive index n5 of the fifth lens G5 is 1.647, and the abbe number v5 of the fifth lens G5 is 48.07; the refractive index n6 of the sixth lens G6 is 1.758, and the abbe number v6 of the sixth lens G6 is 27.04; the refractive index n7 of the seventh lens G7 is 1.636, and the abbe number v7 of the seventh lens G7 is 36.83.

Preferably, the sixth lens G6 and the seventh lens G7 of the present embodiment are glued together, which not only can effectively correct the spherical aberration of the chief ray, but also can eliminate chromatic aberration, and reduce the tolerance adjustment difficulty and tolerance sensitivity of the optical system, so that the high beam lens of the present application is simpler and more convenient in installation and adjustment processes, and improves cost effectiveness.

The object space working distance of the telecentric lens of the embodiment is 110mm, the rear surface of the seventh lens G7 is 20mm away from the image plane, and the conjugate distance of the object image is 260 mm.

Referring to fig. 2, a curvature of field distortion curve of the telecentric lens of the present embodiment shows that the distortion of the telecentric lens is less than 0.1%. Fig. 3 is an MTF curve of the telecentric lens of the embodiment, and it can be seen that the MTF of the telecentric lens of the embodiment reaches 0.3 at 90 line pairs. Fig. 4 is a relative illumination curve of the telecentric lens, the relative illumination of the lens is greater than 0.995 in the full view field, good uniformity of the collected image can be ensured, and the telecentricity of the telecentric lens is less than 0.1 °. The telecentric lens of the embodiment has the advantages that 1 time of magnification is achieved through optical element combination and material selection and optimized design, the F/# is 9, the object space working distance is 110mm, the image space image circle is 11mm in high resolution, high magnification and high brightness, the telecentric lens has lower tolerance sensitivity, and the quality of lens production is greatly improved.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the claims. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims

1. A telecentric lens is characterized in that a first lens group, a second lens group, a prism and a third lens group are sequentially arranged from an object space to an image space,

the first lens group comprises a first lens with positive focal power and a meniscus structure, a second lens with positive focal power and a meniscus structure, and a third lens with positive focal power and a double convex structure;

the second lens group comprises a fourth lens with positive focal power and a meniscus structure;

the third lens group comprises a fifth lens with negative focal power and a meniscus structure, a sixth lens with positive focal power and a meniscus structure and a seventh lens with positive focal power and a meniscus structure.

2. A telecentric lens as recited in claim 1, further comprising an aperture disposed between the fourth lens and the prism.

3. A telecentric lens system as recited in claim 1, wherein the sixth lens and the seventh lens are cemented together.

4. A telecentric lens as recited in claim 1, further comprising a point light source interface disposed at the prism.

5. A telecentric lens as recited in claim 1, wherein the refractive index n1 of the first lens satisfies: 1.742 < n1 < 1.765, and the Abbe number v1 of the first lens satisfies: v1 is more than or equal to 23 and less than or equal to 27; the refractive index n2 of the second lens satisfies: 1.735 < n2 < 1.753, and the Abbe number v2 of the second lens satisfies: 27 is less than or equal to v2 is less than or equal to 29; the refractive index n3 of the third lens satisfies: 1.526 ≦ n3 ≦ 1.714, and the Abbe number v3 of the third lens satisfies: 59 is less than or equal to v3 is less than or equal to 62.

6. A telecentric lens according to claim 5, wherein the refractive index n1 of the first lens is 1.750, the Abbe number v1 of the first lens is 25.51; the refractive index n2 of the second lens is 1.742, and the Abbe number v2 of the second lens is 28.34; the refractive index n3 of the third lens is 1.602, and the Abbe number v3 of the third lens is 60.26.

7. A telecentric lens according to claim 1, wherein the refractive index n4 of the fourth lens satisfies: 1.401 is not less than n4 is not less than 1.588; the abbe number v4 of the fourth lens satisfies: 69 is less than or equal to v4 is less than or equal to 72.

8. A telecentric lens system as recited in claim 7, wherein the fourth lens has a refractive index n4 of 1.499; the fourth lens has an abbe number v4 of 70.46.

9. A telecentric lens according to claim 1, wherein the refractive index n5 of the fifth lens satisfies: 1.587 and n5 and 1.714, wherein the Abbe number v5 of the fifth lens satisfies the following conditions: v5 is more than or equal to 47 and less than or equal to 50; the refractive index n6 of the sixth lens satisfies: 1.685 and n6 and 1.823, and the Abbe number v6 of the sixth lens meets the following requirements: v6 is more than or equal to 25 and less than or equal to 28; the refractive index n7 of the seventh lens satisfies: 1.583 ≦ n7 ≦ 1.725, an Abbe number v7 of the seventh lens satisfying: 34 is less than or equal to v7 is less than or equal to 38.

10. A telecentric lens according to claim 9, wherein the refractive index n5 of the fifth lens is 1.647, and the abbe number v5 of the fifth lens satisfies: 48.07; the refractive index n6 of the sixth lens is 1.758, and the Abbe number v6 of the sixth lens meets the following conditions: 27.04; the refractive index n7 of the seventh lens is 1.636, and the Abbe number v7 of the seventh lens is 36.83.