CN114815200B - Large-relative-aperture off-axis five-inverse non-axial zoom imaging optical system - Google Patents

Abstract

The invention discloses a large relative aperture off-axis five mirror non-axial zoom imaging optical system, which belongs to the field of optical zoom imaging. The present invention adopts the structure of secondary imaging, and the non-axial synchronous zoom primary imaging subsystem is based on the off-axis three-reflection full-motion zoom, adding zoom adjustment in the vertical axis direction to increase the degree of freedom in the optimization of the zoom imaging optical system; The axial movement vector realizes the synchronous adjustment of the axial movement and the vertical axis movement, and realizes the non-axial synchronous zooming of the zoom imaging optical system. The rear relay imaging subsystem realizes the inversion, transmission and zoom imaging of an intermediate image plane through two fixed mirrors. Re-imaging at the primary image plane is performed through the relay imaging subsystem, and the field diaphragm is set at the position of the primary image plane, which significantly reduces the stray light caused by the difficulty of setting the light blocking device due to the movement of the mirror, thereby effectively eliminating the arrival of the detector Stray light on the image plane. The invention does not need to use a free-form surface reflector, thereby reducing processing and testing costs.

Description

A large relative aperture off-axis five mirror non-axial zoom imaging optical system

technical field

The invention belongs to the field of optical zoom imaging, in particular to an off-axis reflective zoom imaging optical system with large relative aperture and large zoom ratio.

Background technique

In the field of airborne earth observation, the design of wide-spectrum, large zoom ratio, and high-resolution zoom optical system is of great significance. The off-axis total reflection zoom optical system has the characteristics of no chromatic aberration, wide imaging spectrum, large field of view search and small field of view aiming, and unobstructed imaging. It meets the application requirements of a new generation of high-performance, light and small airborne earth observation payloads.

The off-axis total reflection zoom optical system is divided into active zoom type and mechanical zoom type according to the principle. The off-axis total reflection active zoom imaging system realizes the change of the optical power of the system by controlling the curvature of the active optical elements (deformable mirror, spatial light modulator, liquid lens, etc.). The off-axis total reflection active zoom imaging system has fast response speed and relatively small volume, but there are still limitations of high difficulty in adjusting the active optical components, high difficulty in off-axis surface fitting, slow data transmission speed, and high cost. The off-axis total reflection mechanical zoom imaging system realizes the change of the overall focal power by controlling the axial movement of the internal mirror of the system. Compared with the off-axis total reflection active zoom imaging system, the response speed is slower and the volume is larger. But the mechanical control is relatively simple and the cost is low. The traditional off-axis total reflection mechanical zoom imaging system generally adopts the structure of three mirrors and four mirrors, which can realize large zoom ratio zoom imaging, but the system has a fixed entrance pupil diameter, and the relative aperture is small, especially in the long In the in-focus state, the relative aperture of the system is extremely small, which is difficult to meet the requirements of high-resolution imaging. In addition, in order to achieve high-resolution imaging in a large zoom ratio range, the free-form surface mirror is used to correct the high-order asymmetric aberration of the system, but the processing and detection difficulties of the free-form mirror greatly increase the The difficulty and cost of developing such systems.

Contents of the invention

In order to overcome the disadvantages of small relative aperture and complex surface shape of the traditional off-axis total reflection mechanical zoom imaging system, the main purpose of the present invention is to provide a large relative aperture off-axis five-mirror non-axial zoom imaging optical system. The secondary imaging structure is adopted, that is, the five mirrors are divided into a non-axial synchronous zoom primary imaging subsystem and a rear relay imaging subsystem according to the imaging structure and function. On the basis of the off-axis three-reflection full-motion zoom, the non-axial synchronous zoom primary imaging subsystem adds zoom adjustment in the vertical axis direction to increase the degree of freedom in the optimization of the zoom imaging optical system; in addition, the non-axial movement vector realizes axial The synchronous adjustment of movement and vertical axis movement realizes non-axial synchronous zooming of the zoom imaging optical system, thereby ensuring good imaging quality under different focal length states. The rear relay imaging subsystem realizes the inversion, transmission and zoom imaging of an intermediate image plane through two fixed mirrors. By re-imaging the primary image plane of the non-axial synchronous zoom primary imaging subsystem through the relay imaging subsystem, the field diaphragm can be set at the position of the primary image plane, which significantly reduces the difficulty of setting the light blocking device due to the movement of the mirror. The stray light from the sensor can effectively eliminate the stray light reaching the image surface of the detector. The invention also has the following advantages: it does not need to use a free-form surface mirror, which reduces the cost of processing and testing.

The purpose of the present invention is achieved through the following technical solutions:

The present invention discloses a large relative aperture off-axis five-mirror non-axial zoom imaging optical system, including a variable diaphragm, a primary reflector, a secondary reflector, a third reflector, a fourth reflector, and a fifth reflector, The image plane of the detector also includes a translation stage for moving the primary reflector, the secondary reflector, and the third reflector.

The iris diaphragm is an aperture diaphragm, and the aperture of the aperture diaphragm changes as the focal length changes. By adjusting the aperture of the aperture diaphragm, the relative aperture of the zoom imaging optical system is guaranteed to be fixed.

The main reflector, the secondary reflector and the third reflector are components of the variable power group and the compensation group, and the zoom imaging is realized by moving the three reflectors non-axially. Wherein, the non-axial movement is realized based on a non-axial movement vector, and the non-axial movement vector is a non-axial movement vector composed of an axial movement amount and a vertical axis movement amount. The focal length of the non-axial zoom imaging optical system can be changed by axial movement; the degree of freedom of the zoom imaging optical system can be increased by moving in the direction of the vertical axis, and the eccentricity of the three mirrors, the primary mirror, the secondary mirror, and the third mirror The role of the aberration field actively balances the wave aberration between the multiple structures of the zoom imaging optical system, and realizes the correction of high-order astigmatism and coma in the non-axial zoom imaging optical system under different focal length structures. The synchronous adjustment of the axial movement and the vertical axis movement is realized through the non-axial movement vector, and the non-axial synchronous zoom of the zoom imaging optical system is realized, thereby ensuring good imaging quality under different focal length states, without using free-form surfaces.

As a preference, the active balance of the wave aberration between the multiple structures of the zoom imaging optical system by using the effect of the eccentricity of the three mirrors on the aberration field is implemented as follows:

Step 1, determine the axial movement amounts of the three mirrors according to the axial movement formula (1).

Among them, r is the radius of curvature of the mirror, t is the distance between the mirrors, α _ji is the obscuration ratio, β _ji is the magnification, and f _j is the focal length under different structures.

Step 2: Determine the primary wave aberration coefficient of the zoom imaging optical system according to formula (2), and the primary wave aberration coefficient is a function of α _ji , β _ji , f _j .

in:

Wherein: said _ki is the quadric surface coefficient of mirror i, and

n _i =1 (i is an odd number), n _i =-1 (i is an even number), n _i '=-1 (i is an odd number), n _i '=1 (i is an even number) (5)

u _j1 ＝0, u _j1 '＝2h _j1 /r ₁ , u _j2 ＝u _j1 ', u _j2 '＝u _j2 /β _j1 , u _j3 ＝u _j2 ', u _j3 '＝u _j3 /β _j2 (6 )

Step 3, based on the primary wave aberration coefficient of the zoom imaging optical system determined in step 2, determine the eccentricity σ _ji of the mirror under different structures through formula (7), and actively balance the zoom imaging optical system according to the eccentricity σ _ji The wave aberration between multiple structures realizes the correction of high-order astigmatism and coma in the non-axial zoom imaging optical system under different focal length structures. The differences Δσ _j1 , Δσ _j2 , and Δσ _j3 of the eccentricity σ _ji are the vertical axis movement amounts of the three mirrors.

Wherein: the vertical axis movement amount is represented by the difference in eccentricity σ _ji of the reflectors in different structures, where j represents the jth structure, and i represents the ith reflector. As shown in formula (7), the coma center and astigmatism center of the off-axis zoom imaging system are always about α _ji , β _ji , f _j , The function of the vertical axis is added to the axial movement to increase the degree of freedom of the system, and the wave image between the multiple structures of the zoom system is actively balanced by using the effect of the off-axis system offset on the aberration field Difference.

The fourth reflector and the fifth reflector constitute a relay imaging subsystem with a magnification of b, and their spatial positions are unchanged, so their curvature radius and thickness parameters can be calculated independently. It is defined that the magnification rate of the fourth reflector is β ₄ , the magnification rate of the fifth reflector is β ₅ , and β ₄ β ₅ =b is satisfied.

The relay imaging subsystem composed of the fourth mirror and the fifth mirror performs re-imaging on the primary image plane of the non-axial synchronous zoom primary imaging subsystem. In order to ensure that the imaging is clear and free of stray light, as a preference, the The field diaphragm is set at the position of the image plane, which can significantly reduce the stray light caused by the movement of the mirror and it is difficult to install the light blocking device, so as to effectively eliminate the stray light that can reach the image plane of the detector.

Preferably, the primary reflector, the third reflector, the fourth reflector and the fifth reflector are concave reflectors, the secondary reflector is a convex reflector, and the surface types of the five reflectors are all 8-order aspheric surfaces. The reflective surfaces of the primary reflector and the secondary reflector are arranged oppositely, the reflective surfaces of the secondary reflector and the third reflector are arranged oppositely, the reflective surfaces of the third reflector and the fourth reflector are arranged oppositely, and the reflective surfaces of the fourth reflector and the fifth reflector are arranged oppositely. The reflective surfaces of the mirrors are arranged oppositely, and the fifth reflective mirror is arranged oppositely to the image surface of the detector. The iris diaphragm and the mirror surface center of the main reflector are placed eccentrically along the Y-axis direction with the same eccentricity. The secondary reflector, the third reflector, the fourth reflector and the fifth reflector are all eccentrically and obliquely placed relative to the optical axis. The amount of eccentricity is not the same as the amount of inclination.

The working method of a large relative aperture off-axis five-mirror non-axial zoom imaging optical system disclosed by the present invention is as follows:

The light passing through the iris is incident on the reflective surface of the primary reflector, and is reflected by the reflective surface of the primary reflector to form first reflected light, and the first reflected light is incident on the reflective surface of the secondary reflector The second reflected light is formed after being reflected by the reflective surface of the secondary reflector, and the second reflected light is incident on the reflective surface of the third reflector, and is reflected by the reflective surface of the third reflector to form the third reflective light. Reflected light, the third reflected light is incident on the reflective surface of the fourth reflective mirror, and the fourth reflected light is formed after being reflected by the reflective surface of the fourth reflective mirror, and the fourth reflected light is incident on the fifth reflective light On the reflective surface of the mirror, the fifth reflected light is formed after being reflected by the reflective surface of the fifth reflective mirror, and the fifth reflected light is received by the image surface of the detector and formed into an image. When the primary reflector, secondary reflector and third reflector are located at specified positions, the system can clearly image a large field of view. When the primary reflector, secondary reflector and third reflector move to the corresponding positions non-axially, The system switches to the telephoto state with amplified resolution to perform clear imaging of objects within the field of view with higher object-side spatial resolution.

The synchronous adjustment of the axial movement and the vertical axis movement is realized through the non-axial movement vector, and the non-axial synchronous zoom of the zoom imaging optical system is realized. The post-relay imaging subsystem is used to re-image the primary intermediate image, and the field diaphragm is added to the stable primary intermediate image plane to effectively eliminate the stray light entering the post-relay imaging subsystem and the detector image plane. Through the above settings, it is guaranteed that the imaging quality is good under different focal lengths, and there is no need to use free-form surfaces, which reduces the cost of processing and testing.

Beneficial effect:

1. A large relative aperture off-axis five mirror non-axial zoom imaging optical system disclosed in the present invention, the fourth reflector and the fifth reflector are fixed reflectors, the main reflector, the secondary reflector and the third reflector are The movable reflector, and the primary reflector, the secondary reflector, and the third reflector form a full-motion non-axial synchronous zoom primary imaging subsystem, and the fourth reflector and fifth reflector form a rear relay imaging subsystem. Zooming is realized by changing the optical power of the mirror group by non-axially moving the primary reflector, the secondary reflector and the third reflector. The rear relay imaging subsystem realizes the inversion, transmission and zoom imaging of an intermediate image plane through two fixed mirrors. By adding a field diaphragm at the position of the primary intermediate image plane, the stray light entering the rear relay imaging subsystem can be effectively eliminated. The synchronous adjustment of the axial movement and the vertical axis movement is realized through the non-axial movement vector, and the non-axial synchronous zoom of the zoom imaging optical system is realized, thereby ensuring good imaging quality under different focal length states, without using free-form surfaces.

2. The present invention discloses a large relative aperture off-axis five-mirror non-axial zoom imaging optical system. The non-axial movement vector is the non-axial movement vector composed of the axial movement amount and the vertical axis movement amount. The focal length of the non-axial zoom imaging optical system can be changed by axial movement; the degree of freedom of the zoom imaging optical system can be increased by moving in the vertical axis direction, and the effect of the eccentricity of the three mirrors on the aberration field can be used to actively balance the multiplicity of the zoom imaging optical system The wave aberration between the structures realizes the correction of high-order astigmatism and coma in the non-axial zoom imaging optical system under different focal length structures.

3. The present invention discloses a large relative aperture off-axis five-mirror non-axial zoom imaging optical system. According to Seidel's aberration theory and vector aberration theory, a correction method for high-order astigmatism and coma of the zoom imaging optical system is established. , using the effect of the eccentricity of the three mirrors on the aberration field to actively balance the wave aberration between the multiple structures of the zoom imaging optical system, and realize the correction of high-order astigmatism and coma in the non-axial zoom imaging optical system under different focal length structures .

4. The present invention discloses a large relative aperture off-axis five-mirror non-axial zoom imaging optical system. By setting the field diaphragm at the stable primary image plane, it can greatly reduce the cost of the non-axial synchronous zoom primary imaging subsystem. The stray light that cannot be eliminated due to the movement of the mirror effectively eliminates the stray light that can reach the image surface of the detector.

5. The large relative aperture off-axis five-mirror non-axial zoom imaging optical system disclosed in the present invention only needs to use high-order aspheric mirrors and does not need to use free-form mirrors, which reduces processing and testing costs.

Description of drawings

Fig. 1 is a schematic diagram of the structure of the device of the present invention.

Figure 2 is a schematic diagram of the space coordinate system.

Fig. 3 is a short-focus state optical path diagram of the device of the present invention.

Fig. 4 is an optical path diagram of the telephoto state of the device of the present invention.

Among them, 01-variable diaphragm, 02-primary reflector, 03-secondary reflector, 04-third reflector, 05-fourth reflector, 06-fifth reflector, 07-detector image plane.

Detailed ways

In order to better illustrate the purpose and advantages of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and examples.

As shown in Figure 1, the main purpose of the present invention is to provide a large relative aperture off-axis five mirror non-axial zoom imaging optical system, including a variable diaphragm 01, a primary mirror 02, a secondary mirror 03, and a third mirror 04, the fourth reflector 05, the fifth reflector 06, and the detector image plane 07.

The system is located in a space coordinate system (XYZ), and the directions of the coordinate axes are shown in FIG. 2 .

The iris diaphragm 01 is the aperture diaphragm of the system, and its aperture changes with the focal length, ensuring that the relative aperture of the system is always 1:4.

The main reflector 02 is a concave reflector with an 8-order aspherical surface, which is used to focus and reflect the light from the target to form the first reflected light.

The secondary reflector 03 is a convex reflector with an 8-order aspheric surface, and is used to reflect the light from the primary reflector 02 again to form the second reflected light.

The third reflector 04 is a concave reflector with an 8-order aspheric surface, which is used to focus the light from the secondary reflector 03 on the primary image plane to form the third reflected light.

The fourth reflector 05 is a concave reflector with an 8th-order aspherical surface and a constant spatial position, and is used to reflect the light from the third reflector 04 to form four reflected lights.

The fifth reflector 06 is a concave reflector with an 8-order aspherical surface and a constant spatial position, and is used to focus and image the light from the fourth reflector 05 on the target surface of the detector 07 .

The primary reflector 02, the secondary reflector 03, and the third reflector 04 are moved to designated positions by a translation stage.

The main reflector 02, the secondary reflector 03, and the third reflector 04 form a full-motion non-axial synchronous zoom primary imaging subsystem, and the fourth reflector 05 and the fifth reflector 06 form a magnification ratio of 1 Relay imaging subsystem.

The relay imaging subsystem re-images the primary image plane of the non-axial synchronous zoom primary imaging subsystem. As a preference, the field diaphragm can be set at the position of the primary image plane, which greatly reduces the difficulty in setting due to the movement of the mirror. The stray light brought by the light blocking device can effectively eliminate the stray light that can reach the image surface of the detector.

The main reflector 02, the secondary reflector 03 and the third reflector 04 are components of the variable power group and the compensation group, and the change of the focal length of the system is realized by moving the three mirrors non-axially, and the zoom ratio is 5 times.

The position of the primary intermediate image plane of the non-axial synchronous zoom primary imaging subsystem remains unchanged, thereby ensuring that the position of the detector image plane 07 remains unchanged.

Wherein, the non-axial movement is realized based on a non-axial movement vector, and the non-axial movement vector is a non-axial movement vector composed of an axial movement amount and a vertical axis movement amount. The focal length of the non-axial zoom imaging optical system can be changed by axial movement; the degree of freedom of the zoom imaging optical system can be increased by moving in the vertical axis direction, and the effect of the eccentricity of the three mirrors on the aberration field can be used to actively balance the multiplicity of the zoom imaging optical system The wave aberration between the structures realizes the correction of high-order astigmatism and coma in the non-axial zoom imaging optical system under different focal length structures. The synchronous adjustment of the axial movement and the vertical axis movement is realized through the non-axial movement vector, and the non-axial synchronous zoom of the zoom imaging optical system is realized, thereby ensuring good imaging quality under different focal length states, without using free-form surfaces.

The non-axial movement of the main reflector 02, the secondary reflector 03 and the third reflector 04 is the movement in one-dimensional direction in the YZ plane, which can be decomposed into the axial (Z direction) movement component and the vertical axis (Y direction). ) moving component, which can be specifically expressed as the different distances from the primary reflector 02, the secondary reflector 03 and the third reflector 04 to the previous surface under different focal length states and the difference between the primary reflector 02, the secondary reflector 03 and the third reflector 04 has a different Y-axis eccentricity. Among them, the change of the focal length of the system is realized by moving in the axial direction (Z direction), the correction of high-order astigmatism and coma aberration under different focal length structures of the system is realized by moving in the vertical axis (Y direction), and the axial The synchronous adjustment of the axial movement and the vertical axis movement realizes the non-axial synchronous zoom of the zoom imaging optical system, thereby ensuring good imaging quality under different focal lengths, without using free-form surfaces.

The general expression for an 8th-order aspheric surface is:

In the formula, z is the vector height of the surface, c is the curvature of the surface, k is the coefficient of the quadratic surface, and α _i is the coefficient of the ith term in the polynomial.

According to the method disclosed in this embodiment to actively balance the wave aberration between the multiple structures of the zoom imaging optical system by using the effect of the eccentricity of the three mirrors on the aberration field, and the surface parameters and non-axis parameters of the mirror determined by subsequent optimization The amount of movement is as follows:

In this embodiment, the radius r of the reflecting surface of the main reflector 02, the secondary reflector 03, the third reflector 04, the fourth reflector 05, and the fifth reflector 06 is the reciprocal of the curvature c, and the quadric surface coefficient k , and the values of various coefficients α _i are shown in Table 1 respectively. It can be understood that the values of the radius r, quadric surface coefficient k, and various coefficients α _i are not limited to those described in Table 1, and those skilled in the art can adjust them according to actual needs.

Table 1 Surface parameters of primary reflector 02, secondary reflector 03, third reflector 04, fourth reflector 05 and fifth reflector 06

The spatial positions of the primary reflector 02 , the secondary reflector 03 , and the third reflector 04 in short-focus and long-focus states are shown in Table 2. It can be understood that the distance between lenses and the values of lens eccentricity are not limited to those described in Table 2, and those skilled in the art can adjust according to actual needs.

Table 2 Spatial position parameters of primary reflector 02, secondary reflector 03, and third reflector 04

The primary reflector 02 , secondary reflector 03 , third reflector 04 , fourth reflector 05 , and fifth reflector 06 can use aluminum alloy, beryllium aluminum alloy, silicon carbide and other materials as processing substrates. In order to improve the reflectivity of the main reflector 02, the secondary reflector 03, the third reflector 04, the fourth reflector 05, and the fifth reflector 06, silver film or gold film can be coated on their respective reflective surfaces to increase reflection. membrane.

The working optical path of the large relative aperture off-axis five-mirror non-axial zoom imaging optical system is as follows: the light passing through the iris 01 is incident on the reflection surface of the main reflector 02, and reflected by the main reflector 02 The first reflected light is formed after surface reflection, and the first reflected light is incident on the reflective surface of the secondary reflector 03, and the second reflected light is formed after being reflected by the reflective surface of the secondary reflector 03, and the second reflected light is incident to the reflective surface of the third reflector 04, the third reflected light is formed after being reflected by the reflective surface of the third reflector 04, and the third reflected light is incident on the reflective surface of the fourth reflector 05, The fourth reflected light is formed after being reflected by the reflecting surface of the fourth reflecting mirror 05, and the fourth reflected light is incident on the reflecting surface of the fifth reflecting mirror 06, and is reflected by the reflecting surface of the fifth reflecting mirror 06 to form The fifth reflected light, the fifth reflected light is received by the image surface 07 of the detector and formed into an image. As shown in Figure 3, it is a schematic diagram of the short-focus state of the system. When the main reflector 02, the secondary reflector 03, and the third reflector 04 are located at designated positions, the system can clearly image a large field of view. When the primary reflector 02, the secondary reflector 04 When the mirror 03 and the third mirror 04 are moved non-axially to the corresponding positions shown in Figure 4, the system switches to the telephoto state with 4.5 times magnification, and the objects within the field of view can be clearly defined with a higher object space resolution. imaging.

The large relative aperture off-axis five-mirror non-axial zoom imaging optical system provided by the embodiment of the present invention has the following advantages:

1. A large relative aperture off-axis five mirror non-axial zoom imaging optical system disclosed in the present invention, the fourth reflector and the fifth reflector are fixed reflectors, the main reflector, the secondary reflector and the third reflector are The movable reflector, and the primary reflector, the secondary reflector and the third reflector form a non-axial synchronous zoom primary imaging subsystem, and the fourth reflector and the fifth reflector form a rear relay imaging subsystem. Zooming is realized by changing the optical power of the mirror group by non-axially moving the primary reflector, the secondary reflector and the third reflector. The rear relay imaging subsystem realizes the inversion, transmission and zoom imaging of an intermediate image plane through two fixed mirrors. By adding a field diaphragm at the position of the primary intermediate image plane, the stray light entering the rear relay imaging subsystem can be effectively eliminated. The synchronous adjustment of the axial movement and the vertical axis movement is realized through the non-axial movement vector, and the non-axial synchronous zoom of the zoom imaging optical system is realized, thereby ensuring good imaging quality under different focal length states, without using free-form surfaces.

2. The present invention discloses a large relative aperture off-axis five-reflection non-axial zoom imaging optical system, the non-axial movement vector is the composite non-axial movement vector of the axial movement amount and the vertical axis movement amount. The focal length of the non-axial zoom imaging optical system can be changed by axial movement; the degree of freedom of the zoom imaging optical system can be increased by moving in the vertical axis direction, and the effect of the eccentricity of the three mirrors on the aberration field can be used to actively balance the multiplicity of the zoom imaging optical system The wave aberration between the structures realizes the correction of high-order astigmatism and coma in the non-axial zoom imaging optical system under different focal length structures.

3. A large relative aperture off-axis five-reflection non-axial zoom imaging optical system disclosed in the present invention, based on the Seidel aberration theory and the vector aberration theory, the correction of high-order astigmatism and coma in the zoom imaging optical system is established The method uses the effect of the eccentricity of the three mirrors on the aberration field to actively balance the wave aberration between the multiple structures of the zoom imaging optical system, and realizes the combination of high-order astigmatism and coma in the non-axial zoom imaging optical system under different focal length structures. Correction.

4. A large relative aperture off-axis five-reflection non-axial zoom imaging optical system disclosed in the present invention can greatly reduce the number of non-axial synchronous zoom primary imaging subsystems by setting a field diaphragm at the stable primary image plane. The stray light that cannot be eliminated due to the movement of the mirror can effectively eliminate the stray light that can reach the image surface of the detector.

5. A large relative aperture off-axis five-reflection non-axial zoom imaging optical system disclosed in the present invention only needs to use high-order aspheric mirrors and does not need to use free-form mirrors, which reduces processing and testing costs.

To sum up, the above are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (4)

1. A large relative aperture off-axis five-reflection non-axial zoom imaging optical system is characterized in that: it comprises an iris diaphragm, a primary reflector, a secondary reflector, a third reflector, a fourth reflector, and a fifth reflector The mirror, the detector image plane, also includes a translation stage for moving the primary reflector, the secondary reflector, and the third reflector; The variable diaphragm is an aperture diaphragm, and the aperture of the aperture diaphragm changes with the focal length; by adjusting the aperture of the aperture diaphragm, the relative aperture of the zoom imaging optical system is guaranteed to be fixed; The main reflector, the secondary reflector and the third reflector are elements for realizing variable magnification and compensation functions, and the zoom imaging is realized by non-axially moving the primary reflector, the secondary reflector and the third reflector; wherein, the The non-axial movement is realized based on the non-axial movement vector, and the non-axial movement vector is the non-axial movement vector synthesized by the axial movement amount and the vertical axis movement amount; the non-axial zoom imaging optical system focal length is realized by axial movement change; increase the degree of freedom of the zoom imaging optical system by moving in the direction of the vertical axis, and actively balance the multiple structures of the zoom imaging optical system by using the effect of the eccentricity of the three mirrors, the primary mirror, the secondary mirror, and the third mirror, on the aberration field The wave aberration between them can realize the correction of high-order astigmatism and coma in the non-axial zoom imaging optical system under different focal length structures; the synchronous adjustment of axial movement and vertical axis movement can be realized through the non-axial movement vector to realize the zoom imaging optical system The system non-axial synchronous zoom, so as to ensure good imaging quality under different focal lengths, without using free-form surfaces; The rear relay imaging subsystem composed of the fourth reflector and the fifth reflector is at the primary intermediate image plane of the non-axial synchronous zoom primary imaging subsystem composed of the main reflector, the secondary reflector and the third reflector For re-imaging, in order to ensure clear imaging without stray light, a field diaphragm is set at the position of the intermediate image plane, which significantly reduces the stray light caused by the difficulty of setting the light-blocking device due to the movement of the mirror, thereby effectively eliminating the problem that can reach the detector image. stray light on the surface. 2. A kind of large relative aperture off-axis five-mirror non-axial zoom imaging optical system as claimed in claim 1, characterized in that: in order to ensure the stable imaging of the zoom imaging optical system, the secondary mirror, the third mirror and The magnification of the fourth reflector satisfies the zoom relationship that the conjugate distance is constant, and ensures that the position of the primary intermediate image plane remains unchanged, thereby ensuring that the position of the detector image plane remains unchanged. 3. A large relative aperture off-axis five mirror non-axial zoom imaging optical system as claimed in claim 1, characterized in that: the main reflector, the third reflector, the fourth reflector and the fifth reflector It is a concave reflector, the secondary reflector is a convex reflector, and the surface types of the five reflectors are all 8-order aspheric surfaces; the reflective surfaces of the primary reflector and the secondary reflector are arranged oppositely, and the reflective surfaces of the secondary reflector and the third reflector are opposite Arrangement, the reflection surfaces of the third reflector and the fourth reflector are arranged oppositely, the reflective surfaces of the fourth reflector and the fifth reflector are arranged oppositely, the fifth reflector and the detector image surface are arranged oppositely; the iris diaphragm and the main The mirror surface center of the reflector is placed eccentrically along the Y-axis direction, and the eccentricity is the same. The secondary reflector, the third reflector, the fourth reflector, and the fifth reflector are all eccentrically and obliquely placed relative to the optical axis. The secondary reflector, the third reflector , The eccentricity and inclination of the fourth reflector and the fifth reflector are different. 4. A large relative aperture off-axis five-mirror non-axial zoom imaging optical system as claimed in claim 1, 2 or 3, characterized in that: the working method is as follows: The light passing through the iris is incident on the reflective surface of the primary reflector, and is reflected by the reflective surface of the primary reflector to form first reflected light, and the first reflected light is incident on the reflective surface of the secondary reflector The second reflected light is formed after being reflected by the reflective surface of the secondary reflector, and the second reflected light is incident on the reflective surface of the third reflector, and is reflected by the reflective surface of the third reflector to form the third reflective light. Reflected light, the third reflected light is incident on the reflective surface of the fourth reflective mirror, and the fourth reflected light is formed after being reflected by the reflective surface of the fourth reflective mirror, and the fourth reflected light is incident on the fifth reflective light On the reflecting surface of the mirror, the fifth reflected light is formed after being reflected by the reflecting surface of the fifth reflecting mirror, and the fifth reflected light is received and imaged by the image surface of the detector; the main reflecting mirror, the secondary reflecting mirror and the third reflecting light When the mirror is at the specified position, the system can clearly image a large field of view. When the main mirror, secondary mirror and third mirror move to the corresponding positions non-axially, the system switches to the telephoto state with enlarged resolution , to perform clear imaging of objects within the field of view with higher object-space spatial resolution; The synchronous adjustment of the axial movement and the vertical axis movement is realized through the non-axial movement vector, and the non-axial synchronous zoom of the zoom imaging optical system is realized; The intermediate image is re-imaging, and the field diaphragm is added to the position of the stable primary intermediate image plane to effectively eliminate the stray light entering the rear relay imaging subsystem and the detector image plane; through the above settings, imaging under different focal lengths is ensured Good quality, no need to use free-form surfaces, reducing processing and inspection costs.