Optical-mechanical integrated analysis method for micro-vibration of spliced telescope

Abstract

The invention relates to the technical field of optical imaging analysis, in particular to an optical-mechanical integrated analysis method for micro-vibration of a spliced telescope, which comprises the following steps of: establishing an optical-mechanical model, and performing micro-vibration analysis on the optical-mechanical model under long exposure time to simulate and obtain node displacement corresponding to a time point; converting node displacement corresponding to the time point into rigid body displacement corresponding to the time point by adopting a first conversion model; establishing an optical system model according to the optical element of the spliced telescope, and processing the rigid body displacement corresponding to the time point by using the optical system model to obtain a point spread function of the spliced telescope corresponding to the time point; and processing the point spread function corresponding to the time point by using a long exposure time model to obtain the point spread function of the spliced telescope under the long exposure time. According to the invention, at least high-data transmission efficiency and high-accuracy micro-vibration optical-mechanical integrated analysis on the spliced telescope can be realized.

Description

Technical Field

[0001] The invention belongs to the technical field of optical imaging analysis, and in particular relates to an optical-mechanical integrated analysis method for micro-vibration of a spliced ​​telescope. Background Art

[0002] The optomechanical integration analysis method is an analysis method that comprehensively considers multiple disciplines such as optics, mechanics, and thermals and conducts related simulation designs. Compared with the traditional optomechanical structural analysis in which optical analysis and structural analysis are separated from each other, the main reason for adopting the optomechanical integration analysis method is that external interference will have a huge impact on some systems with high precision requirements. Therefore, before the overall design of the system, it is necessary to use different analysis software and tools to analyze and verify it, and finally use a comprehensive method to introduce these adverse factors into the whole machine model to judge their impact on the overall system. Since the optomechanical integration analysis method can reduce the repetitive work between various disciplines, shorten the design time of the optomechanical system, and improve the error tolerance of each design part, the design of the optomechanical structure using this method has important guiding significance for engineering design work.

[0003] In recent years, super-large spliced ​​telescopes have become a cutting-edge research field in the world. At present, for optical systems including the entire mirror, in order to meet the requirements of optical design and mechanical design, optomechanical integrated analysis methods are usually used to study the impact of micro-vibration on the imaging quality of the optical system. The degradation of imaging effects caused by micro-vibration is transient. The main mirror of a spliced ​​telescope is composed of multiple sub-mirrors, which makes the optical system of the spliced ​​telescope more sensitive to micro-vibration, and the process of vibration affecting the imaging quality of the spliced ​​telescope is more complicated. Therefore, how to achieve high-accuracy micro-vibration analysis of spliced ​​telescopes has become a technical problem that needs to be solved in optomechanical integrated analysis. Summary of the invention

[0004] In view of this, the present invention aims to provide an optomechanical integrated analysis method for micro-vibrations of a spliced ​​telescope, which is at least conducive to realizing optomechanical integrated analysis of micro-vibrations of the spliced ​​telescope with high data transmission efficiency and high accuracy.

[0005] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0006] The invention provides an optical-mechanical integrated analysis method for micro-vibration of a spliced ​​telescope, comprising: establishing an optical-mechanical model according to an optical element and a mechanical structure of the spliced ​​telescope, performing micro-vibration analysis on the optical-mechanical model under a long exposure time, so as to simulate and obtain the node displacement of the optical element corresponding to a time point; using a first conversion model to convert the node displacement corresponding to the time point into a rigid body displacement corresponding to the time point; establishing an optical system model according to the optical element of the spliced ​​telescope, using the optical system model to process the rigid body displacement corresponding to the time point, so as to obtain the point spread function of the spliced ​​telescope corresponding to the time point; using a long exposure time model to process the point spread function corresponding to the time point, so as to obtain the point spread function of the spliced ​​telescope under the long exposure time.

[0007] Furthermore, the finite element simulation analysis software was used to establish an optomechanical model, and the micro-vibration analysis of the optomechanical model was performed under long exposure time.

[0008] Furthermore, optical design software is used to establish an optical system model.

[0009] Furthermore, the spliced ​​telescope includes a primary mirror, and the optical system model includes an aperture function of the primary mirror. The aperture function of the primary mirror is as follows:

[0010]

[0011] Where N is the number of sub-mirrors of the main mirror, (x j ,y j ) is the center coordinate of the jth sub-mirror, f j (xx j ,yy j ) is the aperture function of the j-th sub-mirror;

[0012] The aperture function f of the jth sub-mirror j (xx j ,yy j ) is as follows:

[0013] f j (xx j ,yy j )=a j (xx j ,yy j )·exp(iφ j (xx j ,yy j ));

[0014] Among them, φ j (xx j ,yy j ) is the phase error of the j-th sub-mirror, a j(xx j ,yy j ) is the transmission intensity function of the j-th sub-mirror.

[0015] Furthermore, the transmission intensity function a of the j-th sub-mirror is j (xx j ,yy j ) is as follows:

[0016]

[0017] Among them, inside means that the incident light is within the area of ​​the j-th sub-mirror, and outside means that the incident light is outside the area of ​​the j-th sub-mirror.

[0018] Furthermore, the optical system model also includes the system point spread function and the complex amplitude distribution of the image plane of the primary mirror. The complex amplitude distribution of the image plane of the primary mirror is the Fourier transform of the aperture function of the primary mirror. The complex amplitude distribution of the image plane of the primary mirror is as follows:

[0019]

[0020] Where λ is the wavelength, f is the focal length, (x f ,y f ) is the image plane coordinate of the primary mirror, (f x ,f y ) is the frequency domain coordinate;

[0021] The system point spread function is the square of the modulus of the complex amplitude distribution in the image plane of the primary mirror;

[0022] When the phase error φ(xx j ,yy j )=0, the point spread function of the system is as follows:

[0023]

[0024] Where A is the area of ​​a single sub-mirror, G(x f ,y f ) is the grid function, F s-PSF (x f ,y f ) is the point spread function of a single sub-mirror.

[0025] Furthermore, numerical analysis software is used to establish a first conversion model and a long exposure time model.

[0026] Furthermore, the first conversion model is as follows:

[0027]

[0028] Among them, (x, y, z) is the initial coordinate of the node on the mirror surface, (x', y', z') is the coordinate of the node on the mirror surface after translation and rotation, T x is the translation along the X axis, T y is the translation along the Y axis, T z is the translation along the Z axis, α is the tilt angle relative to the X axis, β is the tilt angle relative to the Y axis, and γ is the tilt angle relative to the Z axis;

[0029] The node displacement is:

[0030]

[0031] Among them, (x i ,y i , z i ) is the node coordinate of the node number i;

[0032] The rigid body displacement corresponding to the time point is obtained based on the node displacement fitting. The rigid body displacement corresponding to the time point obtained by fitting includes:

[0033] The least square method is used to minimize E, and the requirements are:

[0034] To obtain the rigid body displacement corresponding to the time point;

[0035] The expression of E is as follows:

[0036]

[0037] Among them, dx i ,dy i and dz i It represents the coordinate change of the node position obtained by micro-vibration analysis under long exposure time.

[0038] Furthermore, the long exposure time model includes the energy distribution of the image point diffuse spot and the point spread function under long exposure time;

[0039] The energy distribution of the image point diffuse spot is as follows:

[0040] g(x,t)=h(x)*δ(x-ε(t));

[0041] Wherein, h(x) is the system point spread function in ideal imaging, ε(t) is the image shift caused by vibration during long exposure time, δ(x-ε(t)) is the image point energy distribution when image shift exists, * is the convolution symbol, t is the time point, and x is the image point position coordinate;

[0042] The point spread function for long exposure time is as follows:

[0043]

[0044] Among them, t 0 is the initial time point, t 1 For duration.

[0045] Furthermore, the micro-vibration analysis under long exposure time includes: establishing a micro-vibration signal test platform, the micro-vibration signal test platform includes a spliced ​​telescope, an infrared refrigerator, an accelerometer and a suspension system, the suspension system includes connected slings and springs, the suspension system suspends the spliced ​​telescope and the infrared refrigerator, and multiple accelerometers are arranged on multiple installation points of the infrared refrigerator; the accelerometer collects a data point every unit preset time length, collects multiple data points corresponding to the time point within the preset time length, obtains the average value of the multiple acceleration data points at the same time point as the target data point corresponding to the time point, and uses the multiple target data points corresponding to the time point as vibration parameters under long exposure time to perform micro-vibration analysis under long exposure time.

[0046] Compared with the prior art, the invention can achieve the following beneficial effects:

[0047] The optomechanical integration analysis method for micro-vibration of a spliced ​​telescope involved in an embodiment of the present invention establishes an optomechanical model based on the optical system structure and mechanical structure of the spliced ​​telescope, and uses the optomechanical model as the object of optomechanical integration analysis. Since the spliced ​​telescope needs to be used in a long exposure environment, in the optomechanical integration analysis method for micro-vibration of a spliced ​​telescope involved in an embodiment of the present invention, the influence of micro-vibration on the imaging quality of the spliced ​​telescope is considered as a cumulative effect rather than a transient effect, so that the analysis result is more accurate and true.

[0048] Specifically, the optomechanical integration analysis method first uses finite element simulation to analyze the node displacements of each optical element in the optomechanical model corresponding to the time point when an external load exists, that is, the optomechanical model is subjected to micro-vibration analysis under long exposure time, and then an error equation is established and the least squares method is used to solve the rigid body displacement corresponding to the time point, and then the rigid body displacement corresponding to the time point is set in the optical system model established by the optical design software, so that the position and shape of the optical element can be adjusted by using the optical design software to obtain the image quality evaluation of the optical system at each moment when the load exists, that is, the point spread function corresponding to the time point, and then the long exposure time model is used to process the image quality evaluation of the optical system at each moment to obtain the image quality evaluation under long exposure time. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0050] Figure 1 A schematic diagram of the structure of a spliced ​​telescope according to an embodiment of the present invention;

[0051] Figure 2 A schematic diagram of the structure of a primary mirror of a spliced ​​telescope according to an embodiment of the present invention;

[0052] Figure 3 A schematic diagram of an optical-mechanical model of a spliced ​​telescope according to an embodiment of the present invention;

[0053] Figure 4 A schematic diagram of the structure of a micro-vibration signal testing platform according to an embodiment of the present invention;

[0054] Figure 5 A distribution diagram of vibration source signal data as described in the embodiment of the present invention;

[0055] Figure 6 The wavefront diagram of 10 consecutive time points described in the embodiment of the present invention;

[0056] Figure 7 The point spread function of the central field of view of the optical system of the spliced ​​telescope described in the embodiment of the present invention at the initial time point;

[0057] Figure 8 The X-axis cross-sectional diagram and the Y-axis cross-sectional diagram of the point spread function under different long exposure times described in the embodiment of the present invention are created.

[0058] Explanation of the accompanying drawings: 1. Lifting equipment; 2. Sling; 3. Spring; 4. Spliced ​​telescope; 5. Infrared refrigerator. DETAILED DESCRIPTION

[0059] In order to make the purpose, technical solution and advantages of the invention more clear, the 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 here are only used to explain the invention and do not constitute a limitation of the invention.

[0060] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0061] In the description of the invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the invention, unless otherwise specified, the meaning of "multiple" is two or more.

[0062] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0063] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0064] The invention provides an optical-mechanical integrated analysis method for micro-vibration of a spliced ​​telescope, comprising: establishing an optical-mechanical model according to an optical element and a mechanical structure of the spliced ​​telescope, performing micro-vibration analysis on the optical-mechanical model under a long exposure time, so as to simulate and obtain the node displacement of the optical element corresponding to a time point; using a first conversion model to convert the node displacement corresponding to the time point into a rigid body displacement corresponding to the time point; establishing an optical system model according to the optical element of the spliced ​​telescope, using the optical system model to process the rigid body displacement corresponding to the time point, so as to obtain the point spread function of the spliced ​​telescope corresponding to the time point; using a long exposure time model to process the point spread function corresponding to the time point, so as to obtain the point spread function of the spliced ​​telescope under the long exposure time.

[0065] It should be noted that the optical-mechanical integrated analysis method for micro-vibration of a spliced ​​telescope provided in an embodiment of the present invention is used to simulate the influence of a micro-vibration environment under a long exposure time on the imaging quality of the spliced ​​telescope. In the simulation of the imaging effect under a long exposure time, the influence of micro-vibration on the imaging quality of the optical system of the spliced ​​telescope is considered as a cumulative effect rather than a transient effect, which is conducive to improving the accuracy and authenticity of the analysis results.

[0066] The spliced ​​telescope uses a spliced ​​primary mirror to increase the aperture of the optical system, so it has a higher resolution and light-gathering ability. For the spliced ​​telescope involved in the embodiment of the present invention, please refer to Figure 1 , Figure 1 The optical system of the spliced ​​telescope shown is a coaxial three-mirror anastigmatism telescope, and the spliced ​​telescope can mainly include a primary mirror (PM), a secondary mirror (SM), a tertiary mirror (TM) and a steering mirror (FSM), and the primary mirror can be divided into hexagonal parts. Among them, the primary mirror (PM), the secondary mirror (SM), and the tertiary mirror (TM) all adopt the design method of quadratic curved reflector, and in order to make the structure of the optical system more compact and reasonable, the steering mirror (FSM) is used to fold the light path for imaging.

[0067] In some embodiments of the present invention, reference Figure 2 The main mirror of the spliced ​​telescope can be composed of 18 hexagonal sub-mirrors, and the 18 hexagonal sub-mirrors are labeled A1, A2, A3, A4, A5, A6, B1, B2, B3, B4, B5, B6, C1, C2, C3, C4, C5 and C6. It should be noted that if there is a splicing error between the sub-mirrors, the image quality of the main mirror will be greatly reduced. Usually, the sub-mirrors are required to be confocal and in phase to ensure that the main mirror and the single mirror of the same aperture reach the same diffraction limit, that is, to achieve the same image quality.

[0068] Furthermore, a finite element simulation analysis software is used to establish an optomechanical model, and a micro-vibration analysis of the optomechanical model is performed under a long exposure time. The micro-vibration analysis under a long exposure time is the finite element simulation analysis.

[0069] Further, an optical system model is established using optical design software. In some examples, the optical design software includes ZEMAX. Using the optical system model to process the rigid body displacement corresponding to the time point means that the rigid body displacement corresponding to the time point is set in the optical system model established by the optical design software, and then the point spread function corresponding to the time point is obtained through processing by the optical design software.

[0070] Further, a first conversion model and a long exposure time model are established using numerical analysis software. In some examples, the numerical analysis software includes MATLAB. Using the long exposure time model to process the point spread function corresponding to the time point refers to inputting the point spread function corresponding to the time point into the numerical analysis software, and calculating using the long exposure time model to obtain the point spread function of the spliced ​​telescope under the long exposure time.

[0071] In the optical-mechanical integrated analysis method for micro-vibration of a spliced ​​telescope provided by the invention, firstly, the node changes in the presence of external loads obtained by finite element simulation analysis are converted into a data form acceptable to optical design software, and the data form acceptable to the optical design software is rigid body displacement. Then, the position and shape of the optical element are adjusted by using the optical design software according to the rigid body displacement to obtain an image quality evaluation of the optical system of the spliced ​​telescope at each time point when the load exists, that is, a point spread function corresponding to the time point. Then, the point spread function corresponding to the time point is processed by using numerical analysis software to obtain the point spread function of the optical system of the spliced ​​telescope under long exposure time, and the analysis of the influence of micro-vibration on imaging quality under long exposure time is completed.

[0072] Figure 3 A finite element model of a spliced ​​telescope provided in an embodiment of the present invention, i.e., an optical-mechanical model, in some examples, the steps of establishing the optical-mechanical model may be as follows: first, an optical system model is established using optical design software, a mechanical structure model is established using three-dimensional modeling software according to the optical system model, and the mechanical structure model is finely meshed using finite element software to obtain a finite element model (optical-mechanical model). In some examples, the finite element model may include a total of 278,139 units and 251,765 nodes. In some examples, the three-dimensional modeling software may be solidworks.

[0073] It should be noted that, since finite element simulation analysis software or optical design software cannot independently complete the image quality evaluation when the optical system has an external load, multiple software are required to jointly transfer data to complete the optical-mechanical integrated simulation. Therefore, the embodiment of the present invention first establishes an optical-mechanical model of the spliced ​​telescope and performs finite element simulation analysis under micro-vibration loads under long exposure time to obtain the node coordinate changes of the optical element at each moment under micro-vibration (the node displacement corresponding to the time point), and obtains the optimal rigid body displacement (the rigid body displacement corresponding to the time point) of each optical element at each moment through calculation and fitting. Due to the huge amount of data, in order to improve the transmission speed and accuracy, the embodiment of the present invention uses the built-in DDE (Dynamic Data Exchange) server of the optical design software and the numerical analysis software to establish a dynamic link between the optical design software and the numerical analysis software to realize data transmission, transmits the finite element simulation analysis result to the numerical analysis software to calculate the rigid body displacement corresponding to the time point, and then transmits the rigid body displacement corresponding to the time point to the optical design software, calculates the point spread function corresponding to the time point through the optical design software, and then uses the numerical analysis software to calculate the point spread function corresponding to the time point to obtain the point spread function of the optical system of the spliced ​​telescope under long exposure time, that is, completes the evaluation of the influence of micro-vibration of the spliced ​​telescope on the imaging quality under long exposure time.

[0074] Furthermore, the optical system model includes the aperture function of the primary mirror. When the incident light beam is parallel light of unit amplitude, the aperture function of the primary mirror is as follows:

[0075]

[0076] Where (x, y) is the coordinate of any point on the main mirror, N is the number of sub-mirrors of the main mirror. In some examples, the main mirror is composed of 18 hexagonal sub-mirrors, N = 18, (x j ,y j ) is the center coordinate of the jth sub-mirror, f j (xx j ,yy j ) is the aperture function of the j-th sub-mirror;

[0077] The aperture function f of the jth sub-mirror j (xx j ,yy j ) is as follows:

[0078] f j (xx j ,yy j )=a j (xx j ,yy j)·exp(iφ j (xx j ,yy j ));

[0079] Among them, φ j (xx j ,yy j ) is the phase error of the j-th sub-mirror. When the j-th sub-mirror has position error or surface error, the phase error φ j will change accordingly, j (xx j ,yy j ) is the transmission intensity function of the j-th sub-mirror, i is an imaginary number, and the square of i is equal to -1.

[0080] Furthermore, the transmission intensity function a of the j-th sub-mirror is j (xx j ,yy j ) is as follows:

[0081]

[0082] Among them, inside means that the incident light is within the area of ​​the j-th sub-mirror, and outside means that the incident light is outside the area of ​​the j-th sub-mirror.

[0083] Furthermore, the optical system model also includes the system point spread function and the complex amplitude distribution of the image plane of the primary mirror. The complex amplitude distribution of the image plane of the primary mirror is the Fourier transform of the aperture function of the primary mirror. The complex amplitude distribution of the image plane of the primary mirror is as follows:

[0084]

[0085] Where λ is the wavelength of the incident light beam, f is the focal length of the optical system, (x f ,y f ) is the image plane coordinate of the primary mirror, (f x ,f y ) is the frequency domain coordinate;

[0086] The system point spread function is the square of the modulus of the complex amplitude distribution in the image plane of the primary mirror;

[0087] When the phase error φ of the jth sub-mirror j (xx j ,yy j )=0, that is, when all sub-mirrors are in ideal positions, the system point spread function can be expressed as the product of the grid function and the point spread function of a single sub-mirror. Specifically, the system point spread function is as follows:

[0088]

[0089] Where A is the area of ​​a single sub-mirror, G(x f ,y f ) is a grid function, which is the Fourier transform of the spliced ​​grid. The Fourier transform of the spliced ​​grid is usually a periodic function with peaks. Each peak is the Fourier transform of the full aperture of the spliced ​​telescope. G(x f ,y f ) can be expressed as follows:

[0090]

[0091] F s-PSF (x f ,y f ) is the point spread function of a single sub-mirror, F s-PSF (x f ,y f ) can be expressed as follows:

[0092]

[0093] Furthermore, the first conversion model is as follows:

[0094]

[0095] Among them, (x, y, z) is the initial coordinate of the node on the mirror surface, (x', y', z') is the coordinate of the node on the mirror surface after translation and rotation, T x is the translation along the X axis, T y is the translation along the Y axis, T z is the translation along the Z axis, α is the tilt angle relative to the X axis, β is the tilt angle relative to the Y axis, and γ is the tilt angle relative to the Z axis;

[0096] The node displacement is:

[0097]

[0098] Among them, (x i ,y i , z i ) is the node coordinate of node number i, is the X-axis displacement, is the Y-axis displacement, is the Z-axis displacement;

[0099] Since the nodal displacement of the optical element cannot be directly input into the optical design software, it is necessary to calculate the change in the six degrees of freedom of the optical element, that is, the rigid body displacement. Therefore, the rigid body displacement corresponding to the time point is obtained based on the nodal displacement fitting. The rigid body displacement corresponding to the time point obtained by fitting specifically includes:

[0100] The least square method is used to minimize E, and the requirements are:

[0101] To obtain the rigid body displacement corresponding to the time point, that is, to make E to T x , T y , T z The partial derivatives of , α, β, and γ are 0, and the rigid body displacement can be obtained;

[0102] The expression of E is as follows:

[0103]

[0104] Among them, dx i ,dy i and dz i represents the coordinate change of the node position obtained by micro-vibration analysis under long exposure time, is the error equation and E is the error function.

[0105] Furthermore, the long exposure time model includes the energy distribution of the image point diffuse spot and the point spread function under long exposure time;

[0106] The energy distribution of the image point diffuse spot is as follows:

[0107] g(x,t)=h(x)*δ(x-ε(t));

[0108] Wherein, h(x) is the system point spread function in ideal imaging, ε(t) is the image shift caused by vibration during long exposure time, δ(x) is the Dirac symbol, which means the energy distribution of the ideal image point, δ(x-ε(t)) is the energy distribution of the image point when there is image shift, * is the convolution symbol, t is the time point, and x is the image point position coordinate;

[0109] After introducing the image shift, the energy of the diffuse spot is normalized to obtain the following point spread function under long exposure time:

[0110]

[0111] Among them, t 0 is the initial time point, t 1 is the duration, and * is the convolution symbol.

[0112] It can be seen that when micro-vibration acts on the optical system, the center position of the point spread function will deviate from the ideal position. Therefore, the vibration will cause the diffuse spot diameter of the image point to become larger, the central energy to decrease, and the image blur to cause geometric deformation.

[0113] Figure 6It is the wavefront diagram of 10 consecutive time points within 4 seconds. The wavefront error RMS (Root Mean Square) is less than 0.061λ at most times within 4 seconds, and the wavefront error RMS is less than 0.075λ at all times. Figure 6 (a) in the figure is the wavefront error at time point 0s. Since the micro-vibration signal input by the micro-vibration analysis is random in the time domain, the position change of the sub-mirror caused by the micro-vibration signal transmitted to the primary mirror also has a certain degree of randomness.

[0114] Figure 7 The point spread function is the log value of the central field of view of the optical system of the spliced ​​telescope at the initial time point. Since the sub-mirrors of the primary mirror are arranged symmetrically, the point spread function also has the characteristics of symmetric distribution about the X axis and symmetric distribution about the Y axis. The point spread function has obvious main peaks and side lobes at the initial time point. Since the amplitude of the micro-vibration analysis is small, the impact on the imaging quality of the optical system of the spliced ​​telescope is small. For the convenience of observation, the X-axis and Y-axis shown in the figure are established with the center of the point spread function as the origin.

[0115] Figure 8 The X-axis and Y-axis cross-sectional diagrams of the point spread function under different long exposure times. Specifically, Figure 8 (a) is the X-axis cross-sectional view. Figure 8 (b) is a partial enlarged view of the secondary peak in the X-axis cross-section. Figure 8 (c) is the Y-axis cross-sectional view. Figure 8 (d) is a partial enlarged view of the secondary peak in the Y-axis cross-sectional view. Figure 8 , the x-axis in each figure is Figure 7 The X / Y direction distance from the origin, the y-axis in each figure is the normalized intensity value (peak ratio). Figure 8 , under the action of micro-vibration, the secondary peak and the tertiary peak of the point spread function corresponding to different exposure times gradually separate. The spatial distribution of the point spread function is related to the resolution of the optical system of the spliced ​​telescope. The higher the resolution, the sharper the main peak of the point spread function and the smaller the secondary peak, indicating that the imaging effect of the optical system is better. Whether it is the X-section or the Y-section, the longer the exposure time, the greater the ratio of the secondary peak to the main peak, and the more serious the impact of micro-vibration on the imaging quality.

[0116] Furthermore, the micro-vibration analysis under long exposure time includes: establishing a micro-vibration signal test platform, the micro-vibration signal test platform includes a spliced ​​telescope, an infrared refrigerator, an accelerometer and a suspension system, the suspension system includes connected slings and springs, the suspension system suspends the spliced ​​telescope and the infrared refrigerator, and multiple accelerometers are arranged on multiple installation points of the infrared refrigerator; the accelerometer collects a data point every unit preset time length, collects multiple data points corresponding to the time point within the preset time length, obtains the average value of the multiple acceleration data points at the same time point as the target data point corresponding to the time point, and uses the multiple target data points corresponding to the time point as vibration parameters under long exposure time to perform micro-vibration analysis under long exposure time.

[0117] The embodiment of the present invention applies the measured micro-vibration signal (vibration parameter) to the optomechanical model to obtain the position change of the optical element at different times, and implements image quality evaluation under long exposure time according to the new optomechanical model after the change, which is beneficial to improving the accuracy of micro-vibration analysis and making the imaging result obtained by analysis closer to the actual imaging effect of the spliced ​​telescope.

[0118] Figure 4 A schematic diagram of a micro-vibration signal testing platform provided in an embodiment of the present invention is provided. The spliced ​​telescope 4 and the infrared refrigerator 5 are fixed, and the spliced ​​telescope 4 and the infrared refrigerator 5 are suspended by using a lifting device 1 and a suspension system. A low-rigidity suspension system consisting of a sling 2 and a spring 3 is used to simulate the zero-gravity environment during the on-orbit stage.

[0119] Figure 5 The vibration source signal data distribution diagram is shown in Figure 1. Specifically, accelerometers can be placed at six points on the infrared refrigerator mounting frame to measure micro-vibration signals. The six points on the mounting frame can be six points evenly spaced on the upper surface of the mounting frame. One data point is collected every 0.002 seconds, and a total of 2000 data points are collected within the measurement time of 4 seconds. The six data points are averaged at each moment to obtain the measured micro-vibration signal.

[0120] It should be noted that, since the long exposure time is different from the imaging at each moment, its actual imaging effect is the energy accumulation at a uniform time interval. In order to achieve high-accuracy micro-vibration analysis of the spliced ​​telescope, the embodiment of the present invention acts the measured micro-vibration signal on the supporting structure of the optical element, thereby obtaining the position change of the optical element at different moments. According to the changed optical system model, the image quality evaluation under the long exposure time can be achieved, and the influence of the micro-vibration on the imaging quality of the spliced ​​telescope under the long exposure time can be obtained. In addition, the method alleviates the problems of low efficiency and high error rate caused by manual input by establishing a dynamic link between the numerical analysis software and the optical design software, which is beneficial to improving the data transmission efficiency and data transmission accuracy in the analysis process, and more truly reflects the influence of the spliced ​​telescope on its imaging effect under the long exposure time and micro-vibration scenario.

[0121] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0122] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An optical-mechanical integrated analysis method for micro-vibration of a spliced ​​telescope, characterized in that: include: An optomechanical model is established according to the optical elements and mechanical structure of the spliced ​​telescope, and a micro-vibration analysis is performed on the optomechanical model under a long exposure time to simulate and obtain the node displacement of the optical element corresponding to the time point; Using a first conversion model to convert the node displacement corresponding to the time point into a rigid body displacement corresponding to the time point; Establishing an optical system model according to the optical elements of the spliced ​​telescope, and using the optical system model to process the rigid body displacement corresponding to the time point to obtain a point spread function of the spliced ​​telescope corresponding to the time point; The point spread function corresponding to the time point is processed using a long exposure time model to obtain the point spread function of the spliced ​​telescope under the long exposure time.

2. The optical-mechanical integrated analysis method for micro-vibration of a spliced ​​telescope according to claim 1, characterized in that: The optomechanical model is established by using finite element simulation analysis software, and the optomechanical model is subjected to micro-vibration analysis under the long exposure time.

3. The optical-mechanical integrated analysis method for micro-vibration of a spliced ​​telescope according to claim 1, characterized in that: The optical system model is established using optical design software.

4. The optical-mechanical integrated analysis method for micro-vibration of a spliced ​​telescope according to claim 3, characterized in that: The spliced ​​telescope includes a primary mirror, and the optical system model includes an aperture function of the primary mirror. The aperture function of the primary mirror is as follows: Wherein, N is the number of sub-mirrors of the primary mirror, (x j ,y j ) is the center coordinate of the jth sub-mirror, f j (xx j ,yy j ) is the aperture function of the j-th sub-mirror; The aperture function f of the j-th sub-mirror is j (xx j ,yy j ) is as follows: F j (xx j ,yy j )=a j (xx j ,yy j )·exp(iφ j (xx j ,yy j )); Among them, φ j (xx j ,yy j ) is the phase error of the j-th sub-mirror, a j (xx j ,yy j ) is the transmission intensity function of the j-th sub-mirror.

5. The optical-mechanical integrated analysis method for micro-vibration of a spliced ​​telescope according to claim 4, characterized in that: The transmission intensity function a of the j-th sub-mirror j (xx j ,yy j ) is as follows: Among them, inside means that the incident light is within the area of ​​the j-th sub-mirror, and outside means that the incident light is outside the area of ​​the j-th sub-mirror.

6. The optical-mechanical integrated analysis method for micro-vibration of a spliced ​​telescope according to claim 5, characterized in that: The optical system model also includes a system point spread function and a complex amplitude distribution of the image plane of the primary mirror, the complex amplitude distribution of the image plane of the primary mirror is the Fourier transform of the aperture function of the primary mirror, and the complex amplitude distribution of the image plane of the primary mirror is as follows: Where λ is the wavelength, f is the focal length, (x f ,y f ) is the image plane coordinate of the primary mirror, (f x ,f y ) is the frequency domain coordinate; The system point spread function is the square of the modulus of the complex amplitude distribution in the image plane of the primary mirror; When the phase error φ(xx j ,yy j )=0, the point spread function of the system is as follows: Where A is the area of ​​a single sub-mirror, G(x f ,y f ) is the grid function, F s-PSF (x f ,y f ) is the point spread function of a single sub-mirror.

7. The optical-mechanical integrated analysis method for micro-vibration of a spliced ​​telescope according to claim 1, characterized in that: The first conversion model and the long exposure time model are established using numerical analysis software.

8. The optical-mechanical integrated analysis method for micro-vibration of a spliced ​​telescope according to claim 7, characterized in that: The first conversion model is as follows: Among them, (x, y, z) is the initial coordinate of the node on the mirror surface, (x', y', z') is the coordinate of the node on the mirror surface after translation and rotation, T x is the translation along the X axis, T y is the translation along the Y axis, T z is the translation along the Z axis, α is the tilt angle relative to the X axis, β is the tilt angle relative to the Y axis, and γ is the tilt angle relative to the Z axis; The node displacement is: Among them, (x i ,y i , z i ) is the node coordinate of the node number i; The rigid body displacement corresponding to the time point is obtained based on the node displacement fitting, and the rigid body displacement corresponding to the time point is obtained by fitting, comprising: The least square method is used to minimize E, and the requirements are: To obtain the rigid body displacement corresponding to the time point; The expression of E is as follows: Among them, dx i ,dy i and dz i It represents the coordinate change of the node position obtained by the micro-vibration analysis under the long exposure time.

9. The optical-mechanical integrated analysis method for micro-vibration of a spliced ​​telescope according to claim 7 or 8, characterized in that: The long exposure time model includes energy distribution of image point diffuse spots and point spread function under the long exposure time; The energy distribution of the image point diffuse spot is as follows: g(x,t)=h(x)*δ(x-ε(t)); Wherein, h(x) is the system point spread function in ideal imaging, ε(t) is the image shift caused by vibration during long exposure time, δ(x-ε(t)) is the image point energy distribution when image shift exists, * is the convolution symbol, t is the time point, and x is the image point position coordinate; The point spread function under the long exposure time is as follows: Among them, t0 is the initial time point and t1 is the duration.

10. The optical-mechanical integrated analysis method for micro-vibration of a spliced ​​telescope according to claim 1, characterized in that: The micro-vibration analysis under the long exposure time includes: Establishing a micro-vibration signal test platform, the micro-vibration signal test platform includes the spliced ​​telescope, an infrared refrigerator, an accelerometer and a suspension system, the suspension system includes a connected sling and a spring, the suspension system suspends the spliced ​​telescope and the infrared refrigerator, and a plurality of the accelerometers are arranged on a plurality of mounting points of the infrared refrigerator; The accelerometer collects one data point every unit preset time length, collects multiple data points corresponding to the time point within the preset time length, obtains the average value of the multiple acceleration data points at the same time point as the target data point corresponding to the time point, and uses the multiple target data points corresponding to the time point as vibration parameters under long exposure time to perform micro-vibration analysis under the long exposure time.

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