A method for detecting the magnification of a large-aperture telescope

Abstract

The present invention discloses a method for detecting the magnification of a large-aperture telescope, comprising: S1, installing a detection device in place according to detection requirements; S2, adjusting the pitch angle and yaw angle of the detection device so that straight interference fringes are displayed on a surface interferometer; S3, adjusting the pitch angle and yaw angle of an autocollimator, displaying the angle value between a large-aperture plane mirror and the autocollimator on the autocollimator, and setting the angle value to 0; S4, adjusting the large-aperture plane mirror to a small angle, displaying inclined interference fringes on the surface interferometer, and recording them as θ. T , the angle value displayed on the autocollimator is recorded as θ M ; S5, then adjust the large-aperture plane mirror in the opposite direction to a small angle, and the surface interferometer will show inclined interference fringes, which are recorded as θ T ， , the angle value displayed on the autocollimator is recorded as θ M ， ; S6, calculate the angular magnification M of the telescope under test 角 , and then convert it into its magnification M; S7, replace the sub-telescope and repeat steps S1-S6. This application has high detection accuracy and is easy to promote and apply.

Description

Technical Field

[0001] The present invention relates to the fields of astronomical observation technology and astronomical observation instrument detection technology, and in particular to a method for detecting the magnification of a large-aperture telescope. Background Art

[0002] An optical telescope is an optical instrument used to observe distant objects, consisting of lenses or reflectors, as well as other optical components and structural parts. Reflecting telescopes are widely used in astronomical observations. These telescopes consist of several large-aperture primary and small-aperture secondary mirrors. They can magnify the smallest angles of distant objects by a certain factor, giving them a larger angle in image space, making objects that would otherwise be difficult to see or distinguish with the naked eye clearly discernible.

[0003] Compared to single-aperture telescopes, spatially distributed synthetic aperture (SDSA) uses a telescope array to achieve the equivalent spatial resolution of a single large-aperture telescope, breaking through the diffraction limit imposed by the aperture size of a single-aperture telescope. Synthetic aperture imaging systems involve multiple sub-telescopes, and the magnification of each sub-telescope must be precisely measured. Inconsistent magnifications across sub-telescopes can introduce pupil mapping errors (pupil mapping refers to the similarity between the image formed by the entrance pupil and the image formed by the exit pupil of each sub-telescope), which can affect the field of view of the optical synthetic aperture imaging system. Therefore, accurate measurement of the magnification of each sub-telescope is crucial.

[0004] The optical synthetic aperture imaging system in this application comprises three coaxial reflecting sub-telescopes of identical composition, structure, and parameters, arranged in an equilateral triangle. Each sub-telescope has a designed entrance pupil diameter of 360 mm and an exit pupil diameter of 72 mm, resulting in a designed magnification of 0.2 and an angular magnification of 5. The sub-telescopes in this application have a larger aperture and are coaxial systems. Considering that existing surface interferometers cannot simultaneously image the exit pupils of the sub-telescopes and large-aperture plane mirrors, a novel method for detecting the magnification of large-aperture sub-telescopes in this optical synthetic aperture imaging system is proposed.

[0005] Existing methods and means:

[0006] 1. Zhejiang Zheguang Technology Co., Ltd. has proposed a device and method for measuring the magnification of a self-assembled telescope using the reticle method. A reticle is placed between the eyepiece and the objective lens. The principle of lens imaging is used to accurately calculate the focal length of the objective lens and eyepiece. Starting from the actual magnification of the system's limited farsightedness, the magnification of the afocal telescope system is ultimately obtained. The device and method have a simple structure and are easy to operate.

[0007] 2. Shaanxi Zhiyuan Kefeng Optoelectronics Technology Co., Ltd. has proposed a new type of telescope magnification tester, which includes a collimator assembly, a telescope assembly to be tested, a CCD camera assembly, and a mounting platform assembly. The telescope assembly to be tested is located between the collimator assembly and the CCD camera assembly. The collimator assembly is used to emit a light beam through the telescope assembly to be tested, and then the CCD camera assembly collects the image. The CCD camera assembly measures the image height of the left and right lens barrels of the telescope assembly to be tested. The measured image height is divided by the graticule value in the collimator assembly to obtain the magnification of the telescope to be tested, which improves the accuracy and efficiency of imaging data collection to a certain extent.

[0008] Harbin Institute of Technology has proposed an improved method for measuring the magnification of self-assembled telescopes using the direct comparison method of visual angle. This method places a target ruler at the front of the telescope. During measurement, the user observes the magnified images of the upper and lower indexes through the telescope eyepiece with one eye, while observing the actual target ruler with the other eye. The distance between the indexes and images is then measured directly using the target ruler. The magnification of the telescope is obtained by dividing the distance between the indexes and images. This system is simple and easy to operate, whereas visual counting is subject to large errors.

[0009] Huzhou Normal University has proposed a method for measuring a telescope's pupil and calculating its magnification. This method uses an aperture stop at the front of the telescope to represent the entrance pupil diameter, and an image screen at the back. The size of the image on the screen represents the exit pupil diameter. The magnification of the telescope is calculated by dividing the entrance pupil diameter by the exit pupil diameter. This method is simple and easy to operate, but has relatively low accuracy.

[0010] Disadvantages of existing technology:

[0011] (1) In the existing telescope magnification measurement method, the line error of the graticule and the image recognition error are large. The measurement error of the object and image size by visual inspection is even larger. The measurement error of the telescope entrance pupil diameter and exit pupil diameter is also large, so the error of the calculated magnification is also large.

[0012] (2) The above methods involve image recognition algorithms, which require the development and optimization of algorithms, which is relatively complex and time-consuming.

[0013] (3) The above method requires more instruments, is difficult to debug, is costly, and has a complex system.

[0014] The information disclosed in this background technology section is only intended to deepen the understanding of the overall background technology of the present invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art. Summary of the Invention

[0015] In view of the problems existing in the prior art, the purpose of the present invention is to provide a method for detecting the magnification of a large-aperture telescope to solve the problems existing in the prior art.

[0016] In order to achieve the above object, the present invention adopts the following technical solutions:

[0017] A method for detecting the magnification of a large-aperture telescope, the method comprising the following steps:

[0018] S1. Install the large-aperture plane mirror, the large-aperture plane mirror two-dimensional adjustment seat, the large-aperture telescope, the large-aperture telescope base, the surface interferometer, the surface interferometer base, the autocollimator, and the autocollimator base in place according to the inspection requirements;

[0019] S2. Adjusting the pitch angle and yaw angle of the large-aperture plane mirror, the large-aperture telescope, and the surface interferometer so that the surface interferometer displays straight interference fringes of the parallel light emitted by the large-aperture plane mirror, the large-aperture telescope, the large-aperture plane mirror, and the surface interferometer;

[0020] S3, adjusting the pitch angle and yaw angle of the autocollimator so that the parallel light emitted by it is reflected by the large-aperture plane mirror and returns to the autocollimator, and the angle value between the large-aperture plane mirror and the autocollimator is displayed on the autocollimator, and the angle value is set to 0;

[0021] S4. Adjust the large-aperture plane mirror to a small angle. The surface interferometer will display inclined interference fringes, which are recorded as θ. T The angle between the large-aperture plane mirror and the autocollimator is displayed on the autocollimator and is recorded as θ M ;

[0022] S5. Adjust the large-aperture plane mirror in the opposite direction to a small angle. The surface interferometer will show inclined interference fringes, which are recorded as θ. T ， The angle between the large-aperture plane mirror and the autocollimator is displayed on the autocollimator and is recorded as θ M ， ;

[0023] S6. Calculate the angular magnification M of the telescope under test 角 , and then converted into its magnification M;

[0024] S7. Replace the sub-telescope and repeat steps S1-S6 to obtain the magnifications M1, M2, and M3 of the three sub-telescopes.

[0025] Furthermore, in step S1, the connection and positional relationship between the large-aperture plane mirror, the large-aperture plane mirror two-dimensional adjustment seat, the large-aperture telescope, the large-aperture telescope base, the surface interferometer, the surface interferometer base, the autocollimator, and the autocollimator base is as follows:

[0026] The large-aperture plane mirror is vertically placed in the large-aperture plane mirror two-dimensional adjustment seat, and the pitch angle and yaw angle of the large-aperture plane mirror are adjusted by the large-aperture plane mirror two-dimensional adjustment seat;

[0027] The large-aperture telescope is placed horizontally in the large-aperture telescope base, located between the large-aperture plane mirror and the surface interferometer, with its entrance pupil aligned with the large-aperture plane mirror and its exit pupil aligned with the surface interferometer, so that the surface interferometer displays straight interference fringes of parallel light emitted by the telescope after passing through the large-aperture plane mirror, the large-aperture telescope, the large-aperture plane mirror and returning to the surface interferometer;

[0028] The surface interferometer is placed on the surface interferometer base;

[0029] The autocollimator is placed on the autocollimator base, and its light outlet is aimed at the large-aperture telescope, so that the angle value between the large-aperture plane mirror and the autocollimator is displayed on the autocollimator.

[0030] Furthermore, in step S6, the angular magnification M of the telescope under test is 角 The calculation formula is as follows:

[0031] M 角 =(θ T ， -θ T ) / (θ M ， -θ M );

[0032] The conversion formula for magnification M is:

[0033] ;

[0034] Where t is the time difference between the first and final arrival of a plane wavefront at the telescope at any given moment, c is the speed of light, D is the diameter of the telescope's entrance pupil, and d is the diameter of the exit pupil.

[0035] Furthermore, the surface interferometer adopts a ZYGO interferometer.

[0036] By adopting the above technical solution, the present invention has the following beneficial effects:

[0037] 1) The technologies involved are relatively mature and easy to implement. Surface interferometers are mature products, as are meter-level plane mirrors with surface profiles of 1 / 60 or even 1 / 80 wavelength. Two-dimensional angle adjustment mounts are also very common, meeting the functional and performance requirements of this method.

[0038] 2) High versatility. This method is generally applicable to the magnification measurement of large-aperture on-axis and off-axis telescopes. If the aperture of the telescope being measured is very large, the aperture of the large-aperture plane mirror can be increased, or the telescope being measured can be partially aligned with the large-aperture plane mirror.

[0039] 3) Strong scalability. This method provides ideas and solutions for measuring the magnification of telescopes in other telescope systems;

[0040] 4) High cost-effectiveness. After building the telescope magnification test fixture, this method only requires replacing the telescope under test. Batch testing takes less time and requires fewer steps, which is highly cost-effective.

[0041] 5) High detection accuracy. After multiple tests, this method is more accurate than the traditional method of measuring the size of objects and images, with an accuracy of up to a few ten-thousandths, or four decimal places. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0043] Figure 1 This is a structural diagram of the device used in the method for detecting the magnification of a large-aperture telescope of the present invention.

[0044] Figure 2 Schematic diagram of straight interference fringes on the surface interferometer of the present invention.

[0045] Figure 3 Schematic diagram of oblique interference fringes on the surface interferometer of the present invention.

[0046] Figure 4 Schematic diagram of reverse oblique interference fringes on the surface interferometer of the present invention. DETAILED DESCRIPTION

[0047] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0048] The following describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0049] Combine Figure 1-4 As shown, the present invention proposes a method for detecting the magnification of a large-aperture telescope, comprising the following steps:

[0050] S1. Install the large-aperture plane mirror 1, the large-aperture plane mirror two-dimensional adjustment seat 2, the large-aperture telescope 3, the large-aperture telescope base 4, the surface interferometer 5, the surface interferometer base 6, the autocollimator 7, and the autocollimator base 8 in place according to the test requirements. Figure 1 It also includes the telescope incident light 9 and the telescope outgoing light 10;

[0051] S2, adjusting the pitch angle and yaw angle of the large-aperture plane mirror, the large-aperture telescope, and the surface interferometer so that the surface interferometer displays straight interference fringes 11 after the parallel light emitted by them passes through the large-aperture plane mirror, the large-aperture telescope, and the large-aperture plane mirror and returns to the surface interferometer;

[0052] S3, adjusting the pitch angle and yaw angle of the autocollimator so that the parallel light emitted by it is reflected by the large-aperture plane mirror and returns to the autocollimator, and the angle value between the large-aperture plane mirror and the autocollimator is displayed on the autocollimator, and the angle value is set to 0;

[0053] S4. Adjust the large-aperture plane mirror to a small angle (arc-second level). The surface interferometer displays an inclined interference fringe of 12, which is recorded as θ. T The angle between the large-aperture plane mirror and the autocollimator is displayed on the autocollimator and is recorded as θ M ;

[0054] S5. Then adjust the large-aperture plane mirror in the opposite direction to a small angle (arc-second level). The surface interferometer displays an inclined interference fringe 13, which is recorded as θ. T ， The angle between the large-aperture plane mirror and the autocollimator is displayed on the autocollimator and is recorded as θ M ， ;

[0055] S6. Calculate the angular magnification M of the telescope under test 角 , and then converted into its magnification M;

[0056] S7. Replace the sub-telescope and repeat steps S1-S6 to obtain the magnifications M1, M2, and M3 of the three sub-telescopes.

[0057] In this application, the connection and positional relationship of the large-aperture plane mirror, the large-aperture plane mirror two-dimensional adjustment seat, the large-aperture telescope, the large-aperture telescope base, the surface interferometer, the surface interferometer base, the autocollimator, and the autocollimator base in step S1 is as follows:

[0058] The large-aperture plane mirror is vertically placed in the large-aperture plane mirror two-dimensional adjustment seat, and the pitch angle and yaw angle of the large-aperture plane mirror are adjusted by the large-aperture plane mirror two-dimensional adjustment seat;

[0059] The large-aperture telescope is placed horizontally in the large-aperture telescope base, located between the large-aperture plane mirror and the surface interferometer, with its entrance pupil aligned with the large-aperture plane mirror and its exit pupil aligned with the surface interferometer, so that the surface interferometer displays straight interference fringes of parallel light emitted by the telescope after passing through the large-aperture plane mirror, the large-aperture telescope, the large-aperture plane mirror and returning to the surface interferometer;

[0060] The surface interferometer is placed on the surface interferometer base;

[0061] The autocollimator is placed on the autocollimator base, and its light outlet is aimed at the large-aperture telescope, so that the angle value between the large-aperture plane mirror and the autocollimator is displayed on the autocollimator.

[0062] Furthermore, in step S6, the angular magnification M of the telescope under test is 角 The calculation formula is as follows:

[0063] M 角 =(θ T ， -θ T ) / (θ M ， -θ M );

[0064] The conversion formula for magnification M is:

[0065] ;

[0066] Where t is the time difference between the first and final arrival of a plane wavefront at the telescope at any given moment, c is the speed of light, D is the diameter of the telescope's entrance pupil, and d is the diameter of the exit pupil.

[0067] In this application, the surface interferometer adopts ZYGO interferometer; the angle measurement principle of ZYGO interferometer is as follows:

[0068] The horizontal tilt measured by the ZYGO interferometer is the second-order coefficient Z2 of the Zernike polynomial, with the unit being wavelength λ. The measurement uses a circular mask with n pixels in the mask diameter. The calibration result of the spatial physical size corresponding to the unit pixel of the ZYGO interferometer is a. The horizontal deflection angle corresponding to the tilt measurement result of the ZYGO interferometer is:

[0069] .

[0070] This application proposes a method for accurately detecting the magnification of large-aperture telescopes. The core is to obtain its magnification value by measuring the telescope's angular magnification, and the two are in a reciprocal relationship. The magnification of a large-aperture telescope is detected using a surface interferometer, an autocollimator, and an angle-adjustable large-aperture plane mirror. The entrance pupil of the large-aperture telescope is aligned with the large-aperture plane mirror, the surface interferometer is simultaneously aligned with the exit pupil of the large-aperture telescope, and the autocollimator is aligned with the large-aperture plane mirror. When the large-aperture plane mirror undergoes a small angular change, the surface interferometer displays interference fringes of parallel light emitted by it after passing through the large-aperture telescope, the large-aperture plane mirror, and the large-aperture telescope. The angle value reflected by the interference fringes is calculated, and the angle value of the large-aperture plane mirror is directly displayed on the autocollimator. The comparison of the two is the angular magnification of the telescope. Using this method, it is possible to achieve higher-precision magnification of large-aperture telescopes with fewer instruments and equipment, fewer mechanisms and devices, and simpler operation, providing a guarantee for the control of pupil mapping error and field of view angle of optical synthetic aperture imaging systems.

[0071] Compared with the existing technology, the innovations and technical effects of this application mainly include:

[0072] 1) This method can achieve accurate measurement of the magnification of small-aperture telescopes by using large-aperture plane mirrors and surface interferometers.

[0073] 2) This method determines the magnification of the telescope by comparing the interference fringes of the telescope's outgoing light after being reflected by the plane mirror and the interference fringes of the plane mirror's reflected light itself, both displayed simultaneously on the plane interferometer.

[0074] 3) This method uses the same reflector as the reference for interference fringe comparison. As a rigid body, the reflector can truly reflect the angle represented by the interference fringes, thereby improving detection accuracy.

[0075] 4) After the telescope magnification test fixture is built using this method, only the telescope to be tested needs to be replaced. This reduces the time and steps required for batch testing, and improves the detection efficiency.

[0076] In addition, the present application can also be expanded in the following aspects: the telescope to be measured can be a coaxial system or an off-axis system; the entrance pupil of the telescope to be measured can be aligned with the plane mirror and the exit pupil can be aligned with the surface interferometer, or the entrance pupil can be aligned with the surface interferometer and the exit pupil can be aligned with the plane mirror; the aperture and shape of the plane mirror are not limited, as long as they meet the requirements; an autocollimator or other precision angle measuring instruments can be used to accurately measure the rotation angle of a large-aperture plane mirror; the entrance pupil or exit pupil of the telescope to be measured can be completely or partially aligned with the large-aperture plane mirror.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for detecting the magnification of a large-aperture telescope, characterized in that: The large-aperture telescope comprises three coaxial reflecting sub-telescopes with the same composition, structure and parameters, which are distributed in an equilateral triangle. The detection method comprises the following steps: S1. Install the large-aperture plane mirror, the large-aperture plane mirror two-dimensional adjustment seat, the large-aperture telescope, the large-aperture telescope base, the surface interferometer, the surface interferometer base, the autocollimator, and the autocollimator base in place according to the inspection requirements; S2. Adjusting the pitch angle and yaw angle of the large-aperture plane mirror, the large-aperture telescope, and the surface interferometer so that the surface interferometer displays straight interference fringes of the parallel light emitted by the large-aperture plane mirror, the large-aperture telescope, the large-aperture plane mirror, and the surface interferometer; S3, adjusting the pitch angle and yaw angle of the autocollimator so that the parallel light emitted by it is reflected by the large-aperture plane mirror and returns to the autocollimator, and the angle value between the large-aperture plane mirror and the autocollimator is displayed on the autocollimator, and the angle value is set to 0; S4. Adjust the large-aperture plane mirror to a small angle. The surface interferometer will display inclined interference fringes, which are recorded as θ. T The angle between the large-aperture plane mirror and the autocollimator is displayed on the autocollimator and is recorded as θ M ; S5. Adjust the large-aperture plane mirror in the opposite direction to a small angle. The surface interferometer will show inclined interference fringes, which are recorded as θ. T ， The angle between the large-aperture plane mirror and the autocollimator is displayed on the autocollimator and is recorded as θ M ， ; S6. Calculate the angular magnification M of the telescope under test 角 , and then converted into its magnification M; the angular magnification M of the telescope being measured 角 The calculation formula is as follows: M 角 =(θ T ， -θ T ) / (θ M ， -θ M ); S7. Replace the sub-telescope and repeat steps S1-S6 to obtain the magnifications M1, M2, and M3 of the three sub-telescopes.

2. The method for detecting the magnification of a large-aperture telescope according to claim 1, characterized in that: In step S1, the connection and positional relationship among the large-aperture plane mirror, the large-aperture plane mirror two-dimensional adjustment seat, the large-aperture telescope, the large-aperture telescope base, the surface interferometer, the surface interferometer base, the autocollimator, and the autocollimator base is as follows: The large-aperture plane mirror is vertically placed in the large-aperture plane mirror two-dimensional adjustment seat, and the pitch angle and yaw angle of the large-aperture plane mirror are adjusted by the large-aperture plane mirror two-dimensional adjustment seat; The large-aperture telescope is placed horizontally in the large-aperture telescope base, located between the large-aperture plane mirror and the surface interferometer, with its entrance pupil aligned with the large-aperture plane mirror and its exit pupil aligned with the surface interferometer, so that the surface interferometer displays straight interference fringes of parallel light emitted by the telescope after passing through the large-aperture plane mirror, the large-aperture telescope, the large-aperture plane mirror and returning to the surface interferometer; The surface interferometer is placed on the surface interferometer base; The autocollimator is placed on the autocollimator base, and its light outlet is aimed at the large-aperture telescope, so that the angle value between the large-aperture plane mirror and the autocollimator is displayed on the autocollimator.

3. The method for detecting the magnification of a large-aperture telescope according to claim 1, characterized in that: The conversion formula for the magnification M in step S6 is: ； Where t is the time difference between the first and final arrival of a plane wavefront at the telescope at any given moment, c is the speed of light, D is the diameter of the telescope's entrance pupil, and d is the diameter of the exit pupil.

4. The method for detecting the magnification of a large-aperture telescope according to claim 1, wherein: The surface interferometer adopts a ZYGO interferometer.

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