A variable array optical synthetic aperture imaging system

Abstract

The present invention discloses a variable-array optical synthetic aperture imaging system, comprising: a target, a high-precision turntable, a collimator, a long-stroke tilted granite base, a long-stroke linear air-floating guide, a subaperture support structure, a subaperture, a mass balance device for the long-stroke linear air-floating guide, a short-stroke tilted granite base, a short-stroke linear air-floating guide, a folding mirror support structure, a folding mirror, a mass balance device for the short-stroke linear air-floating guide, a spectroscope, a light-combining telescope, and an imaging camera. The present invention increases the number of subapertures, adds high-precision adjustment functions for subaperture baselines, adds high-precision adjustment functions for the baseline of the beam-reduction optical path, and is equipped with a synchronous rotation function for the target. This system achieves better UV coverage, obtains more complete spatial frequency information, shortens observation time, and significantly improves observation quality.

Description

Technical Field

[0001] The present invention relates to the technical field of astronomical observation, and in particular to a variable array optical synthetic aperture imaging system. Background Art

[0002] According to the diffraction limit formula, the spatial resolution of a telescope is limited by the wavelength of light and the aperture of the optical system. As the demand for spatial resolution in optical systems continues to increase, the aperture of optical systems operating within a given wavelength band needs to be continuously increased to improve spatial resolution. However, in practice, due to various limitations such as manufacturing materials, manufacturing technology, mechanical structure, rocket payload volume, and weight, increasing the aperture of a single-aperture system is extremely difficult. Spatially distributed synthetic aperture technology offers a new approach to improving the spatial resolution of optical imaging systems. Compared to a single-aperture telescope, spatially distributed synthetic aperture technology utilizes 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 and meeting the high-resolution requirements of applications such as exoplanet detection, solar observation, and observation of terrestrial objects. By varying the subaperture baseline—that is, the center-to-center distance between the subaperture optical axes—better UV coverage can be achieved. UV coverage simply refers to the sampling of the spatial frequency information of the observed source in the optical band by the optical interferometer array. The longer the baseline in the optical interferometer array, the higher the detected frequency, and the shorter the baseline, the lower the detected frequency. To improve spatial frequency coverage, for a given number of sub-apertures, the baseline length of the sub-aperture array can be changed to obtain different frequency sampling values.

[0003] The existing methods and means are as follows:

[0004] 1. The Very Large Telescope (VLT), built by the European Southern Observatory in Chile, consists of four primary mirrors, each 8.2 meters in diameter, and four movable auxiliary mirrors, each 1.8 meters in diameter. These telescopes can operate individually or in pairs or groups of three, forming a massive interferometer array. The beams from the different telescopes are combined through an underground tunnel, resulting in a baseline of up to 200 meters and an angular resolution of 0.001 inches, 25 times that of a single telescope operating independently.

[0005] 2. The Large Binocular Telescope (LBT) built by the University of Arizona on Mount Graham consists of two 8.4-meter binocular telescopes fixed on the same frame, with an equivalent aperture of 11.8 meters. The maximum angular resolution of the LBT is equivalent to that of a 22.8-meter telescope, and it does not have a variable baseline function.

[0006] 3. The Wide-Field Imaging Interferometry (WIIT) established by NASA verifies wide-field interferometric imaging algorithms for space interferometer projects such as SPIRIT (infrared), SPECS (submillimeter wave), and TPF-I. It also establishes and verifies system models. Two sub-telescopes are installed at both ends of a linear air-floating translation stage. Each sub-telescope has an aperture of 25 mm, and the baselines of the two sub-telescopes are variable between 25 mm and 250 mm. UV coverage is achieved through baseline adjustment, synchronous rotation of the target (simulated observation target) and the detector.

[0007] 4. The Changchun Institute of Optics, Mechanics and Physics, Chinese Academy of Sciences, conducted optical design for a Golay-3 array synthetic aperture telescope system. This system's field of view was increased to facilitate the acquisition and tracking of high-speed moving targets, while a modular design facilitated the expansion of the subaperture array. The subaperture array chosen for this design was the simplest Golay-3 array, with a fill factor of F=0.44. After dividing the system into three subsystems and conducting optical design for each, the subsystems were combined and the image quality of the overall system analyzed.

[0008] 5. The National Astronomical Observatories of the Chinese Academy of Sciences designed and built a Fizeau Imaging Interferometer Test (FIIT), which mainly consists of a light source module for simulating infinite objects, three 100mm aperture sub-telescopes in a Golay-3 distribution (equilateral triangle), three yaw / pitch correction modules and an optical path delay module, as well as three detection telescopes and a beam synthesis telescope for phase imaging. It achieved broadband white light (400-700nm) phase imaging without variable baseline function in the laboratory.

[0009] Wang Haitao, Zhu Yongkai, Cai Jiahui, Zhang Yajing, and Tian Guiyun of Nanjing University of Aeronautics and Astronautics conducted research on UV coverage and aperture arrangement in optical synthesis telescopes. They increased UV coverage by rotating the pupil plane of four subapertures as a whole. The four subapertures are at varying distances from the center of rotation, so the paths of the four subapertures form four concentric circles of varying radii.

[0010] 7. Wang Changwei, Jiang Yuesong, He Yuntao, Liu Li, and Jiang Yingcai from the Beijing University of Aeronautics and Astronautics proposed a novel optical comprehensive aperture imaging system based on a fiber array. This invention uses a Cassegrain telescope array to receive light waves radiated by the target, couples the light waves into a single-mode polarization-maintaining fiber for transmission, uses a fiber collimator array to coherently image the light beam, and uses a piezoelectric ceramic phase modulator and a fiber delay line to compensate for phase errors. It has no variable baseline function.

[0011] 8. Liang Shitong, Yang Jianfeng, Xue Bin, and Ruan Ping from the Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, proposed a large-aperture total reflection optical synthetic aperture imaging system. The system has two sub-telescopes. Each focus-free sub-telescope is composed of two RC systems arranged in sequence along the direction of light incidence. Two small-aperture systems with the same structure are designed without a variable baseline function.

[0012] Disadvantages of existing technology:

[0013] (1) Currently, most of the existing and proposed optical synthetic aperture imaging systems at home and abroad have only been subjected to theoretical analysis and software simulation, and a small number of scientific research units have conducted experimental verification of individual methods. Simple theoretical analysis and software simulation cannot fully simulate the real working scenes and various complex error conditions, and the feasibility and accuracy of the proposed synthetic aperture imaging system are limited.

[0014] (2) Currently, most existing optical synthetic aperture imaging systems at home and abroad use static methods with unadjustable baselines. The sub-aperture cannot perform high-precision baseline changes and simulate the synchronous rotation of the observation target and the detector or the overall rotation of the observation equipment. It cannot achieve better UV coverage, and thus obtains less information of different spatial frequencies, resulting in poor observation effects.

[0015] (3) The number of sub-apertures in the variable baseline optical synthetic aperture imaging systems currently available or proposed at home and abroad is relatively small, mostly two. In order to achieve better UV coverage, the number of times the sub-aperture changes the baseline and the number of times the simulated observation target and detector rotate are large, resulting in low observation efficiency and long observation time. The amount of image synthesis is large, and environmental fluctuations within a complete observation cycle will lead to low accuracy of the synthesized image.

[0016] 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

[0017] In response to the problems existing in the prior art, the present invention aims to provide a variable-array optical synthetic aperture imaging system. Four subapertures with identical structures and parameters are distributed on two tilted high-precision linear translation stages, with two subapertures placed on each stage. Four identical folding mirrors are distributed on two other tilted high-precision linear translation stages, with two folding mirrors placed on each stage. The light beam, after being focused by the four subapertures, is incident on the two folding mirrors. After passing through the folding mirrors, the light enters a light-combining telescope for imaging. A rotatable target is placed at the focal plane of the collimator. Improved UV coverage is achieved by the optical synthetic aperture imaging system through variable baseline motion of the subapertures and folding mirrors, target rotation, and rotational reconstruction of the observed image. Compared with existing methods, this method increases the number of subapertures, adds high-precision adjustment of the subaperture baseline, adds high-precision adjustment of the baseline of the focused optical path, and incorporates a synchronous rotation function for the target. This achieves better UV coverage, acquires more complete spatial frequency information, shortens observation time, and significantly improves observation quality.

[0018] In order to achieve the above object, the present invention adopts the following technical solutions:

[0019] A variable-array optical synthetic aperture imaging system comprises: a target, a high-precision turntable, a collimator, a long-stroke tilted granite base, a long-stroke linear air-floating guide, a subaperture support structure, a subaperture, a mass balance device for the long-stroke linear air-floating guide, a short-stroke tilted granite base, a short-stroke linear air-floating guide, a folding mirror support structure, a folding mirror, a mass balance device for the short-stroke linear air-floating guide, a spectroscope, a light-combining telescope, and an imaging camera. The target is mounted in the center hole of the high-precision turntable at the focal plane of the collimator, and the imaging camera is mounted at the focal plane of the light-combining telescope. The high-precision turntable drives the target to rotate, and the imaging camera captures images after passing through the optical system.

[0020] The collimator is a reflective off-axis system comprising a primary mirror, a secondary mirror and a folding mirror, and is used to convert the light generated by the light source into parallel light with a diameter of 1 meter for emission;

[0021] The sub-aperture is mounted on two long-stroke, high-precision linear air-floating guide rails through a supporting structure. Each air-floating guide rail contains two sliding sleeves, and each sliding sleeve is mounted with a sub-aperture and its supporting structure. The long-stroke, high-precision linear air-floating guide rails are placed obliquely on a long-stroke inclined granite base.

[0022] The deflecting mirror is a flat reflector, which is mounted on two small-stroke linear air-floating guide rails through a deflecting mirror support structure. Each air-floating guide rail contains two sliding sleeves, and each sliding sleeve is mounted with a deflecting mirror and its support structure. The small-stroke linear air-floating guide rails are tilted and placed on a small-stroke tilted granite base.

[0023] The beam splitter is installed between the large and small X-array mechanisms to deflect a portion of the light after the sub-aperture is focused and enter the light combining telescope.

[0024] Furthermore, the subaperture is a double parabola off-axis afocal system with an aperture of 80 mm and an angular magnification of 5.

[0025] Furthermore, the long-stroke linear air-floating guide rail and the short-stroke linear air-floating guide rail have the same structure and composition, including a granite guide rail, a granite sleeve, a linear motor, a grating scale feedback module, a photoelectric switch and a buffer device.

[0026] Furthermore, a mass balancing device is provided in conjunction with the granite sleeve, and the mass balancing device consists of a synchronous belt, a fixed pulley and a counterweight hammer; the synchronous belt is connected to the granite sleeve, and is fixed to the counterweight block after passing through the fixed pulley. When the granite sleeve moves on the granite guide rail, the counterweight block moves up and down, balancing the gravity component of the granite sleeve and the load thereon along the direction of movement in real time.

[0027] By adopting the above technical solution, the present invention has the following beneficial effects:

[0028] The present invention increases the number of sub-apertures, adds a high-precision adjustment function for the sub-aperture baseline, adds a high-precision adjustment function for the baseline of the beam reduction optical path, and is equipped with a synchronous rotation function of the target, which can achieve better UV coverage, obtain more complete spatial frequency information, shorten the observation time, and greatly improve the observation effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] 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.

[0030] Figure 1 This is the overall structural diagram of the variable array synthetic aperture imaging system of the present invention.

[0031] Figure 2 This is a detailed structural diagram of the variable array synthetic aperture imaging system of the present invention.

[0032] Figure 3 This is a schematic diagram of the structure of the linear air-floating guide rail 5 / 10 of the present invention.

[0033] Figure 4 It is a schematic diagram of the large and small baselines of the present invention.

[0034] Figure 5 Schematic diagram of the mass balancing device of the inclined air-floating linear guide rail of the present invention.

[0035] Figure 6 This is a mechanical analysis diagram of the inclined air-bearing linear guide rail of the present invention. DETAILED DESCRIPTION

[0036] 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. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0037] 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.

[0038] Combine Figure 1-3 As shown, the variable array synthetic aperture imaging system proposed in the present invention includes a target 1 and its high-precision turntable 2, a collimator 3, a large-stroke inclined granite base 4, a large-stroke linear air-floating guide 5, a sub-aperture support structure 6, a sub-aperture 7, a large-stroke linear air-floating guide mass balance device 8, a small-stroke inclined granite base 9, a small-stroke linear air-floating guide 10, a folding mirror support structure 11, a folding mirror 12, a small-stroke linear air-floating guide mass balance device 13, a spectrometer 14, a light-combining telescope 15, an imaging camera 16, etc.

[0039] The specific connection relationship is as follows:

[0040] 1) Target 1 is mounted in the center hole of high-precision turntable 2 at the focal plane of the collimator. Imaging camera 16 is mounted at the focal plane of light-combining telescope 15. High-precision turntable 2 drives target 1 to rotate, and imaging camera collects the image after passing through the optical system.

[0041] 2) The collimator 3 is a reflective off-axis system consisting of a primary mirror, a secondary mirror, and a folding mirror, which can convert the light generated by the light source into parallel light with a diameter of 1 meter.

[0042] 3) The subaperture 7 is a double parabolic off-axis afocal system with an aperture of 80 mm and an angular magnification of 5. It is mounted on two long-stroke, high-precision linear air-bearing guide rails 5 through a support structure 6. Each air-bearing guide rail 5 contains two sliding sleeves, and a subaperture 7 and its supporting structure 6 are mounted on each sliding sleeve.

[0043] 4) The long-stroke, high-precision linear air-bearing guide 5 is tilted and placed on a long-stroke, tilted granite base 4. It is fixed at both ends and supported at three points, one at the ends and the other in the middle. The air-bearing guide 5 has minimal friction, so a mass balance device 8 consisting of a timing belt, pulleys, and counterweights balances the gravity component in its direction of motion. Driven by a linear motor, this achieves high-precision variable baseline motion. The long-stroke, tilted granite base 4, the long-stroke linear air-bearing guide 5, the sub-aperture support structure 6, the sub-aperture 7, and the long-stroke linear air-bearing guide mass balance device 8 comprise the long-stroke variable baseline mechanism, referred to as the large X-shaped variable array mechanism.

[0044] 5) The folding mirror 12 is a plane reflector, which is mounted on two small-stroke linear air-floating guide rails 10 through a support structure 11. Each air-floating guide rail 10 contains two sliding sleeves, and a folding mirror 12 and its support structure 11 are mounted on each sliding sleeve.

[0045] A short-stroke linear air-bearing guide 10 is tilted and placed on a short-stroke tilted granite base 9. It is fixed at both ends and supported at three points, one at the ends and the middle. The air-bearing guide 10 has minimal friction, so a mass balance device 13 consisting of a timing belt, pulleys, and counterweights balances the gravity component in its direction of motion. Driven by a linear motor, this achieves high-precision variable baseline motion. The short-stroke tilted granite base 9, the short-stroke linear air-bearing guide 10, the folding mirror support structure 11, the folding mirror 12, and the short-stroke linear air-bearing guide mass balance device 13 together form the short-stroke variable baseline mechanism, also known as the small X-shaped variable array mechanism.

[0046] 6) The beam splitter 14 is installed between the large and small X-ray array mechanisms, deflecting a portion of the light after sub-aperture beam reduction into the light-combining telescope 15. The imaging camera 16 is installed on a translation stage, and its image detector is adjusted to the focal plane of the light-combining telescope 15 by adjusting the translation stage.

[0047] 7) The long-stroke linear air-floating guide 5 and the short-stroke linear air-floating guide 10 have the same structure and composition, mainly including a granite guide 17, a granite sleeve 18, a linear motor 19, a grating scale feedback module 20, a photoelectric switch 21, a buffer device 22, etc.

[0048] The working principle of the present invention is as follows:

[0049] Two linear air-bearing guides with long travel and tilted mountings drive the four sub-apertures in synchronous zooming motion about the optical axis of the collimator, changing the baselines between the sub-apertures. In Fizeau imaging mode, the beams of the sub-apertures undergo synchronous zooming motion via a deflecting mirror using linear air-bearing guides with short travel and tilted mountings, changing the baselines between the narrowed beams. The baseline ratio between a sub-aperture and the narrowed beam is the angular magnification of the sub-aperture. The imaging camera images the narrowed beams, and the target is rotated. This process is repeated several times to complete the array motion of the synthetic aperture imaging system of the present invention. The captured image is then reconstructed through rotation, achieving better UV coverage.

[0050] When the synthetic aperture imaging system of the present invention changes its array, the relative positions of the sub-apertures and the folding mirror will change. Each time the array mechanism changes its array, six baselines can be generated. The four sub-apertures can generate six images through pairwise interference imaging, which can reduce the total observation time, improve the observation efficiency, and enhance the system's adaptability to the environment.

[0051] Combine Figure 4 As shown, the working process of the present invention is as follows:

[0052] In Fizeau imaging mode:

[0053] 1) Target 1 (simulated observation target) is installed inside the center hole of high-precision turntable 2. Turntable 2 drives target 1 to a specified position and then locks it. This position is recorded as θ0;

[0054] 2) The large X-array mechanism drives the four sub-apertures 7 to move synchronously along the X trajectory, so that the baseline 23 of the sub-aperture at the diagonal position is the largest, which is recorded as L0;

[0055] 3) The small X-array mechanism drives the four folding mirrors 12 to move synchronously along the X trajectory, so that the baseline 24 of the folding mirror at the diagonal position is the largest, which is recorded as l0 = L0 / sub-aperture angle magnification;

[0056] 4) After passing through target 1, light from the light source enters collimator 3. The outgoing parallel light enters sub-aperture 7. The outgoing light has completed beam reduction, passes through a two-mirror structure, enters folding mirror 12, is reflected by beam splitter 14, and enters light combining telescope 15. Finally, it is focused onto imaging camera 16. The four light beams interfere with each other to form a total of six interference images.

[0057] 5) The large and small X-array mechanisms respectively drive the subaperture 7 and the folding mirror 12 to move to positions corresponding to the specified baseline lengths. The baselines are denoted as L1 and l1, respectively. The four light beams interfere with each other to form a total of six interference images.

[0058] 6) Repeat 5) several times;

[0059] 7) Repeat 1)-6) several times to complete a system transformation.

[0060] Michelson imaging mode:

[0061] 1) Target 1 (simulated observation target) is installed inside the center hole of high-precision turntable 2. Turntable 2 drives target 1 to a specified position and then locks it. This position is recorded as θ0;

[0062] 2) The large X-array mechanism drives the four sub-apertures 7 to move synchronously along the X trajectory, so that the baseline 23 of the sub-aperture at the diagonal position is the largest, which is recorded as L0;

[0063] 3) The small X array mechanism drives the four folding mirrors 12 to maintain their position at a specified baseline length;

[0064] 4) After passing through target 1, light from the light source enters collimator 3. The outgoing parallel light enters sub-aperture 7. The outgoing light has completed beam reduction, passes through a two-mirror structure, enters folding mirror 12, is reflected by beam splitter 14, and enters light combining telescope 15. Finally, it is focused onto imaging camera 16. The four light beams interfere with each other to form a total of six interference images.

[0065] 5) The large X-array mechanism drives the sub-aperture 7 to move to the position corresponding to the specified baseline length, which is recorded as L1. The folding mirror 12 remains in position, and the four light beams interfere with each other to form a total of six interference images;

[0066] 6) Repeat 5) several times;

[0067] 7) Repeat 1)-6) several times to complete a system transformation;

[0068] 5. Design of mass balancing device for inclined air-floating linear guide rail:

[0069] Combine Figure 5 As shown, the air-floating linear guide 17 is obliquely installed on the inclined granite base 4 / 9. The friction of the air-floating guide is extremely small. If there is no device to balance the gravity component of the sleeve 18 and the load thereon along the direction of movement, a huge driving force will be required to overcome the gravity component, which will increase the structural complexity, increase the cost, and reduce the control accuracy.

[0070] Therefore, a special mass balancing device is designed to balance the gravitational forces acting on the granite sleeve 18 and its load along its direction of motion. The device consists of a timing belt 25, a fixed pulley 26, and a counterweight 27. The timing belt 25 is connected to the granite sleeve 18, passes through the fixed pulley 26, and is secured to the counterweight 27. As the granite sleeve 18 moves on the granite guide rail 17, the counterweight moves up and down, effectively balancing the gravitational forces acting on the granite sleeve 18 and its load along its direction of motion.

[0071] Combine Figure 6As shown, the force analysis and calculation process of the mass balance device is as follows:

[0072] H=2*F 压 *L / (G+ F 压 )-H 套 / 2

[0073] M 锤 =F 拉 / g=(F 压 / g+M 套 ） / 2

[0074] Where H is the vertical distance between the synchronous belt 25 and the sliding sleeve 18, F 压 is the pressure exerted by the load on the sleeve 18, L is the distance between the mass center of the load on the sleeve 18 and the mass center of the sleeve 18, G is the gravity of the sleeve 18, and H is the 套 The thickness of the sleeve 18, M 锤 is the mass of the counterweight 27, F 拉 is the tension on the synchronous belt 25, M 套 is the mass of the sleeve 18. Where H and M 锤 To ask for the amount.

[0075] In summary, compared to the prior art, this invention primarily incorporates tilted, high-precision air-bearing guide rails for simultaneously changing the positions of four sub-telescopes and their reduced beams. The sub-telescopes and their reduced beam movement trajectories form two X-shaped configurations. The sub-telescopes and their movement mechanisms are referred to as the large X-array subsystem, while the reduced beam and its movement mechanisms are referred to as the small X-array subsystem. In Fizeau imaging mode, their displacement is 1 / 5 of the large X-array displacement (sub-telescope reduction ratio), and each array change produces six interferometric images. Its key innovations are as follows:

[0076] 1) Utilizing four sub-apertures and their reduced beams to perform proportional spatial variable baseline motion in conjunction with target rotation to achieve UV coverage of a spatially distributed synthetic aperture imaging system;

[0077] 2) The spatial variable baseline motion of the reduced beam and the spatial variable baseline motion of the subaperture can work independently, enabling both Fizeau-type spatially distributed synthetic aperture imaging and Michelson-type spatially distributed synthetic aperture imaging;

[0078] 3) High-precision tilted air-floating linear guides are used to achieve spatial variable baseline motion of the sub-aperture and its reduced beam. The use of granite guides and sliding sleeves can reduce damping, improve resolution, increase the stability of the motion mechanism, reduce motion linearity error and attitude angle error, and improve variable baseline accuracy.

[0079] 4) The tilting air-bearing translation stage with built-in linear motor, grating scale and external mass balance device can reduce motor driving force, power consumption and heat generation, improve motion accuracy, save space and cost;

[0080] 5) The combined use of two inclined air-floating guide rails can effectively solve the problem that the existing horizontal air-floating guide rail can only drive the subaperture to change the baseline in one direction of movement. The present invention can realize that the two inclined air-floating guide rails can drive the two subapertures to change the baseline simultaneously in two directions of movement without interfering with each other, thereby improving the efficiency of baseline change and observation.

[0081] 6) The inclined air-floating guide rail with a sliding sleeve buffer device and a photoelectric switch can better protect the precision optical components and mechanical structures, preventing collisions and damage to the device caused by power outages, component damage, and improper operation.

[0082] Compared with the prior art, the present invention has the following outstanding technical effects:

[0083] 1) The technologies involved are relatively mature and easy to implement. The feasibility and reliability of this invention are high based on existing domestic and international high-precision air-floating linear translation stage technology, target rotation high-precision turntable technology, and mass balance technology.

[0084] 2) High versatility. This method is widely applicable to variable array spatially distributed synthetic aperture imaging systems;

[0085] 3) Strong scalability. This method provides ideas and basis for the application of space-based small satellite formations and co-hosting in space-distributed synthetic aperture imaging systems;

[0086] 4) High cost performance. The sub-aperture has a small diameter, a small fill factor, and a long baseline length, which makes it highly cost-effective.

[0087] 5) Short observation time. Each baseline change can obtain 6 interferometric images, which has high observation efficiency and short observation time. The observation errors caused by factors such as equipment fluctuations, environmental fluctuations and changes in the observation target are greatly reduced, and the synthesized images are more accurate and reliable.

[0088] 5) High baseline accuracy. The inclined air-floating linear guide with mass balancing device is used for array change, which has high motion accuracy and ensures high baseline accuracy.

[0089] 6) High safety. A sleeve buffer device and photoelectric switch are designed for the inclined air-floating linear guide to prevent collision and damage to the device, thereby improving safety.

[0090] 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 variable array optical synthetic aperture imaging system, characterized in that: include: Target (1), high-precision turntable (2), collimator (3), long-stroke tilted granite base (4), long-stroke linear air-floating guide (5), sub-aperture support structure (6), sub-aperture (7), long-stroke linear air-floating guide mass balance device (8), short-stroke tilted granite base (9), short-stroke linear air-floating guide (10), folding mirror support structure (11), folding mirror (12), short-stroke linear air-floating guide mass balance device (13), spectrometer (14), light-combining telescope (15) and imaging camera (16); wherein, The target (1) is installed in the center hole of the high-precision turntable (2) at the focal plane of the collimator, and the imaging camera (16) is installed at the focal plane of the light-combining telescope (15). The high-precision turntable (2) drives the target (1) to rotate, and the imaging camera collects the image after passing through the optical system; The collimator (3) is a reflective off-axis system comprising a primary mirror, a secondary mirror and a folding mirror, and is used to convert the light generated by the light source into parallel light with a diameter of 1 meter for emission; The sub-aperture (7) is mounted on two long-stroke high-precision linear air-floating guide rails (5) through a supporting structure (6), each air-floating guide rail having two sliding sleeves, and each sliding sleeve is mounted with a sub-aperture (7) and its supporting structure (6); the long-stroke high-precision linear air-floating guide rail (5) is tilted and placed on a long-stroke tilted granite base (4); The folding mirror (12) is a plane reflecting mirror, which is mounted on two small-stroke linear air-floating guide rails (10) through a folding mirror support structure (11). Each air-floating guide rail contains two sliding sleeves, and each sliding sleeve is mounted with a folding mirror (12) and its support structure. The small-stroke linear air-floating guide rail (10) is tilted and placed on a small-stroke tilted granite base (9). The beam splitter (14) is installed between the large and small X-array mechanisms, and deflects a portion of the light after the sub-aperture beam reduction into the light combining telescope (15).

2. The variable array optical synthetic aperture imaging system according to claim 1, characterized in that: The subaperture (7) is a double paraboloid off-axis afocal system with an aperture of 80 mm and an angular magnification of 5.

3. The variable array optical synthetic aperture imaging system according to claim 1, characterized in that: The long-stroke linear air-floating guide rail (5) and the short-stroke linear air-floating guide rail (10) have the same structural form and composition, including a granite guide rail (17), a granite sleeve (18), a linear motor (19), a grating scale feedback module (20), a photoelectric switch (21) and a buffer device (22).

4. The variable array optical synthetic aperture imaging system according to claim 3, characterized in that: A mass balancing device is provided in conjunction with the granite sleeve (18), and the mass balancing device is composed of a synchronous belt (25), a fixed pulley (26) and a counterweight (27); the synchronous belt (25) is connected to the granite sleeve (18), and is fixed to the counterweight (27) after passing through the fixed pulley (26). When the granite sleeve (18) moves on the granite guide rail (17), the counterweight moves up and down, balancing the granite sleeve (18) and the load thereon in real time along the direction of movement.

Images