A complex folded axicon group optical axis consistency assembling method

Abstract

This invention discloses a method for aligning the optical axis of a complex folding-axis mirror assembly, solving the problems of difficult attitude positioning of the diffraction primary mirror and diffraction correction mirror, and difficulties in building the assembly and detection optical path, which lead to the inability to eliminate a large amount of chromatic aberration in the camera. Specifically, the method includes: Step 1, adjusting the mounting surface of the main structure plate to be horizontal; Step 2, transferring the centering reference of the diffraction primary mirror to the centering reference A on the main structure plate through the secondary and tertiary mirrors; Step 3, determining the attitudes of the fourth, fifth, and sixth mirrors through the centering reference A; Step 4, positioning the front correction mirror on the mounting surface of the main structure plate; and Step 5, adjusting the attitudes of the rear correction mirror, steering mirror, relay mirror, and diffraction primary mirror by detecting the transmitted wave, thus completing the alignment of the optical axis of the complex folding-axis mirror assembly.

Description

Technical Field

[0001] This invention relates to a method for aligning optical axes, specifically a method for aligning optical axes of a complex folding mirror assembly. Background Technology

[0002] The complex folded-axis camera is a diffractive infrared optical system. Its main components include a diffractive primary mirror, a relay mirror, a diffraction correction mirror, and an aberration correction mirror group, with a total optical path length of approximately 3700 mm. Due to the limited structural envelope of the camera, the optical path is folded through several sets of mirrors within the optical system, resulting in a final total structural length of no more than 1300 mm. Specifically, this includes 5 sets of mirrors, 4 sets of transmission mirrors, 1 primary mirror set, and 1 main camera structure. The components have over 50 degrees of freedom for adjustment, making attitude positioning difficult and the assembly and adjustment of the detection optical path challenging.

[0003] Complex folded-axis cameras employ achromatic principles in their design. The diffraction primary mirror and diffraction correction mirror require very precise positioning and orientation accuracy, with an angular error requirement of 20″ and an eccentricity error requirement of 0.025mm. They are 2900mm apart in the optical path and situated in a non-orthogonal spatial folding optical path, making alignment extremely difficult. Insufficient alignment precision will result in significant chromatic aberration within the camera, leading to image quality far below requirements. Therefore, a high-precision alignment method is urgently needed for such complex folded-axis cameras. Summary of the Invention

[0004] The purpose of this invention is to provide a method for aligning the optical axis of a complex folding mirror assembly, in order to solve the technical problems of difficulty in positioning the diffraction primary mirror and the diffraction correction mirror, difficulty in building the optical path for assembly and detection, resulting in the inability to eliminate a large number of chromatic aberrations in the camera and the inability to meet the imaging quality requirements.

[0005] To achieve the above objectives, the present invention provides a method for aligning the optical axis of a complex folding-axis lens assembly for use in a complex folding-axis camera. The complex folding-axis camera includes a ring-shaped main structural plate, a first support column, a second support column, and a third support column arranged vertically below the main structural plate in a clockwise direction, a diffraction primary mirror arranged parallel to the main structural plate, a secondary mirror arranged above the main structural plate and sharing the optical axis with the diffraction primary mirror, a third mirror, a relay mirror, a fourth mirror, a front correction mirror, a fifth mirror, a rear correction mirror, and a sixth mirror arranged above the main structural plate and sharing the optical path with the secondary mirror, and a steering mirror located above the sixth mirror and sharing the optical axis with the sixth mirror; the top of the main structural plate is a mounting surface.

[0006] Its special feature is that it includes the following steps:

[0007] Step 1: Adjust the mounting surface of the main structural panel to be horizontal;

[0008] Step 2: Transfer the through-center reference of the diffraction primary mirror to the through-center reference A on the main structure plate using the secondary and tertiary mirrors;

[0009] Step 3: Determine the attitudes of the four-mirror, five-mirror, and six-mirror systems using the center-piercing reference A;

[0010] Step 4: Position the front alignment mirror on the mounting surface of the main structural plate;

[0011] Step 5: By detecting the attitudes of the corrector mirror, steering mirror, relay mirror, and diffraction primary mirror after adjusting the transmitted wavefront, the optical axis consistency of the complex folding mirror group is completed.

[0012] Furthermore, step 2 specifically involves:

[0013] 2.1 Install a diffraction primary mirror below the main structural plate, and set a first plane mirror at the center of the diffraction primary mirror. Install a secondary mirror above the main structural plate, and set a third mirror on the mounting surface of the main structural plate near the third support column. Set a theodolite T3 on one side of the main structural plate. Adjust the diffraction primary mirror, secondary mirror, third mirror, and theodolite T3 so that the laser emitted by theodolite T3 can be reflected by the first plane mirror, secondary mirror, and third mirror respectively and return to the field of view of theodolite T3, and make the elevation angle of theodolite T3 90°. Set the center reference A between theodolite T3 and the three mirrors. Trim the base of the center reference A so that the autocollimation image of the center reference A is at the center of the field of view of the theodolite T3 in the elevation direction.

[0014] 2.2. Translate the diffraction primary mirror, the three mirrors, and the theodolite T3 so that the center of the diffraction ring of the primary mirror, the center of the cross of the reference point A, and the center of the field of view of the theodolite T3 coincide.

[0015] 2.3 Adjust the azimuth and elevation angles of the three mirrors so that the autocollimation image of the first plane mirror is at the center of the field of view in the elevation direction of the theodolite T3;

[0016] 2.4 Adjust the azimuth angle of the theodolite T3 so that the autocollimation image of the first plane mirror coincides with the central crosshair of the theodolite T3's field of view; then adjust the azimuth angle of the center reference A so that its autocollimation image coincides with the central crosshair of the theodolite T3's field of view.

[0017] 2.5. Translate the diffraction primary mirror so that the center of its diffraction ring, the center of the cross of the pivot reference A, and the center of the field of view of the theodolite T3 coincide. Then the pivot reference of the diffraction primary mirror will be completely transferred to the center of the cross of the pivot reference A.

[0018] Furthermore, step 3 specifically involves:

[0019] 3.1 Install four, five, and six mirrors respectively on the mounting surface of the main structural plate; the four mirrors are located on the side of the center reference A away from the three mirrors; install the relay mirror center reference between the four mirrors and the center reference A, install the center reference B between the four mirrors and the five mirrors, install the rear correction mirror center reference between the five mirrors and the six mirrors, and install the steering mirror center reference on the reflected light path of the six mirrors; install the first folding axis mirror between the center reference A and the three mirrors; arrange the theodolite T4 on one side of the first folding axis mirror; adjust the theodolite T4 to the earth level so that its pitch angle is 90°; make the height of the cross centers of the center reference A, center reference B, relay mirror center reference, rear correction mirror center reference, and steering mirror center reference consistent;

[0020] 3.2 Adjust the attitude of the first folding mirror so that the laser emitted by the theodolite T4 is reflected by the first folding mirror, reflected by the center reference A, and reflected back to the theodolite T4 by the first folding mirror in sequence, and make the center reference A and the theodolite T4 self-align and pass through each other.

[0021] 3.3 Adjust the repeater's centering reference so that it is aligned with centering reference A;

[0022] 3.4 Adjust the elevation and azimuth angles of the four mirrors so that the crosshair center of the pivot reference B coincides with the crosshair center of the theodolite T4 field of view; then adjust the azimuth angle of the pivot reference B so that it aligns with the autocollimation pivot of the theodolite T4.

[0023] 3.5. For the center-piercing reference of the five-mirror and rear correction mirror, and the center-piercing reference of the six-mirror and steering mirror, the same procedure as above shall be adopted.

[0024] 3.4 Using the same method, make sure that the center reference of the rear correction mirror and the center reference of the turning mirror are both aligned with the center reference of the theodolite T4 autocollimation, then the attitudes of the four, five, and six mirrors are determined.

[0025] Furthermore, step 4 specifically involves:

[0026] 4.1 Remove the center reference of the relay mirror and the center reference of the rear correction mirror. Install the second folding mirror on the main structural plate between the center reference A and the four mirrors. Place the theodolite T5 on one side of the second folding mirror. Adjust the theodolite T5 to the earth level so that its pitch angle is 90°. Install the front correction mirror on the main structural plate between the center reference B and the five mirrors so that the height of the front correction mirror is consistent with the center of the center reference B.

[0027] 4.2 Adjust the attitude of the second folding mirror so that the center reference B is aligned with the theodolite T5; move the front correction mirror so that the center of the diffraction ring of the front correction mirror coincides with the center cross of the center reference B;

[0028] 4.3. Set a second plane mirror at the center of the front correction mirror on the side closest to the center reference B, and adjust the azimuth and elevation angles of the front correction mirror so that the second plane mirror is aligned with the theodolite T5 for autocollimation.

[0029] Furthermore, step 5 specifically includes:

[0030] 5.1 Install the third folding-axis mirror on the main structural plate, between the fifth and sixth mirrors. Set up an interferometer on one side of the third folding-axis mirror, with the interferometer's working end corresponding to the third folding-axis mirror. Set up the third plane mirror at the end of the theodolite T5 furthest from the second folding-axis mirror. Change the azimuth angle of the theodolite T5 by 180° so that it is aligned with the third plane mirror. Adjust the third plane mirror to autoalign with the theodolite T5. Set the reset mark of the through-center reference B on the main structural plate and remove the through-center reference B. Detect and record the transmitted wavefront of the front correction mirror using the interferometer.

[0031] 5.2 Install the rear correction mirror on the main structure plate between the fifth and sixth mirrors. Translate the third folding mirror along the optical axis so that it is positioned between the rear correction mirror and the sixth mirror. Correspondingly, translate the interferometer and detect the transmitted wavefront of the combination of the front and rear correction mirrors using the interferometer. Adjust the orientation of the rear correction mirror according to the detection result and the transmitted wavefront recorded in step 5.1 until the two are consistent.

[0032] 5.3 Remove the center reference of the steering mirror, install the steering mirror on the reflection optical axis of the six mirrors, translate the third folding mirror along the optical axis so that it is located on the reflection optical axis of the six mirrors, and translate the interferometer accordingly. Detect the transmitted wavefront of the combination of the front correction mirror, the rear correction mirror and the steering mirror through the interferometer. Adjust the attitude of the steering mirror according to the detection result and the transmitted wavefront recorded in step 5.1 until the two are consistent.

[0033] 5.4. Based on the reset mark of the center reference B, reset the center reference B, translate the second folding mirror along the optical axis to bring it close to the center reference A, and correspondingly translate the theodolite T5 and the third plane mirror to adjust the attitude of the second folding mirror so that the center reference B and the theodolite T5 are aligned and aligned.

[0034] 5.5 Install a relay mirror on the main structural plate, between the four mirrors and the second folding mirror. Detect the transmitted wavefront of the relay mirror, front correction mirror, rear correction mirror and steering mirror combination using an interferometer. Adjust the attitude of the relay mirror according to the detection result and the transmitted wavefront recorded in step 5.1 until the two are consistent.

[0035] 5.6 Remove the center reference A, center reference B, second folding mirror, and third folding mirror. Reverse the complex folding camera by 90° so that the optical axis of the diffraction primary mirror is in the horizontal plane of the earth. Set up the theodolite T6 on the side of the diffraction primary mirror away from the secondary mirror, and set up the fourth plane mirror on the side of the theodolite T6 away from the diffraction primary mirror. The working end of the theodolite T6 is opposite to the diffraction primary mirror. Adjust the theodolite T6 to be horizontal with the earth and set its elevation angle to 90°. Adjust the attitude of the complex folding camera so that the autocollimation image of the diffraction primary mirror is autocollimated with the theodolite T6. Change the azimuth angle of the theodolite T6 by 180° so that its working end is opposite to the fourth plane mirror. Adjust the fourth plane mirror so that it is autocollimated with the theodolite T6.

[0036] 5.7 Remove the theodolite T6, move the interferometer to the optical axis on the side of the turning mirror away from the six mirrors, and use the interferometer to detect the transmitted wavefront of the combination of the diffraction primary mirror, relay mirror, front correction mirror, rear correction mirror and turning mirror. Adjust the attitude of the diffraction primary mirror according to the detection result and the transmitted wavefront recorded in step 5.1 until the two are consistent; complete the optical axis consistency installation and adjustment of the complex folding mirror group.

[0037] Furthermore, step 1 specifically includes:

[0038] 1.1 Place the reference datum A on the mounting surface of the main structural plate near the first support column, and set up the theodolite T1 on the outside of the main structural plate near the second support column. Adjust the theodolite T1 so that its field of view center coincides with the cross center of the reference datum A. At the same time, adjust the pitch angle of the theodolite T1 to 90° so that the line of sight of the theodolite T1 is in the XOY plane of the geodetic coordinate system C0. Move the reference datum A along the line of sight of the theodolite T1 to a position near the second support column. Adjust the height of the second support column so that the cross center of the reference datum A coincides with the field of sight center of the theodolite T1.

[0039] 1.2 Move the reference datum A to a position close to the first support column, and set up the theodolite T2 on one side of the main structural plate near the third support column. Adjust the theodolite T2 so that its field of view center coincides with the crosshair center of the reference datum A. At the same time, adjust the pitch angle of the theodolite T2 to 90° so that the line of sight of the theodolite T2 is in the XOY plane of the geodetic coordinate system C0. Move the reference datum A along the line of sight of the theodolite T2 to a position close to the third support column, and adjust the height of the third support column so that the crosshair center of the reference datum A coincides with the field of sight center of the theodolite T2.

[0040] 1.3 Repeat steps 1.1 and 1.2 multiple times until the mounting surface of the main structural plate is horizontal.

[0041] The beneficial effects of this invention are:

[0042] 1. The method for aligning the optical axis of complex folding mirror groups provided by this invention ensures that all mirror groups are in a horizontal measurement coordinate system during the assembly process, which is beneficial for the rapid and accurate positioning of the reflecting and transmitting mirror groups and can efficiently complete the alignment of the mirror groups.

[0043] 2. The through-center reference A established in this invention plays a crucial role in the 3700mm optical path, facilitating the extraction of the diffraction primary mirror reference and the precise alignment of the diffraction correction mirror on the main structure plate, thereby eliminating a large amount of chromatic aberration in the camera and improving image quality. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the structure of a complex folding-axis camera;

[0045] Figure 2 This is a diagram showing the state of the main structural plate mounting surface being adjusted to be horizontal in an embodiment of the present invention;

[0046] Figure 3 This is a schematic diagram of the structure for arranging the center reference A and the theodolite T3 in an embodiment of the present invention;

[0047] Figure 4 This is a schematic diagram of the structure of the relay mirror through-center reference, the rear correction mirror reference, the turning mirror through-center reference, the first folding axis mirror, and the theodolite T4 arranged in this embodiment of the invention.

[0048] Figure 5 This is a state diagram of the installation of the front correction mirror in an embodiment of the present invention;

[0049] Figure 6 This is a schematic diagram of the structure of the complex folded-axis camera in an embodiment of the present invention when the optical axis of the diffraction primary mirror is horizontal with the earth.

[0050] Icon labels:

[0051] 1-Diffraction primary mirror, 10-Center of primary mirror diffraction ring, 2-Secondary mirror, 3-Third mirror, 4-Fourth mirror, 5-Fifth mirror, 6-Sixth mirror, 7-Main structure plate, 71-First support column, 72-Second support column, 73-Third support column, 81-Relay mirror, 810-Relay mirror through-center reference, 82-Front correction mirror, 820-Center of front correction mirror diffraction ring, 83-Rear correction mirror, 830-Rear correction mirror reference, 84-Steering mirror, 840-Steering mirror through-center reference, 91-First folding axis mirror, 92-Second folding axis mirror, 93-Third folding axis mirror, 94-Third plane mirror, 95-Fourth plane mirror, 01-04 are the placement positions of through-center reference A. Detailed Implementation

[0052] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0053] like Figure 1 As shown, the complex folding-axis camera includes a circular main structural plate 7, a first support column 71, a second support column 72, and a third support column 73 arranged vertically below the main structural plate 7 in a clockwise direction, a diffraction primary mirror 1 arranged parallel to the main structural plate 7, a secondary mirror 2 arranged on the main structural plate 7 and sharing the optical axis with the diffraction primary mirror 1, a third mirror 3, a relay mirror 81, a fourth mirror 4, a front correction mirror 82, a fifth mirror 5, a rear correction mirror 83, and a sixth mirror 6 arranged on the main structural plate 7 and sharing the optical path with the secondary mirror 2, and a turning mirror 84 located above the sixth mirror 6 and sharing the optical axis with the sixth mirror 6; the top of the main structural plate 7 is the mounting surface; the third mirror 3, the fourth mirror 4, the fifth mirror 5, and the sixth mirror 6 are all reflecting mirrors. To ensure the optical axis of this complex folding-axis camera is aligned, the method provided in this embodiment of the invention is as follows:

[0054] 1) First, adjust the main structural slab 7 to be level with the ground, such as... Figure 2 As shown, the specific method is as follows: Place the reference datum A on the mounting surface of the main structural plate 7. Arrange theodolites T1 and T2. After leveling theodolites T1 and T2 to the horizontal, adjust their elevation angles to 90°, meaning the lines of sight of theodolites T1 and T2 are within the XOY plane of the geodetic coordinate system C0. First, place the reference datum A at position 01, close to the first support column 71. Adjust the translation in the y and z directions of the local coordinate system of theodolite T1 and adjust the azimuth angle so that the crosshair center of the reference datum A coincides with the crosshair center of the field of view of theodolite T1. Move the reference datum A to position 02, close to the second support column 72. Under the monitoring of theodolite T1, adjust the height of the second support column 72 so that the crosshair center of the reference datum A at position 02 coincides with the crosshair center of the field of view of theodolite T1. Then, the reference datum A was placed at positions 03 and 04 respectively. Under the monitoring of the theodolite T2, the height of the third support column 73 was adjusted in the same way. After repeated iterative adjustments, the XOY plane of the coordinate system C1 where the main structural plate 7 is located is parallel to the XOY plane of the geodetic coordinate system C0, thus achieving the geodetic level adjustment of the mounting surface of the main structural plate 7.

[0055] 2) such as Figure 3As shown, a diffraction primary mirror 1, secondary mirror 2, third mirror 3, and a center reference A are installed on the mounting surface of the main structural plate 7. The center position of the diffraction primary mirror 1 can be observed through the center 10 of the diffraction ring of the primary mirror, and the optical axis of the diffraction primary mirror 1 can be observed through a first plane mirror set on its surface. A theodolite T3 is arranged on one side of the main structural plate 7, with the working end of the theodolite T3 facing the center reference A. The diffraction primary mirror 1, secondary mirror 2, third mirror 3, and the theodolite T3 are adjusted so that the laser emitted by the theodolite T3 can be reflected by the first plane mirror, secondary mirror 2, and third mirror 3 respectively and return to the field of view of the theodolite T3, and the elevation angle of the theodolite T3 is set to 90°. Under the monitoring of the theodolite T3, the base shim of the center reference A is trimmed to ensure that the autocollimation image of the center reference A is at the center of the field of view in the elevation direction of the theodolite T3. Translate the diffraction primary mirror 1 and the three mirrors 3 so that the center 10 of the diffraction ring of the primary mirror and the crosshairs of the pivot reference A both coincide with the center crosshairs of the theodolite T3's field of view. Adjust the azimuth and elevation angles of the three mirrors 3 so that the autocollimated image of the first plane mirror on the diffraction primary mirror 1 is at the center of the field of view of the theodolite T3 in the elevation direction. Adjust the azimuth angle of the theodolite T3 to bring the autocollimated image of the first plane mirror at the diffraction primary mirror 1 to the center of the theodolite T3's field of view, and adjust the azimuth angle of the pivot reference A so that its autocollimated image moves to the center of the theodolite T3's field of view. Then adjust the translation of the diffraction primary mirror 1 so that the center 10 of the diffraction ring of the primary mirror coincides with the center of the pivot reference A in the theodolite T3's field of view. At this point, the reference of the diffraction primary mirror 1 has been completely transferred to the pivot reference A.

[0056] 3) such as Figure 4 As shown, reference fixtures such as repeater reference 810, reference B, rear correction reference 830, and steering reference 840 are installed. Reflectors such as four-mirror 4, five-mirror 5, and six-mirror 6 are installed. The first folding-axis mirror 91 is placed at reference A, and the theodolite T4 is arranged to one side of the first folding-axis mirror 91. After leveling the theodolite T4, its elevation angle is adjusted to 90°. The attitude of the first folding-axis mirror 91 is adjusted so that the theodolite T4 is self-aligned with reference A. The translation and attitude of the repeater reference 810 on the mounting surface of the main structural plate 7 are adjusted so that it is self-aligned with reference A. The elevation angle of the four-mirror 4 on the mounting surface of the main structural plate 7 is adjusted so that the crosshairs of the reticle of reference B are centered in the field of view of the theodolite T4 in the elevation direction. Then adjust the azimuth angle of the four mirrors 4 on the mounting surface of the main structural plate 7 so that the crosshairs of the reticle of the pivot reference B are in the center of the field of view in the azimuth direction of the theodolite T4. Then adjust the azimuth angle of the pivot reference B on the mounting surface of the main structural plate 7 so that its reticle autocollimation image is autocollimated with the theodolite T4.

[0057] 4) The position and attitude adjustment of the five mirrors 5 and the rear correction mirror through the center reference 830 is the same as the through process of the four mirrors 4 and through the center reference B; the position and attitude adjustment of the six mirrors 6 and the turning mirror through the center reference 840 is also the same as the through process of the four mirrors 4 and through the center reference B; all are monitored using the theodolite T4.

[0058] 5) such as Figure 5 As shown, a second folding mirror 92 is installed on the main structural plate 7, between the center reference A and the four mirrors 4; a theodolite T5 is arranged on one side of the second folding mirror 92; the theodolite T5 is adjusted to be horizontal, with its elevation angle at 90°; a front correction mirror 82 is installed on the main structural plate 7, between the center reference B and the five mirrors 5, so that the height of the front correction mirror 82 is consistent with the center of the center reference B; under the monitoring of the theodolite T4, the center 820 of the diffraction ring of the front correction mirror is adjusted to the center of the theodolite's field of view T4. The azimuth and elevation angles of the front correction mirror 82 are adjusted so that the autocollimated image of the second plane mirror moves to the center of the theodolite T4's field of view. At this time, the diffraction surface on the diffraction primary mirror 1 and the diffraction surface on the front correction mirror 82 achieve autocollimation and centering. A second folding-axis mirror and a third plane mirror 94 are placed in the optical path. The attitude of the third plane mirror 94 is adjusted by self-aligning with the center reference B and then by rotating the theodolite T5 horizontally by 180°. A third folding-axis mirror 93 and an interferometer are placed behind the five mirrors 5 to detect the transmitted wavefront of the pre-correction mirror.

[0059] 6) such as Figure 6 As shown, after installing the rear correction mirror 83, the third folding-axis mirror 93 and the interferometer are rearranged, and the attitude of the rear correction mirror 83 is fine-tuned based on the transmission wavefront detection results. Next, the steering mirror 84 is installed, the third folding-axis mirror 93 and the interferometer are rearranged, and the attitude of the steering mirror 84 is fine-tuned based on the transmission wavefront detection results. Using the through-center reference B as a reference, the second folding-axis mirror 92 and the third plane mirror 94 are rearranged, and the relay mirror 81 is installed. The attitude of the relay mirror 81 is fine-tuned based on the transmission wavefront detection results. Finally, all through-center references are removed, and the optical axis of the diffraction primary mirror 1 is flipped to the horizontal plane of the earth using a flipping device. The fifth plane mirror 95 is placed in front of the diffraction primary mirror 1, and the fifth plane mirror 95 is autocollimated with the diffraction primary mirror using a theodolite T6. The interferometer is then set up, completing the overall camera inspection.

[0060] It should be noted that:

[0061] 1. Both the through-center reference A and through-center reference B are of the form of a base + reticle assembly structure. The accuracy of the base and reticle assembly is ensured by centering machining, with a radial gap not exceeding 0.01mm. The center height of the through-center reference to the mounting surface of the main structural plate 7 differs from the center height of the corresponding lens assembly by no more than 0.01mm. The base can be installed on the main structural plate 7 by screw connection, and the reticle assembly can be repeatedly disassembled and reassembled on the base, providing repeatability.

[0062] 2. When aligning references A and B, the reticle assembly is mounted on the base. During wavefront transmission testing of the mirror assembly, the reticle assembly is removed, leaving only the base. After aligning the repeater mirror aligner 810, the rear correction mirror aligner 830, and the steering mirror aligner 840, positioning blocks are glued around the references for resetting and installing the repeater mirror 81, the rear correction mirror 83, the steering mirror 84, and other mirror assemblies.

[0063] 3. All lens groups installed on the main structural plate 7 shall have their center height measured and the bottom shims trimmed to ensure that the center height of all lens groups does not differ from the theoretical value by more than 0.01mm.

[0064] 4. The initial position of all mirror groups and the center reference installation is monitored by the corresponding theodolite. Based on the adjustable margin of the through hole, the position is shifted to the extreme positions on both sides and then fixed in the middle position. Further adjustments are made according to the center requirements.

[0065] Autocollimation means that the reflected image of the reticle or reference mirror coincides with the central crosshair of the theodolite's field of view, indicating infinity imaging; through-center means that the central crosshair of the reticle or reference mirror coincides with the center of the theodolite's field of view, indicating finite distance imaging. Both autocollimation and through-center means must meet the above coincidence requirements, with autocollimation accuracy within 5″ and through-center accuracy within 0.02mm.

[0066] In this embodiment, the total optical path length is 3700mm. Following the steps described above, the ground level is adjusted. By adjusting the height of each supporting column, the mounting surface of the camera's main structural plate 7 is ensured to be horizontal. The distance between positions 01-02 and 03-04 on the main structural plate 7 is approximately 1000mm. This distance can be adjusted under the monitoring of a theodolite until the height difference does not exceed 0.02mm, and the angle between the mounting surface and the ground level does not exceed 5″. When establishing the centering reference A, the distance between the diffraction primary mirror 1 and the centering reference A along the optical axis is 2200mm. The accuracy of the centering reference can reach 0.02mm. Therefore, after the orientation of the centering reference A is determined, the deviation from the theoretical optical axis direction is within 2″. Then, using the centering reference A as the assembly and adjustment reference for the entire machine, the orientation of the reflecting mirror is determined. After each lens group's centering reference and centering reference A are aligned, positioning blocks are glued or pins are driven at the lens group's mounting position for resetting and installation. The front correction mirror is aligned with the reference point A, ensuring an autocollimation accuracy of 5″ and within 0.02mm. The remaining lens groups are then reset using the positioning blocks or pins of the lens group reference points, and further fine-tuned based on the transmitted wavefront detection data. This fine-tuning should not exceed 0.02mm. After fine-tuning, the overall detection result is 0.122λ@3390nm on-axis, meeting the actual requirement of 0.136λ@3390nm, and the off-axis 0.4° field aberration is essentially symmetrical.

[0067] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present invention should be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for aligning the optical axis of a complex folding-axis mirror assembly, used in a complex folding-axis camera, the complex folding-axis camera comprising an annular main structure plate (7), a first support column (71), a second support column (72) and a third support column (73) arranged vertically below the main structure plate (7) in a clockwise direction, a diffraction primary mirror (1) arranged parallel to the main structure plate (7), a secondary mirror (2) arranged above the main structure plate (7) and sharing the optical axis with the diffraction primary mirror (1), a third mirror (3), a relay mirror (81), a fourth mirror (4), a front correction mirror (82), a fifth mirror (5), a rear correction mirror (83), and a sixth mirror (6) arranged above the main structure plate (7) and sharing the optical path with the second mirror (2), and a turning mirror (84) located above the sixth mirror (6) and sharing the optical axis with the sixth mirror (6); the upper part of the main structure plate (7) is a mounting surface; Its features are, Includes the following steps: Step 1: Adjust the mounting surface of the main structural plate (7) to be horizontal; Step 2: Transfer the through-center reference of the diffraction primary mirror (1) to the through-center reference A on the main structural plate (7) through the secondary mirror (2) and the third mirror (3); specifically: 2.1 Install a diffraction primary mirror (1) below the main structural plate (7), and set a first plane mirror at the center of the diffraction primary mirror (1). Install a secondary mirror (2) above the main structural plate (7). Set a third mirror (3) on the mounting surface of the main structural plate (7) near the third support column (73). Set a theodolite T3 on one side of the main structural plate (7). Adjust the diffraction primary mirror (1), secondary mirror (2), third mirror (3) and the theodolite T3 so that the laser emitted by the theodolite T3 can be reflected by the first plane mirror, secondary mirror (2) and third mirror (3) respectively and return to the field of view of the theodolite T3. Set the pitch angle of the theodolite T3 to 90°. Set the center reference A between the theodolite T3 and the third mirror (3). Trim the base of the center reference A so that the autocollimation image of the center reference A is at the center of the field of view in the pitch direction of the theodolite T3. 2.

2. Translate the diffraction primary mirror (1), the three mirrors (3) and the theodolite T3 so that the center (10) of the diffraction primary mirror (1), the cross center of the through-center reference A and the cross center of the field of view of the theodolite T3 coincide. 2.3 Adjust the azimuth and elevation angles of the three mirrors (3) so that the autocollimation image of the first plane mirror is at the center of the field of view in the elevation direction of the theodolite T3; 2.4 Adjust the azimuth angle of the theodolite T3 so that the autocollimation image of the first plane mirror coincides with the central crosshair of the theodolite T3's field of view; then adjust the azimuth angle of the center reference A so that its autocollimation image coincides with the central crosshair of the theodolite T3's field of view. 2.

5. Translate the diffraction primary mirror (1) so that the center of its diffraction ring (10), the cross center of the through reference A, and the cross center of the field of view of the theodolite T3 coincide. Then the through reference of the diffraction primary mirror (1) is completely transferred to the cross center of the through reference A. Step 3: Determine the attitudes of the four-mirror (4), five-mirror (5), and six-mirror (6) using the center-piercing reference A; Step 4: Position the front correction mirror (82) on the mounting surface of the main structural plate (7); Step 5: By detecting the attitude of the correction mirror (83), steering mirror (84), relay mirror (81) and diffraction master mirror (1) after adjusting the transmission wavefront, the optical axis consistency of the complex folding mirror group is completed.

2. The method for aligning the optical axis of a complex folding-axis lens assembly according to claim 1, characterized in that, Step 3 specifically involves: 3.1 Install four mirrors (4), five mirrors (5), and six mirrors (6) on the mounting surface of the main structural plate (7); four mirrors (4) are located on the side of the through-center reference A away from three mirrors (3); a relay mirror through-center reference (810) is installed between four mirrors (4) and through-center reference A, through-center reference B is installed between four mirrors (4) and five mirrors (5), and a rear correction mirror through-center reference (830) is installed between five mirrors (5) and six mirrors (6); and a relay mirror through-center reference (810) is installed on the opposite side of the six mirrors (6). A turning mirror through-center reference (840) is installed on the beam path; a first folding mirror (91) is installed between the through-center reference A and the three mirrors (3); a theodolite T4 is arranged on one side of the first folding mirror (91); the theodolite T4 is adjusted to the ground level so that its pitch angle is 90°; the height of the cross centers of the through-center reference A, through-center reference B, relay mirror through-center reference (810), rear correction mirror through-center reference (830), and turning mirror through-center reference (840) are consistent; 3.2 Adjust the attitude of the first folding mirror (91) so that the laser emitted by the theodolite T4 is reflected by the first folding mirror (91), reflected by the center reference A, and reflected back to the theodolite T4 by the first folding mirror (91) in sequence, and make the center reference A and the theodolite T4 self-aligned and aligned. 3.3 Adjust the repeater's centering reference (810) so that it is aligned with centering reference A; 3.4 Adjust the pitch and azimuth angles of the four mirrors (4) so ​​that the cross center of the center reference B coincides with the cross center of the theodolite T4 field of view; then adjust the azimuth angle of the center reference B so that it aligns with the center of the theodolite T4 autocollimation. 3.5 For the five mirrors (5) and the center reference of the rear correction mirror (830), the six mirrors (6) and the center reference of the turning mirror (840), the same method as in step 3.4 is used to make the center reference of the rear correction mirror (830) and the center reference of the turning mirror (840) both aligned with the autocollimation of the theodolite T4, then the attitudes of the four mirrors (4), five mirrors (5) and six mirrors (6) are determined.

3. The method for aligning the optical axis of a complex folding-axis lens assembly according to claim 2, characterized in that, Step 4 specifically involves: 4.1 Remove the relay mirror's center reference (810) and the rear correction mirror's center reference (830), and install the second folding mirror (92) on the main structural plate (7) between the center reference A and the four mirrors (4); arrange the theodolite T5 on one side of the second folding mirror (92); adjust the theodolite T5 to the earth level so that its pitch angle is 90°; install the front correction mirror (82) on the main structural plate (7) between the center reference B and the five mirrors (5) so that the height of the front correction mirror (82) is consistent with the center of the center reference B; 4.2 Adjust the attitude of the second folding mirror (92) so that the center reference B is aligned with the theodolite T5; move the front correction mirror (82) so that the center of the diffraction ring (820) of the front correction mirror coincides with the center cross of the center reference B; 4.

3. Set a second plane mirror at the center of the front correction mirror (82) on the side close to the center reference B, and adjust the azimuth and elevation angles of the front correction mirror (82) so that the second plane mirror is aligned with the theodolite T5.

4. The method for aligning the optical axis of a complex folding-axis lens assembly according to claim 3, characterized in that, Step 5 specifically involves: 5.1 Install a third folding mirror (93) on the main structural plate (7) between the five mirrors (5) and the six mirrors (6). Set an interferometer on one side of the third folding mirror (93), with the working end of the interferometer corresponding to the third folding mirror (93). Set a third plane mirror (94) at the end of the theodolite T5 away from the second folding mirror (92). Change the azimuth angle of the theodolite T5 by 180° so that it is opposite to the third plane mirror (94). Adjust the third plane mirror (94) so ​​that it is self-aligned with the theodolite T5. Set a reset mark for the through-center reference B on the main structural plate (7) and remove the through-center reference B. Detect and record the transmitted wavefront of the front correction mirror (82) through the interferometer. 5.2 Install the rear correction mirror (83) on the main structure plate (7) between the five mirrors (5) and the six mirrors (6). Translate the third folding mirror (93) along the optical axis so that it is located between the rear correction mirror (83) and the six mirrors (6). Correspondingly, translate the interferometer and detect the transmitted wavefront of the combination of the front correction mirror (82) and the rear correction mirror (83) through the interferometer. Adjust the attitude of the rear correction mirror (83) according to the detection results and the transmitted wavefront recorded in step 5.1 until the two are consistent. 5.3 Remove the center reference (840) of the steering mirror, install the steering mirror (84) on the reflection optical axis of the six mirrors (6), translate the third folding mirror (93) along the optical axis so that it is located on the reflection optical axis of the six mirrors (6), and translate the interferometer accordingly. Detect the transmission wavefront of the combination of the front correction mirror (82), the rear correction mirror (83) and the steering mirror (84) through the interferometer. Adjust the attitude of the steering mirror (84) according to the detection result and the transmission wavefront recorded in step 5.1 until the two are consistent. 5.

4. Based on the reset mark of the center reference B, reset the center reference B, translate the second folding mirror (92) along the optical axis to bring it close to the center reference A, and translate the theodolite T5 and the third plane mirror (94) accordingly, adjust the attitude of the second folding mirror (92) so that the center reference B and the theodolite T5 are aligned and aligned. 5.5 Install a relay mirror (81) on the main structural plate (7) between the four mirrors (4) and the second folding mirror (92). Detect the transmitted wavefront of the combination of the relay mirror (81), the front correction mirror (82), the rear correction mirror (83), and the steering mirror (84) using an interferometer. Adjust the attitude of the relay mirror (81) according to the detection result and the transmitted wavefront recorded in step 5.1 until the two are consistent. 5.6 Remove the center reference A, center reference B, second folding mirror (92) and third folding mirror (93), reverse the complex folding camera by 90° so that the optical axis of the diffraction master mirror (1) is in the horizontal plane of the earth, set the theodolite T6 on the side where the diffraction master mirror (1) is far away from the secondary mirror (2), and set the fourth plane mirror (95) on the side where the theodolite T6 is far away from the diffraction master mirror (1); the working end of the theodolite T6 is opposite to the diffraction master mirror (1); adjust the theodolite T6 to be horizontal with the earth and make its pitch angle 90°, adjust the attitude of the complex folding camera so that the autocollimation image of the diffraction master mirror (1) is autocollimated with the theodolite T6, change the azimuth angle of the theodolite T6 by 180° so that its working end is opposite to the fourth plane mirror (95), and adjust the fourth plane mirror (95) so that it is autocollimated with the theodolite T6; 5.7 Remove the theodolite T6 and move the interferometer to the optical axis of the turning mirror (84) away from the six mirrors (6). Detect the transmission wavefront of the combination of the diffraction master mirror (1), relay mirror (81), front correction mirror (82), rear correction mirror (83) and turning mirror (84) using the interferometer. Adjust the attitude of the diffraction master mirror (1) according to the detection result and the transmission wavefront recorded in step 5.1 until the two are consistent; complete the optical axis consistency adjustment of the complex folding mirror group.

5. The method for aligning the optical axis of a complex folding-axis lens assembly according to any one of claims 1-4, characterized in that, Step 1 is as follows: 1.1 Place the reference datum A on the mounting surface of the main structural plate (7) near the first support column (71), and set the theodolite T1 on the outside of the main structural plate (7) near the second support column (72). Adjust the theodolite T1 so that its field of view center coincides with the cross center of the reference datum A. At the same time, adjust the pitch angle of the theodolite T1 to 90° so that the line of sight of the theodolite T1 is in the XOY plane of the geodetic coordinate system C0. Move the reference datum A along the line of sight of the theodolite T1 to a position near the second support column (72). Adjust the height of the second support column (72) so that the cross center of the reference datum A coincides with the field of sight center of the theodolite T1. 1.2 Move the reference point A to a position close to the first support column (71), and set the theodolite T2 on one side of the main structural plate (7) close to the third support column (73). Adjust the theodolite T2 so that its field of view center coincides with the cross center of the reference point A. At the same time, adjust the pitch angle of the theodolite T2 to 90° so that the line of sight of the theodolite T2 is in the XOY plane of the geodetic coordinate system C0. Move the reference point A along the line of sight of the theodolite T2 to a position close to the third support column (73). Adjust the height of the third support column (73) so that the cross center of the reference point A coincides with the field of sight center of the theodolite T2. 1.3 Repeat steps 1.1 and 1.2 multiple times until the mounting surface of the main structural plate (7) is horizontal.

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