阅读说明：本技术 一种镜头 (Lens ) 是由 林法官 刘凯 丁洪兴 于 2019-09-27 设计创作，主要内容包括：本发明公开了一种镜头,所述镜头包括由物侧至像侧依次排列的第一透镜组、第二透镜组和像面；所述第一透镜组位置固定,第二透镜组可沿光轴进行移动；透镜组满足以下条件：1.4<|f调/f系统|<1.7；其中,f调为第二透镜组的焦距,f系统为所述镜头的系统焦距。由于在本发明实施例中,在镜头中按照特定的顺序由物侧至像侧依次排列两个透镜组,第一透镜组位置固定,第二透镜组可沿光轴进行移动实现镜头变工作距,并且镜头中的透镜组满足：1.4<|f调/f系统|<1.7,满足机器视觉特有的近工作距及其范围宽广的要求。(The invention discloses a lens, which comprises a first lens group, a second lens group and an image plane, wherein the first lens group, the second lens group and the image plane are sequentially arranged from an object side to an image side; the first lens group is fixed in position, and the second lens group can move along the optical axis; the lens group satisfies the following conditions: 1.4< | f-modulation/f system | < 1.7; and f is the focal length of the second lens group, and the f system is the system focal length of the lens. Since in the embodiment of the present invention, two lens groups are arranged in the lens in order from the object side to the image side in a specific order, the first lens group is fixed in position, the second lens group is movable along the optical axis to realize the lens variable working distance, and the lens groups in the lens satisfy: 1.4< | f-modulation/f system | <1.7, and meets the special requirements of near working distance and wide range of machine vision.)

1. The lens is characterized by comprising a first lens group, a second lens group and an image surface, wherein the first lens group, the second lens group and the image surface are sequentially arranged from an object side to an image side and are fixed in position;

the lens group satisfies the following conditions:

1.4< | f-modulation/f system | < 1.7;

and f is the focal length of the second lens group, and the f system is the system focal length of the lens.

2. The lens barrel according to claim 1, wherein the first lens group includes a first negative power lens and a first positive power lens arranged in order from an object side to an image side.

3. The lens barrel according to claim 1, wherein the second lens group includes a first sub-lens group, a fourth negative power lens, a sixth positive power lens, a seventh positive power lens, an eighth positive power lens, and a ninth positive power lens, which are arranged in order from the object side to the image side.

4. The lens barrel according to claim 3, wherein the first sub-lens group includes a second positive power lens, a third positive power lens, a first sub-lens group, and a second sub-lens group, which are arranged in order from the object side to the image side;

the first sub-lens group comprises a fourth positive focal power lens and a second negative focal power lens;

the second sub-lens group includes a fifth positive power lens and a third negative power lens.

5. The lens barrel as claimed in claim 4, wherein the third, fifth and sixth positive power lenses have abbe numbers greater than 65.

6. The lens barrel according to claim 3, wherein the first sub-lens group includes a third sub-lens group, a twelfth positive power lens, and a fourth sub-lens group, which are arranged in order from the object side to the image side;

the third sub-lens group comprises a tenth positive focal power lens, a fifth negative focal power lens and an eleventh positive focal power lens;

the fourth sub-lens group includes a thirteenth positive power lens and a sixth negative power lens.

7. The lens barrel as claimed in claim 6, wherein the abbe numbers of the twelfth positive power lens and the thirteenth positive power lens are each greater than 65.

8. The lens barrel as claimed in claim 2, wherein the refractive index of the first positive power lens is greater than 1.9.

9. The lens barrel according to claim 3, wherein a diaphragm is disposed between the first sub-lens group and the fourth negative power lens.

10. The lens barrel according to claim 1, wherein an optical filter is disposed between the second lens group and an image plane.

Technical Field

The invention relates to the technical field of optical imaging, in particular to a lens.

Background

Machine vision is to use a machine to replace human eyes for measurement and judgment. The machine vision system is a machine vision product, namely an image pickup device converts a target to be detected into image signals, and then an image processing system performs various operations on the signals to extract target characteristics, so that the control of the action of field equipment is realized.

At present, the general machine vision lens cannot meet the requirements of large view field, large caliber, long focal length, high resolution and close object distance, and cannot meet the requirements of high-end products. And due to the increasing development of machine vision products, higher requirements are put forward on performances such as the detection range of a lens. The current vision lens structure can not further shorten the object distance and meet the requirement of image quality. Therefore, it becomes important to develop a wide-working-distance machine vision lens.

Disclosure of Invention

The embodiment of the invention provides a lens, which is used for providing a wide-working-distance machine vision lens.

The embodiment of the invention provides a lens, which comprises a first lens group, a second lens group and an image plane, wherein the first lens group, the second lens group and the image plane are sequentially arranged from an object side to an image side;

the first lens group is fixed in position, and the second lens group can move along the optical axis;

the lens group satisfies the following conditions:

1.4< | f-modulation/f system | < 1.7;

and f is the focal length of the second lens group, and the f system is the system focal length of the lens.

Further, the first lens group includes a first negative power lens and a first positive power lens arranged in order from the object side to the image side.

Further, the second lens group includes a first sub-lens group, a fourth negative power lens, a sixth positive power lens, a seventh positive power lens, an eighth positive power lens, and a ninth positive power lens, which are arranged in order from the object side to the image side.

Further, the first sub-lens group comprises a second positive power lens, a third positive power lens, a first sub-lens group and a second sub-lens group which are arranged in sequence from the object side to the image side;

the first sub-lens group comprises a fourth positive focal power lens and a second negative focal power lens;

the second sub-lens group includes a fifth positive power lens and a third negative power lens.

Further, the abbe numbers of the third positive power lens, the fifth positive power lens and the sixth positive power lens are all larger than 65.

Further, the first sub-lens group comprises a third sub-lens group, a twelfth positive power lens and a fourth sub-lens group which are arranged in sequence from the object side to the image side;

the third sub-lens group comprises a tenth positive focal power lens, a fifth negative focal power lens and an eleventh positive focal power lens;

the fourth sub-lens group includes a thirteenth positive power lens and a sixth negative power lens.

Further, the abbe numbers of the twelfth positive power lens and the thirteenth positive power lens are both greater than 65.

Further, the refractive index of the first positive power lens is greater than 1.9.

Further, a diaphragm is arranged between the first sub-lens group and the fourth negative power lens.

Further, an optical filter is arranged between the second lens group and the image plane.

The embodiment of the invention provides a lens, which comprises a first lens group, a second lens group and an image plane, wherein the first lens group, the second lens group and the image plane are sequentially arranged from an object side to an image side; the first lens group is fixed in position, and the second lens group can move along the optical axis; the lens group satisfies the following conditions: 1.4< | f-modulation/f system | < 1.7; and f is the focal length of the second lens group, and the f system is the system focal length of the lens. Since in the embodiment of the present invention, two lens groups are arranged in the lens in order from the object side to the image side in a specific order, the first lens group is fixed in position, the second lens group is movable along the optical axis to realize the lens variable working distance, i.e., variable magnification, and the lens groups in the lens satisfy: 1.4< | f-modulation/f system | <1.7, and meets the special requirements of near working distance and wide range of machine vision.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic view of a lens structure provided in embodiment 1 of the present invention;

fig. 2 is a graph of a transfer function (MTF) of a lens provided in embodiment 1 of the present invention when a working distance is infinity;

fig. 3 is a graph of a transfer function (MTF) of a lens according to embodiment 1 of the present invention at a magnification of-0.028;

fig. 4 is a graph of a transfer function (MTF) of a lens according to embodiment 1 of the present invention at a magnification of-0.150;

fig. 5 is a schematic view of a lens structure provided in embodiment 2 of the present invention;

fig. 6 is a graph of a transfer function (MTF) of a lens provided in embodiment 2 of the present invention when a working distance is infinity;

fig. 7 is a graph of transfer function (MTF) of a lens provided in embodiment 2 of the present invention at a magnification of-0.028;

fig. 8 is a graph of a transfer function (MTF) of a lens provided in embodiment 2 of the present invention at a magnification of-0.150.

Detailed Description

The present invention will be described in further detail with reference to the attached drawings, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.