Lunar-based synthetic aperture telescope system

Abstract

The present invention provides a lunar-based synthetic aperture telescope system, including N lunar-based synthetic aperture telescopes and synthetic aperture modules. The present invention designs the hardware structure of the lunar-based synthetic aperture telescope, interconnects all lunar-based synthetic aperture telescopes through optical fibers, synthesizes the light field information of the subaperture obtained by each lunar-based synthetic aperture telescope through the synthetic aperture module, and then processes the synthesized light beam to obtain a high-resolution image. The present invention realizes the detection of the Earth-Moon space and the Earth's extremely high orbit, and can achieve the isolation of lunar dust and the buffering during landing. The N lunar-based synthetic aperture telescopes of the present invention can make the most of the existing payload through optical fiber interconnection, and physically isolate the photon collection of the subaperture from the synthetic aperture.

Description

Technical Field

[0001] The present invention relates to the field of astronomical observation of the Earth-Moon system, and specifically provides a moon-based synthetic aperture telescope system. Background Art

[0002] According to a recent report from the U.S. Air Force Research Laboratory, the space region between the Earth and the Moon, i.e., the cis-lunar space, is considered the next frontier. With the acceleration of lunar development and the increase in rocket carrying capacity, there is an increasing demand for deep space and cis-lunar astronomical observations using the advantages of the thin lunar atmosphere and extremely stable environment. Aiming at the construction of my country's lunar scientific research station in the future, the present invention conducts research on large-field-of-view high-resolution interferometer array technology. Compared with ground-based optical interferometer arrays, space-based optical interferometer arrays have received continuous attention due to their advantages such as being unaffected by atmospheric turbulence, good environmental stability, wide observation range, wide band coverage, and easy array change. At present, ground-based interferometer arrays have made certain progress, and interference has been achieved in the infrared band, while space-based interferometer arrays are in the stage of technical exploration. The lunar-based interferometer array combining the two is still in a blank stage of research.

[0003] Relying on the large-scale international space station to be built in my country in the future, the fiber-optic interconnection system can make the most of the existing payloads to collect and process photons, achieve physical isolation, and use the excellent environmental control equipment in the cabin to perform high-precision beam synthesis. At the same time, in conjunction with the existing large-aperture survey telescope, a wide area search can be carried out to obtain potential habitable planets through further detailed observation.

[0004] The widespread application of large-aperture free-form surfaces is of great significance to achieving compact optical systems while taking into account large field of view and high-resolution imaging. The processing and inspection of free-form surfaces is difficult and time-consuming, which poses a huge challenge to optical processing and assembly, and also seriously restricts the realization of design indicators and the efficiency of equipment manufacturing. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a lunar-based synthetic aperture telescope system, which mainly designs the hardware structure of the lunar-based synthetic aperture telescope, interconnects all lunar-based synthetic aperture telescopes through optical fibers, synthesizes the light field information of the sub-aperture obtained by each lunar-based synthetic aperture telescope through a synthetic aperture module, and then processes the synthesized light beam to obtain a high-resolution image.

[0006] The moon-based synthetic aperture telescope system provided by the present invention comprises: N moon-based synthetic aperture telescopes and synthetic aperture modules, wherein N is an integer greater than 1;

[0007] The lunar-based synthetic aperture telescope includes: a protective shell, an optical imaging element, an optical fiber, and a transfer robot. The protective shell is wrapped around the optical imaging element. The rear end of the imaging surface of the optical imaging element is connected to an optical fiber. The other end of the optical fiber is connected to the synthetic aperture module. The transfer robot is fixedly connected to the bottom of the protective shell.

[0008] The protective shell is filled with gas to open and protect the lunar-based synthetic aperture telescope;

[0009] The optical imaging element is used for optical imaging;

[0010] The transfer robot is used to move the lunar synthetic aperture telescope to a preset position and align it with the observation target;

[0011] N lunar synthetic aperture telescopes are interconnected by optical fiber, and the optical fiber is used to transmit the light field information of the sub-aperture of each lunar synthetic aperture telescope to the synthetic aperture module;

[0012] The synthetic aperture module obtains the light field information of the sub-aperture of each lunar-based synthetic aperture telescope through holographic detection, and synthesizes the light field information of the sub-aperture.

[0013] Preferably, the protective shell is spherical.

[0014] Preferably, the optical imaging element comprises: a variable diffraction grating, a lens group, a prism and a camera.

[0015] Preferably, the lens group performs optical imaging by refraction or reflection. The lens group that performs optical imaging by refraction includes a correcting lens, and the lens group that performs optical imaging by reflection includes a lightweight mirror.

[0016] Preferably, a prism is used to split light and transmit the light beam obtained by the lens group to the camera and the optical fiber.

[0017] Preferably, the synthetic aperture module synthesizes the light field information of the sub-apertures into a circular aperture.

[0018] Preferably, the calculation formula for the optical image information of the circular aperture is as follows:

[0019] Amplitude transmittance t A (ξ,η):

[0020]

[0021] Where N is the number of subapertures, ξ and η are the frequency coordinates, circ is the circular function, (ξ i ,η i ) represents the center coordinate of the i-th subaperture, φ irepresents the phase shift of the ith subaperture, D represents the aperture length of the subaperture, e represents the natural base which is a constant, j is the imaginary unit, δ represents the pulse function, and N represents the total number of lunar-based synthetic aperture telescopes;

[0022] Beam complex amplitude distribution I A :

[0023]

[0024] Where λ represents the wavelength, (ρ i ,δ i ) represents the polar coordinate position of the subaperture array, J1 represents the first-kind Bessel function, and θ represents the incident angle of the light beam.

[0025] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0026] 1. The present invention realizes the detection of the cis-lunar space and the earth's extremely high orbit, and can protect and open the system of the present invention when the lunar-based synthetic aperture telescope system is released into orbit and lands, realizes the isolation of lunar dust and the buffering during landing, and realizes automatic collaborative operation through the transfer robot.

[0027] 2. The optical fiber interconnection of the present invention can make the most of the existing load and physically isolate the photon collection of the sub-aperture from the synthetic aperture.

[0028] 3. The present invention cooperates with the existing large-aperture survey telescope to search a wide area and make detailed observations of large-field and long-distance space.

[0029] 4. The present invention takes into account both large field of view and high-resolution imaging, and at the same time, designs the hardware structure of the lunar-based synthetic aperture telescope. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a structural diagram of a lunar-based synthetic aperture telescope provided according to an embodiment of the present invention;

[0031] Figure 2 is a working schematic diagram of a lunar-based synthetic aperture telescope system provided according to an embodiment of the present invention;

[0032] Figure 3 is a schematic diagram of imaging of a correction lens provided according to an embodiment of the present invention;

[0033] Figure 4 is a structural diagram of a lightweight mirror provided according to an embodiment of the present invention.

[0034] The reference numerals therein include: lunar-based synthetic aperture telescope 1, protective shell 11, variable diffraction grating 12, lens group 13, correction lens 13', lightweight mirror 13", tangential piezoelectric ceramic sheet 13-1", prism 14, camera 15, optical fiber 16, optical fiber connector 17, synthetic aperture module 2, sub-aperture 21, synthetic aperture 22. DETAILED DESCRIPTION

[0035] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the same modules are represented by the same reference numerals. In the case of the same reference numerals, their names and functions are also the same. Therefore, the detailed description thereof will not be repeated.

[0036] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0037] Figure 1 The structure of a lunar-based synthetic aperture telescope provided according to an embodiment of the present invention is shown.

[0038] like Figure 1 As shown, the lunar synthetic aperture telescope 1 mainly includes: a protective shell 11, a variable diffraction grating 12, a lens group 13, a prism 14, a camera 15, an optical fiber 16, and an optical fiber connector 17. The protective shell 11 is completely wrapped around the outside of the lunar synthetic aperture telescope 1. The inside of the protective shell 11 can be filled with gas. When the lunar synthetic aperture telescope 1 is released and landed in orbit, the gas expands due to the reduction of external pressure. Under the action of the internal gas, the protective shell 11 protects and opens the lunar synthetic aperture telescope 1. The incident light reflected from the observation target first enters the variable diffraction grating 12 for diffraction, and then passes through the lens group 13 to transmit the incident light to the prism 14. The prism 14 is fixed at the focus of the lens group 13, and the diffracted incident light is divided into two beams, one beam enters the camera 15, and the other beam enters the optical fiber 16, and finally enters the synthetic aperture module 2 through the optical fiber connector 17.

[0039] The lunar-based synthetic aperture telescope 1 also includes a transfer robot connected to the bottom of the protective shell, which is used to move the lunar-based synthetic aperture telescope to a preset position and align the observation target to prepare for imaging. The specific structure of the transfer robot is a common manipulator structure. The structure and control of the manipulator are existing technologies and will not be described in detail here.

[0040] Figure 2 A lunar-based synthetic aperture telescope system provided according to an embodiment of the present invention is shown.

[0041] like Figure 2As shown, the lunar-based synthetic aperture telescope system includes: N lunar-based synthetic aperture telescopes 1 and a synthetic aperture module 2, wherein N is an integer greater than 1. The N lunar-based synthetic aperture telescopes 1 are used to reach a predetermined position, aim, and accurately image the same observation target, and then transmit the light field information of each sub-aperture 21 to the synthetic aperture module 2 through the optical fiber 16, and process it to form a synthetic aperture 22, so as to achieve large field of view and high resolution imaging.

[0042] The following is the working process of the lunar-based synthetic aperture telescope system:

[0043] The present invention is carried on a transport rocket, and gas is filled in the protective shell 11 before the rocket is launched. After the release in orbit, due to the reduction of external pressure, the gas in the protective shell 11 expands, and finally the system is opened, and a buffering effect is generated during the landing process. After landing, the transfer robot moves, and moves the N moon-based synthetic aperture telescopes 1 to preset positions respectively, and ensures that the N moon-based synthetic aperture telescopes 1 aim at the same observation target through its own pointing function. The N moon-based synthetic aperture telescopes 1 image the observation target, and each moon-based synthetic aperture telescope 1 obtains the light field information of a sub-aperture 21, and a synthetic aperture 22 is digitized by laser communication through the optical fiber interface 17. The synthetic aperture 22 is a circular aperture, that is, the light field information of each sub-aperture 21 is obtained through holographic detection, and the corresponding point spread function is inversely solved by using the light field information, and based on the synthesis of the point spread function, the system fuzzy point spread function is obtained, and the resolution of the system is improved by deconvolution. The point spread function obtained by the synthetic aperture method has the same envelope as that of a single aperture, but has more internal fluctuations.

[0044] The calculation formula for optical image information processing of circular aperture is as follows:

[0045] Amplitude transmittance t A (ξ,η):

[0046]

[0047] Where N is the number of subapertures, ξ and η are the frequency coordinates, circ is the circular function, (ξ i ,η i ) represents the center coordinate of the i-th subaperture, φ i represents the phase shift of the i-th subaperture, D represents the aperture length of the subaperture, e represents the natural base which is a constant, j is the imaginary unit, δ represents the pulse function, and N represents the total number of lunar-based synthetic aperture telescopes.

[0048] For observations in the synthetic aperture band, since small-aperture systems are already relatively mature, the use of synthetic aperture technology can quickly and economically improve observation capabilities. The beam complex amplitude distribution of large-aperture systems is A :

[0049]

[0050] Where λ represents the wavelength, (ρ i ,δ i ) represents the polar coordinate position of the subaperture array, J1 represents the first-kind Bessel function, and θ represents the incident angle of the light beam.

[0051] Taking three sparse sub-apertures evenly distributed on the circumference as an example, the complex amplitude of the beam I of the system of multi-aperture synthesis of large aperture tri-aperture The distribution of is as follows:

[0052]

[0053] It can be seen from the above formula that the envelope of the complex amplitude distribution of the system is close to that of a single-aperture telescope. However, due to the separation of the apertures, the complex amplitude distribution of the light beam will be modulated, resulting in attenuation of its edge portion.

[0054] Figure 3 A correction lens provided according to an embodiment of the present invention is shown.

[0055] Figure 4 The structure of a lightweight mirror provided according to an embodiment of the present invention is shown.

[0056] The lunar-based synthetic aperture telescope is not affected by atmospheric turbulence, but will be affected by slowly varying errors such as thermal loads. Therefore, active optics need to be introduced for correction. At the same time, active optics can also relax the tolerance of low-order surface shapes manufactured in situ, effectively reducing the construction cost and development cycle of lunar-based large-aperture telescope systems.

[0057] In this embodiment, active optics is introduced through the lens group 13 for correction. The lens group 13 performs optical imaging by refraction or reflection. When the refraction method is used for optical imaging, Figure 3 As shown, the lens group 13 uses a correcting lens 13' to achieve optical imaging.

[0058] When using reflection for optical imaging, such as Figure 4As shown, the lens group 13 uses a lightweight mirror 13" to achieve optical imaging. A tangential piezoelectric ceramic sheet 13-1" is organically integrated in the lightweight mirror 13". The tangential piezoelectric ceramic sheet 13-1" and the mirror surface of the lightweight mirror 13" are constructed to have the same shape. The area change of the tangential piezoelectric ceramic sheet 13-1" is used to drive the lightweight mirror 13" to bend. Since the bending mode conforms to the constitutive equation of the thin plate and is formally consistent with the Poisson's equation, it can be directly driven by the curvature.

[0059] Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and cannot be understood as limiting the present invention. Those skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

[0060] The above specific implementations of the present invention do not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A lunar-based synthetic aperture telescope system, characterized in that: include: N lunar-based synthetic aperture telescopes and synthetic aperture modules, where N is an integer greater than 1; The lunar-based synthetic aperture telescope comprises: a protective shell, an optical imaging element, an optical fiber and a transfer robot, wherein the protective shell is wrapped around the optical imaging element, the optical fiber is connected to the rear end of the imaging surface of the optical imaging element, the other end of the optical fiber is connected to the synthetic aperture module, and the transfer robot is fixedly connected to the bottom of the protective shell; The protective shell is filled with gas for opening and protecting the lunar-based synthetic aperture telescope; The optical imaging element is used for optical imaging; The transfer robot is used to move the lunar-based synthetic aperture telescope to a preset position and align it with an observation target; N of the lunar-based synthetic aperture telescopes are interconnected by optical fibers, and the optical fibers are used to transmit light field information of a sub-aperture of each lunar-based synthetic aperture telescope to the synthetic aperture module; The synthetic aperture module obtains the light field information of each sub-aperture of the lunar-based synthetic aperture telescope through holographic detection, and synthesizes the light field information of the sub-aperture.

2. The lunar-based synthetic aperture telescope system according to claim 1, characterized in that: The protective shell is spherical.

3. The lunar-based synthetic aperture telescope system according to claim 1, wherein: The optical imaging element includes: a variable diffraction grating, a lens group, a prism and a camera.

4. The lunar-based synthetic aperture telescope system according to claim 3, characterized in that: The lens group performs optical imaging by refraction or reflection. The lens group that performs optical imaging by refraction includes a correction lens, and the lens group that performs optical imaging by reflection includes a lightweight mirror.

5. The lunar-based synthetic aperture telescope system according to claim 3, characterized in that: The prism is used for light splitting and transmits the light beam obtained by the lens group to the camera and the optical fiber.

6. The lunar-based synthetic aperture telescope system according to claim 1, wherein: The synthetic aperture module synthesizes the light field information of the sub-apertures into a circular aperture.

7. The lunar-based synthetic aperture telescope system according to claim 6, characterized in that: The calculation formula of the optical image information of the circular aperture is as follows: Amplitude transmittance t A (ξ,η): Wherein, N represents the number of subapertures, that is, the total number of the lunar-based synthetic aperture telescope, ξ and η represent frequency coordinates, circ represents the circular domain function, (ξ i ,η i ) represents the center coordinate of the i-th subaperture, φ i represents the phase shift of the ith subaperture, D represents the aperture length of the subaperture, e represents the natural base which is a constant, j is the imaginary unit, and δ represents the pulse function; Beam complex amplitude distribution I A : Where λ represents the wavelength, (ρ i ,δ i ) represents the polar coordinate position of the subaperture array, J1 represents the first-kind Bessel function, and θ represents the incident angle of the light beam.

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