阅读说明：本技术 一种大视场长焦距离轴三反式平行光管光学系统 (Large-view-field long-focus off-axis three-reflection type collimator optical system ) 是由 沈阳 王虎 薛要克 解永杰 刘阳 林上民 刘杰 刘美莹 于 2020-05-29 设计创作，主要内容包括：本发明涉及光学装调检测领域,具体涉及一种大视场长焦距离轴三反式平行光管光学系统。解决离轴反射式平行光管加工、装配困难,造价昂贵,且成像视场较小的问题。沿光束传播方向依次包括靶标板、折轴镜、三镜、次镜与主镜；光束经过靶标板入射至折轴镜,经折轴镜反射后以离轴的方式入射至三镜,依次经过三镜、次镜、主镜的反射后达到光阑,以平行光出射；主镜和三镜均为凹二次曲面镜,次镜为球面反射镜。本发明采用离轴三反式设计,实现了焦距1500mm、入瞳直径200mm、方视场1°×1°的系统参数,全视场出射波前RMS值优于λ/78@632.8nm。(The invention relates to the field of optical adjustment detection, in particular to a large-view-field long-focal-length off-axis three-reflection type collimator optical system. The problems that the off-axis reflective collimator is difficult to process and assemble, high in manufacturing cost and small in imaging field of view are solved. The device sequentially comprises a target plate, a folding axis mirror, a third mirror, a secondary mirror and a main mirror along the propagation direction of a light beam; the light beam is incident to the folding axis mirror through the target plate, is incident to the three mirrors in an off-axis mode after being reflected by the folding axis mirror, reaches the diaphragm after being reflected by the three mirrors, the secondary mirror and the primary mirror in sequence, and is emitted as parallel light; the primary mirror and the tertiary mirror are both concave secondary curved mirrors, and the secondary mirror is a spherical reflector. The invention adopts off-axis three-reflection design, realizes the system parameters of 1500mm focal length, 200mm entrance pupil diameter and 1 degree multiplied by 1 degree of square field of view, and the RMS value of the emergent wavefront of the whole field of view is superior to lambda/78 @632.8 nm.)

1. A big long focal length off-axis three-reflection type collimator optical system of visual field, its characterized in that: the device comprises a target plate (5), a folding axis mirror (4), a three-mirror (3), a secondary mirror (2) and a main mirror (1) in sequence along the light beam propagation direction; the device also comprises a diaphragm arranged in a reflection light path of the primary mirror (1); the three mirrors (3) and the secondary mirror (2) are coaxial with the primary mirror (1);

the light beam is incident to the folding axis mirror (4) through the target plate (5), is reflected by the folding axis mirror (4), is incident to the three mirrors (3) in an off-axis mode, sequentially passes through the three mirrors (3), the secondary mirror (2) and the primary mirror (1), is reflected to reach a diaphragm, and is emitted as parallel light;

the primary mirror (1) and the tertiary mirror (3) are both concave secondary curved mirrors, and the secondary mirror (2) is a spherical mirror;

the curvature radius R1 of the primary mirror (1) satisfies-2 f ' < R1< -f ', the curvature radius R2 of the secondary mirror (2) satisfies-f ' < R2< -0.5f ', and the curvature radius R3 of the tertiary mirror (3) satisfies-f ' < R3< -0.5f ', wherein f ' is the focal length of the optical system.

2. The large-field-of-view long-focus off-axis three-mirror collimator optical system according to claim 1, wherein: the distance L1 between the primary mirror (1) and the secondary mirror (2) meets the condition that L1 is not more than 0.5 f', and the concic coefficient C1 of the primary mirror (1) meets the condition that-1 < C1< -2;

the distance L2 between the secondary mirror (2) and the tertiary mirror (3) meets the condition that L2 is not more than 0.5 f';

the distance L3 between the three mirrors (3) and the folding axis mirror (4) meets the condition that L3 is not more than 0.5 f', and the consecutive coefficient C3 of the three mirrors (3) meets the condition that-0.5 < C3< 0.

3. The large-field-of-view long-focus off-axis three-mirror collimator optical system according to claim 2, wherein: the folding axial lens (4) is an optical flat plate made of fused quartz, and the thickness of the folded axial lens is less than or equal to 30 mm.

4. The large-field-of-view long-focus off-axis three-mirror collimator optical system according to claim 3, wherein: the distances between the primary mirror (1) and the secondary mirror (2), between the secondary mirror (2) and the third mirror (3) and between the third mirror (3) and the folding axis mirror (4) are equal.

Technical Field

The invention relates to the field of optical adjustment detection, in particular to a large-view-field long-focal-length off-axis three-reflection type collimator optical system.

Background

The collimator is an important tool for adjusting and adjusting optical instruments, and is often used for simulating parallel light beams emitted by infinite targets. The optical measurement instrument is also an important component in the optical measurement instrument, and focal plane assemblies such as a reticle, a star point plate, a discrimination plate and the like are placed on the focal plane of the collimator tube, so that various parameters and performances of an optical system to be measured can be detected and calibrated.

In many cases, the spectral range of the emergent light beam of the collimator must be ensured to be as wide as possible, including ultraviolet to infrared, so as to meet the test requirements of optical instruments with different working spectral bands.

The transmission type collimator is the most common collimator, is relatively mature in design and processing, and is suitable for mass production; however, due to the adoption of the transmission glass element, the problem of chromatic aberration is inevitable, and particularly in the application of large field of view, long focal length and wide spectrum band, the secondary spectrum of the system is difficult to correct.

The reflective collimator covers a wide range, but has a small field of view available. In addition, the common reflection type collimator adopts a coaxial optical system, a central barrier exists, and meanwhile, the reflection surfaces of the reflection type collimator are aspheric surfaces, so that the reflection type collimator is difficult to process and assemble and has high cost; although the off-axis reflective collimator does not have a central block, the reflecting surfaces are off-axis aspheric surfaces, so that the off-axis reflective collimator is more difficult to process and assemble, very expensive in manufacturing cost, smaller in imaging field of view and not beneficial to testing.

Disclosure of Invention

The invention aims to provide an off-axis three-reflection type collimator optical system with a large view field and a long focal length, which solves the problems that an off-axis reflection type collimator is difficult to process and assemble, high in manufacturing cost and small in imaging view field. The collimator optical system has the characteristics of large imaging view field, long focal length, wide working spectrum, high imaging quality and the like.

The technical scheme of the invention is to provide a large-view-field long-focal-length off-axis three-reflection type collimator optical system which is characterized in that: the device sequentially comprises a target plate, a folding axis mirror, a third mirror, a secondary mirror and a main mirror along the propagation direction of a light beam; the diaphragm is arranged in a reflection light path of the main mirror; the three mirrors, the secondary mirror and the primary mirror are coaxial;

the light beam is incident to the folding axis mirror through the target plate, is incident to the three mirrors in an off-axis mode after being reflected by the folding axis mirror, reaches the diaphragm after being reflected by the three mirrors, the secondary mirror and the primary mirror in sequence, and is emitted as parallel light;

the primary mirror and the tertiary mirror are both concave secondary curved mirrors, and the secondary mirror is a spherical reflector;

the curvature radius R1 of the primary mirror satisfies-2 f ' < R1< -f ', the curvature radius R2 of the secondary mirror satisfies-f ' < R2< -0.5f ', and the curvature radius R3 of the tertiary mirror satisfies-f ' < R3< -0.5f ', wherein f ' is the focal length of the optical system.

Further, the distance L1 between the primary mirror and the secondary mirror meets L1 ≤ 0.5 f', and the conic coefficient C1 of the primary mirror is-1 < C1< -2;

the distance L2 between the secondary mirror and the tertiary mirror meets the condition that L2 is not more than 0.5 f';

the distance L3 between the three mirrors and the folding axis mirror meets the condition that L3 is less than or equal to 0.5 f', and the consecutive coefficient C3 of the three mirrors meets the condition that-0.5 < C3< 0.

Furthermore, the folding axial lens is an optical flat plate made of fused quartz, and the thickness of the folding axial lens is less than or equal to 30 mm.

Furthermore, the distances between the primary mirror and the secondary mirror, between the secondary mirror and the third mirror, and between the third mirror and the folding axis mirror are equal.

The invention has the beneficial effects that:

1. the invention adopts off-axis three-reflection design, realizes the system parameters of 1500mm focal length, 200mm entrance pupil diameter and 1 degree multiplied by 1 degree of square field of view, and the RMS value of the emergent wavefront of the whole field of view is superior to lambda/78 @632.8 nm;

2. the secondary mirror surface is a spherical surface, so that the detection problem of a convex aspheric surface is avoided, and the system is very favorable for adjustment; the three primary mirrors adopt concave quadric surfaces, so that the detection is convenient;

3. the invention adopts a mode of deflecting the aperture in a field of view to realize the non-blocking design among the reflectors, the three reflectors are in a coaxial relationship, and the axial optical intervals among the three reflectors are consistent, thereby being very beneficial to assembly and adjustment.

Drawings

FIG. 1 is a schematic diagram showing an overall configuration of an optical system according to an embodiment;

FIG. 2 is a schematic diagram of an optical path structure of an optical system according to an embodiment;

FIG. 3 is an MTF curve for an optical system of an embodiment;

FIG. 4 is a speckle pattern of an optical system of an embodiment;

FIG. 5 shows the wavefront RMS value of an example optical system.

The reference numbers in the figures are: 1-primary mirror, 2-secondary mirror, 3-tertiary mirror, 4-folding axis mirror, 5-target board.

Detailed Description

The invention is further described with reference to the following figures and specific embodiments.

As shown in fig. 1, which is a schematic diagram of the general structure of the optical system of this embodiment, a primary mirror 1, a secondary mirror 2, a tertiary mirror 3, a folding axis mirror 4 and a target plate 5 are disposed on an optical path. The system diaphragm is located in front of the main mirror 1, and no intermediate image plane exists in the system. The light rays sequentially pass through the target plate 5, the folding axis mirror 4, the three mirrors 3, the secondary mirror 2 and the primary mirror 1 in the propagation direction and then exit as parallel light through the diaphragm. The primary mirror 1, the secondary mirror 2 and the three mirrors 3 are coaxially arranged, light beams sequentially enter the three mirrors 3 in an off-axis mode, the secondary mirror 2 and the primary mirror 1 are arranged, and the non-blocking design among the reflectors is achieved in a mode of a field-of-view deflection aperture. In the optical system, a primary mirror 1 and a tertiary mirror 3 are both secondary curved mirrors, the secondary mirror is a spherical reflector, and a folding axis mirror is an optical flat plate.

Defining the focal length of the optical system to be f ', the curvature radius R1 of the primary mirror satisfies-2 f' < R1< -f ', the distance L1 between the primary mirror and the secondary mirror satisfies L1 ≤ 0.5 f', and the conc coefficient C1 of the primary mirror satisfies-1 < C1< -2; the curvature radius R2 of the secondary mirror meets-f ' < R2< -0.5f ', and the distance L2 between the secondary mirror and the tertiary mirror meets L2 which is not more than 0.5f '; the curvature radius R3 of the three mirrors meets-f ' < R3< -0.5f ', the distance L3 between the three mirrors and the folding axis mirror meets L3 which is not more than 0.5f ', and the concic coefficient C3 of the three mirrors meets-0.5 < C3< 0; the folding axial lens is made of fused quartz, and the thickness of the folding axial lens is less than or equal to 30 mm.

The system focal length of the optical system provided by the embodiment is 1500mm, the imaging field of view is 2 degrees multiplied by 2 degrees of a circular field of view, the working waveband is 400-900nm, the diameter of the entrance pupil of the system is 200mm, and no vignetting exists in the full field of view. As shown in FIG. 3, FIG. 4 and FIG. 5, the MTFs are close to the diffraction limit in the whole field of view in the 400-900nm band range, and the RMS error values of the wavefront in the whole field of view are better than λ/[email protected] nm.