Dual-aperture interferometric imaging experimental system and its alignment positioning method
By using a dual-aperture interferometric imaging experimental system and its assembly and positioning method, the problem of pose error control in sparse aperture imaging systems with long baseline lengths was solved, achieving efficient and precise positioning with fewer optical components and a simpler optical path, supporting subsequent experimental verification.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHANGCHUN INST OF OPTICS FINE MECHANICS & PHYSICS CHINESE ACAD OF SCI
- Filing Date
- 2024-04-03
- Publication Date
- 2026-06-02
AI Technical Summary
Existing sparse aperture imaging systems face significant challenges in controlling the relative pose error between sub-apertures when the baseline length is long, which affects imaging resolution and lacks effective precision positioning methods.
A dual-aperture interferometric imaging experimental system was adopted, including a point source simulation unit, a beam splitter prism, an off-axis parabolic lens group, a beam adjustment unit, and a beam combination unit. The system was assembled and positioned using mechanical coarse adjustment, star-point method coarse adjustment, optical fine adjustment, and co-phase error detection and correction methods.
It achieves effective control of the relative pose error between each sub-aperture with a baseline length on the order of 1m, simplifies optical components and optical paths, and supports precise positioning research in subsequent experiments.
Smart Images
Figure CN118280188B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of interferometric imaging instrument technology, and in particular to a dual-aperture interferometric imaging experimental system and its assembly and positioning method. Background Technology
[0002] To overcome the limitations of traditional telescopes in terms of system aperture, astronomers proposed sparse aperture imaging technology based on the principle of interferometric imaging. This technique utilizes multiple small-aperture optical systems arranged in a specific array shape to form an equivalent large-aperture optical system, achieving high-resolution imaging. Interferometric imaging has extremely high requirements for co-phase error, typically needing to be less than one-tenth of the observation wavelength, generally on the order of tens of nanometers. Therefore, the precise positioning and co-phase correction of the optical system have a crucial impact on imaging resolution.
[0003] From the perspective of precise mechanical positioning, the longer the baseline length of the system, the more difficult it is to control the relative pose error between the various sub-apertures, and the more difficult it is to meet the interference conditions of the various sub-beams in the sparse aperture imaging system. The baseline length of sparse aperture imaging experiments conducted by domestic scholars is generally within 200 mm. If a mask-equivalent sub-aperture scheme is used, the baseline length is generally even shorter, within 50 mm; existing technologies such as those described in publications like "Research on Key Issues of Optical Sparse Aperture Imaging Systems" and "Research on Synthetic Aperture Optical Imaging Systems" are relevant. Therefore, developing an optical system that can control the relative pose error between the various sub-apertures with an equivalent baseline length on the order of 1 m, and researching its precise positioning methods, is of great significance. Summary of the Invention
[0004] To address the aforementioned problems, this invention provides a dual-aperture interferometric imaging experimental system and its assembly and positioning method.
[0005] The primary objective of this invention is to provide a dual-aperture interferometric imaging experimental system, comprising: a point light source simulation unit, a beam splitter prism, an off-axis parabolic mirror group, a beam adjustment unit, and a beam combination unit;
[0006] The light beam emitted from the point light source simulation unit is split into two beams by the beam splitter and then incident on the off-axis parabolic lens group.
[0007] The off-axis parabolic lens assembly includes two off-axis parabolic lenses, which are symmetrically arranged on both sides of the beam splitter to collide the two beams of light emitted from the beam splitter into parallel light before they are incident on the beam adjustment unit.
[0008] The light beam undergoes optical path conversion via the beam adjustment unit, and then converges onto the camera plane via the beam combining unit.
[0009] Preferably, the radius of curvature of the off-axis parabolic mirror is 1.4 to 1.6 m, and the absolute distance between the two off-axis parabolic mirrors is not less than 1 m.
[0010] Preferably, the off-axis parabolic mirror assembly further includes an aperture stop, which is disposed in front of the off-axis parabolic mirror.
[0011] Preferably, the two mirrors of the beam splitter are plane mirrors with a beam splitting ratio of 1:1; the distance between the beam splitter and the point light source simulation unit along the optical axis is 140-160mm.
[0012] Preferably, the beam adjustment unit includes two planar mirrors, and the included angle between the planar mirrors is the same as the apex angle of the beam splitter.
[0013] Preferably, the beam combining unit includes an aspherical lens, which is used to reduce spherical aberration when the beam is focused.
[0014] Preferably, filters with different transmittance are provided at the point light source simulation unit, and the light beam emitted from the point light source simulation unit is filtered by the filters before being incident on the beam splitter.
[0015] Preferably, the point light source simulation unit emits spherical waves; the radius of curvature of the off-axis parabolic mirror is 1.5m; and the distance between the beam splitter and the point light source simulation unit along the optical axis is 150mm.
[0016] The second objective of this invention is to provide a method for assembling and positioning a dual-aperture interferometric imaging experimental system, which includes the following steps:
[0017] S1. Mechanical coarse adjustment: Based on the theoretical positions of each optical device in the dual-aperture interferometric imaging experimental system, the pose of each optical device is calibrated using spatial relative distance and relative angle measuring instruments;
[0018] S2. Coarse adjustment by star point method: The aberrations of the dual-aperture interferometric imaging experimental system are qualitatively evaluated by observing the shape and intensity distribution of the light spot in front of, on, and behind the ideal focal point of the dual-aperture interferometric imaging experimental system.
[0019] S3. Optical fine-tuning: Set up the test optical path and use a dynamic laser interferometer to detect the aberrations of the optical devices before the beam combining unit;
[0020] S4. Detection and correction of common phase error: The common phase error of the optical system is detected by the focal plane detection method, and the common phase error is corrected to achieve precise positioning of the system.
[0021] Preferably, the specific method for constructing the test optical path in step S3 includes: replacing the point light source simulation unit with a dynamic laser interferometer, and replacing the beam combining unit with a plane mirror.
[0022] Compared with the prior art, the present invention can achieve the following beneficial effects:
[0023] The dual-aperture interferometric imaging experimental system of this invention has fewer optical components and a simpler optical path, which can reduce the difficulty of controlling the relative pose error between each sub-aperture when the baseline length is on the order of 1m. This facilitates the research on the system's precision positioning method during subsequent demonstration and verification experiments. Attached Figure Description
[0024] Figure 1 This is a schematic diagram of the structure of a dual-aperture interferometric imaging experimental system provided according to an embodiment of the present invention.
[0025] Figure 2 This is a point light source simulation diagram of a dual-aperture interferometric imaging experimental system provided according to an embodiment of the present invention.
[0026] Figure 3 This is a schematic diagram of using the star point method to observe the shape of the light spot to qualitatively evaluate the aberrations of an optical system according to an embodiment of the present invention; (A) no aberration; (B) spherical aberration; (C) coma; (D) astigmatism.
[0027] Figure 4 A schematic diagram of the test optical path setup provided in an embodiment of the present invention.
[0028] Figure 5 The imaging results of the dual-aperture interferometric imaging experimental system with different fill factors according to the embodiments of the present invention are shown in the figures: (A) fill factor 0.0408; (B) fill factor 0.0987; (C) fill factor 0.1488; (D) fill factor 0.1893.
[0029] Figure label:
[0030] 1. Point light source; 2. Filter; 3. Beam splitter; 4. Off-axis parabolic mirror; 5. Aperture stop; 6. Plane mirror; 7. Aspherical lens; 8. Camera; 9. Dynamic laser interferometer;
[0031] 101. Precision pinhole. Detailed Implementation
[0032] 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.
[0033] 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.
[0034] This invention provides a dual-aperture interferometric imaging experimental system, comprising: a point light source simulation unit, a beam splitter, an off-axis parabolic mirror group, a beam adjustment unit, and a beam combination unit;
[0035] The beam emitted from the point light source simulation unit is split into two beams by the beam splitter and then incident on the off-axis parabolic lens group.
[0036] The off-axis parabolic lens assembly includes two off-axis parabolic lenses, which are symmetrically arranged on both sides of the beam splitter to collide the two beams of light emitted from the beam splitter into parallel light before they are incident on the beam adjustment unit.
[0037] The light beam undergoes optical path conversion via the beam adjustment unit, and then converges onto the camera plane via the beam combining unit.
[0038] Preferably, the point light source simulation unit emits spherical waves; in a specific embodiment, the point light source simulation unit includes a helium-neon laser, a microscope objective, a spatial filter, and a precision pinhole, and the wavelength of the helium-neon laser emitted by the helium-neon laser is λ = 632.8 nm.
[0039] Preferably, neutral density filters with different transmittance are set at the point light source simulation unit, and the light beam emitted by the point light source simulation unit is filtered by the neutral density filters before being incident on the beam splitter.
[0040] Preferably, the two mirrors of the beam splitter are plane mirrors with a beam splitting ratio of 1:1; the distance between the beam splitter and the point light source simulation unit along the optical axis is 150mm; in a specific embodiment, the apex angle of the beam splitter is 90° and the size of each mirror is 70mm*70mm.
[0041] Preferably, the radius of curvature of the off-axis parabolic mirror is 1.4 to 1.6 m, and the absolute distance between the two off-axis parabolic mirrors is not less than 1 m; in a specific embodiment, the radius of curvature of the off-axis parabolic mirror is 1.5 m, and the absolute distance between the two off-axis parabolic mirrors is 1.2 m; the conic coefficient of the off-axis parabolic mirror is -1, the effective aperture is 70 mm, and the aperture eccentricity is 105 mm.
[0042] Preferably, the off-axis parabolic lens assembly further includes an aperture stop, which is positioned in front of the off-axis parabolic lens.
[0043] Preferably, the beam adjustment unit includes two circular plane mirrors, and the included angle between the two circular plane mirrors is the same as the apex angle of the beam splitter; in a specific embodiment, the aperture of each independent plane mirror is 100mm.
[0044] Preferably, the beam adjustment unit is an integrated reflector with the same structure as the beam splitter prism and is axially symmetrical with the beam splitter prism.
[0045] The beam combining unit employs an aspherical lens to reduce spherical aberration during beam focusing. In a specific embodiment, the aspherical lens has a back cutoff of 800 mm, a conicity of -2.2954, a radius of curvature of 412.07 mm, and an effective aperture of 150 mm.
[0046] The present invention also provides a method for assembling and positioning a dual-aperture interferometric imaging experimental system, comprising the following steps:
[0047] S1. Mechanical coarse adjustment: Based on the theoretical positions of each optical device in the dual-aperture interferometric imaging experimental system, the pose of each optical device is calibrated using spatial relative distance and relative angle measuring instruments;
[0048] S2. Coarse adjustment by star point method: Qualitatively evaluate the aberrations of the dual-aperture interferometric imaging experimental system by observing the shape and intensity distribution of the light spot in front of, on, and behind the ideal focal point of the dual-aperture interferometric imaging experimental system.
[0049] S3. Optical fine-tuning: Set up the test optical path and use a dynamic laser interferometer to detect the aberrations of each optical device before the beam combining unit;
[0050] S4. Detection and correction of common phase error: The common phase error of the optical system is detected by the focal plane detection method, and the common phase error is corrected to achieve precise positioning of the system.
[0051] Example 1
[0052] like Figure 1 As shown, this embodiment provides a dual-aperture interferometric imaging experimental system, including: a point light source 1, a filter 2, a beam splitter 3, an off-axis parabolic mirror group, a beam adjustment unit, and a beam combination unit;
[0053] A filter 2 with different transmittance is set at the point light source 1. The point light source 1 emits an ideal spherical wave, which is filtered by the filter 2 and then incident on the beam splitter 3. The beam is split into two beams, left and right, by the beam splitter 3. The filter 2 is a neutral density filter. The distance between the beam splitter 3 and the point light source 1 along the optical axis is 150mm. The two mirrors of the beam splitter 3 are plane mirrors with a beam splitting ratio of 1:1 and a vertices angle of 90°. The size of each mirror is 70mm*70mm.
[0054] like Figure 2 As shown, the simulation of the ideal point light source 1 is achieved by combining a helium-neon laser, a microscope objective, a spatial filter, and a precision pinhole 101. The wavelength of the helium-neon laser emitted by the helium-neon laser is λ = 632.8 nm.
[0055] The off-axis parabolic mirror assembly comprises two off-axis parabolic mirrors 4, symmetrically positioned on either side of the beam splitter 3. These mirrors collimate the two beams of light emitted from the beam splitter 3 into parallel beams before they are incident on the beam adjustment unit. The off-axis parabolic mirror assembly is a left-right symmetrical two-path optical structure, serving as two sub-apertures in the dual-aperture interferometric imaging experimental system. The radius of curvature of each off-axis parabolic mirror is 1.5m, and the absolute distance between the two mirrors is 1.2m. The conicity of each mirror is -1, the effective aperture is 70mm, and the aperture eccentricity is 105mm. The two off-axis parabolic mirrors collimate the two spherical wave beams into parallel beams, positioning them at half their own radius of curvature, which plays a crucial role in the success of the interferometric imaging.
[0056] The beam adjustment unit includes two circular plane mirrors 6, and the included angle between the two plane mirrors 6 is the same as the apex angle of the beam splitter 3; the aperture of each independent plane mirror 6 is 100mm.
[0057] The beam combining unit uses an aspherical lens 7 to reduce spherical aberration when focusing the beam; the aspherical lens 7 has a back intercept of 800 mm, a conicity of -2.2954, a radius of curvature of 412.07 mm, and an effective aperture of 150 mm.
[0058] Example 2
[0059] In this embodiment, the beam adjustment unit in the dual-aperture interferometric imaging experimental system is an integrated reflector with the same structure as the beam splitter prism and is axially symmetrical with the beam splitter prism; the rest of the structure is the same as in Embodiment 1.
[0060] Example 3
[0061] The present invention also provides a method for assembling and positioning a dual-aperture interferometric imaging experimental system, comprising the following steps:
[0062] S1. Mechanical coarse adjustment: Based on the theoretical positions of each optical device in the dual-aperture interferometric imaging experimental system, the pose of each optical device is calibrated using spatial relative distance and relative angle measuring instruments;
[0063] S2. Coarse adjustment using the star-point method: (e.g., ...) Figure 3 As shown, the aberrations of the dual-aperture interferometric imaging experimental system are qualitatively evaluated by observing the shape and intensity distribution of the light spot in front of, above, and behind the ideal focal point.
[0064] S3. Optical Fine-tuning: Construct the test optical path and use a dynamic laser interferometer to detect the aberrations of each optical component before the beam combining unit; such as... Figure 4 As shown, in this embodiment, the point light source simulation unit in the dual-aperture interferometric imaging experimental system is replaced with a dynamic laser interferometer, the aspherical lens is replaced with a plane mirror, and the filters, aperture stops, and cameras in the system's optical path are removed. The dynamic laser interferometer adopts the principle of polarized light interference, which can convert the time-domain phase shift of the traditional phase-shifting interferometer into the spatial-domain phase shift. It also uses phase-dependent charge-coupled device (CCD) technology, which can achieve full-resolution measurement using a single CCD frame rate. Therefore, it can effectively overcome external interference and avoid the adverse effects of environmental vibration, airflow disturbance, and other factors on the test, ultimately achieving efficient and accurate testing of the surface shape of optical components and the wavefront of the optical system.
[0065] S4. Detection and Correction of Common Phase Error: The common phase error of the optical system is detected using the focal plane detection method. In this embodiment, two images at unknown defocus points are obtained by adjusting the position of the aspherical lens along the optical axis. These images are used as input, and an improved phase difference algorithm is used to identify the translation error and the two defocus points present in the system.
[0066] After four levels of precise positioning, the imaging results of the dual-aperture interferometric imaging experimental system in this embodiment at different fill factors are as follows: Figure 5 As shown: (A) Fill factor 0.0408; (B) Fill factor 0.0987; (C) Fill factor 0.1488; (D) Fill factor 0.1893.
[0067] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.
[0068] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.
Claims
1. A dual-aperture interferometric imaging experimental system, characterized in that, include: Point light source simulation unit, beam splitter, off-axis parabolic mirror group, beam adjustment unit and beam combination unit; The light beam emitted from the point light source simulation unit is split into two beams by the beam splitter and then incident on the off-axis parabolic lens group. The off-axis parabolic mirror assembly includes two off-axis parabolic mirrors, symmetrically arranged on both sides of the beam splitter prism, used to collimate the two beams of light emitted from the beam splitter prism into parallel light before they are incident on the beam adjustment unit; the radius of curvature of the off-axis parabolic mirror is 1.4~1.6m, and the absolute distance between the two off-axis parabolic mirrors is not less than 1m; the two mirrors of the beam splitter prism are plane mirrors with a beam splitting ratio of 1:1; the distance between the beam splitter prism and the point light source simulation unit along the optical axis is 140~160mm; The light beam undergoes optical path conversion through the beam adjustment unit, and then converges onto the camera plane after passing through the beam combining unit; the beam adjustment unit includes two planar mirrors, and the included angle between the planar mirrors is the same as the apex angle of the beam splitter.
2. The dual-aperture interferometric imaging experimental system according to claim 1, characterized in that: The off-axis parabolic mirror assembly also includes an aperture stop, which is positioned in front of the off-axis parabolic mirror.
3. The dual-aperture interferometric imaging experimental system according to claim 1, characterized in that: The beam combining unit includes an aspherical lens, which is used to reduce spherical aberration when the beam is focused.
4. The dual-aperture interferometric imaging experimental system according to claim 3, characterized in that: Filters with different transmittance are set at the point light source simulation unit. The light beam emitted from the point light source simulation unit is filtered by the filter before being incident on the beam splitter.
5. The dual-aperture interferometric imaging experimental system according to claim 4, characterized in that: The point light source simulation unit emits spherical waves; the radius of curvature of the off-axis parabolic mirror is 1.5m; the distance between the beam splitter and the point light source simulation unit along the optical axis is 150mm.
6. A method for assembling and positioning a dual-aperture interferometric imaging experimental system, used for assembling and adjusting the dual-aperture interferometric imaging experimental system according to any one of claims 1-5, characterized in that, Includes the following steps: S1. Mechanical coarse adjustment: Based on the theoretical positions of each optical device in the dual-aperture interferometric imaging experimental system, the pose of each optical device is calibrated using spatial relative distance and relative angle measuring instruments; S2. Coarse adjustment by star point method: The aberrations of the dual-aperture interferometric imaging experimental system are qualitatively evaluated by observing the shape and intensity distribution of the light spot in front of, on, and behind the ideal focal point of the dual-aperture interferometric imaging experimental system. S3. Optical fine-tuning: Set up the test optical path and use a dynamic laser interferometer to detect the aberrations of the optical devices before the beam combining unit; S4. Detection and correction of common phase error: The common phase error of the optical system is detected by the focal plane detection method, and the common phase error is corrected to achieve precise positioning of the system.
7. The assembly and positioning method for a dual-aperture interferometric imaging experimental system according to claim 6, characterized in that: The specific method for constructing the test optical path in step S3 includes: replacing the point light source simulation unit with a dynamic laser interferometer, and replacing the beam combining unit with a plane mirror.