Variable-array optical synthetic aperture imaging system

Abstract

The invention discloses an optical synthetic aperture imaging system with a variable array. The device comprises a target, a high-precision rotary table, a collimator, a large-stroke inclined granite base, a large-stroke linear air floating guide rail, a sub-aperture supporting structure, a sub-aperture, a large-stroke linear air floating guide rail mass balancing device, a small-stroke inclined granite base, a small-stroke linear air floating guide rail, a reflex mirror supporting structure and a reflex mirror. The invention discloses a small-stroke linear air floating guide rail mass balancing device, a spectroscope, a light combination telescope and an imaging camera. According to the invention, the number of sub-apertures is increased, a sub-aperture base line high-precision adjusting function is added, a beam shrinkage light path base line high-precision adjusting function is added, and a synchronous rotation function of a target is provided, so that better UV coverage can be realized, more complete spatial frequency information can be obtained, the observation time is shortened, and the observation effect is greatly improved.

Description

Technical Field

[0001] The 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. With the increasing requirements for the spatial resolution of optical systems, it is necessary to continuously increase the aperture of optical systems working in a certain band to improve the spatial resolution. However, in practical applications, due to various factors such as manufacturing materials, manufacturing technology, mechanical structure, rocket carrying volume and weight, it is extremely difficult to increase the aperture of a single aperture system. Spatially distributed synthetic aperture technology provides a new path to improve the spatial resolution of optical imaging systems. Compared with a single-aperture telescope, the spatially distributed synthetic aperture uses a telescope array to achieve the equivalent of a single large-aperture telescope's spatial resolution, breaking through the diffraction limit of a single-aperture telescope due to the limitation of the aperture size, and meeting the high-resolution requirements of exoplanet detection, solar observation, and observation of terrestrial objects. By changing the baseline of the subaperture, that is, the center distance of the subaperture optical axis, better UV coverage can be achieved. UV coverage is simply 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, given the number of sub-apertures, the baseline length of the sub-aperture array can be changed to obtain different frequency sampling values. The existing methods and means are as follows: 1. The Very Large Telescope (VLT) built by the European Southern Observatory in Chile consists of four primary mirrors with a diameter of 8.2m and four movable auxiliary mirrors with an aperture of 1.8m. These telescopes can work alone or in pairs or in groups of three to form a huge interferometer array. The light beams from different telescopes are combined through underground tunnels. The baseline can reach 200m and the angular resolution is 0.001″, which is 25 times that of a single telescope working independently.

[0003] 2. The Large Binocular Telescope (LBT) built by the University of Arizona on Mount Graham has two 8.4-meter binocular telescopes fixed on the same frame, with an equivalent aperture of 11.8 meters. The maximum angular resolution of LBT is equivalent to that of a 22.8-meter telescope, and it has no variable baseline function.

[0004] 3. The Wide Field Imaging Interferometry (WIIT) device established by NASA verifies the wide field interferometric imaging algorithm for space interferometer projects such as SPIRIT (infrared), SPECS (submillimeter wave), and TPF-I, establishes and verifies the system model. Two sub-telescopes are installed at both ends of a linear air-floating translation stage. The aperture of each sub-telescope is 25mm, and the baselines of the two sub-telescopes are variable between 25mm and 250mm. UV coverage is achieved through baseline adjustment, synchronous rotation of the target (simulated observation target) and the detector.

[0005] 4. The Changchun Institute of Optics, Mechanics and Physics of the Chinese Academy of Sciences designed the Golay-3 array synthetic aperture telescope system optically to increase the field of view of the system so as to capture and track high-speed moving targets, and the modular design facilitated the expansion of the sub-aperture array. The sub-aperture array selected in the design is the simplest Golay-3 array with a filling factor of F=0.44. After dividing the system into three subsystems and performing optical designs separately, the subsystems were combined and the image quality of the total system was analyzed.

[0006] 5. The National Astronomical Observatory of the Chinese Academy of Sciences designed and built a Fizeau Imaging Interferometer Test Device (FIIT), which mainly consists of a light source module for simulating infinite objects, three sub-telescopes with an aperture of 100 mm 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 has realized broadband white light (400-700nm) phase imaging without variable baseline function in the laboratory.

[0007] 6. Wang Haitao, Zhu Yongkai, Cai Jiahui, Zhang Yajing, and Tian Guiyun from Nanjing University of Aeronautics and Astronautics conducted research on UV coverage and aperture arrangement of optical synthetic aperture telescopes. The UV coverage was increased by rotating the pupil plane composed of four sub-apertures as a whole. The distances from the four sub-apertures to the rotation center were different, so the rotation paths of the four sub-apertures formed four concentric circles with different radii.

[0008] 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. The invention receives the light waves radiated by the target through a Cassegrain telescope array, couples the light waves into a single-mode polarization-maintaining fiber for transmission, uses a fiber collimator array to make the light beam coherently imaged, and uses a piezoelectric ceramic phase modulator and a fiber delay line to compensate for phase errors. It has no variable baseline function.

[0009] 8. Liang Shitong, Yang Jianfeng, Xue Bin and Ruan Ping from the Xi'an Institute of Optics and Precision Mechanics of the 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 an RC system arranged in sequence along the direction of light incidence. Two small-aperture systems with the same structure are designed without a variable baseline function.

[0010] Disadvantages of existing technology: (1) Currently, most of the existing and proposed optical synthetic aperture imaging systems at home and abroad have only undergone theoretical analysis and software simulation, and a small number of scientific research units have experimentally verified individual methods. Pure theoretical analysis and software simulation cannot fully simulate the actual working scenarios and various complex error conditions, and the feasibility and accuracy of the proposed synthetic aperture imaging system are limited.

[0011] (2) Currently, most existing optical synthetic aperture imaging systems at home and abroad use static methods with non-adjustable 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, so less information on different spatial frequencies is obtained, and the observation effect is poor.

[0012] (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 the detector rotate is relatively 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.

[0013] 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 acknowledging or suggesting in any form that the information constitutes the prior art already known to those skilled in the art. Summary of the invention

[0014] In view of the problems existing in the prior art, the purpose of the present invention is to provide a variable array optical synthetic aperture imaging system, wherein four subapertures with the same structure and parameters are distributed on two tilted high-precision linear displacement platforms, and two subapertures are placed on each linear displacement platform. Four identical folding mirrors are distributed on another two tilted high-precision linear displacement platforms, and two folding mirrors are placed on each linear displacement platform. The light beam after being reduced by the four subapertures is incident on the two folding mirrors, and the light after passing through the folding mirrors enters the light-combining telescope for imaging. A rotatable target is placed at the focal plane of the collimator, and better UV coverage of the optical synthetic aperture imaging system is achieved through variable baseline movement of the subaperture and the folding mirror, target rotation, and rotational reconstruction of the observed image. Compared with the existing method, this method increases the number of subapertures, increases the high-precision adjustment function of the subaperture baseline, increases the high-precision adjustment function of the reduced beam optical path baseline, 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.

[0015] In order to achieve the above object, the present invention adopts the following technical solutions: An optical synthetic aperture imaging system with a variable array comprises: a target, a high-precision turntable, a collimator, a long-stroke tilted granite base, a long-stroke linear air-floating guide rail, a sub-aperture support structure, a sub-aperture, a large-stroke linear air-floating guide rail mass balance device, a short-stroke tilted granite base, a short-stroke linear air-floating guide rail, a folding mirror support structure, a folding mirror, a small-stroke linear air-floating guide rail mass balance device, a spectroscope, a light-combining telescope and an imaging camera; wherein the target is installed in the central hole of the high-precision turntable at the focal plane of the collimator, the imaging camera is installed at the focal plane of the light-combining telescope, the high-precision turntable drives the target to rotate, and the imaging camera collects images after passing through the optical system; 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; The sub-aperture is installed 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 installed 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. The folding mirror is a plane reflector, which is installed on two small-stroke linear air-floating guide rails through a folding mirror support structure. Each air-floating guide rail contains two sliding sleeves, and each sliding sleeve is installed with a folding mirror and its support structure. The small-stroke linear air-floating guide rail is tilted and placed on a small-stroke tilted granite base. The beam splitter is installed between the large and small X-array mechanisms to deflect a portion of the light after the sub-aperture beam reduction and enter the light combining telescope.

[0016] Furthermore, the subaperture is a double parabola off-axis afocal system with an aperture of 80 mm and an angular magnification of 5.

[0017] Furthermore, the long-stroke linear air-floating guide and the short-stroke linear air-floating guide have the same structure and composition, including a granite guide, a granite sleeve, a linear motor, a grating scale feedback module, a photoelectric switch and a buffer device.

[0018] 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, thereby balancing the gravity component of the granite sleeve and the load thereon along the movement direction in real time.

[0019] By adopting the above technical solution, the present invention has the following beneficial effects: The present invention increases the number of sub-apertures, increases the high-precision adjustment function of the sub-aperture baseline, increases the high-precision adjustment function of the beam reduction optical path baseline, 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

[0020] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 The figure is an overall structural diagram of the variable array synthetic aperture imaging system of the present invention.

[0022] Figure 2 It is a detailed structural diagram of the variable array synthetic aperture imaging system of the present invention.

[0023] Figure 3 It is a schematic diagram of the structure of the linear air floating guide rail 5 / 10 of the present invention.

[0024] Figure 4 It is a schematic diagram of the large and small baselines of the present invention.

[0025] Figure 5 It is a schematic diagram of the mass balancing device of the inclined air-floating linear guide rail of the present invention.

[0026] Figure 6 It is a mechanical analysis diagram of the inclined air-floating linear guide rail of the present invention. DETAILED DESCRIPTION

[0027] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0029] Combination Figure 1-3 As shown, the variable array synthetic aperture imaging system proposed in the present invention includes a target 1 and a high-precision turntable 2 thereof, a collimator 3, a long-stroke inclined granite base 4, a long-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 spectroscope 14, a light-combining telescope 15, an imaging camera 16, etc.

[0030] The specific connection relationship is as follows: 1) 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.

[0031] 2) The collimator 3 is a reflective off-axis system comprising 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.

[0032] 3) The sub-aperture 7 is a double parabolic off-axis afocal system with an aperture of 80 mm and an angular magnification of 5. It is installed on two large-stroke high-precision linear air-floating guide rails 5 through a supporting structure 6. Each air-floating guide rail 5 contains two sliding sleeves, and one sub-aperture 7 and its supporting structure 6 are installed on each sliding sleeve.

[0033] 4) The long-stroke high-precision linear air-floating guide rail 5 is tilted and placed on the long-stroke tilted granite base 4. It adopts the method of fixing at both ends and supporting at three points at both ends and the middle. The friction of the air-floating guide rail 5 is extremely small, so the mass balance device 8 composed of a synchronous belt, a pulley and a counterweight is used to balance the gravity component in the direction of its movement, and high-precision variable baseline movement is achieved under the drive of the linear motor. The long-stroke tilted granite base 4, the long-stroke linear air-floating guide rail 5, the sub-aperture support structure 6, the sub-aperture 7, the large-stroke linear air-floating guide rail mass balance device 8, etc. constitute a large-stroke variable baseline mechanism, referred to as the large X-variable array mechanism.

[0034] 5) The folding mirror 12 is a plane reflecting mirror, which is installed on two small-stroke linear air-floating guide rails 10 through a supporting structure 11. Each air-floating guide rail 10 contains two sliding sleeves, and a folding mirror 12 and its supporting structure 11 are installed on each sliding sleeve.

[0035] The small-stroke linear air-floating guide rail 10 is placed obliquely on the small-stroke inclined granite base 9, and adopts the method of being fixed at both ends and supported at three points at both ends and the middle. The friction of the air-floating guide rail 10 is extremely small, so the mass balance device 13 composed of a synchronous belt, a pulley and a counterweight is used to balance the gravity component in the direction of its movement, and high-precision variable baseline movement is achieved under the drive of the linear motor. The small-stroke inclined granite base 9, the small-stroke linear air-floating guide rail 10, the folding mirror support structure 11, the folding mirror 12, the small-stroke linear air-floating guide rail mass balance device 13, etc. constitute a small-stroke variable baseline mechanism, referred to as a small X-array variable array mechanism.

[0036] 6) The beam splitter 14 is installed between the large and small X-array mechanisms to deflect 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.

[0037] 7) The long-stroke linear air-floating guide 5 and the short-stroke linear air-floating guide 10 have the same structure and composition, and mainly include 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.

[0038] The working principle of the present invention is as follows: Two linear air-floating guide rails with large strokes and tilted installations drive the four sub-apertures to perform synchronous zooming motion with the collimator optical axis as the center, and the baselines between the sub-apertures can be changed. In Fizeau imaging mode, the beam after the sub-aperture is shrunk is subjected to synchronous zooming motion by means of a folding mirror and a linear air-floating guide rail with small strokes and tilted installations, and the baselines between the shrunk beams can be changed. The baseline ratio between the sub-aperture and the shrunk beam is the angular magnification of the sub-aperture. The imaging camera images the shrunk beam, and the target is rotated and the above process is repeated several times to complete the array movement of the synthetic aperture imaging system of the present invention. The acquired image is rotated and reconstructed, and UV coverage can be better achieved.

[0039] When the synthetic aperture imaging system of the present invention changes its array, the relative positions of the sub-apertures and the folding mirrors will change. Each time the array mechanism changes its array, six baselines can be generated. Two-by-two interference imaging of the four sub-apertures can generate six images, which can reduce the total observation time, improve the observation efficiency, and enhance the system's adaptability to the environment.

[0040] Combination Figure 4 As shown, the working process of the present invention is as follows: In Fizeau imaging mode: 1) Target 1 (simulated observation target) is installed inside the center hole of high-precision turntable 2. Turntable 2 drives target 1 to a certain position and then locks it. This position is recorded as θ 0 ; 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, denoted as L 0 ; 3) The small X-array mechanism drives the four folding mirrors 12 to move synchronously along the X track, so that the baseline 24 of the folding mirror at the diagonal position is the largest, which is recorded as l 0 =L 0 / subaperture angle magnification; 4) The light from the light source passes through the target 1 and enters the collimator 3. The emitted parallel light enters the sub-aperture 7. The emitted light has completed the beam reduction. After passing through the two-mirror structure, it enters the folding mirror 12, and then enters the light combining telescope 15 after being reflected by the beam splitter 14. Finally, it is focused on the imaging camera 16. The four light beams interfere with each other to form a total of six interference images. 5) The large and small X-array mechanisms drive the sub-aperture 7 and the folding mirror 12 to move to the positions corresponding to the specified baseline lengths, and the baselines are respectively recorded as L 1 and l 1 , the four light beams interfere with each other to form a total of 6 interference images; 6) Repeat 5) several times; 7) Repeat 1)-6) several times to complete a system transformation.

[0041] Michelson imaging mode: 1) Target 1 (simulated observation target) is installed inside the center hole of high-precision turntable 2. Turntable 2 drives target 1 to a certain position and then locks it. This position is recorded as θ 0 ; 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, denoted as L 0 ; 3) The small X array mechanism drives the four folding mirrors 12 to maintain positioning at a specified baseline length; 4) The light from the light source passes through the target 1 and enters the collimator 3. The emitted parallel light enters the sub-aperture 7. The emitted light has completed the beam reduction. After passing through the two-mirror structure, it enters the folding mirror 12, and then enters the light combining telescope 15 after being reflected by the beam splitter 14. Finally, it is focused on the imaging camera 16. The four light beams interfere with each other to form a total of six interference images. 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 L 1, the folding mirror 12 remains in position, and the four light beams interfere with each other to form a total of six interference images; 6) Repeat 5) several times; 7) Repeat 1)-6) several times to complete a system change; 5. Design of mass balancing device for inclined air-floating linear guide: Combination 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, increasing the structural complexity, increasing the cost, and reducing the control accuracy.

[0042] Therefore, a special mass balancing device is designed to balance the gravity component of the granite sleeve 18 and the load thereon along the moving direction. The device consists 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, and the gravity component of the granite sleeve 18 and the load thereon along the moving direction is balanced in real time.

[0043] Combination Figure 6 As shown, the force analysis and calculation process of the mass balance device is as follows: H=2*F 压 *L / (G+ F 压 )-H 套 / 2 M 锤 =F 拉 / g=(F 压 / g+M 套 ） / 2 Where H is the vertical distance between the synchronous belt 25 and the sliding sleeve 18, F 压 is the pressure of the load on the sleeve 18 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, H 套 is 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 For the amount of intercession.

[0044] In summary, compared with the prior art, the present invention mainly adds an inclined high-precision air-floating guide rail for simultaneously changing the positions of four sub-telescopes and their reduced beams. The movement trajectories of the sub-telescopes and their reduced beams form two X-shaped configurations. The sub-telescopes and their moving mechanisms are called large X-array variable subsystems, and the reduced beams and their moving mechanisms are called small X-array variable subsystems. In the Fizeau imaging mode, their displacement is 1 / 5 of the displacement of the large X-array variable (sub-telescope reduction ratio), and each array change can obtain 6 interference images. Its main innovations are as follows: 1) Using four sub-apertures and their reduced beams to perform proportional spatial variable baseline motion in conjunction with target rotation motion to achieve UV coverage of the spatially distributed synthetic aperture imaging system; 2) The spatial variable baseline motion of the reduced beam and the spatial variable baseline motion of the subaperture can work independently, and both Fizeau-type spatial distributed synthetic aperture imaging and Michelson-type spatial distributed synthetic aperture imaging can be performed; 3) Use high-precision tilted air-floating linear guide rails to realize the spatial variable baseline motion of the sub-aperture and its reduced beam. The use of granite guide rails and sliding sleeves can reduce damping, improve resolution, increase the stability of the motion mechanism, reduce motion straightness error and attitude angle error, and improve variable baseline accuracy; 4) The tilting air-floating stage with built-in linear motor, grating ruler and external mass balance device can reduce the motor driving force, power consumption and heat generation, improve motion accuracy, save space and cost; 5) The combined use of two inclined air-floating guides can effectively solve the deficiency that the existing horizontal air-floating guide can only drive the sub-aperture to change the baseline in one direction of movement. The present invention can realize that the two inclined air-floating guides can respectively drive the two sub-apertures to change the baseline in two directions of movement at the same time without interfering with each other, thereby improving the baseline change and observation efficiency.

[0045] 6) The inclined air-floating guide rail with a sleeve buffer device and a photoelectric switch can better protect the precision optical components and mechanical structures, and prevent collision and damage to the device caused by power outages, component damage and improper operation.

[0046] Compared with the prior art, the present invention has the following outstanding technical effects: 1) The technology involved is relatively mature and easy to implement. The feasibility and reliability of the invention are high based on the existing high-precision air-floating linear displacement stage technology, target rotation high-precision turntable technology, mass balance technology, etc. at home and abroad; 2) Strong versatility. This method is generally applicable to variable array spatially distributed synthetic aperture imaging systems; 3) Strong scalability. This method provides ideas and basis for the space-based small satellite formation and co-rack application of space-distributed synthetic aperture imaging system; 4) High cost performance. The sub-aperture has a small diameter, a small filling factor, a large baseline length, and a high cost performance; 5) Short observation time. Each time the baseline is changed, 6 interferometric images can be obtained, with high observation efficiency and short observation time. The observation errors caused by factors such as equipment fluctuations, environmental fluctuations and changes in the observed target are greatly reduced, and the synthesized images are more accurate and reliable; 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; 6) High safety. A sleeve buffer device and a photoelectric switch are designed for the inclined air-floating linear guide to prevent collision and damage to the device and improve safety.

[0047] 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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned 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 rail (5), sub-aperture support structure (6), sub-aperture (7), long-stroke linear air-floating guide rail mass balance device (8), short-stroke tilted granite base (9), short-stroke linear air-floating guide rail (10), folding mirror support structure (11), folding mirror (12), short-stroke linear air-floating guide rail mass balance device (13), beam splitter (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 installed on two long-stroke high-precision linear air-floating guide rails (5) through a supporting structure (6); each air-floating guide rail contains two sliding sleeves, and each sliding sleeve is installed 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 installed on two small-stroke linear air-floating guide rails (10) through a folding mirror support structure (11), each air-floating guide rail comprising two sliding sleeves, and each sliding sleeve is installed 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 to enter 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 parabola 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, and include 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, thereby balancing the gravity component of the granite sleeve (18) and the load thereon along the moving direction in real time.

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