A correction method and device for a space-expandable telescope

Abstract

The present invention relates to a correction method and device for a space-deployable telescope. This method and device first monitor and provide feedback on the alignment of the space-deployable telescope during its deployment process after entering orbit using a back-end fiber optic interconnection system. The alignment of the space-deployable telescope is then corrected using a parallel gradient descent algorithm. This invention addresses the integrated testing process of large-aperture telescopes, studying the interactions between the internal components of a large-aperture spliced ​​telescope under different operating conditions. It analyzes the kinematic and mechanical mechanisms of the interactions between the components of the large-aperture spliced ​​mirror. Finally, it analyzes the establishment, maintenance, dynamic changes, and control mechanisms of the precision transfer network for the large-aperture spliced ​​telescope from the perspectives of multimodal control interaction, functional synergy, and system integration.

Description

Technical Field

[0001] The invention relates to a correction method and device for a space-expandable telescope. Background Art

[0002] Space telescopes, also known as ground-based telescopes, offer the advantages of wide observation windows and immunity to atmospheric turbulence, enabling deeper and more detailed observations of the universe. Future large-aperture space telescopes will reach 10 to 15 meters, making such large telescopes impractical for direct launch. Due to launch vehicle limitations, the next generation of large-aperture space telescopes will utilize in-orbit deployment or in-orbit manufacturing. Compared to integrated launch telescopes, in-orbit deployment eliminates the need for traditional mechanical structures to ensure the relative positional accuracy of optical components. Instead, adjustable and controllable active optical links transform the system into a controllable electromechanical system, ultimately achieving high-precision alignment.

[0003] To achieve high-precision, rapid positioning and calibration of the system, a series of alignment methods must be constructed, progressing from large-scale precision to small-scale, high-precision, layer-by-layer iterations to achieve system alignment, ultimately achieving nanometer-level alignment accuracy over a span of 10 to 15 meters. Currently, the most advanced on-orbit deployment device is the James Webb Telescope, whose deployment is completely guided by the final camera. However, the James Webb telescope's deployment process only has one degree of freedom, namely the primary mirror units belonging to the two wings. However, as the aperture of the telescope increases in the future, the degree of freedom of deployment will gradually increase. To ensure precise control and alignment of these multiple degrees of freedom, new measurement devices and equipment are needed to ensure the effective alignment of multiple sub-mirrors.

[0004] The Hubble Space Telescope incorporates a built-in active telescope adjustment function, laying the foundation for numerous future technologies. Meanwhile, the European Astronomical Observatory's Gaia telescope achieves high-precision alignment using two 1.5-meter-long mirror segments, segmenting and calibrating the aperture using a Hartmann sensor to achieve high-precision system co-ordination. This method works well for binocular systems, but the next generation of segmented telescopes often have hundreds of segmented segments. Therefore, there is an urgent need to develop a high-throughput system alignment method that can be integrated on a large scale. The next generation of large-aperture telescopes, the Will, will use laser ranging for large-scale system calibration, but in-depth research has yet to be conducted on the alignment and adjustment of its multiple segmented mirrors. The segmented mirror units and scientific terminals of large-aperture segmented telescope systems will be regionalized and modularized to enable precise astronomical observations and large-scale digital sky surveys. Summary of the Invention

[0005] The embodiments of the present invention provide a space-deployable telescope correction method and device to at least solve the technical problems of existing high-throughput system alignment methods without large-scale integration.

[0006] According to one embodiment of the present invention, a method for correcting a space-deployable telescope is provided, comprising the following steps:

[0007] During the deployment process of the space deployable telescope after it enters orbit, the back-end optical fiber interconnection system is used to monitor and provide feedback on the alignment of the space deployable telescope;

[0008] Correcting the alignment of a space-deployable telescope based on a parallel gradient descent algorithm.

[0009] Furthermore, the back-end optical fiber interconnection system is used to monitor and provide feedback on the alignment of the space-deployable telescope, including:

[0010] The parallel gradient descent algorithm is used to calculate the wavefront slope, restore the wavefront, and conduct feedback testing on the telescope system.

[0011] The pattern method is used to obtain the plucking information from the slope information. By obtaining the slopes of all sampling points of the wavefront, the overall wavefront is finally reconstructed based on the decomposition of the Zernike polynomials, and the tilt of the corresponding sub-aperture is obtained from the plucking.

[0012] Furthermore, the alignment of the space-deployable telescope is corrected based on a parallel gradient descent algorithm, including:

[0013] A photonic interconnected scanning mechanism is set up on the same surface, and the wavefront slope is restored and the inclination angle is corrected by establishing a corresponding relationship between the overall wavefront slope and the Zernike polynomial.

[0014] Furthermore, the method specifically includes:

[0015] Select a suitable drawing of the telescope system to insert the all-photon scanning device, and select a position that does not affect the smooth operation of the telescope system for optical head scanning;

[0016] Match the coupler connected to the optical fiber to a specific sub-diameter unit to ensure that the light received by the coupler comes from a single sub-diameter unit;

[0017] Collect the energy and mode information drawn from the optical fiber at the output end of the optical fiber and record the information;

[0018] Move the coupler to the area corresponding to the next sub-diameter unit and repeat the above steps until all sub-diameter units are scanned.

[0019] Furthermore, when the telescope collects the light beam, a fiber optic Internet prism system is set on the same surface as the telescope to track the light spots of each piece one by one. After obtaining the position of each light spot, it is adjusted to a common focus by adjusting the position of each light spot.

[0020] Furthermore, the segmented boundaries are sensed by using the optical fiber mutual contamination method, a boundary stability detection optical path is inserted into the existing optical path, and the final detection results are fed back;

[0021] A high-throughput, densely packed method is adopted to sense the boundary stability of the system with a single exposure, and on this basis, the pointing of the system's main mirror is adjusted.

[0022] Furthermore, single-mode optical fiber is used to detect and correct the wavefront tilt and locate its defocus along the optical axis; the phase information of the fringes is obtained by fitting, and the spatial filtering characteristics of the optical fiber are used to obtain the wavefront information within the sub-aperture.

[0023] Furthermore, by using the incoherent synthesis theory, a synthetic complex light field distribution model in the non-narrowband case is obtained, and a theoretical analysis tool is obtained by expressing the analytical expression of the intensity and phase of the synthesized light.

[0024] Furthermore, the structure function is used for analysis to obtain different defocus values, and the defocus values ​​are matched one-to-one with the structure function to determine the rough co-directional process of the system.

[0025] According to another embodiment of the present invention, a space-expandable telescope correction device is provided, comprising:

[0026] A monitoring and feedback unit, used to monitor and provide feedback on the alignment of the space-deployable telescope using a back-end optical fiber interconnection system during the deployment process of the space-deployable telescope after it enters orbit;

[0027] A correction unit is used to correct the alignment of the space deployable telescope based on a parallel gradient descent algorithm.

[0028] A processor is used to run a program, wherein when the program is run, any one of the above-mentioned space-deployable telescope correction methods is executed.

[0029] A processor is used to run a program, wherein when the program is run, any one of the above-mentioned space-deployable telescope correction methods is executed.

[0030] The method and device for correcting a deployable telescope in an embodiment of the present invention first monitors and provides feedback on the telescope's alignment during its deployment after entering orbit using a back-end fiber optic interconnection system. The alignment of the telescope is then corrected using a parallel gradient descent algorithm. This invention addresses the integrated testing process of large-aperture telescopes, studying the interactions between the internal components of a large-aperture spliced ​​telescope under different operating conditions. It analyzes the kinematic and mechanical mechanisms of interaction between the components of the large-aperture spliced ​​mirror. Finally, it analyzes the establishment, maintenance, dynamic changes, and control mechanisms of the precision transfer network for the large-aperture spliced ​​telescope from the perspectives of multimodal control interaction, functional synergy, and system integration. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0032] Figure 1 This is a flow chart of the space-deployable telescope correction method of the present invention;

[0033] Figure 2 This is a system architecture diagram of the present invention;

[0034] Figure 3 The result of reconstructing the system wavefront in the present invention is Figure I ;

[0035] Figure 4 The result of reconstructing the system wavefront in the present invention is Figure II ;

[0036] Figure 5 The result of reconstructing the system wavefront in the present invention is Figure III ;

[0037] Figure 6 The process of mode field coupling of the single-mode optical fiber in the present invention Figure IV ;

[0038] Figure 7 A diagram showing the process of mode field coupling of a single-mode optical fiber in the present invention;

[0039] Figure 8 This is a diagram of the experimental platform constructed in the present invention;

[0040] Figure 9 This is the output result after simulating the pre-broadcasting by using the unit deformable mirror in the present invention. Figure I ;

[0041] Figure 10 This is the output result after simulating the pre-broadcasting by using the unit deformable mirror in the present invention. Figure II ;

[0042] Figure 11 The output result after simulating the pre-broadcasting by using the unit deformable mirror in the present invention is Figure III ;

[0043] Figure 12 This is the output result after simulating the pre-broadcasting by using the unit deformable mirror in the present invention. Figure IV ;

[0044] Figure 13 A schematic diagram of light interference performed by the system of the present invention;

[0045] Figure 14 Interference fringe pattern of light interference performed by the system of the present invention;

[0046] Figure 15 This is a result diagram of analyzing interference fringes using power spectrum in the present invention;

[0047] Figure 16 This is a module diagram of the space-expandable telescope correction device of the present invention. DETAILED DESCRIPTION

[0048] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described 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 making creative efforts should fall within the scope of protection of the present invention.

[0049] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0050] Example 1

[0051] According to an embodiment of the present invention, a method for correcting a space-expandable telescope is provided. Figure 1 , including the following steps:

[0052] S100: During the deployment process of the space deployable telescope after it enters orbit, the back-end optical fiber interconnection system is used to monitor and provide feedback on the alignment of the space deployable telescope;

[0053] S200: Correcting the alignment of the space-deployable telescope based on a parallel gradient descent algorithm.

[0054] The space-deployable telescope correction method in the embodiment of the present invention first monitors and provides feedback on the alignment of the space-deployable telescope during its deployment process after entering orbit using a back-end fiber optic interconnection system. The alignment of the space-deployable telescope is then corrected using a parallel gradient descent algorithm. This method focuses on the integrated testing process of large-aperture telescopes, studying the interactions between the internal components of large-aperture spliced ​​telescopes under different operating conditions. It analyzes the kinematic and mechanical mechanisms of the interactions between the components of the large-aperture spliced ​​mirror. Finally, it analyzes the establishment, maintenance, dynamic changes, and control mechanisms of the precision transfer network for large-aperture spliced ​​telescopes from the perspectives of multimodal control interaction, functional synergy, and system integration.

[0055] The use of a back-end fiber optic interconnection system to monitor and provide feedback on the alignment of a space-based deployable telescope includes:

[0056] The parallel gradient descent algorithm is used to calculate the wavefront slope, restore the wavefront, and conduct feedback testing on the telescope system.

[0057] The pattern method is used to obtain the plucking information from the slope information. By obtaining the slopes of all sampling points of the wavefront, the overall wavefront is finally reconstructed based on the decomposition of the Zernike polynomials, and the tilt of the corresponding sub-aperture is obtained from the plucking.

[0058] Among them, the correction of the alignment of the space deployable telescope based on the parallel gradient descent algorithm includes:

[0059] A photonic interconnected scanning mechanism is set up on the same surface, and the wavefront slope is restored and the inclination angle is corrected by establishing a corresponding relationship between the overall wavefront slope and the Zernike polynomial.

[0060] The method specifically includes:

[0061] Select a suitable drawing of the telescope system to insert the all-photon scanning device, and select a position that does not affect the smooth operation of the telescope system for optical head scanning;

[0062] Match the coupler connected to the optical fiber to a specific sub-diameter unit to ensure that the light received by the coupler comes from a single sub-diameter unit;

[0063] Collect the energy and mode information drawn from the optical fiber at the output end of the optical fiber and record the information;

[0064] Move the coupler to the area corresponding to the next sub-diameter unit and repeat the above steps until all sub-diameter units are scanned.

[0065] Among them, when the telescope collects the light beam, a fiber optic Internet prism system is set on the same surface of the telescope to track the light spots of each piece one by one. After obtaining the position of each light spot, it is adjusted to the common focus by adjusting the position of each light spot.

[0066] Among them, the segmented boundaries are sensed by using the optical fiber mutual contamination method, and a boundary stability detection optical path is inserted into the existing optical path, and the final detection results are fed back;

[0067] A high-throughput, densely packed method is adopted to sense the boundary stability of the system with a single exposure, and on this basis, the pointing of the system's main mirror is adjusted.

[0068] Among them, single-mode optical fiber is used to detect and correct the wavefront tilt and locate its defocus along the optical axis; the phase information of the fringes is obtained by fitting, and the spatial filtering characteristics of the optical fiber are used to obtain the wavefront information within the sub-aperture.

[0069] Among them, the incoherent synthesis theory is used to obtain the synthetic complex light field distribution model in the non-narrowband case, and the theoretical analysis tool is obtained by expressing the analytical expression of the intensity and phase of the synthesized light.

[0070] Among them, the structure function is used for analysis to obtain different defocus values, and the defocus values ​​are matched one-to-one with the structure function to determine the rough co-directional process of the system.

[0071] The following is a detailed description of the space-expandable telescope correction method of the present invention using a specific embodiment:

[0072] The present invention focuses on the deployment process of a space-deployable telescope after it enters orbit, utilizes a back-end optical fiber interconnection system to monitor and provide feedback on the alignment of the telescope, and corrects its alignment based on a parallel gradient descent algorithm.

[0073] This invention utilizes mode field coupling theory. When a light beam is tilted, its efficiency in coupling into the optical fiber changes. Since the input light intensity can be assumed to remain constant, the variation in the final light intensity reflects the variation in the iron law. Furthermore, considering the scanning of non-single-mode fibers, the system's mode field information also affects the final result. Specifically, this includes:

[0074] Step 1: Select the appropriate system surface to insert the all-photon scanning device. Due to the flexibility brought by fiber optic interconnection, the optical head scanning can be selected according to the actual needs of the system without affecting the actual smooth operation of the system.

[0075] Step 2: Align the coupler connected to the optical fiber with a specific sub-path unit to ensure that the light received by the coupler comes from a single sub-path unit.

[0076] Step 3: Collect the energy and mode information drawn out by the optical fiber at the output end of the optical fiber and record the information.

[0077] Step 4: Move the coupler to the area corresponding to the next sub-diameter unit and repeat the above steps until all sub-diameter units are scanned.

[0078] The proposed algorithm calculates the slope of the wavefront and restores the pre-broadcast, which is then used to conduct feedback testing on the system. To obtain string-plucking information from the slope information, the present invention employs a pattern approach. This approach obtains the slopes of all sampling points of the wavefront and, based on the decomposition of Zernike polynomials, ultimately reconstructs the overall wavefront. The plucking information then derives the tilt of the corresponding subaperture.

[0079] The collection and control of photons by a large-aperture spliced ​​telescope is essentially the result of the fine division of labor and coordinated control of many components in its imaging link in time and space. Traditional research has mostly focused on aspects such as end-to-end (optical transfer function) and the impact of external input on the system. In the process of executing control, the forms, functions and mechanisms of energy exchange and precision transfer between components are still unclear. The present invention focuses on the integrated detection process of large-aperture telescopes, studies the interaction mode between the internal components of large-aperture spliced ​​telescopes under different working conditions, analyzes the kinematic and mechanical mechanisms of the interaction between the component units of large-aperture spliced ​​mirrors, and analyzes the establishment, maintenance, dynamic changes and control mechanisms of the precision transfer network of large-aperture spliced ​​telescopes from the perspectives of system multi-modal control interaction, functional coordination and system integration.

[0080] For splicing, the system of the present invention establishes a photonic interconnected scanning mechanism on the same surface. By establishing a correspondence between the overall wavefront slope and the Zernike polynomial, the wavefront slope can be restored and the tilt angle corrected. The present invention accurately simulates the wavefront input conditions and its modes, using a deformable mirror for sub-aperture simulation.

[0081] The basic algorithm of the present invention:

[0082] The parallel gradient descent algorithm searches for the optimal direction randomly each time. Although the algorithm's convergence is statistically guaranteed, its slow convergence speed becomes particularly prominent when real-time requirements are high. Let the performance index of the adaptive optical system be β, and the change in performance index obtained by increasing the perturbation voltage be Δβ. Since energy drastic changes do not occur in actual engineering applications and scientific research practices, it is assumed that the system performance index β is differentiable. Through Taylor expansion, we can obtain:

[0083]

[0084] Among them, o(c 2 ) is the remaining term in the expansion.

[0085] In order to obtain the gradient of the performance index, both sides are multiplied by δu i , taking the expectation we can get:

[0086]

[0087] Assume {δu i}, each element in is independent and identically distributed, we can get:

[0088]

[0089] where σ 2 is {δu i}, using formula (3), we can obtain the unbiased estimate of the descent gradient of the evaluation index through statistical laws;

[0090] From the above we can get:

[0091] c n+1 =c n +δβδc (4)

[0092] Equation (4) is the core formula of the algorithm. Choosing a reasonable perturbation voltage can achieve better convergence characteristics. On the other hand, it can be seen from Equation (4) that the parallel gradient descent algorithm is a method that relies on mathematical statistics to obtain an estimate to approximate the gradient. Similarly, using unbiased estimation can obtain an estimate of the optimal step size.

[0093] Specifically, when the space deployment telescope reaches the designated position, its lenses are deployed. When the telescope can collect light beams, a fiber optic Internet prism system is set up on the same surface of the telescope. The light spots of each lens are tracked one by one. After the position of each light spot is obtained, it is adjusted to the common focus by adjusting the position of each light spot.

[0094] Large-aperture space-deployable telescopes face the challenge of balancing detection dynamic range and accuracy during their in-orbit deployment. This invention utilizes a fiber-optic interconnect architecture to collect and transmit photons via optical waveguides, overcoming the drawbacks of large spatial spans, such as the large space occupied and heavy weight of light input. Furthermore, the optical waveguide system's lightweight and radiation-resistant characteristics can reduce the launch payload and electromagnetic compatibility burden, further improving the system's carrying capacity and effectively increasing the payload limit in the future. Furthermore, the use of optical waveguides, such as optical fibers, for detection eliminates the need for area or linear array detectors. Point intensity detectors integrated at the waveguide outlets can monitor and predict the system's alignment and imaging, effectively improving detection efficiency and closed-loop bandwidth.

[0095] In interferometric imaging and system alignment, the detection results are sparse on a plane. Consequently, conventional detectors have low utilization rates, significantly impacting the overall system weight and limiting the system's readout speed. This invention utilizes a point detector, which collects energy from a single point and uses an algorithmic model to obtain system alignment and imaging results.

[0096] To achieve stable operation of a spatially deployable segmented telescope, segment boundary sensing is required during operation. Therefore, fiber interpolation is employed to insert boundary stability into the existing optical path, detect the optical path, and provide feedback on the final detection results. A high-throughput, densely packed approach can be used to reduce latency caused by sampling time. The system's boundary stability can be sensed using a single exposure, and the primary mirror's pointing direction can be adjusted based on this information, ultimately achieving optimal imaging quality and stability. Based on the fundamental principle of optical waveguide mode coupling, the highest coupling efficiency is achieved when the characteristic function of the input mode is most similar to the mode itself. For single-mode fiber, for example, the highest coupling efficiency is achieved when the incident light spot is most similar to a Gaussian function. For few-mode fiber and input modes, the number of fibers increases, but due to the orthogonality between the modes, independent calculations can be performed for each mode. Specifically, a scanning pentaprism acquires tilt and wavefront information for each point on the mirror surface, and uses this information to reconstruct the projection front. Assuming that each piece of the large-aperture space-stitched telescope is an absolutely rigid body, only one sampling is required to obtain the tilt information of the plucked string and reconstruct the wavefront based on the tilt information.

[0097] Based on the theory of same-plane cleavage, multiple fiber types can be integrated into the same prism. For single-mode fiber, for example, the primary source of distortion is the tilt before plucking. For few-mode fiber, this information can be used to determine the difference in cleavage height. For multimode fiber, this information can be used to determine the system's brightness and transmission characteristics. For space-based splicing telescopes, high-throughput, closely packed light waves can be used to separately capture light from different modes, ultimately enabling the perception of the system's alignment status and the extraction and suppression of boundary anomalies.

[0098] Figure 2 The system architecture diagram of the present invention shows the details of the collection of different types of optical waveguides and their corresponding relationship with the system front-end mirrors. Based on the measured slope, the result of reconstructing the system wavefront is as follows: Figure 3-6 As shown in the figure, the structure function is used to characterize the restoration accuracy of the system at different scales. The process of mode field coupling in single-mode fiber is as follows: Figure 7 shown.

[0099] Based on the fundamental principle of optical waveguide mode coupling, the highest coupling efficiency is achieved when the input mode has the highest similarity to the waveguide's characteristic function. For single-mode fiber, for example, the highest coupling efficiency is achieved when the incident light spot is closest to a Gaussian function. For few-mode fiber and the input mode, the number of coupling factors increases compared to single-mode fiber, but due to the orthogonality between the modes, independent calculations can be performed for each mode.

[0100] Specifically, single-mode fiber is used to detect and correct wavefront tilt, while multimode fiber's greater sensitivity to defocus allows for positioning over a wide range of defocus along the optical axis. Phase information of the fringes is obtained through fitting, and the spatial filtering properties of fiber are used to acquire wavefront information within the sub-aperture.

[0101] An optical fiber is a cylindrical waveguide composed of two or more layers of dielectric material. Maxwell's equations, along with boundary conditions, describe the different modes propagating through the fiber. Single-mode fiber has only the fundamental mode, F01. Its profile is a Bessel function in the core and a Hankel function in the cladding. Under certain conditions, this profile can be approximated by a Gaussian:

[0102]

[0103] in,

[0104]

[0105] For single-mode fiber:

[0106]

[0107] in, · represents the scalar product, and |||| represents the modulo.

[0108] The experimental platform built is as follows Figure 8 As shown in the figure, the unit deformable mirror is used to simulate the pre-production process, and the final mold factory picture is as follows Figure 9-12 As shown, by analyzing it using the structure function, it can be obtained that different defocus values ​​can be matched one-to-one with the structure function to determine the rough co-directional process of the system.

[0109] Based on the basic principles of Fourier optics, the interference process of a single wavelength light wave can be analytically expressed using a complex light field. On this basis, the incoherent synthesis theory is used to obtain a synthetic complex light field distribution model in the non-narrowband case. By expressing the analytical expression of the intensity and phase of the synthesized light, a theoretical analysis tool is provided for subsequent research. Specifically: The schematic diagram of the system performing light interference is shown in the figure below: Figure 13 The interference fringes obtained are shown as Figure 14 As shown. Figure 13-14 It can be seen that by using optical fiber for synthetic interference, the phase difference between the two paths can be obtained.

[0110] Using complex light field theory, the wavefront W(u) of a single wavelength can be expressed as:

[0111]

[0112] Where λ is the wavelength, A is the amplitude of a single phase spatial frequency component, u is the spatial coordinate within the pupil, f is the spatial frequency domain coordinate, and E is the aperture function. is the initial phase.

[0113] Assuming that W1 and W2 are the wavefronts obtained by two heterogeneous sub-apertures, the process of complex light field beam synthesis can be expressed as follows:

[0114] W s (u)=W1(u)+W2(u) (8)

[0115] The interference fringe intensity can be obtained by the square of the complex light field mode, as shown in the following formula:

[0116] I=|W(u)| 2 (9)

[0117] After obtaining the expression of a single wavelength, the interference intensity of different wavelengths can be obtained by I(λ,x), where P(λ) is a matrix whose rows correspond to the spectral response function of the detector:

[0118]

[0119] λ is the wavelength, and the filter function includes the shape of the passband and the frequency response of the detector. Based on this, a quantitative description of the fringes obtained by two-way interference under non-narrowband conditions can be obtained. On this basis, by repeatedly using formula (8), a theoretical model for broadband fringe tracking under heterogeneous sub-apertures can be established. The interference fringes are analyzed using the power spectrum, see Figure 15 , it can be seen that the characteristic frequency formed by interference is very obvious, and various types of information carried by the interference can be extracted from it.

[0120] Example 2

[0121] According to another embodiment of the present invention, a space-expandable telescope correction device is provided. Figure 16 ,include:

[0122] The monitoring and feedback unit 201 is used to monitor and provide feedback on the alignment of the space-deployable telescope using the back-end optical fiber interconnection system during the deployment process of the space-deployable telescope after it enters orbit;

[0123] The correction unit 202 is configured to correct the alignment of the space deployable telescope based on a parallel gradient descent algorithm.

[0124] The space-deployable telescope correction device in the embodiment of the present invention first monitors and provides feedback on the alignment of the space-deployable telescope during its deployment process after entering orbit using a back-end fiber optic interconnection system. It then corrects the alignment of the space-deployable telescope using a parallel gradient descent algorithm. This invention focuses on the integrated testing process of large-aperture telescopes, studying the interactions between the internal components of large-aperture spliced ​​telescopes under different operating conditions. It analyzes the kinematic and mechanical mechanisms of the interactions between the components of the large-aperture spliced ​​mirror. Finally, it analyzes the establishment, maintenance, dynamic changes, and control mechanisms of the precision transfer network for large-aperture spliced ​​telescopes from the perspectives of multimodal control interaction, functional synergy, and system integration.

[0125] The following is a detailed description of the space-expandable telescope correction device of the present invention using a specific embodiment:

[0126] The present invention focuses on the deployment process of a space-deployable telescope after it enters orbit, utilizes a back-end optical fiber interconnection system to monitor and provide feedback on the alignment of the telescope, and corrects its alignment based on a parallel gradient descent algorithm.

[0127] This invention utilizes mode field coupling theory. When a light beam is tilted, its efficiency in coupling into the optical fiber changes. Since the input light intensity can be assumed to remain constant, the variation in the final light intensity reflects the variation in the iron law. Furthermore, considering the scanning of non-single-mode fibers, the system's mode field information also affects the final result. Specifically, this includes:

[0128] Step 1: Select the appropriate system surface to insert the all-photon scanning device. Due to the flexibility brought by fiber optic interconnection, the optical head scanning can be selected according to the actual needs of the system without affecting the actual smooth operation of the system.

[0129] Step 2: Align the coupler connected to the optical fiber with a specific sub-path unit to ensure that the light received by the coupler comes from a single sub-path unit.

[0130] Step 3: Collect the energy and mode information drawn out by the optical fiber at the output end of the optical fiber and record the information.

[0131] Step 4: Move the coupler to the area corresponding to the next sub-diameter unit and repeat the above steps until all sub-diameter units are scanned.

[0132] The proposed algorithm calculates the slope of the wavefront and restores the pre-broadcast, which is then used to conduct feedback testing on the system. To obtain string-plucking information from the slope information, the present invention employs a pattern approach. This approach obtains the slopes of all sampling points of the wavefront and, based on the decomposition of Zernike polynomials, ultimately reconstructs the overall wavefront. The plucking information then derives the tilt of the corresponding subaperture.

[0133] The collection and control of photons by a large-aperture spliced ​​telescope is essentially the result of the fine division of labor and coordinated control of many components in its imaging link in time and space. Traditional research has mostly focused on aspects such as end-to-end (optical transfer function) and the impact of external input on the system. In the process of executing control, the forms, functions and mechanisms of energy exchange and precision transfer between components are still unclear. The present invention focuses on the integrated detection process of large-aperture telescopes, studies the interaction mode between the internal components of large-aperture spliced ​​telescopes under different working conditions, analyzes the kinematic and mechanical mechanisms of the interaction between the component units of large-aperture spliced ​​mirrors, and analyzes the establishment, maintenance, dynamic changes and control mechanisms of the precision transfer network of large-aperture spliced ​​telescopes from the perspectives of system multi-modal control interaction, functional coordination and system integration.

[0134] For splicing, the system of the present invention establishes a photonic interconnected scanning mechanism on the same surface. By establishing a correspondence between the overall wavefront slope and the Zernike polynomial, the wavefront slope can be restored and the tilt angle corrected. The present invention accurately simulates the wavefront input conditions and its modes, using a deformable mirror for sub-aperture simulation.

[0135] The basic algorithm of the present invention:

[0136] The parallel gradient descent algorithm searches for the optimal direction randomly each time. Although the algorithm's convergence is statistically guaranteed, its slow convergence speed becomes particularly prominent when real-time requirements are high. Let the performance index of the adaptive optical system be β, and the change in performance index obtained by increasing the perturbation voltage be Δβ. Since energy drastic changes do not occur in actual engineering applications and scientific research practices, it is assumed that the system performance index β is differentiable. Through Taylor expansion, we can obtain:

[0137]

[0138] Among them, o(c 2 ) is the remaining term in the expansion.

[0139] In order to obtain the gradient of the performance index, both sides are multiplied by δu i , taking the expectation we can get:

[0140]

[0141] Assume {δu i}, each element in is independent and identically distributed, we can get:

[0142]

[0143] where σ 2 is {δu i}, using formula (3), we can obtain the unbiased estimate of the descent gradient of the evaluation index through statistical laws;

[0144] From the above we can get:

[0145] c n+1 =c n +δβδc (4)

[0146] Equation (4) is the core formula of the algorithm. Choosing a reasonable perturbation voltage can achieve better convergence characteristics. On the other hand, it can be seen from Equation (4) that the parallel gradient descent algorithm is a method that relies on mathematical statistics to obtain an estimate to approximate the gradient. Similarly, using unbiased estimation can obtain an estimate of the optimal step size.

[0147] Specifically, when the space deployment telescope reaches the designated position, its lenses are deployed. When the telescope can collect light beams, a fiber optic Internet prism system is set up on the same surface of the telescope. The light spots of each lens are tracked one by one. After the position of each light spot is obtained, it is adjusted to the common focus by adjusting the position of each light spot.

[0148] Large-aperture space-deployable telescopes face the challenge of balancing detection dynamic range and accuracy during their in-orbit deployment. This invention utilizes a fiber-optic interconnect architecture to collect and transmit photons via optical waveguides, overcoming the drawbacks of large spatial spans, such as the large space occupied and heavy weight of light input. Furthermore, the optical waveguide system's lightweight and radiation-resistant characteristics can reduce the launch payload and electromagnetic compatibility burden, further improving the system's carrying capacity and effectively increasing the payload limit in the future. Furthermore, the use of optical waveguides, such as optical fibers, for detection eliminates the need for area or linear array detectors. Point intensity detectors integrated at the waveguide outlets can monitor and predict the system's alignment and imaging, effectively improving detection efficiency and closed-loop bandwidth.

[0149] In interferometric imaging and system alignment, the detection results are sparse on a plane. Consequently, conventional detectors have low utilization rates, significantly impacting the overall system weight and limiting the system's readout speed. This invention utilizes a point detector, which collects energy from a single point and uses an algorithmic model to obtain system alignment and imaging results.

[0150] To achieve stable operation of a spatially deployable segmented telescope, segment boundary sensing is required during operation. Therefore, fiber interpolation is employed to insert boundary stability into the existing optical path, detect the optical path, and provide feedback on the final detection results. A high-throughput, densely packed approach can be used to reduce latency caused by sampling time. The system's boundary stability can be sensed using a single exposure, and the primary mirror's pointing direction can be adjusted based on this information, ultimately achieving optimal imaging quality and stability. Based on the fundamental principle of optical waveguide mode coupling, the highest coupling efficiency is achieved when the characteristic function of the input mode is most similar to the mode itself. For single-mode fiber, for example, the highest coupling efficiency is achieved when the incident light spot is most similar to a Gaussian function. For few-mode fiber and input modes, the number of fibers increases, but due to the orthogonality between the modes, independent calculations can be performed for each mode. Specifically, a scanning pentaprism acquires tilt and wavefront information for each point on the mirror surface, and uses this information to reconstruct the projection front. Assuming that each piece of the large-aperture space-stitched telescope is an absolutely rigid body, only one sampling is required to obtain the tilt information of the plucked string and reconstruct the wavefront based on the tilt information.

[0151] Based on the theory of same-plane cleavage, multiple fiber types can be integrated into the same prism. For single-mode fiber, for example, the primary source of distortion is the tilt before plucking. For few-mode fiber, this information can be used to determine the difference in cleavage height. For multimode fiber, this information can be used to determine the system's brightness and transmission characteristics. For space-based splicing telescopes, high-throughput, closely packed light waves can be used to separately capture light from different modes, ultimately enabling the perception of the system's alignment status and the extraction and suppression of boundary anomalies.

[0152] Figure 2 The system architecture diagram of the present invention shows the details of the collection of different types of optical waveguides and their corresponding relationship with the system front-end mirrors. Based on the measured slope, the result of reconstructing the system wavefront is as follows: Figure 3-6 As shown in the figure, the structure function is used to characterize the restoration accuracy of the system at different scales. The process of mode field coupling in single-mode fiber is as follows: Figure 7 shown.

[0153] Based on the fundamental principle of optical waveguide mode coupling, the highest coupling efficiency is achieved when the input mode has the highest similarity to the waveguide's characteristic function. For single-mode fiber, for example, the highest coupling efficiency is achieved when the incident light spot is closest to a Gaussian function. For few-mode fiber and the input mode, the number of coupling factors increases compared to single-mode fiber, but due to the orthogonality between the modes, independent calculations can be performed for each mode.

[0154] Specifically, single-mode fiber is used to detect and correct wavefront tilt, while multimode fiber's greater sensitivity to defocus allows for positioning over a wide range of defocus along the optical axis. Phase information of the fringes is obtained through fitting, and the spatial filtering properties of fiber are used to acquire wavefront information within the sub-aperture.

[0155] An optical fiber is a cylindrical waveguide composed of two or more layers of dielectric material. Maxwell's equations, along with boundary conditions, describe the different modes propagating through the fiber. Single-mode fiber has only the fundamental mode, F01. Its profile is a Bessel function in the core and a Hankel function in the cladding. Under certain conditions, this profile can be approximated by a Gaussian:

[0156]

[0157] in,

[0158]

[0159] For single-mode fiber:

[0160]

[0161] in, · represents the scalar product, and |||| represents the modulo.

[0162] The experimental platform built is as follows Figure 8 As shown in the figure, the unit deformable mirror is used to simulate the pre-production process, and the final mold factory picture is as follows Figure 9-12 As shown, by analyzing it using the structure function, it can be obtained that different defocus values ​​can be matched one-to-one with the structure function to determine the rough co-directional process of the system.

[0163] Based on the basic principles of Fourier optics, the interference process of a single wavelength light wave can be analytically expressed using a complex light field. On this basis, the incoherent synthesis theory is used to obtain a synthetic complex light field distribution model in the non-narrowband case. By expressing the analytical expression of the intensity and phase of the synthesized light, a theoretical analysis tool is provided for subsequent research. Specifically: The schematic diagram of the system performing light interference is shown in the figure below: Figure 13 The interference fringes obtained are shown as Figure 14 As shown. Figure 13-14 It can be seen that by using optical fiber for synthetic interference, the phase difference between the two paths can be obtained.

[0164] Using complex light field theory, the wavefront W(u) of a single wavelength can be expressed as:

[0165]

[0166] Where λ is the wavelength, A is the amplitude of a single phase spatial frequency component, u is the spatial coordinate within the pupil, f is the spatial frequency domain coordinate, and E is the aperture function. is the initial phase.

[0167] Assuming that W1 and W2 are the wavefronts obtained by two heterogeneous sub-apertures, the process of complex light field beam synthesis can be expressed as follows:

[0168] W s (u)=W1(u)+W2(u) (8)

[0169] The interference fringe intensity can be obtained by the square of the complex light field mode, as shown in the following formula:

[0170] I=|W(u)| 2 (9)

[0171] After obtaining the expression of a single wavelength, the interference intensity of different wavelengths can be obtained by I(λ,x), where P(λ) is a matrix whose rows correspond to the spectral response function of the detector:

[0172]

[0173] λ is the wavelength, and the filter function includes the shape of the passband and the frequency response of the detector. Based on this, a quantitative description of the fringes obtained by two-way interference under non-narrowband conditions can be obtained. On this basis, by repeatedly using formula (8), a theoretical model for broadband fringe tracking under heterogeneous sub-apertures can be established. The interference fringes are analyzed using the power spectrum, see Figure 15 , it can be seen that the characteristic frequency formed by interference is very obvious, and various types of information carried by the interference can be extracted from it.

[0174] Example 3

[0175] A storage medium stores a program file capable of implementing any one of the above-mentioned space-expandable telescope correction methods.

[0176] Example 4

[0177] A processor is used to run a program, wherein when the program is run, any one of the above-mentioned space-deployable telescope correction methods is executed.

[0178] The serial numbers of the above embodiments of the present invention are for description only and do not represent the advantages or disadvantages of the embodiments.

[0179] In the above embodiments of the present invention, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0180] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the system embodiments described above are only exemplary. For example, the division of units can be a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0181] Units described as separate components may or may not be physically separate, and components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple units. Some or all of the units may be selected to achieve the purpose of the present embodiment according to actual needs.

[0182] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0183] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server or network device, etc.) to execute all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, magnetic disk or optical disk, etc. Various media that can store program codes.

[0184] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for correcting a space-expandable telescope, characterized in that: The following steps are involved: During the deployment process of the space deployable telescope after it enters orbit, the back-end optical fiber interconnection system is used to monitor and provide feedback on the alignment of the space deployable telescope; The alignment of a space-deployable telescope is corrected based on a parallel gradient descent algorithm; The monitoring and feedback of the alignment of the space deployable telescope using the back-end optical fiber interconnection system includes: The parallel gradient descent algorithm is used to calculate the wavefront slope, restore the wavefront, and conduct feedback testing on the telescope system. The pattern method is used to obtain wavefront information from the slope information. By obtaining the slopes of all sampling points of the wavefront, the overall wavefront is finally reconstructed based on the decomposition of the Zernike polynomials, and the tilt of the corresponding sub-aperture is obtained from the wavefront.

2. The space-expandable telescope correction method according to claim 1, characterized in that: The correction of the alignment of the space deployable telescope based on the parallel gradient descent algorithm includes: A photonic interconnected scanning mechanism is set up on the same surface, and the wavefront slope is restored and the inclination angle is corrected by establishing a corresponding relationship between the overall wavefront slope and the Zernike polynomial.

3. The space-expandable telescope correction method according to claim 2, characterized in that: The method specifically includes: Select a suitable drawing of the telescope system to insert the all-photon scanning device, and select a position that does not affect the smooth operation of the telescope system for optical head scanning; Match the coupler connected to the optical fiber to a specific sub-diameter unit to ensure that the light received by the coupler comes from a single sub-diameter unit; Collect the energy and mode information drawn from the optical fiber at the output end of the optical fiber and record the information; Move the coupler to the area corresponding to the next sub-diameter unit and repeat the above steps until all sub-diameter units are scanned.

4. The space-expandable telescope correction method according to claim 3, characterized in that: When the telescope collects the light beam, a fiber optic internet prism system is set on the same surface of the telescope to track the light spots one by one. After the position of each light spot is obtained, it is adjusted to the common focus by adjusting the position of each light spot.

5. The space-expandable telescope correction method according to claim 4, characterized in that: The segmented boundaries are sensed by using optical fiber mutual contamination, a boundary stability detection optical path is inserted into the existing optical path, and the final detection results are fed back; A high-throughput, densely packed method is adopted to sense the boundary stability of the system with a single exposure, and on this basis, the pointing of the system's main mirror is adjusted.

6. The space-expandable telescope correction method according to claim 5, characterized in that: Single-mode optical fiber is used to detect and correct wavefront tilt and locate its defocus along the optical axis; the phase information of the fringes is obtained by fitting, and the spatial filtering characteristics of the optical fiber are used to obtain the wavefront information within the sub-aperture.

7. The space-expandable telescope correction method according to claim 6, characterized in that: By using the incoherent synthesis theory, the synthetic complex light field distribution model in the non-narrowband case is obtained, and the theoretical analysis tool is obtained by expressing the analytical expression of the intensity and phase of the synthesized light.

8. The space-expandable telescope correction method according to claim 7, characterized in that: The structure function is used for analysis to obtain different defocus values, and the defocus values ​​are matched one-to-one with the structure function to determine the rough co-directional process of the system.

9. A space-expandable telescope correction device using the space-expandable telescope correction method according to claim 1, characterized in that: include: A monitoring and feedback unit, used to monitor and provide feedback on the alignment of the space-deployable telescope using a back-end optical fiber interconnection system during the deployment process of the space-deployable telescope after it enters orbit; A correction unit is used to correct the alignment of the space deployable telescope based on a parallel gradient descent algorithm.

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