Off-axis three-mirror optical system co-reference assembling and adjusting method and device based on computer holography

Abstract

The application discloses a kind of off-axis three-mirror optical system common datum alignment method and device based on computer holography, belong to optical alignment technical field, and the alignment of relative position of interferometer and computer holography element is realized using interferometer alignment diffraction area;The preliminary positioning and detection of primary mirror are realized using primary mirror detection diffraction area and primary mirror mark point diffraction area;The preliminary positioning and detection of three-mirror are realized using three-mirror detection diffraction area and three-mirror mark point diffraction area;The optical axis of primary three-mirror is led out to transition plane mirror through optical axis diffraction area;The optical axis of interferometer and collimating plane mirror is adjusted and consistent with transition plane mirror, and the on-axis field alignment of off-axis three-mirror optical system is realized;The position of secondary mirror is adjusted by the wave aberration of off-axis three-mirror optical system detected by interferometer.Each alignment degree of freedom is decoupled using computer holography element, and the datum transmission precision of primary three-mirror is converted into the machining precision of computer holography element, which greatly improves the alignment efficiency and alignment precision.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of optical alignment technology, and more particularly relates to a method and device for co-reference alignment of a Rug type off-axis three-mirror optical system using a computer holographic element. BACKGROUND

[0002] The off-axis three-mirror optical system has the advantages of no central obstruction, large field of view, high imaging quality, etc. However, due to the 18 degrees of freedom for alignment, the degrees of freedom are large, and the misalignments caused by each degree of freedom are coupled with each other, which makes it difficult to determine the accurate positions of the mirrors of the off-axis three-mirror optical system, and the alignment is difficult and the alignment precision is low. The Rug type off-axis three-mirror optical system has a primary image point, and the radii of curvature of the main three mirrors are quite different, so the traditional Rug type off-axis three-mirror optical system alignment method uses a traditional compensator or a laser tracker to transfer the reference of each mirror, and the alignment method is complex, and the alignment precision is low due to the low reference transfer precision. SUMMARY

[0003] In view of the above defects or improvement needs of the prior art, the present application provides a co-reference alignment method and device for a Rug type off-axis three-mirror optical system based on computer holography, which solves the technical problem of the existing Rug type off-axis three-mirror optical system alignment being too complex and having low precision.

[0004] To achieve the above-mentioned purpose, according to one aspect of the present application, a co-reference alignment device for an off-axis three-mirror optical system based on computer holography is provided, comprising: a computer holographic element, an interferometer, a transition flat mirror, a collimating flat mirror, and a theodolite.

[0005] The computer holographic element is designed with a main mirror detection diffraction area, a three-mirror detection diffraction area, a main mirror mark point diffraction area, a three-mirror mark point diffraction area, an interferometer alignment diffraction area, and an optical axis diffraction area.

[0006] The measurement beam emitted by the interferometer returns to the interferometer through the interferometer alignment diffraction area, and when the interferometer forms zero fringes, the alignment of the interferometer and the computer holographic element is completed, and then no further adjustment is needed.

[0007] The measurement beam emitted by the interferometer returns to the interferometer after passing through the main mirror detection diffraction area and the main mirror, and the main mirror is adjusted so that the detected wave aberration of the main mirror meets the requirements and zero fringes are formed on the interferometer, at which time the alignment of the main mirror is completed.

[0008] The measurement beam emitted by the interferometer returns to the interferometer after passing through the three-mirror detection diffraction area and the three-mirror, and the three-mirror is adjusted so that the detected wave aberration of the three-mirror meets the requirements and zero fringes are formed on the interferometer, at which time the alignment of the three-mirror is completed.

[0009] The measurement beam emitted by the interferometer passes through the optical axis diffraction area and the transition plane mirror and returns to the interferometer, the transition plane mirror is adjusted to form zero fringes on the interferometer, and the optical axes of the primary mirror and the three mirrors are led out to the transition plane mirror;

[0010] The calculation holographic element is removed, the interferometer, the secondary mirror and the collimating plane mirror are initially placed, the measurement beam emitted by the interferometer passes through the primary mirror, the secondary mirror, the three mirrors and the collimating plane mirror without cutting light, the collimating plane mirror is adjusted to be consistent with the optical axis of the transition plane mirror by using the theodolite, the angle of the interferometer is adjusted to form zero fringes after the measurement beam emitted by the interferometer returns through the transition plane mirror, at this time, the measurement beam emitted by the interferometer is the on-axis light of the off-axis three-mirror optical system; the position of the secondary mirror is adjusted through the wave aberration of the off-axis three-mirror optical system detected by the interferometer until the wave aberration of the off-axis three-mirror optical system meets the technical requirements, at this time, all the mirrors of the off-axis three-mirror optical system are completed.

[0011] In some optional embodiments, the device further comprises a six-dimensional adjustment table, an air floating table and a two-dimensional adjustment table.

[0012] The adjustment of the primary mirror, the secondary mirror, the three mirrors and the interferometer is realized by the six-dimensional adjustment table, the calculation holographic element, the transition plane mirror and the collimating plane mirror are placed on the two-dimensional adjustment table to realize the adjustment, and the six-dimensional adjustment table and the two-dimensional adjustment table are placed on the air floating table.

[0013] In some optional embodiments, the primary mirror detection diffraction area can diffract the measurement beam emitted from the interferometer and irradiated thereon to generate diffracted light for incidence to the primary mirror; the three-mirror detection diffraction area can diffract the measurement beam emitted from the interferometer and irradiated thereon to generate diffracted light for incidence to the three mirror; the interferometer alignment diffraction area can reflect the measurement beam emitted from the interferometer back to the interferometer to realize the alignment of the interferometer and the calculation holographic element; the primary mirror mark point diffraction area can diffract the measurement beam emitted from the interferometer to generate convergence points of three specific positions at the edge of the primary mirror to realize the initial positioning of the spatial position of the primary mirror; the three-mirror mark point diffraction area can diffract the measurement beam emitted from the interferometer to generate convergence points of three specific positions at the edge of the three mirror to realize the initial positioning of the spatial position of the three mirror; the optical axis diffraction area can diffract the measurement beam emitted from the interferometer to generate a parallel light beam consistent with the optical axis of the primary three mirror, and the parallel light beam can form zero fringes on the interferometer if it returns to the interferometer by the original route, wherein the primary mirror detection diffraction area, the three-mirror detection diffraction area, the primary mirror mark point diffraction area, the three-mirror mark point diffraction area, the interferometer alignment diffraction area and the optical axis diffraction area are all arranged on the same substrate.

[0014] In some alternative embodiments, the optical axes of the primary mirror, the secondary mirror and the tertiary mirror in the off-axis three-mirror optical system are consistent, and the primary mirror and the secondary mirror have a primary image point, the outgoing and incoming light waves are plane waves, and the outgoing and incoming light axes are consistent with the optical axis of the primary-tertiary mirror.

[0015] In some alternative embodiments, the interferometer is capable of measuring the wave aberration of the optical path of the interference fringes obtained by measuring the light beams passing through the primary mirror, the diffraction zone and the primary mirror and returning to the interferometer, capable of measuring the wave aberration of the optical path of the interference fringes obtained by measuring the light beams passing through the tertiary mirror, the diffraction zone and the tertiary mirror and returning to the interferometer, capable of measuring the wave aberration of the optical path of the interference fringes obtained by measuring the light beams passing through the off-axis three-mirror optical system and the collimating plane mirror and returning to the interferometer, and capable of emitting plane measurement light waves.

[0016] According to another aspect of the present application, there is provided a common reference assembly method for a computer holography-based off-axis three-mirror optical system, comprising:

[0017] A computer holography element is provided for positioning the primary mirror and the tertiary mirror of the Rug-type off-axis three-mirror optical system, and the computer holography element is designed with a primary-tertiary mirror detection diffraction zone, a primary-tertiary mirror mark point diffraction zone, an interferometer alignment diffraction zone and an optical axis diffraction zone;

[0018] An interferometer is provided, and the computer holography element is aligned by using the interferometer alignment diffraction zone. The measurement light beams emitted by the interferometer return to the interferometer through the interferometer alignment diffraction zone. When the interferometer forms zero fringes, the alignment of the interferometer and the computer holography element is completed, and no further adjustment is needed. The outer edge of the primary mirror is preliminarily calibrated by the primary-tertiary mirror mark point diffraction zone. The measurement light beams emitted by the interferometer return to the interferometer through the primary mirror detection diffraction zone and the primary mirror. The primary mirror is adjusted so that the detected primary mirror wave aberration meets the requirements and the interferometer forms zero fringes. At this time, the assembly of the primary mirror is completed.

[0019] The outer edge of the tertiary mirror is preliminarily calibrated by the tertiary mirror mark point diffraction zone. The measurement light beams emitted by the interferometer return to the interferometer through the tertiary mirror detection diffraction zone and the tertiary mirror. The tertiary mirror is adjusted so that the detected tertiary mirror wave aberration meets the requirements and the interferometer forms zero fringes. At this time, the assembly of the tertiary mirror is completed.

[0020] A transition plane mirror is provided. The measurement light beams emitted by the interferometer return to the interferometer through the optical axis diffraction zone and the transition plane mirror. The transition plane mirror is adjusted so that the interferometer forms zero fringes, and the optical axis of the primary-tertiary mirror is led out to the transition plane mirror.

[0021] Remove the computer holographic element, provide a collimating mirror, initially place the interferometer, the secondary mirror and the collimating mirror, so that the measurement beam emitted by the interferometer passes through the primary mirror, the secondary mirror, the tertiary mirror and the collimating mirror without cutting light, adjust the collimating mirror and the transition plane mirror to be consistent with the optical axis using the theodolite, adjust the angle of the interferometer so that the measurement beam emitted by the interferometer forms zero fringes after returning through the transition plane mirror, at this time the measurement beam emitted by the interferometer is the on-axis light of the off-axis three-mirror optical system; adjust the position of the secondary mirror through the wave aberration of the off-axis three-mirror optical system detected by the interferometer, until the wave aberration of the off-axis three-mirror optical system meets the technical requirements, at this time all the mirrors of the off-axis three-mirror optical system are completed.

[0022] In some optional embodiments, the adjustment of the primary mirror, the secondary mirror, the tertiary mirror and the interferometer is realized through a six-dimensional adjustment table, the computer holographic element, the transition plane mirror and the collimating mirror are placed on a two-dimensional adjustment table to realize adjustment, and all the adjustment tables are placed on an air floating table.

[0023] In some optional embodiments, the primary mirror detection diffraction area can diffract the measurement beam emitted by the interferometer and irradiated thereon to generate diffracted light for incidence to the primary mirror; the tertiary mirror detection diffraction area can diffract the measurement beam emitted by the interferometer and irradiated thereon to generate diffracted light for incidence to the tertiary mirror; the interferometer alignment diffraction area can reflect the measurement beam emitted by the interferometer back to the interferometer to realize alignment of the interferometer and the computer holographic element; the primary mirror mark point diffraction area can diffract the measurement beam emitted by the interferometer to generate convergence points of three specific positions at the edge of the primary mirror, thereby realizing initial positioning of the spatial position of the primary mirror; the tertiary mirror mark point diffraction area can diffract the measurement beam emitted by the interferometer to generate convergence points of three specific positions at the edge of the tertiary mirror, thereby realizing initial positioning of the spatial position of the tertiary mirror; the optical axis diffraction area can diffract the measurement beam emitted by the interferometer to generate a parallel light beam consistent with the optical axis of the primary and tertiary mirrors, and if the parallel light beam returns to the interferometer by the original route, zero fringes can be formed on the interferometer, wherein the primary mirror detection diffraction area, the tertiary mirror detection diffraction area, the primary mirror mark point diffraction area, the tertiary mirror mark point diffraction area, the interferometer alignment diffraction area and the optical axis diffraction area are all arranged on the same substrate.

[0024] In some optional embodiments, the optical axis of the primary mirror, the secondary mirror and the tertiary mirror in the Rug type off-axis three-mirror optical system is consistent, the primary and secondary mirrors have a primary image point, the outgoing and incoming light are plane waves, and the outgoing and incoming optical axes are consistent with the optical axis of the primary and tertiary mirrors.

[0025] In some optional embodiments, the interferometer is capable of measuring wavefront aberration of the optical path by measuring interference fringes obtained by the light beam passing through the main mirror detection diffraction area and returning to the interferometer after the main mirror, capable of measuring wavefront aberration of the optical path by measuring interference fringes obtained by the light beam passing through the three-mirror detection diffraction area and returning to the interferometer after the three-mirror, capable of measuring wavefront aberration of the optical path by measuring interference fringes obtained by the light beam passing through the off-axis three-mirror optical system and returning to the interferometer after the collimating plane mirror, and capable of emitting a plane measurement light wave.

[0026] Overall, compared with the prior art, the above technical solutions conceived by the present application can achieve the following beneficial effects:

[0027] The alignment method uses a computer hologram and an interferometer to realize alignment of the main three-mirror of the off-axis three-mirror optical system, without using a laser tracker or other instruments, and the relative positions of the main mirror and the three-mirror can be accurately adjusted under the guidance of the computer hologram. Then, the on-axis field of view of the off-axis three-mirror optical system is found by using the computer hologram, and the alignment of the secondary mirror is completed under the on-axis field of view. This method reduces the alignment degrees of freedom and can decouple the misalignment of each degree of freedom, and has high alignment accuracy. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a computer hologram element diffraction area schematic diagram provided by an embodiment of the present application;

[0029] Figure 2 is a main three-mirror alignment optical path schematic diagram built by an alignment method provided by an embodiment of the present application;

[0030] Figure 3 is a secondary mirror alignment optical path schematic diagram built by an alignment method provided by an embodiment of the present application;

[0031] In the figure: 1-main mirror, 2-three-mirror, 3-computer hologram element, 4-interferometer, 5-secondary mirror, 6-collimating plane mirror, 7-six-dimensional adjustment table, 8-air float table, 9-two-dimensional adjustment table, 10-transition plane mirror, 11-theodolite, 12-main mirror detection diffraction area, 13-three-mirror detection diffraction area, 14-main mirror mark point diffraction area, 15-interferometer alignment diffraction area, 16-optical axis diffraction area, 17-three-mirror mark point diffraction area. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0033] Computational holographic elements can accurately generate multiple wavefronts of almost arbitrary shapes with precise relative positional relationships. This accuracy and design flexibility endow computational holographic elements with powerful capabilities in guiding the adjustment of optical components. This invention utilizes computational holography and interferometric detection methods to achieve precise adjustment of optical components one by one, decoupling each degree of freedom in the assembly and adjustment process. The accurate relative positional relationships between the various optical components depend on the ability of computational holography to generate multiple wavefronts with precise relative positions. This transforms the reference transfer accuracy of the three main mirrors into the processing accuracy of the computational holographic elements, greatly improving assembly and adjustment efficiency and accuracy.

[0034] The following, in conjunction with the accompanying drawings, provides a specific embodiment of the assembly and adjustment device for an off-axis three-mirror optical system constructed using the method of the present invention:

[0035] like Figure 1 As shown, a computational holographic element 3 is provided for positioning the primary mirror 1 and the three mirrors 2 of the Rug-type off-axis three-mirror optical system. The computational holographic element 3 is designed with a primary mirror detection diffraction area 12, a three-mirror detection diffraction area 13, a primary mirror marker point diffraction area 14, a three-mirror marker point diffraction area 17, an interferometer alignment diffraction area 15, and an optical axis diffraction area 16.

[0036] The primary mirror detection diffraction region 12 can diffract the measurement beam emitted from the interferometer 4 and incident on it, generating diffracted light for incident on the primary mirror 1; its included three-mirror detection diffraction region 13 can diffract the measurement beam emitted from the interferometer 4 and incident on it, generating diffracted light for incident on the three-mirror 2; its included interferometer alignment diffraction region 15 can reflect the measurement beam emitted from the interferometer 4 back to the interferometer 4, realizing the alignment of the interferometer 4 and the computational holographic element 3; its included primary mirror marker point diffraction region 14 can diffract the measurement beam emitted from the interferometer 4... The measurement beam diffracts to generate three convergence points at specific locations on the edge of the primary mirror 1, thus achieving initial positioning of the primary mirror 1 in space. The three-mirror marker diffraction region 17 it contains can diffract the measurement beam emitted by the interferometer 4 to generate three convergence points at specific locations on the edge of the three mirrors 2, thus achieving initial positioning of the three mirrors 2 in space. The optical axis diffraction region 16 it contains can diffract the measurement beam emitted by the interferometer 4 to generate a parallel beam that is consistent with the optical axis of the primary three mirrors. If this beam returns to the interferometer 4 along the original path, it can form a zero fringe on the interferometer 4.

[0037] The computer holographic element 3 has the primary mirror detection diffraction area 12 and the three-mirror detection diffraction area 13, and can detect the primary mirror 1 and the three-mirror 2 simultaneously according to the theoretical design. Since the relative positions of the primary mirror detection diffraction area 12 and the three-mirror detection diffraction area 13 are fixed, the relative positions of the primary mirror 1 and the three-mirror 2 light waves emitted by the interferometer 4 through the computer holographic element 3 are also fixed. As long as the primary mirror 1 and the three-mirror 2 are adjusted to make the wave aberration of the interference fringes generated after the light waves pass through the primary mirror 1 and the three-mirror 2 and return to the interferometer 4 minimum, the relative positions of the primary mirror 1 and the three-mirror 2 are determined. Then, the on-axis light of the off-axis three-mirror optical system is determined by using the optical axis diffraction area 16 on the computer holographic element 3, and the secondary mirror 5 is adjusted in the on-axis field of view, so that the adjustment of the entire off-axis three-mirror optical system is completed.

[0038] Specifically, a computer holographic Rug-type off-axis three-mirror optical system common reference adjustment method includes the following steps:

[0039] Step one: building Figure 2 The light path is shown. Take the interferometer 4 as the reference, adjust the computer holographic element 3, align the computer holographic element 3 by using the interferometer alignment diffraction area 15, and then determine the position of the primary mirror 1 by using the primary mirror detection diffraction area 12. The specific method is as follows: place the interferometer 4 on the six-dimensional adjustment table 7, place the computer holographic element 3 on the two-dimensional adjustment table 9, and place all the adjustment tables on the air floating table 8. Since the interferometric detection has high requirements for environmental stability, the air floating table 8 can reduce the influence of micro-vibration on the interferometric detection accuracy. Then the measurement light beam emitted by the interferometer 4 returns to the interferometer after passing through the interferometer alignment diffraction area 15. When the interferometer 4 forms zero fringes, the alignment of the interferometer 4 and the computer holographic element 3 is completed and no longer adjusted. The primary mirror 1 is placed on the six-dimensional adjustment table 7, the outer edge of the primary mirror 1 is preliminarily calibrated by the primary mirror mark point diffraction area 14, the measurement light beam emitted by the interferometer 4 returns to the interferometer 4 after passing through the primary mirror detection diffraction area 12 and the primary mirror 1, and the interference fringes are formed. The six-dimensional adjustment table 7 is used to adjust the primary mirror 1, so that the detected wave aberration of the primary mirror 1 meets the requirements and zero fringes are formed on the interferometer 4. At this time, the primary mirror 1 is adjusted and completed.

[0040] Step two: according to Figure 2 The light path is shown. The position of the three-mirror 2 is determined by using the three-mirror detection diffraction area 13. The specific method is as follows: place the three-mirror 2 on the six-dimensional adjustment table 7, preliminarily calibrate the outer edge of the three-mirror 2 by the three-mirror mark point diffraction area 17, and return the measurement light beam emitted by the interferometer 4 to the interferometer 4 after passing through the three-mirror detection diffraction area 13 and the three-mirror 2 to form interference fringes. The six-dimensional adjustment table 7 is used to adjust the three-mirror 2, so that the detected wave aberration of the three-mirror 2 meets the requirements and zero fringes are formed on the interferometer 4. At this time, the three-mirror 2 is adjusted and completed;

[0041] Step 3: The optical axis reference of the primary mirror 1 and the three mirrors 2 is led out to the transition plane mirror 10 through the optical axis diffraction area 16. Specifically, the transition plane mirror is placed on the two-dimensional adjustment stage 9. The measurement beam emitted by the interferometer 4 returns to the interferometer 4 after passing through the optical axis diffraction area 16 and the transition plane mirror 10. The transition plane mirror 10 is adjusted to form zero fringes on the interferometer 4, thereby leading out the optical axis of the primary mirror and the three mirrors to the transition plane mirror 10.

[0042] Step Four: According to Figure 3 In the optical path, the holographic element 3 is removed, and the optical axes of the interferometer 4 and collimating plane mirror 6 are adjusted to be aligned with the optical axes of the primary mirror and the three mirrors. Then, the secondary mirror 5 is installed and adjusted in the on-axis field of view to ensure that the wavefront aberration of the entire off-axis three-mirror optical system meets the technical requirements. Specifically, the secondary mirror 5 is placed on the six-dimensional adjustment stage 7, and the collimating plane mirror 6 is placed on the two-dimensional adjustment stage 9. The interferometer 4, secondary mirror 5, and collimating plane mirror 6 are initially positioned so that the measurement beam emitted by the interferometer 4 has no cut-off light after passing through the primary mirror, secondary mirror, three mirrors, and collimating plane mirror 6. The theodolite 11 is used to adjust the collimating plane mirror 6 to be aligned with the optical axis of the transition plane mirror 10. The angle of the interferometer 4 is adjusted so that the measurement beam emitted by it returns after passing through the transition plane mirror 10, forming zero fringes. At this point, the measurement beam emitted by the interferometer 4 is the on-axis light of the off-axis three-mirror optical system. The measurement beam emitted by the interferometer 4 returns to the interferometer after passing through the off-axis three-mirror optical system and the collimating plane mirror 6, forming interference fringes. The wavefront aberration of the off-axis three-mirror optical system is detected by the interferometer 4. The position of the secondary mirror 5 is adjusted based on the wavefront aberration detected by the interferometer 4 until the wavefront aberration of the off-axis three-mirror optical system meets the technical requirements. At this point, all mirrors of the off-axis three-mirror optical system have been assembled and adjusted.

[0043] This assembly and adjustment method overcomes existing technical problems by utilizing computational holographic element 3 and interferometer 4 to perform common-reference assembly and adjustment of the Rug-type off-axis three-mirror optical system. It achieves high-precision adjustment of the three primary mirrors without the need for other instruments such as laser trackers. This invention transforms the reference transfer accuracy of the three primary mirrors into the processing accuracy of the computational holographic element. The accurate relative positional relationship between the three primary mirrors depends on the ability of computational holography to generate multiple accurately positioned wavefronts, thus achieving decoupling of each assembly and adjustment degree of freedom and greatly improving assembly and adjustment accuracy. Using computational holographic element 3, the on-axis field of view of the off-axis three-mirror optical system can also be found, allowing the assembly and adjustment of the secondary mirror 5 to be completed within the on-axis field of view without needing to switch to the off-axis field of view, thereby improving assembly and adjustment efficiency.

[0044] The plane light wave emitted by this interferometer 4 has an aperture of 150mm, the effective aperture of the primary mirror 1 is 144mm, the effective aperture of the secondary mirror 5 is 37.5mm, and the effective aperture of the third mirror 2 is 88.8mm.

[0045] It should be noted that the various steps / components described in the present application can be split into more steps / components or two or more steps / components or parts of the operation of steps / components can be combined into new steps / components, as required by implementation, to achieve the objectives of the present application.

[0046] Those skilled in the art will easily understand that the above description is only the preferred embodiment of the present application and is not intended to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A common reference mounting device for off-axis three-mirror optical system based on computer holography, characterized in that, It comprises: a computer holographic element, an interferometer, a transition mirror, a collimating mirror and a theodolite; the computer holographic element is designed with a main mirror detection diffraction area, a three-mirror detection diffraction area, a main mirror mark point diffraction area, a three-mirror mark point diffraction area, an interferometer alignment diffraction area and an optical axis diffraction area; the measurement beam emitted by the interferometer passes through the interferometer alignment diffraction area and returns to the interferometer, when the interferometer forms zero fringes, the alignment of the interferometer and the computer holographic element is completed, and no further adjustment is needed; the measurement beam emitted by the interferometer passes through the main mirror detection diffraction area and the main mirror and returns to the interferometer, the main mirror is adjusted so that the detected wave aberration of the main mirror meets the requirements and zero fringes are formed on the interferometer, at this time, the main mirror is completed; the measurement beam emitted by the interferometer passes through the three-mirror detection diffraction area and the three-mirror and returns to the interferometer, the three-mirror is adjusted so that the detected wave aberration of the three-mirror meets the requirements and zero fringes are formed on the interferometer, at this time, the three-mirror is completed; the measurement beam emitted by the interferometer passes through the optical axis diffraction area and the transition mirror and returns to the interferometer, the transition mirror is adjusted so that zero fringes are formed on the interferometer, and the optical axes of the main mirror and the three-mirror are led out to the transition mirror; remove the computer holographic element, and preliminarily place the interferometer, the secondary mirror and the collimating mirror, so that the measurement beam emitted by the interferometer passes through the main mirror, the secondary mirror, the three-mirror and the collimating mirror without cutting light, the collimating mirror is adjusted to be consistent with the optical axis of the transition mirror using the theodolite, the angle of the interferometer is adjusted so that the measurement beam emitted by the interferometer forms zero fringes after returning through the transition mirror, at this time, the measurement beam emitted by the interferometer is the on-axis light of the off-axis three-mirror optical system; the position of the secondary mirror is adjusted through the wave aberration of the off-axis three-mirror optical system detected by the interferometer until the wave aberration of the off-axis three-mirror optical system meets the technical requirements, at this time, all the mirrors of the off-axis three-mirror optical system are completed.

2. The apparatus of claim 1, wherein, The device further comprises a six-dimensional adjustment table, an air floating table and a two-dimensional adjustment table; the adjustment of the main mirror, the secondary mirror, the three-mirror and the interferometer is realized through the six-dimensional adjustment table, the computer holographic element, the transition mirror and the collimating mirror are placed on the two-dimensional adjustment table to realize adjustment, and the six-dimensional adjustment table and the two-dimensional adjustment table are placed on the air floating table.

3. The apparatus of claim 1, wherein, The main mirror detection diffraction area can diffract the measurement beam emitted from the interferometer and irradiated thereon to generate diffracted light for incidence to the main mirror; the three-mirror detection diffraction area can diffract the measurement beam emitted from the interferometer and irradiated thereon to generate diffracted light for incidence to the three mirror; the interferometer alignment diffraction area can reflect the measurement beam emitted from the interferometer back to the interferometer to realize alignment of the interferometer and the computer holographic element; the main mirror mark point diffraction area can diffract the measurement beam emitted from the interferometer to generate converging points of three specific positions of the edge of the main mirror, thereby realizing preliminary positioning of the spatial position of the main mirror; the three-mirror mark point diffraction area can diffract the measurement beam emitted from the interferometer to generate converging points of three specific positions of the edge of the three mirror, thereby realizing preliminary positioning of the spatial position of the three mirror; and the optical axis diffraction area can diffract the measurement beam emitted from the interferometer to generate a parallel light beam consistent with the optical axis of the main three mirror, and the parallel light beam can form zero fringes on the interferometer if it returns to the interferometer along the original path, wherein the main mirror detection diffraction area, the three-mirror detection diffraction area, the main mirror mark point diffraction area, the three-mirror mark point diffraction area, the interferometer alignment diffraction area and the optical axis diffraction area are arranged on the same substrate.

4. The apparatus of claim 1, wherein, The main mirror, the secondary mirror and the three mirror in the off-axis three-mirror optical system are consistent in optical axis, the main mirror and the secondary mirror have a primary image point, the outgoing and incoming light are plane waves, and the outgoing and incoming optical axes are consistent with the optical axis of the main three mirror.

5. The apparatus of any one of claims 1 to 4, wherein, The interferometer can measure wave aberration of a measurement light path of interference fringes obtained by returning the measurement beam to the interferometer after passing through the main mirror detection diffraction area and the main mirror, can measure wave aberration of a measurement light path of interference fringes obtained by returning the measurement beam to the interferometer after passing through the three-mirror detection diffraction area and the three mirror, can measure wave aberration of a measurement light path of interference fringes obtained by returning the measurement beam to the interferometer after passing through the off-axis three-mirror optical system and the collimating plane mirror, and can emit a plane measurement light wave.

6. A co-reference adjustment method for off-axis three-mirror optical system based on computer holography, characterized in that, It comprises: A computer holographic element is provided for positioning of the main mirror and the three mirror of the Rug type off-axis three-mirror optical system, and the computer holographic element is designed with a main three-mirror detection diffraction area, a main three-mirror mark point diffraction area, an interferometer alignment diffraction area and an optical axis diffraction area; An interferometer is provided, and the interferometer is aligned with the computer holographic element by using the interferometer alignment diffraction area; the measurement beam emitted by the interferometer returns to the interferometer after passing through the interferometer alignment diffraction area; when the interferometer forms zero fringes, the alignment of the interferometer and the computer holographic element is completed, and no further adjustment is needed; the outer edge of the main mirror is preliminarily calibrated by the main mirror mark point diffraction area; the measurement beam emitted by the interferometer returns to the interferometer after passing through the main mirror detection diffraction area and the main mirror; the main mirror is adjusted so that the detected wave aberration of the main mirror meets the requirements and zero fringes are formed on the interferometer, and at this time, the main mirror is completed and adjusted; The outer edge of the three mirror is preliminarily calibrated by the three-mirror mark point diffraction area; the measurement beam emitted by the interferometer returns to the interferometer after passing through the three-mirror detection diffraction area and the three mirror; the three mirror is adjusted so that the detected wave aberration of the three mirror meets the requirements and zero fringes are formed on the interferometer, and at this time, the three mirror is completed and adjusted; The transition flat mirror is provided, the measuring beam emitted by the interferometer passes through the optical axis diffraction area and the transition flat mirror to return to the interferometer, and the transition flat mirror is adjusted to form zero fringes on the interferometer, and the optical axis of the primary three mirrors is led out to the transition flat mirror; The computer generated hologram element is removed, the collimating flat mirror is provided, and the interferometer, the secondary mirror and the collimating flat mirror are initially placed to make the measuring beam emitted by the interferometer pass through the primary mirror, the secondary mirror, the tertiary mirror and the collimating flat mirror without cutting light, the collimating flat mirror is adjusted to be consistent with the optical axis of the transition flat mirror by using the theodolite, the angle of the interferometer is adjusted to make the measuring beam emitted by the interferometer form zero fringes after returning through the transition flat mirror, at this time, the measuring beam emitted by the interferometer is the on-axis light of the off-axis three-mirror optical system, the position of the secondary mirror is adjusted through the wave aberration of the off-axis three-mirror optical system detected by the interferometer, until the wave aberration of the off-axis three-mirror optical system meets the technical requirements, at this time, all the mirrors of the off-axis three-mirror optical system are completed.

7. The method of claim 6, wherein, The adjustment of the primary mirror, the secondary mirror, the tertiary mirror and the interferometer is realized by the six-dimensional adjustment table, the computer generated hologram element, the transition flat mirror and the collimating flat mirror are placed on the two-dimensional adjustment table to realize the adjustment, and all the adjustment tables are placed on the air floating table.

8. The method of claim 6, wherein, The primary mirror detection diffraction area can diffract the measuring beam emitted by the interferometer and irradiated thereon to generate diffracted light for incidence to the primary mirror; the tertiary mirror detection diffraction area can diffract the measuring beam emitted by the interferometer and irradiated thereon to generate diffracted light for incidence to the tertiary mirror; the interferometer alignment diffraction area can reflect the measuring beam emitted by the interferometer back to the interferometer to realize the alignment of the interferometer and the computer generated hologram element; the primary mirror mark point diffraction area can diffract the measuring beam emitted by the interferometer to generate convergence points of three specific positions at the edge of the primary mirror to realize the initial positioning of the spatial position of the primary mirror; the tertiary mirror mark point diffraction area can diffract the measuring beam emitted by the interferometer to generate convergence points of three specific positions at the edge of the tertiary mirror to realize the initial positioning of the spatial position of the tertiary mirror; and the optical axis diffraction area can diffract the measuring beam emitted by the interferometer to generate a parallel light beam consistent with the optical axis of the primary three mirrors, if the parallel light beam returns to the interferometer by the original route, zero fringes can be formed on the interferometer, wherein the primary mirror detection diffraction area, the tertiary mirror detection diffraction area, the primary mirror mark point diffraction area, the tertiary mirror mark point diffraction area, the interferometer alignment diffraction area and the optical axis diffraction area are all arranged on the same substrate.

9. The method of claim 6, wherein, The primary mirror, the secondary mirror and the tertiary mirror in the Rug type off-axis three-mirror optical system are consistent in the optical axis, the primary mirror and the secondary mirror have a primary image point, the outgoing and incoming light are plane waves, and the outgoing and incoming optical axes are consistent with the optical axis of the primary three mirrors.

10. The method according to any one of claims 6 to 9, characterized in that, The interferometer can measure the wave aberration of the interference fringe measurement light path obtained by the measuring beam passing through the primary mirror detection diffraction area and the primary mirror and returning to the interferometer, can measure the wave aberration of the interference fringe measurement light path obtained by the measuring beam passing through the tertiary mirror detection diffraction area and the tertiary mirror and returning to the interferometer, can measure the wave aberration of the interference fringe measurement light path obtained by the measuring beam passing through the off-axis three-mirror optical system and the collimating flat mirror and returning to the interferometer, and can emit a plane measuring light wave.

Images