CN211236531U

CN211236531U - Lens capable of eliminating self stray light

Info

Publication number: CN211236531U
Application number: CN202020036942.6U
Authority: CN
Inventors: 杜勇刚; 谭晓军; 魏荣财; 周峰
Original assignee: Dongguan Pomeas Precision Instrument Co ltd
Current assignee: Dongguan Pomeas Precision Instrument Co ltd
Priority date: 2020-01-08
Filing date: 2020-01-08
Publication date: 2020-08-11
Anticipated expiration: 2030-01-08

Abstract

The utility model relates to a can eliminate self stray light's camera lens, include preceding lens group, beam splitter, back lens group according to the preface by object plane to image planes, and above three optical axis coincidence, the side has the light source, the light path of the light that the light source sent is through beam splitter, preceding lens group outgoing to the object plane, produces the reverberation at the object plane reflection, and the reverberation light path is through preceding lens group, beam splitter, back lens group to image planes formation of image in proper order, and the light path between light source and beam splitter is equipped with the polarizer, and beam splitter is equipped with the polarisation subassembly to the light path between the image planes, and the light path between preceding lens group and the object plane is equipped with the optical rotation ware, and optical rotation angle is not the integral multiple of 90 degrees, the polarization direction of polarizer and the polarization direction quadrature of polarisation subassembly. Because the reflected light on the surface of the lens of the front lens group and the polarized light passing through the polarizer have the same polarization direction and can be cut off by the polarization component orthogonal to the polarization direction of the polarizer, the stray light generated by the reflection of the lens cone and the front lens group is eliminated.

Description

Lens capable of eliminating self stray light

Technical Field

The utility model relates to an imaging field, concretely relates to can eliminate self stray light's camera lens.

Background

Referring to fig. 1, in the conventional lens, when light emitted by an internal light source passes through a front lens group 3, due to a certain reflectivity on the surface of a lens, part of light is reflected, so that stray light is formed on an image surface 6, and normal imaging observation is affected.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the problem that there is stronger stray light problem in current camera lens.

The lens capable of eliminating the stray light of the lens comprises a front lens group, a light splitter and a rear lens group in sequence from an object plane to an image plane, optical axes of the front lens group, the light splitter and the rear lens group are overlapped, a light source is arranged on the side face, a light path of light emitted by the light source sequentially passes through the light splitter and the front lens group and then is emitted to the object plane, reflected light is generated by reflection of the object plane, and the reflected light sequentially passes through the front lens group, the light splitter and the rear lens group and then is imaged on the image plane.

Still include polarizer, polarisation subassembly, optical rotator, the light path between light source and the optical splitter is arranged in to the polarizer, the light path between optical splitter to the image plane is arranged in to the polarisation subassembly, the optical rotator is arranged in the light path between preceding lens group and the object plane, optical rotator optical rotation angle is not the integral multiple of 90 degrees, the polarization direction of polarizer and polarisation subassembly's polarization direction quadrature.

Preferably, the angle of rotation of the optical rotator is 45 degrees.

Specifically, the light path between the rear lens group and the image plane is placed in the polarization component, the optical rotator is an 1/4 wave plate, the polarization component is a polarizer, the lens is a telecentric lens, the light source is a coaxial light source, the optical splitter is two triangular prisms with isosceles right triangle sections, the two triangular prisms are combined into a square prism, and the surfaces of the two triangular prisms, which are attached to each other, are provided with a semi-reflecting and semi-permeable coating film.

Has the advantages that:

because the reflected light on the surface of the lens of the front lens group, part of the reflected light of structural members such as the lens cone and the like and the polarized light passing through the polarizer have the same polarization direction, the reflected light and the polarized light are cut off by the polarization component orthogonal to the polarization direction of the polarizer, and the stray light generated by the reflection of the lens cone and the front lens group is eliminated.

The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:

fig. 1 is a schematic diagram of a basic structural form of a lens in the prior art.

Fig. 2 is a schematic diagram of a basic structural form of the lens of the present embodiment.

Detailed Description

The present embodiment is a telecentric lens with a built-in coaxial light source 1, which can eliminate stray light generated by reflection from the front lens group 3.

Referring to fig. 2, the lens of the present embodiment sequentially includes an optical rotator 7, a front lens group 3, a beam splitter 9, a rear lens group 4, and a polarization assembly 5 from an object plane 8 to an image plane 6, which are coaxial, and further includes a lateral coaxial light source 1 and a polarizer 2, wherein light emitted from the coaxial light source 1 is incident on the beam splitter 9 through the polarizer 2.

The light emitted by the coaxial light source 1 is emitted after passing through the polarizer 2, and then sequentially passes through the beam splitter 9, the front lens group 3 and the optical rotator 7 with the rotation angle of 45 degrees, and because the reflected light on the lens surface of the front lens group 3 and the partial reflected light of the structural members such as the lens barrel and the like and the polarized light passing through the polarizer 2 are in the same polarization direction and can be cut off by the polarization component 5 orthogonal to the polarization direction of the polarizer 2, the stray light generated by the reflection of the lens barrel and the front lens group 3 is eliminated by adding the polarization component 5 orthogonal to the polarization direction of the polarizer 2 between the beam splitter 9 and the image plane 6 in the embodiment;

preferably, add polarisation subassembly 5 in this embodiment between back lens group 4 and image plane 6, put diaphragm (not shown in the figure) and form object space telecentric optics on the image space focal plane of preceding lens group 3 for the object space chief ray is on a parallel with the optical axis chief ray, even like this object distance changes, but the image height in the depth of field scope does not change, and the object size of surveying promptly can not change, can eliminate the object space because the inaccurate bringing of focusing, reading error. The diaphragm is placed on an object space focal plane of the rear lens group 4 to form an image space telecentric light path, and the image space chief ray is parallel to the optical axis, so that the imaging size in the focal depth range is unrelated to the image distance, and the rear lens group 4 and the front lens group 3 form a bilateral telecentric lens together with the diaphragm.

During operation, the optical rotator 7 can rotate the polarization angle of light passing through the optical rotator 7 by a certain angle, so that the included angle formed by the polarization direction of light emitted from the optical rotator 7 with the rotation angle of 45 degrees and the polarization direction of the polarizer 2 is 45 degrees, the light is reflected by the object plane 8 and then is optically rotated by the optical rotator 7 again, at this time, the polarization direction of light reflected by the object plane 8 is orthogonal to the polarization direction of the polarizer 2 and cannot be cut off by the polarization assembly 5, and therefore, the light reflected by the object plane 8 can sequentially pass through the optical rotator 7, the front lens group 3, the rear lens group 4 and the polarization assembly 5 and then is imaged on the image plane 6.

It should be noted that the optical rotation angle of the optical rotator 7 can be imaged on the image plane 6 as long as it is not a multiple of 90 degrees, but the transmittance of light transmitted through the polarization module 5 is different, wherein the optical rotation angle of 45 degrees is the most effective, and theoretically there is no loss of light energy at the polarization module 5.

In this embodiment, the beam splitter 9 is specifically two triangular prisms whose cross sections are isosceles right triangles, the two triangular prisms are combined into a square prism, and the surfaces of the two triangular prisms, which are attached to each other, are provided with a semi-reflective semi-permeable coating film.

In this embodiment, the ratio of the intensity of the transmitted light to the intensity of the reflected light of the transflective film is specifically 1: 1.

It should be noted that the beam splitter 9 is not limited to the embodiment of the beam splitter prism, and other similar beam splitting structures, such as a beam splitter, a beam splitting module, and the like, may be used as long as the optical path can be realized. The semi-transparent semi-reflecting film is not limited to the light intensity ratio of 1:1, and the 1:1 is only the optimal ratio obtained by calculation.

In this embodiment, the optical rotator 7 with a rotation angle of 45 degrees is specifically an 1/4 wave plate.

In this embodiment, the polarizer assembly 5 is specifically a polarizer.

It should be finally noted that the above embodiments are only intended to illustrate the technical solution of the present invention and not to limit the scope of the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced with other equivalents without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. The utility model provides a can eliminate camera lens of self stray light, includes preceding lens group (3), beam splitter (9), back lens group (4) of arranging according to the preface by object plane (8) to image plane (6), and the coincidence of above three optical axis, and the side of beam splitter (9) has light source (1), the light path of the light that light source (1) sent is through beam splitter (9), preceding lens group (3) outgoing to object plane (8) in proper order, its characterized in that:

still include polarizer (2), polarisation subassembly (5), optical rotator (7), light path between light source (1) and optical splitter (9) is arranged in polarizer (2), optical splitter (9) to the light path between image plane (6) are arranged in polarisation subassembly (5), optical rotator (7) are arranged in the light path between preceding lens group (3) and object plane (8), the optical rotation angle of optical rotator (7) is not the integral multiple of 90 degrees, the polarization direction of polarizer (2) and the polarization direction quadrature of polarisation subassembly (5).

2. A lens barrel according to claim 1, wherein: after light emitted by the light source (1) is emitted to the object plane (8), the light is reflected on the object plane (8) to generate reflected light, and the light path of the reflected light sequentially passes through the optical rotator (7), the front lens group (3), the rear lens group (4) and the polarization assembly (5) and then is imaged on the image plane (6).

3. A lens barrel according to claim 1, wherein: the optical rotation angle of the optical rotator (7) is 45 degrees.

4. A lens barrel according to claim 3, wherein: the optical rotator (7) is an 1/4 wave plate.

5. A lens barrel according to claim 1, wherein: the lens is a telecentric lens, and the light source (1) is a coaxial light source.

6. A lens barrel according to claim 1, wherein: the polarizing component (5) is a polarizer.

7. A lens barrel according to claim 1, wherein: the beam splitter (9) is composed of two triangular prisms with isosceles right triangle sections, and the two triangular prisms are combined and glued to form a square prism.

8. A lens barrel according to claim 7, wherein: and the surfaces of the two triangular prisms of the light splitter (9) which are jointed are provided with semi-reflecting and semi-permeable coating films.

9. A lens barrel according to claim 8, wherein: the light intensity ratio of the transmitted light to the reflected light of the light splitter (9) is 1: 1.

10. A lens barrel according to any one of claims 1 to 9, wherein: the polarizing component (5) is arranged on a light path between the rear lens group (4) and the image plane (6).