Telescope detection method based on focal plane integrated interferometry

Abstract

The present application relates to the field of optical detection technology, and specifically provides a telescope detection method based on focal plane integrated interference, mainly utilizing the reversible characteristics of spatial light path, first establishing an optical reference at the front end of the telescope system, then setting a photon interference device on the focal plane, and the coherent light propagates reversely along the optical path of the optical reference, interference fringes are generated at the pupil, a detector is set at the front end of the telescope system to collect the interference fringes, the aberration of the telescope system is obtained by using interference fringes of different frequencies, and whether the mirror surface in the telescope system has a surface shape problem is judged by the interference fringes.The present application has the advantages of simple operation, less influence from external environment, shorter detection time, and can effectively reduce the non-common-path aberration and system vibration caused by vibration and component replacement, and reduce the accuracy of visibility measurement.In addition, the interference fringes of different frequencies can also be used to calculate the modulation transfer function of the system.

Description

Technical Field

[0001] This invention relates to the field of optical detection technology, and specifically provides a telescope detection method based on focal plane integrated interferometry. Background Technology

[0002] With the rapid development of astronomical research, the requirements for large-aperture telescopes are becoming increasingly stringent, and large-aperture telescope systems are gradually evolving towards higher precision and greater integration. Large-aperture telescope systems require optical inspection. Existing optical inspection methods typically involve measuring the surface shape of each mirror and calculating its position and optical path, a highly complex calculation process. Furthermore, existing inspection methods are significantly affected by the external environment, require high field-of-view brightness, and are time-consuming, thus consuming observation time.

[0003] Therefore, a simple and effective testing method is urgently needed to address the difficulties in integrating and testing large-aperture telescopes. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a telescope detection method based on focal plane integrated interferometry. It mainly utilizes the reversibility of spatial optical paths to determine whether there are surface shape problems in the mirrors of the telescope system through interference fringes.

[0005] The telescope detection method based on focal plane integrated interferometry provided by this invention includes the following steps:

[0006] S1. Inject the beam into the front end of the telescope system, determine the focal plane based on the imaging point of the beam at the rear end of the telescope system, and establish an optical reference.

[0007] S2. A photon interferometer is set up on the focal plane. The photon interferometer emits coherent light. The coherent light enters from the rear end of the telescope system and produces interference fringes after passing through the pupil plane. The exit aperture angle of the coherent light is greater than the field aperture angle of the telescope system.

[0008] S3. Set up a detector at the front end of the telescope system to collect interference fringes, and use interference fringes of different frequencies to obtain the aberrations of the telescope system.

[0009] Preferably, the photonic interference device is a dense array waveguide, the dense array waveguide is aperture encoded, and optical switches are used to control the light output or cut-off of each aperture.

[0010] Preferably, interference fringes of different frequencies are obtained by adjusting the aperture of the light source to change the interference spacing.

[0011] Preferably, the optical switch is automatically controlled using a programmable gating circuit.

[0012] Preferably, multiple discrete detectors are set according to different fields of view of the telescope system.

[0013] Preferably, movable detectors are set according to different fields of view of the telescope system.

[0014] Preferably, coherent light is collected by multiple spatial optical couplers arranged side by side, and the coherent light is transmitted to an integrated detector for detection via multimode optical fiber.

[0015] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0016] This invention, based on the reversibility of the optical path, allows for system detection externally to the telescope system. The shape of the interference fringes reveals whether there are surface shape issues with the mirrors, or problems with the optical path design and field of view of the telescope system. This method is simple, less affected by external environmental factors, and has a short detection time. Furthermore, the modulation transfer function of the system can be calculated using the interference fringe responses at different frequencies. The use of coded gating circuits to automatically control the optical switch effectively reduces phase differences and system vibrations caused by vibrations and component replacements, thus improving the accuracy of visibility measurements. Attached Figure Description

[0017] Figure 1 This is a flowchart of a telescope detection method based on focal plane integrated interferometry provided according to an embodiment of the present invention;

[0018] Figure 2 This is a schematic diagram of a telescope detection structure based on focal plane integrated interferometry according to an embodiment of the present invention;

[0019] Figure 3 This is a schematic diagram of the structure of a photonic interference device provided in an embodiment of the present invention;

[0020] Figure 4 This is a schematic diagram of the structure of a symmetrically arranged photon interference device provided according to an embodiment of the present invention;

[0021] Figure 5 This is a first mode interference fringe pattern provided according to an embodiment of the present invention;

[0022] Figure 6 This is a second-mode interference fringe pattern provided according to an embodiment of the present invention;

[0023] Figure 7 This is a third-mode interference fringe pattern provided according to an embodiment of the present invention;

[0024] Figure 8 This is a fourth-mode interference fringe pattern provided according to an embodiment of the present invention.

[0025] The reference numerals in the figures include:

[0026] 1. Light source; 2. Grating; 3. Telescope system; 4. Photon interferometer. Detailed Implementation

[0027] In the following description, embodiments of the invention will be described with reference to the accompanying drawings. In the description below, the same modules are denoted by the same reference numerals. Where the same reference numerals are used, their names and functions are also the same. Therefore, their detailed description will not be repeated.

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0029] Figure 1 The flowchart of a telescope detection method based on focal plane integrated interferometry provided in an embodiment of the present invention is shown.

[0030] like Figure 1 As shown, to address the difficulty of integrated testing of large-aperture telescopes, this invention utilizes the reversibility of spatial optical paths to provide a telescope testing method based on focal plane integrated interferometry, specifically including the following steps:

[0031] Figure 2 The structure of a telescope detection based on focal plane integrated interferometry provided in an embodiment of the present invention is shown.

[0032] like Figure 2 As shown, S1, before the detection begins, an optical reference needs to be established. Specifically, the light source 1 is directly aligned with the telescope system 3. The beam emitted by the light source 1 enters the telescope system 3 from the front end. The focal plane is determined based on the imaging point of the beam at the rear end of the telescope system 3. The telescope system 3 can correspond to any existing large-aperture space telescope system. The propagation path of the beam in the telescope system 3, as well as the positions of the components in the system and the pupil plane, are determined according to the specific system design. This method does not require determining the above factors and only uses the optical truss as an illustration.

[0033] Furthermore, a spectrometer can be connected to the rear end of the telescope system 3 to collect the light beam. The beam is then split at the front end of the telescope system 3, and the two beams obtained from the split are used to calculate the wavefront slope and to obtain spectral information from the spectrometer. The output of the spectrometer is used to perform spectral calibration on the system. The calibration process requires planar movement of the pupil of the telescope system 3 to achieve calibration for multiple fields of view.

[0034] As a preferred embodiment, a grating can be added between the light source 1 and the telescope system 3 to convert the light beam emitted by the light source 1 into several linear beams. The linear beams are easier to observe for propagation and light convergence.

[0035] S2. Taking advantage of the reversibility of spatial optical paths, a photon interference device 4 is set up on the focal plane obtained by establishing an optical reference.

[0036] Figure 3 The structure of a photonic interference device provided according to an embodiment of the present invention is shown.

[0037] like Figure 3 As shown, the photonic interferometer 4 is a densely arrayed waveguide with three rows and three columns. The densely arrayed waveguides are aperture-encoded, for example, aperture (1,1), aperture (1,2), aperture (2,1), aperture (2,2), etc. Optical switches control the emission or shutdown of each aperture. An coded gating circuit automatically controls the optical switches, enabling automated system detection and improving detection efficiency. Furthermore, the optical switches achieve solid-state optical path switching, reducing phase differences caused by vibration and component replacement, and avoiding reduced accuracy in visibility measurements. Two apertures of the photonic interferometer 4 emit light simultaneously, while the other apertures are shut off. The two beams form a coherent beam, which enters from the rear end of the telescope system 3, producing interference fringes after passing through the pupil plane. The exit aperture angle of the coherent beam is larger than the field-of-view aperture angle of the telescope system.

[0038] S3. A detector is set at the front end of the telescope system 3 to collect interference fringes. The aberrations of the telescope system are obtained using interference fringes of different frequencies. Multiple discrete detectors can be set according to different fields of view of the telescope system 3, ultimately realizing the measurement and detection of the reverse optical path of the entire field of view.

[0039] As a preferred embodiment, a movable detector is set according to different fields of view of the telescope system 3 to realize the measurement and detection of the reverse optical path of the entire field of view.

[0040] As a preferred embodiment, coherent light is collected by multiple spatial optical couplers arranged side by side, and transmitted and rearranged using multimode optical fiber. The coherent light is then transmitted to a small integrated detector for detection, which can effectively reduce the size and weight of the system, improve the uniformity of the response, and avoid contrast detection errors caused by different responses between multiple detectors and background noise.

[0041] To obtain interference fringes of different frequencies, the interference spacing can be changed by adjusting the aperture of the light-emitting device. For example, using apertures (1,1) and (1,2) as the light-emitting combination, and apertures (1,1) and (1,3) as the light-emitting combination, the following can be obtained: Figure 5 and Figure 6The first and second mode interference fringes shown demonstrate how the interference spacing can be changed.

[0042] Using apertures (1,1) and (2,1) as the light-emitting combination; and apertures (1,2) and (2,1) as the light-emitting combination, the following results were obtained: Figure 7 and Figure 8 The third and fourth mode interference fringes shown not only change the interference spacing but also change the direction of the interference fringes.

[0043] Based on the imaging observation of the interference fringes, it can be determined whether there is a surface shape problem in the mirror of the telescope system 3. Furthermore, by analyzing the position of the photon interferometer 4, the light output, and the response and contrast of the interference fringes, it can also be used to calculate the modulation transfer function of the telescope system 3.

[0044] In addition, for special systems with two sets of tandem optical systems, the photonic interferometer 4 of the present invention can be positioned at the intermediate focal plane, and as shown in the figure... Figure 4 As shown, two photonic interference devices 4 need to be set up symmetrically side by side. By using a roof prism, the transmission direction of the two sets of coherent light is changed by 45° respectively, turning the two sets of coherent light that originally transmitted in the same direction into two sets of coherent light that transmitted in opposite directions, and then entering the two optical systems respectively, and simultaneously detecting the two optical systems.

[0045] Although embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

[0046] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A telescope detection method based on focal plane integrated interferometry, characterized in that, Includes the following steps: S1. Inject the beam into the front end of the telescope system, determine the focal plane based on the imaging point of the beam at the rear end of the telescope system, and establish an optical reference. S2. A photonic interferometer is set on the focal plane. The photonic interferometer emits coherent light. The coherent light enters from the rear end of the telescope system and generates interference fringes after passing through the pupil plane. The exit aperture angle of the coherent light is greater than the field aperture angle of the telescope system. The photonic interference device is a dense array waveguide. The dense array waveguide is aperture encoded, and optical switches are used to control the light output or cut-off of each aperture. S3. Set up a detector at the front end of the telescope system to collect interference fringes, and use interference fringes of different frequencies to obtain the aberrations of the telescope system; change the interference spacing by adjusting the aperture of the light output to obtain interference fringes of different frequencies.

2. The telescope detection method based on focal plane integrated interferometry as described in claim 1, characterized in that, The optical switch is automatically controlled using a programmable gating circuit.

3. The telescope detection method based on focal plane integrated interferometry as described in claim 1, characterized in that, Multiple discrete detectors are set up according to different fields of view of the telescope system.

4. The telescope detection method based on focal plane integrated interferometry as described in claim 1, characterized in that, The detector is movable according to the different fields of view of the telescope system.

5. The telescope detection method based on focal plane integrated interferometry as described in claim 1, characterized in that, The coherent light is acquired by multiple spatial optical couplers arranged side by side, and then transmitted to an integrated detector for detection via multimode optical fiber.

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