A method for adjusting optical axis consistency of a cassette folded axial telescope objective

Abstract

The application discloses a kind of light axis consistency debugging methods of cassette folding axis telescope objective, to solve the problem of low efficiency of existing debugging method, and poor precision and stability.The debugging method provided by the application sets a first through hole in the center of aspheric secondary mirror, and sets the back surface as a plane structure perpendicular to the center axis, forming a plane reflection reference, which is indirectly used as the light axis reference in the subsequent debugging steps, and the system wave phase difference detection and the debugging work of the light axis consistency of all components can be completed simultaneously in the self-collimation interference detection light path, saving the step of installing plane mirror assembly for calibration, improving the light axis consistency debugging efficiency, the precision and stability of adjustment.

Description

Technical Field

[0001] The invention relates to a cassette-type folding-axis telescopic optical system, and in particular to an optical axis consistency debugging method for a cassette-type folding-axis telescopic objective lens. Background Art

[0002] A high-orbit satellite can cover almost the entire hemisphere, forming a regional communication system. Since high-orbit satellite communication has a long distance, a larger-aperture communication telescope system is required.

[0003] For large-aperture communication telescopes, the traditional optical axis consistency debugging method requires the use of an optical reticle fixture to draw out the primary mirror assembly's separate optical axis, serving as the primary optical axis reference for debugging the secondary mirror assembly and other components. Typically, a flat reflector assembly is installed on the outside of the support cylinder to calibrate the optical axis direction, or a cross-hair reticle fixture is installed on the central axis of the primary mirror assembly to mark the primary optical axis direction. This method involves a process step in which the reference reticle and the optical axis for debugging overlap, reducing debugging efficiency. It is also unsuitable for compact optomechanical systems that lack space for an optical axis pointing fixture, and its accuracy and stability are also poor. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for debugging the optical axis consistency of a cassette-type folding-axis telescope objective lens, so as to solve the technical problems that the existing debugging methods are low in efficiency and poor in precision and stability.

[0005] In order to achieve the above object, the present invention provides a method for debugging the optical axis consistency of a cassette-type folding-axis telescope objective lens, which is special in that it includes the following steps:

[0006] Step 1: Processing the back surface of the secondary mirror in the telescope objective lens to be debugged into a plane perpendicular to its central axis, coating the plane with a reflective film, and providing a first through hole along the central axis of the secondary mirror; the back surface of the secondary mirror is the side away from the primary mirror in the telescope objective lens to be debugged;

[0007] Step 2: Set up the interferometer and theodolite accordingly; install a standard plane lens on the interferometer, focus the theodolite to infinity, and adjust the theodolite's posture so that the parallel light emitted by the theodolite is parallel to the parallel light emitted by the interferometer; then replace the interferometer lens with a standard spherical lens, focus the theodolite to emit converged light, and adjust the theodolite's posture so that the principal optical axis of the converged light emitted by the theodolite coincides with the principal optical axis of the converged light emitted by the interferometer;

[0008] Step 3: Replace the interferometer lens with a standard plane lens, set a plane reflector with a second through hole in the center between the theodolite and the interferometer, adjust the plane reflector's posture so that it achieves zero-fringe self-alignment with the interferometer, and make the second through hole located at the center of the interferometer's optical path;

[0009] Step 4, place the to-be-adjusted telescope between the plane mirror and the interferometer, so that the primary mirror is opposite to the interferometer and the secondary mirror is opposite to the plane mirror; adjust the attitude of the to-be-adjusted telescope, so that the back surface of the secondary mirror is collimated with the parallel light emitted by the theodolite;

[0010] Step 5, replace the lens of the interferometer with a standard spherical lens, and translate the to-be-adjusted telescope in a direction perpendicular to the optical axis of the interferometer, so that interference fringes appear in the interferometer;

[0011] Step 6, measure the system wave phase difference of the to-be-adjusted telescope; if the coma component in the system wave phase difference is less than or equal to a first preset value, proceed to step 7; if the coma component in the system wave phase difference is greater than the first preset value, finely adjust the secondary mirror in a direction perpendicular to the optical axis of the interferometer, so that it is less than or equal to the first preset value, and then proceed to step 7;

[0012] Step 7, install a reference tool at the eyepiece installation position of the to-be-adjusted telescope; install a fold mirror in the to-be-adjusted telescope; the reference tool includes an optical scale and an optical scale mirror frame arranged on the periphery of the optical scale;

[0013] Step 8, focus the theodolite to infinity, so that the parallel light emitted by the theodolite passes through a first through hole in the center of the secondary mirror, reaches the fold mirror, and then forms reflected light by reflecting off the fold mirror, the reflected light is returned to the theodolite by the optical scale, and the attitude of the fold mirror is adjusted so that the autocollimation image returned to the theodolite coincides with the center of the theodolite;

[0014] Step 9, focus the theodolite to a finite distance, and translate the reference tool along the optical axis direction of the reflected light, so that the center of the optical scale coincides with the center of the theodolite;

[0015] Step 10, repeatedly perform steps 8 to 9 until the autocollimation image and the through image observed in the theodolite both coincide with the center of the theodolite;

[0016] Step 11, replace the lens of the interferometer with a standard plane lens, and place the interferometer opposite the eyepiece installation position of the to-be-adjusted telescope, and adjust the attitude of the interferometer so that the reference tool reaches zero fringe autocollimation;

[0017] Step 12, remove the reference tool, install the eyepiece, translate the eyepiece along the optical axis direction of the reflected light, so that the defocus component in the system wave phase difference of the to-be-adjusted telescope is less than or equal to a second preset value, and translate the eyepiece along a direction perpendicular to the reflected light, so that the coma component in the system wave phase difference of the to-be-adjusted telescope is less than or equal to a third preset value, and the optical axis consistency adjustment of the to-be-adjusted telescope is completed.

[0018] Further, after step 1 and before step 2, there is a centering step of the secondary mirror:

[0019] The reference mirror, the secondary mirror seat and the secondary mirror are sequentially installed on the centering platform of the vertical centering instrument from bottom to top; the parallel light emitted by the vertical centering instrument is used to irradiate the back of the secondary mirror and the reference mirror; the posture of the secondary mirror on the secondary mirror seat (15) is adjusted, so that the autocollimation image reflected by the secondary mirror is coincident with the autocollimation image reflected by the reference mirror, and then the secondary mirror and the secondary mirror seat are installed on the to-be-adjusted telescope objective lens.

[0020] Further, in step 3, the second through-hole aperture of the center of the plane mirror is 50 mm.

[0021] Further, in step 6, the first preset value, the second preset value in step 12 and the third preset value are all 0.01.

[0022] Further, in step 7, the surface type of the optical scale is less than or equal to 0.02 lambda, wherein lambda is the wavelength of the light emitted by the interferometer.

[0023] Further, in step 1, the first through-hole aperture arranged on the secondary mirror is 8 mm.

[0024] Further, in step 6, when the secondary mirror is translated and fine-adjusted, the secondary mirror seat is translated and fine-adjusted.

[0025] Advantages of the present application:

[0026] 1. The adjusting method provided by the present application sets a first through-hole in the center of the secondary mirror of the aspheric surface, sets the back of the secondary mirror as a plane structure perpendicular to the central axis, forms a plane reflection reference, indirectly uses the plane reflection reference as the optical axis reference in the subsequent adjusting steps, simultaneously completes the system wave phase difference detection and the adjusting work of the optical axis consistency of all components in the autocollimation interference detection light path, saves the step of installing the plane mirror assembly for calibration, and improves the optical axis consistency adjusting efficiency, the adjusting precision and the stability.

[0027] 2. The first through-hole set in the center of the secondary mirror can also eliminate stray light, and further improve the adjusting precision of the optical axis consistency. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a structural schematic diagram of a to-be-adjusted telescope objective lens of the present application;

[0029] Figure 2 is a structural schematic diagram of an embodiment of the present application to step 5;

[0030] Figure 3 is a structural schematic diagram of an embodiment of the present application to step 7;

[0031] Figure 4 is a structural schematic diagram of an embodiment of the present application to step 12;

[0032] Figure 5 is the structure diagram of the embodiment of the present application to carry out the step of aligning the secondary mirror with the heart.

[0033] Reference numerals:

[0034] 01 - reflected light;

[0035] 1 - to-be-adjusted telescope objective, 11 - secondary mirror, 12 - primary mirror, 13 - folding mirror, 14 - eyepiece, 15 - secondary mirror seat, 16 - force-bearing cylinder, 2 - interferometer, 3 - theodolite, 4 - plane mirror, 5 - reference tooling, 6 - vertical centering instrument, 7 - reference mirror. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0037] As shown in Figure 1 , the cassette folding telescope objective, i.e., the to-be-adjusted telescope objective 1, generally consists of a primary mirror assembly, a secondary mirror assembly, an eyepiece assembly, a folding mirror assembly, and a force-bearing cylinder 16. The primary mirror assembly and the secondary mirror assembly form a telescope objective. The primary mirror assembly includes a primary mirror 12 and a primary mirror frame, the secondary mirror assembly includes a secondary mirror 11 and a secondary mirror frame, and the eyepiece assembly includes an eyepiece 14, an eyepiece frame, and an eyepiece cylinder. The primary mirror assembly is assembled with the force-bearing cylinder 16 after traditional centering processing.

[0038] The secondary mirror 11 is an aspheric mirror, the back surface (non-working surface that does not play a role of turning back incident light) of which is designed and processed into a plane that is strictly perpendicular to the optical axis of the secondary mirror reflecting surface (working surface that is coated with a high-reflection film and plays a role of reflecting incident light), and a reflecting film is coated on the plane. After the centering adjustment of the secondary mirror assembly is performed with the plane of the back surface of the secondary mirror 11 as a reference, the secondary mirror assembly is loaded into the force-bearing cylinder 16. That is, the back of the secondary mirror 11 is the direction of the optical axis of the telescope objective, and when parallel light is strictly aligned with the direction of the optical axis and is incident, the image point formed by the position of the focal plane of the telescope objective is the actual focal point position. The direction of the optical axis and the focal point position can be used to demarcate the actual primary optical axis of the telescope objective. The folding mirror turns the actual primary optical axis of the telescope objective by 90° to be perpendicular to the mounting end surface of the eyepiece and to pass through the mounting hole of the eyepiece. Then, the two-dimensional precision adjustment of the telescope objective assembly and the telescope eyepiece assembly is performed again to minimize the aberration coefficient caused by coaxiality. In this way, the optical axis consistency adjustment process of the entire cassette folding telescope optical system is completed with high precision. The specific steps are as follows:

[0039] Step 1, after the primary mirror 12 and the primary mirror frame are assembled, the primary mirror assembly is precisely optically centered, the outer circle and the end face of the primary mirror frame are turned, the outer circle of the turned primary mirror frame is coaxial with the main optical axis of the primary mirror 12 with an accuracy of ≦0.01 mm, and the end face of the turned primary mirror 12 is strictly perpendicular to the main optical axis of the primary mirror 12. And the fitting gap between the turned outer circle of the primary mirror frame and the installation inner diameter of the primary mirror assembly on the load cylinder 16 is 0.15±0.01. The primary mirror assembly is assembled with the load cylinder 16.

[0040] The back surface of the secondary mirror 11 is set as a plane perpendicular to the central axis thereof, and a reflective film is coated on the plane, and a first through hole is arranged along the central axis direction of the secondary mirror 11, and the aperture of the first through hole is 8 mm; the back surface of the secondary mirror 11 is the surface away from the primary mirror 12 in the to-be-adjusted telescope objective lens 1; after the secondary mirror 11 and the secondary mirror frame are assembled, the secondary mirror assembly is installed into the secondary mirror seat 15, and then the secondary mirror 11 is centered, as shown in Figure 5 The back surface of the secondary mirror 11 is set as a plane perpendicular to the central axis thereof, and a reflective film is coated on the plane, and a first through hole is arranged along the central axis direction of the secondary mirror 11, and the aperture of the first through hole is 8 mm; the back surface of the secondary mirror 11 is the surface away from the primary mirror 12 in the to-be-adjusted telescope objective lens 1; after the secondary mirror 11 and the secondary mirror frame are assembled, the secondary mirror assembly is installed into the secondary mirror seat 15, and then the secondary mirror 11 is centered, as shown in

[0041] The eyepiece assembly is a transmissive optical system, and the assembly is completed using a traditional centering processing technology. That is, each transmissive glass is assembled into the eyepiece frame and fastened, and each lens assembly is assembled with the eyepiece cylinder according to requirements after being centered by a traditional centering processing technology.

[0042] Step 2, the interferometer 2 and the theodolite 3 are correspondingly arranged; the standard plane mirror is installed on the interferometer 2, the theodolite 3 is focused to infinity, the attitude of the theodolite 3 is adjusted so that the theodolite 3 is parallel to the parallel light emitted by the interferometer 2; the standard spherical mirror is replaced by the mirror of the interferometer 2, the theodolite 3 is focused to emit converging light, and the attitude of the theodolite 3 is adjusted so that the main optical axis of the converging light emitted by the theodolite 3 coincides with the main optical axis of the converging light emitted by the interferometer 2.

[0043] Specifically, the light emitted by the interferometer 2 can be switched between parallel light and converging light by replacing the standard mirror of the interferometer 2. The theodolite 3 is placed at the center of the light path of the interferometer 2, focused to infinity, and adjusted in azimuth and pitch so that it is strictly parallel to the parallel light emitted by the interferometer 2; the theodolite 3 is focused to converging light, and adjusted in left and right and high and low translation so that it is strictly coincident with the main optical axis of the interferometer 2.

[0044] Step 3, the lens of the interferometer 2 is replaced by a standard plane lens, a plane mirror 4 with a second through hole in the center is arranged between the theodolite 3 and the interferometer 2, the attitude of the plane mirror 4 is adjusted so that it reaches zero fringe self- collimation with the interferometer 2, and the second through hole is located in the center of the light path of the interferometer 2; the aperture of the second through hole is 50mm.

[0045] Specifically, the lens of the interferometer 2 is replaced by a standard plane lens, the tilt of the plane mirror 4 (with a second through hole of φ50mm in the center, and a surface value ≦0.015λ) is adjusted so that it reaches zero fringe self- collimation with the interferometer 2, and the translation of the plane mirror 4 is adjusted so that the second through hole is in the center of the light path of the interferometer 2.

[0046] Step 4, the telescope objective 1 to be adjusted is placed between the plane mirror 4 and the interferometer 2, so that the primary mirror 12 is opposite to the interferometer 2, and the secondary mirror 11 is opposite to the plane mirror 4; the attitude of the telescope objective 1 to be adjusted is adjusted so that the back surface of the secondary mirror 11 is collimated with the parallel light emitted by the theodolite 3, that is, the back surface of the secondary mirror 11 is perpendicular to the parallel light emitted by the theodolite 3.

[0047] Specifically, the telescope objective 1 to be adjusted is placed in the light path, and the tilt of the telescope objective group is adjusted so that the back surface of the secondary mirror 11 is self-collimated with the parallel light emitted by the theodolite 3.

[0048] Step 5, the lens of the interferometer 2 is replaced by a standard spherical lens, forming a light path as shown by the dashed line in Figure 2 , and the telescope objective 1 to be adjusted is translated in a direction perpendicular to the optical axis of the interferometer 2, so that interference fringes appear in the interferometer 2.

[0049] Step 6, the system wave phase difference of the telescope objective 1 to be adjusted is measured; if the coma component in the system wave phase difference is less than or equal to 0.01, step 7 is performed; if the coma component in the system wave phase difference is greater than 0.01, the secondary mirror 11 is finely adjusted by translation in a direction perpendicular to the optical axis of the interferometer 2, so that it is less than or equal to 0.01, and then step 7 is performed; at this time, the coaxiality adjustment of the telescope objective group is completed; when the secondary mirror 11 is finely adjusted by translation, the secondary mirror 11 is translated by finely adjusting the secondary mirror seat 15.

[0050] Step 7, as shown in Figure 3 , a reference tool 5 is installed at the eyepiece mounting place (usually provided with a flange) of the telescope objective 1 to be adjusted; an axicon mirror 13 is installed in the telescope objective 1 to be adjusted; the reference tool 5 includes an optical scale and an optical scale mirror frame arranged on the periphery of the optical scale; the surface value of the optical scale is ≦0.02λ, where λ is the wavelength of the light emitted by the interferometer 2. The optical scale is a plane reflective glass with a cross-shaped wire engraved in the center. Before installation, the reference tool 5 needs to be processed by optical centering, so that the parallelism between the machined mounting end surface and the optical reflection surface of the optical scale is ≦2″, and the coaxiality accuracy between the machined mounting outer diameter and the center of the optical scale is ≦

[0051] 0.01mm, the outer diameter size and the inner diameter of the eyepiece mounting flange are matched with a clearance of 0.02mm.

[0052] Step 8, focus the theodolite 3 to infinity, so that the parallel light emitted by the theodolite 3 passes through the first through hole in the center of the secondary mirror 11, then reaches the fold mirror 13, and then the reflected light 01 is reflected by the fold mirror 13 to form a reflected light 01, and the reflected light 01 is returned to the theodolite 3 by the optical scale in the reference tool 5, and the attitude of the fold mirror 13 is adjusted so that the autocollimation image returned to the theodolite 3 coincides with the center of the theodolite 3.

[0053] Step 9, focus the theodolite 3 to a limited distance, and translate the reference tool 5 along the optical axis direction of the reflected light 01 so that the center of the optical scale coincides with the center of the theodolite 3.

[0054] Step 10, repeatedly steps 8 to 9 until the autocollimation image and the through image observed in the theodolite 3 coincide with the center of the theodolite 3.

[0055] Specifically, steps 8 to 9 are repeated multiple times, and whether the cross hair of the optical scale in the reference tool 5 coincides with the center of the theodolite 3 is observed, and if not, the reference tool 5 is adjusted until the autocollimation image and the through image observed in the theodolite 3 coincide with the center of the theodolite 3. In a specific implementation, the autocollimation accuracy is 3" and the through accuracy is 0.02mm.

[0056] Step 11, replace the lens of the interferometer 2 with a standard plane lens, and place the interferometer 2 opposite to the eyepiece mounting position of the telescope objective lens 1 to be adjusted, and adjust the attitude of the interferometer 2 so that it reaches zero fringe autocollimation with the reference tool 5.

[0057] Step 12, as shown in Figure 4 , remove the reference tool 5 and install the eyepiece 14, translate the eyepiece 14 along the optical axis direction of the reflected light 01 so that the defocus component in the system wave phase difference of the telescope objective lens 1 to be adjusted is ≦0.01, and translate the eyepiece 14 along the direction perpendicular to the reflected light 01 so that the coma component in the system wave phase difference of the telescope objective lens 1 to be adjusted is ≦0.01, and the optical axis consistency adjustment of the telescope objective lens 1 to be adjusted is completed.

[0058] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto, any change or replacement within the technical scope disclosed by the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for adjusting the optical axis consistency of a folded telescope objective, characterized in that The method comprises the following steps: Step 1, the back surface of the secondary mirror (11) in the to-be-adjusted telescope objective lens (1) is processed to be a plane perpendicular to the central axis thereof, a reflective film is coated on the plane, and a first through hole is arranged along the central axis of the secondary mirror (11); the back surface of the secondary mirror (11) is a surface away from the primary mirror (12) in the to-be-adjusted telescope objective lens (1); Step 2, an interferometer (2) and a theodolite (3) are correspondingly arranged; the interferometer (2) is installed with a standard plane lens, the theodolite (3) is focused to infinity, the attitude of the theodolite (3) is adjusted, so that the parallel light emitted by the theodolite (3) is parallel to the parallel light emitted by the interferometer (2); then the lens of the interferometer (2) is replaced with a standard spherical lens, the theodolite (3) is focused to emit convergent light, and the attitude of the theodolite (3) is adjusted, so that the convergent light emitted by the theodolite (3) is coaxial with the convergent light emitted by the interferometer (2); Step 3, the lens of the interferometer (2) is replaced with a standard plane lens, a plane mirror (4) with a second through hole in the center is arranged between the theodolite (3) and the interferometer (2), the attitude of the plane mirror (4) is adjusted, so that the plane mirror (4) and the interferometer (2) reach zero fringe self-collimation, and the second through hole is located at the center of the light path of the interferometer (2); Step 4, the to-be-adjusted telescope objective lens (1) is placed between the plane mirror (4) and the interferometer (2), so that the primary mirror (12) of the to-be-adjusted telescope objective lens (1) is opposite to the interferometer (2), and the secondary mirror (11) of the to-be-adjusted telescope objective lens (1) is opposite to the plane mirror (4); the attitude of the to-be-adjusted telescope objective lens (1) is adjusted, so that the back surface of the secondary mirror (11) is collimated with the parallel light emitted by the theodolite (3); Step 5, the lens of the interferometer (2) is replaced with a standard spherical lens, the to-be-adjusted telescope objective lens (1) is adjusted in translation along a direction perpendicular to the optical axis of the interferometer (2), so that interference fringes appear in the interferometer (2); Step 6, the system wave phase difference of the to-be-adjusted telescope objective lens (1) is measured; if the coma component in the system wave phase difference is less than or equal to a first preset value, step 7 is performed; if the coma component in the system wave phase difference is greater than the first preset value, the secondary mirror (11) is finely adjusted in translation along a direction perpendicular to the optical axis of the interferometer (2), so that the coma component is less than or equal to the first preset value, and then step 7 is performed; Step 7, a reference tool (5) is installed at the eyepiece (14) of the to-be-adjusted telescope objective lens (1); an anamorphic mirror (13) is installed in the to-be-adjusted telescope objective lens (1); the reference tool (5) comprises an optical scale plate and an optical scale plate mirror frame arranged at the periphery of the optical scale plate; Step 8, the theodolite (3) is focused to infinity, so that the parallel light emitted by the theodolite (3) passes through the first through hole in the center of the secondary mirror (11) and then reaches the anamorphic mirror (13), and then the anamorphic mirror (13) reflects to form reflected light (01); the reflected light (01) is self-collimated back to the theodolite (3) by the optical scale plate, and the attitude of the anamorphic mirror (13) is adjusted, so that the self-collimated image self-collimated back to the theodolite (3) is coincident with the center of the theodolite (3). Step 9, focus the theodolite (3) to a limited distance, and translate the adjustment reference tool (5) along the optical axis direction of the reflected light (01), so that the center of the optical scale is coincident with the center of the theodolite (3); Step 10, repeat steps 8 to 9 multiple times until the autocollimation image and the through image observed in the theodolite (3) are both coincident with the center of the theodolite (3); Step 11, replace the lens of the interferometer (2) with a standard plane lens, and install the interferometer (2) opposite to the eyepiece (14) mounting position of the to-be-adjusted telescope objective lens (1), and adjust the posture of the interferometer (2) to achieve zero fringe autocollimation with the adjustment reference tool (5); Step 12, remove the adjustment reference tool (5), install the eyepiece (14), translate the eyepiece (14) along the optical axis direction of the reflected light (01), so that the defocus component in the system wave phase difference of the to-be-adjusted telescope objective lens (1) is less than or equal to a second preset value, and translate the eyepiece (14) along a direction perpendicular to the reflected light (01), so that the coma component in the system wave phase difference of the to-be-adjusted telescope objective lens (1) is less than or equal to a third preset value, and the optical axis consistency adjustment of the to-be-adjusted telescope objective lens (1) is completed.

2. The method of collimating the optical axis of a catadioptric telescope objective according to claim 1, characterized in that After step 1 and before step 2, the centering step of the secondary mirror (11) is further included: The reference mirror (7), the secondary mirror seat (15) and the secondary mirror (11) are sequentially installed from bottom to top on the centering platform of the vertical centering instrument (6); the parallel light emitted by the vertical centering instrument (6) irradiates the back of the secondary mirror (11) and the reference mirror (7); the posture of the secondary mirror (11) on the secondary mirror seat (15) is adjusted so that the autocollimation image reflected by the secondary mirror (11) is coincident with the autocollimation image reflected by the reference mirror (7), and then the secondary mirror (11) and the secondary mirror seat (15) are installed on the to-be-adjusted telescope objective lens (1).

3. The method of collimating the optical axis of a catadioptric telescope objective according to claim 1 or 2, characterized in that: In step 3, the second through hole aperture of the center of the plane mirror (4) is 50mm.

4. The method of collimating the optical axis of a catadioptric telescope objective according to claim 3, characterized in that: In step 6, the first preset value, the second preset value in step 12 and the third preset value are all 0.

01.

5. The method of collimating the optical axis of a folded card telescope objective according to claim 4, characterized in that: In step 7, the surface type of the optical scale is less than or equal to 0.02λ, where λ is the wavelength of the light emitted by the interferometer (2).

6. The method of collimating the optical axis of a folded card telescope objective according to claim 5, characterized in that: In step 1, the first through hole aperture provided on the secondary mirror (11) is 8mm.

7. The method of collimating the optical axis of a folded card telescope objective according to claim 6, characterized in that: In step 6, when the secondary mirror (11) is translated and fine adjusted, the secondary mirror seat (15) is translated and fine adjusted.

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