Weak starlight simulator star point position cascade modulation device and method

Abstract

The invention relates to a weak starlight simulator star point position cascade modulation device and method. The device comprises a curved surface condensation system, an integrator, a relay system and a telecentric cascade system. The free-form surface condensation system comprises a first lens and a second lens, one surface of the first lens is a plane, the other surface of the first lens is a free-form surface, and two surfaces of the second lens are free-form surfaces; the free-form surface condensation system is used for collecting and primarily processing light rays emitted by the light source; the integrator is used for uniformizing light; the relay system is used for realizing stable transmission of light, and the telecentric cascade system is used for mapping an image of the dimming LCOS into the imaging LCOS in an equal ratio. According to the method, the dimming LCOS is mapped to the surface of the imaging LCOS in an equal-ratio mode, expansion of the imaging LCOS gray scale adjustment dimension is achieved, and the correction precision of the simulated star point position is improved.

Description

Technical Field

[0001] The invention relates to the field of aerospace equipment target range calibration, and in particular to a star point position cascade modulation device and method for a weak starlight simulator. Background Art

[0002] In the field of aerospace, the precise operation of spacecraft is highly dependent on accurate attitude navigation systems, and star sensors play a key role in this. As an essential device for the calibration test of star sensors at the target range, the importance of faint starlight simulators is self-evident. Traditional faint starlight simulators face many challenges. Optical system aberrations often cause the simulated star point positions to shift, seriously interfering with the calibration accuracy of star sensors. For example, in some high-precision space missions, tiny star point position deviations may accumulate during long-term flight, resulting in large errors in spacecraft attitude control.

[0003] The grayscale resolution of the star map display device LCOS has become the main bottleneck for improving the accuracy of simulated star point position correction. Although there have been many attempts in the past, such as increasing the focal length, although it alleviates the influence of aberrations to a certain extent, it reduces the relative illumination of the edge field of view star points and limits the application scope of the simulator; the simulated star point sampling partition correction is restricted by the grayscale resolution of the LCOS single pixel, and the accuracy is difficult to break through; the use of MEMS technology to translate the imaging LCOS breaks through the single pixel size limitation, but under the influence of the aberration coupling of the collimated optical system, it is difficult to apply it to the full field of view correction. The existing weak starlight simulator technology has significant deficiencies in the accuracy of star point position simulation, and innovative technologies are urgently needed to meet the growing high-precision needs of aerospace engineering and ensure the accuracy and reliability of spacecraft attitude control and navigation.

[0004] Therefore, it is necessary to provide a new device and method for cascading modulation of the star point position of a weak starlight simulator. Summary of the invention

[0005] Based on the above-mentioned problems existing in the prior art, the purpose of an embodiment of the present invention is to provide a cascade modulation device and method for the star point position of a weak starlight simulator, by proportionally mapping the dimming LCOS to the imaging LCOS surface, thereby expanding the grayscale adjustment dimension of the imaging LCOS and improving the correction accuracy of the simulated star point position.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a cascade modulation device for the star point position of a weak starlight simulator, comprising: a curved surface focusing system, an integrator, a relay system and a telecentric cascade system; the free-form surface focusing system comprises a first lens and a second lens, wherein one side of the first lens is a plane and the other side is a free-form surface, and both sides of the second lens are free-form surfaces;

[0007] The free-form surface focusing system is used to collect and preliminarily process the light emitted by the light source, so that the light converges to the light inlet of the integrator to form a small-angle and relatively uniform radiation distribution;

[0008] The integrator is located after the free-form surface focusing system, and the integrator is used to homogenize the light;

[0009] The relay system is located after the integrator, and is used to achieve stable transmission of light, ensuring that the light processed by the integrator can be accurately transmitted to the telecentric cascade system to maintain the transmission characteristics and energy distribution of the light;

[0010] The telecentric cascade system is used to proportionally map the image of the dimming LCOS into the imaging LCOS.

[0011] Furthermore, the other side of the first lens is a free-form surface and the shapes of the two free-form surfaces of the second lens are based on the geometric relationship between the light source and the optical path, and the relationship formula between the coordinates of each free-form surface of the lens and the divergence angle of the light emitted by the light source is derived and determined through iterative calculation.

[0012] A cascade modulation method for the star point position of a weak starlight simulator is applied to the above-mentioned cascade modulation device for the star point position of a weak starlight simulator, and the method comprises:

[0013] S1, sequentially setting a free-form surface focusing system, an integrator, a relay system and a telecentric cascade system, wherein the free-form surface focusing system comprises a first lens and a second lens, one side of the first lens is a plane and the other side is a free-form surface, and both sides of the second lens are free-form surfaces;

[0014] S2, based on scalar diffraction theory, establish the light intensity distribution function model of each sub-eye of the light integrator field lens and projection lens, analyze the main factors affecting the grayscale resolution of dimming LCOS and establish the optimization design principle of the focusing system;

[0015] S3, the coordinates of discrete points are preprocessed by the straight line thinning method, the discrete point interval is divided based on the Bezier curve control point setting and parameter iteration rules, an irradiation evaluation model with uniformity and collimation weights is constructed, and the Bezier curve of the free-form surface light collection system is optimized using the simulated annealing algorithm;

[0016] S4, a simulation verification is carried out by comparing the star point position cascade modulation device of the focusing system using a spherical surface, before and after optimization. The light propagation and irradiation conditions are monitored by setting receiving surfaces on the front end of the field mirror and the imaging LCOS surface, and the correction accuracy of the simulated star point position is calculated based on the energy distribution principle.

[0017] Furthermore, in S2, the complex amplitude distribution of a monochromatic plane wave with an incident wavelength of λ is represented by U0(y), and the wavefront incident on the rear surface of the field mirror is represented by:

[0018]

[0019] Among them, U1(y1) is the wavefront incident on the rear surface of the field mirror, U0(y0) is the complex amplitude distribution of the monochromatic plane wave with incident wavelength, and t m1 is a quantity related to transmittance, y1 is the coordinate of the rear surface of the field lens, δ(y1-np) is a comb function used to indicate the array arrangement of sub-eye lenses, p is the spacing of sub-eye lenses, is a rectangular function, which means the aperture function of the sub-eye lens; is the phase function. k is the wave number ( λ is the wavelength of light), f is the focal length of the sub-eye lens, N is the number of sub-eye lenses, and n is the summation variable;

[0020] According to the imaging principle, the interval between the field lens and the projection lens is d1 = f1, and the light field distribution incident on the projection lens is expressed as:

[0021]

[0022] Where f1 is the focal length of the lens, U 1-2 (y2) is the light field distribution incident on the projection mirror, d1 is the interval between the field mirror and the projection mirror, and d1=f1, y2 is the coordinate at the projection mirror, i is the imaginary unit, F{} is the Fourier transform, j is the imaginary part, z is the propagation distance of the wave, and k is the wave number.

[0023] Furthermore, in S3, the use of a straight line sparse method to pre-process the coordinates of discrete points includes: setting points P1 and P i There are i-2 discrete points between them; use the point-to-line distance formula to determine the distance between i-2 discrete points and the line P1P i The distance d max If d max Less than the maximum allowable error ε, points P1 and P i There are i-2 discrete points between them, separated by the straight line P1P i Replacement, thereby completing the preprocessing of three sets of discrete point coordinates.

[0024] Furthermore, in S3, the discrete point interval division based on the Bezier curve includes:

[0025] Step S31, select a Bezier curve with n+1 control points, set P n-1 , P n , P n+1 is the set of control points that make up the curve.

[0026] Step S32, when line segment P n-1 P n and line segment P n P n+1 The angle β between the two should be smaller than the target value βtargate, and When P n+1 Belongs to the control point set.

[0027] Step S33, after calculating each set of curve point sets, determine whether the number of points is less than the target control point number n+1. If the number is less than n+1, it is regarded as a regular line segment point set.

[0028] Furthermore, in S3, the discrete point interval division based on the Bezier curve includes:

[0029] Step S31, select a Bezier curve with n+1 control points, set P n-1 , P n , P n+1 is the set of control points that make up the curve.

[0030] Step S32, when line segment P n-1 P n and line segment P n P n+1 The angle β between the two should be smaller than the target value βtargate, and , Pn+1 belongs to the control point set.

[0031] Step S33, after calculating each set of curve point sets, determine whether the number of points is less than the target control point number n+1. If the number is less than n+1, it is regarded as a regular line segment point set.

[0032] Further, in S3, the use of the simulated annealing algorithm to optimize the Bezier curve of the free-form surface light collection system includes: setting the initial annealing temperature to T initial , the termination temperature is T final , calculate the optimization parameters of the initial Bezier curve, the evaluation function is D; the simulated annealing algorithm will iterate M times at each temperature to fully search the solution space; during the search process, if the current solution D m+1 The evaluation function of is less than the previous solution D m If the evaluation function is m+1 ; If the current solution is D m+1 The evaluation function of the solution D is greater than the previous solution D m When the evaluation function is used, a probability k of accepting a solution related to temperature will be generated at this time; according to the preset probability function, it is determined whether the new solution is used as the solution of the free surface light collecting system; as the temperature decreases, the probability of accepting a solution worse than the original one continues to decrease, gradually changing from searching the breadth of the solution space to searching the depth of the solution space until the optimal solution is selected.

[0033] The embodiment of the present invention further provides a network side server, including:

[0034] At least one processor; and a memory in communication with the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the above-mentioned cascade modulation method of the star point position of the weak starlight simulator.

[0035] An embodiment of the present invention further provides a computer-readable storage medium storing a computer program, which implements the above-mentioned cascade modulation method of the star point position of the weak starlight simulator when executed by a processor.

[0036] The beneficial effects of the present invention are as follows: the star point position cascade modulation method of the weak starlight simulator of the present invention comprises: sequentially setting a free-form surface focusing system, an integrator, a relay system and a telecentric cascade system, wherein the free-form surface focusing system comprises a first lens and a second lens, one side of the first lens is a plane and the other side is a free-form surface, and both sides of the second lens are free-form surfaces; based on the scalar diffraction theory, a light intensity distribution function model of each sub-eye of the light integrator field lens and the projection lens is established, the main factors affecting the grayscale resolution of the dimming LCOS are analyzed and the optimization design principle of the focusing system is established; the coordinates of discrete points are pre-processed by a linear sparse method, the discrete point intervals are divided based on the setting of Bezier curve control points and parameter iteration rules, an irradiation evaluation model containing uniformity and collimation weights is constructed, and the optimization of the Bezier curve of the free-form surface light collection system is completed by using a simulated annealing algorithm; a star point position cascade modulation device using a spherical surface, a focusing system before optimization, and a focusing system after optimization is compared for simulation verification, the light propagation and irradiation are monitored by setting a receiving surface on the front face of the field lens and the imaging LCOS surface, and the correction accuracy of the simulated star point position is calculated according to the energy distribution principle. Based on the imaging principle of proportional mapping of a telecentric system, the present invention proportionally maps the image of a dimming LCOS to the surface of an imaging LCOS, realizes the superposition of two LCOS grayscales, and improves the correction accuracy of the simulated star point position; based on the scalar diffraction theory, a light intensity distribution function model of each sub-eye in an integrator field lens and a projection lens is established, the light intensity distribution law inside the optical system is deeply analyzed, and it is accurately determined that the uniformity and collimation of the focusing system and the mismatch of the integrator are the main factors affecting the grayscale resolution of the imaging LCOS; an evaluation model for the irradiation characteristics of the focusing system is established in a weighted matching manner, and combined with the simulated annealing method, a free-form surface optimization design of the focusing system is performed, and key performance indicators such as the irradiation uniformity and collimation of the focusing system are fully considered, thereby realizing the precise optimization of the focusing system. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0038] In the figure:

[0039] Figure 1 A schematic diagram of the structure of a cascade modulation device for star point position of a weak starlight simulator provided in the first embodiment of the present invention;

[0040] Figure 2 A flow chart of a star point position cascade modulation method for a weak starlight simulator provided in the second embodiment of the present invention;

[0041] Figure 3 A schematic diagram showing the effect of the dimming LCOS irradiation uniformity on the grayscale resolution of a single pixel of the imaging LCOS provided in the second embodiment of the present invention;

[0042] Figure 4 A schematic diagram of the optical path of a free-form surface light collection system provided in the second embodiment of the present invention;

[0043] Figure 5 A schematic diagram of the optimization process of a free-form surface focusing system based on a simulated annealing algorithm provided in the second embodiment of the present invention;

[0044] Figure 6 A schematic diagram of ray tracing of a star point position cascade modulation architecture provided in the second embodiment of the present invention;

[0045] Figure 7 A comparison diagram of the free-form surface focusing system before and after optimization provided in the second embodiment of the present invention;

[0046] Figure 8 A comparison diagram of LCOS irradiance distribution after imaging using a spherical surface and a free-form surface focusing system before and after optimization provided in the second embodiment of the present invention;

[0047] Fig. 9 A comparison diagram of simulated star point correction distances provided in the second embodiment of the present invention;

[0048] Fig.10 It is a structural diagram of a network-side server provided according to a third embodiment of the present invention.

[0049] Among them, the reference numerals in the figure are:

[0050] A cascade modulation device 100 for the star point position of a faint starlight simulator;

[0051] Free-form surface focusing system 1, first lens 11, second lens 12;

[0052] Integrator 2; relay system 3; telecentric cascade system 4. DETAILED DESCRIPTION

[0053] It should be mentioned before discussing the exemplary embodiments in more detail that some exemplary embodiments are described as processes or methods depicted as flow charts. Although the flow charts describe the operations as sequential processes, many of the operations therein can be implemented in parallel, concurrently or simultaneously. In addition, the order of the operations can be rearranged. The process can be terminated when its operation is completed, but can also have additional steps not included in the accompanying drawings. The process can correspond to a method, function, procedure, subroutine, subprogram, etc.

[0054] It should be understood that, although the terms "first", "second", etc. may be used herein to describe various units, these units should not be limited by these terms. These terms are used only to distinguish one unit from another unit. For example, without departing from the scope of the exemplary embodiments, the first unit may be referred to as the second unit, and similarly the second unit may be referred to as the first unit. The term "and / or" used herein includes any and all combinations of one or more of the listed associated items.

[0055] The present invention will now be described in detail with reference to the accompanying drawings. This figure is a simplified schematic diagram, which only illustrates the basic structure of the present invention in a schematic manner, and therefore only shows the components related to the present invention.

[0056] First embodiment:

[0057] like Figure 1 As shown, a star point position cascade modulation device 100 of a weak starlight simulator of the present invention comprises: a free-form surface focusing system 1, an integrator 2, a relay system 3 and a telecentric cascade system 4.

[0058] In some embodiments, the free-form surface focusing system 1 is used to collect and preliminarily process the light emitted by the light source, so that the light converges to the light inlet of the integrator 2 to form a small angle and relatively uniform radiation distribution. The free-form surface focusing system 1 provides relatively stable input conditions for the precise processing of subsequent light, and is the starting link of light convergence of the entire optical system. The performance of the free-form surface focusing system 1 affects the quality and distribution of subsequent light. The integrator 2 is located after the free-form surface focusing system 1, and the integrator 3 is used to homogenize the light. The light inlet of the integrator 2 corresponds to the field lens, and the light outlet corresponds to the projection lens. The irradiation surface at the field lens of the integrator 2 is divided by the sub-eye lens, which can effectively eliminate the spherical aberration and coma outside the aperture axis, avoid the deformation of the segmented image and the light entering the wrong channel. On the one hand, the integrator 2 improves the quality of the light, making the light entering the subsequent system more uniform and stable; on the other hand, it ensures that the light is transmitted along the correct path, plays an important role in light sorting and screening in the entire optical link, and provides high-quality light input for the telecentric mapping system.

[0059] In some of the embodiments, the relay system 3 is located after the integrator 2. The relay system 3 is used to achieve stable transmission of light, ensure that the light processed by the integrator 2 can be accurately transmitted to the telecentric cascade system 4, maintain the transmission characteristics and energy distribution of the light, and ensure the coherence and stability of the entire optical system. The stability of the performance of the relay system 3 has an indirect but important impact on the final imaging effect. The telecentric cascade system 4 is located after the relay system and is used to ensure that the light propagates in a parallel manner. The telecentric cascade system 4 is used to proportionally map the image of the dimming LCOS to the imaging LCOS. Through this mapping process, the grayscale adjustment dimension of the imaging LCOS is expanded from one dimension to two dimensions. Under ideal conditions, it provides new dimensions and possibilities for precise control of the star point position. It is one of the core systems for realizing high-precision star point simulation, which is directly related to the accuracy and controllability of the simulated star point position.

[0060] Specifically, the light emitted by the light source first enters the free-form surface focusing system 1, and after being processed by the system, it converges to the light inlet (field lens) of the integrator 2 to form a relatively uniform radiation distribution. The integrator 2 uses sub-eye lenses to divide the irradiation surface at the field lens. The irradiation surface at the field lens of the integrator 2 is divided by the sub-eye lenses, which eliminates the spherical aberration and coma outside the aperture axis, prevents the deformation of the segmented image, and also prevents it from falling into the non-corresponding projection image channel. After being processed by the sub-eye lenses, the irradiation distribution in each sub-eye lens is better than the uniformity at the light inlet of the integrator 2. The segmented image divided by the sub-eye lenses is then superimposed by the sub-eye lenses corresponding to the integrator projection lens group and incident on the telecentric mapping system 4. The telecentric mapping system 4 uses its special optical structure and principle to map the image ratio of the dimming LCOS into the imaging LCOS, so that the grayscale adjustment dimension of the imaging LCOS is expanded from one dimension to two dimensions. Under ideal optical conditions, it is only necessary to adjust the grayscale of any pixel that makes up the simulated star point in the two LCOS to achieve precise control of the energy center position of any star point in the star map, which greatly improves the accuracy and flexibility of star point position simulation.

[0061] In the prior art, such as Figure 2 As shown, due to the mismatch between the focusing system 1 and the integrator 2, the irradiance distribution superimposed on the dimming LCOS surface presents an uneven state with high center and low edge. This non-uniform irradiance distribution reduces the grayscale adjustment capability of the simulated star point located in the central field of view, and may even cause the grayscale resolution of some areas of the dimming LCOS to be lost. Therefore, the matching degree between the focusing system and the integrator is improved by improving the uniformity of the irradiation surface of the field mirror and controlling the incident light aperture angle of its sub-eye.

[0062] In some embodiments, the free-form surface light collecting system 1 includes a first lens 11 and a second lens 12, wherein one side of the first lens 11 is a plane and the other side is a free-form surface, and both sides of the second lens 12 are free-form surfaces. The use of two lenses ensures that light uniformity and collimation are achieved while collecting light, thereby facilitating the calculation of the surface shape, aperture, thickness and lens shape of the free-form surface light collecting system 1, so that the free-form surface light collecting system 1 has both light collecting and collimation characteristics.

[0063] Specifically, based on the geometric relationship between the light source and the optical path, a formula for the relationship between the coordinates of each free-form surface of the lens and the divergence angle of the light emitted by the light source is derived, and through iterative calculation, it is determined that the other side of the first lens 11 is a free-form surface and the shapes of the two free-form surfaces of the second lens 12 are determined, so that the free-form surface light collecting system 1 can achieve light collection while achieving uniform light and collimation, thereby improving the accuracy of simulated star point position correction.

[0064] The star point position cascade modulation device of the faint starlight simulator of the present invention comprises: a free-form surface focusing system 1, an integrator 2, a relay system 3 and a telecentric cascade system 4, wherein the free-form surface focusing system 1 comprises a first lens 11 and a second lens 12, wherein one side of the first lens 11 is a plane and the other side is a free-form surface, and both sides of the second lens 12 are free-form surfaces, based on the geometric relationship between the light source and the optical path, a relationship formula between the coordinates of each free-form surface of the lens and the divergence angle of the light emitted by the light source is derived, and the other side of the first lens 11 is determined to be a free-form surface and the shapes of the two free-form surfaces of the second lens 12 are determined through iterative calculation, and the surface shapes are continuously adjusted and optimized through calculation to achieve the best optical performance, so that the free-form surface collecting system 1 realizes light collection while realizing uniform light and collimation, thereby improving the clarity and accuracy of imaging, and further improving the accuracy of correction of the simulated star point position.

[0065] Second implementation method:

[0066] like Fig.10 As shown, a flow chart of a cascade modulation method for star point position of a weak starlight simulator proposed by the present invention.

[0067] As an example, the method for cascading star point position modulation of a weak starlight simulator includes:

[0068] Step S1, sequentially setting up a free-form surface focusing system, an integrator, a relay system and a telecentric cascade system, wherein the free-form surface focusing system includes a first lens and a second lens, one side of the first lens is a plane and the other side is a free-form surface, and both sides of the second lens are free-form surfaces.

[0069] Specifically, the light emitted by the light source first enters the free-form surface focusing system, and after being processed by the system, it converges to the light inlet (field lens) of the integrator to form a relatively uniform radiation distribution. The integrator uses sub-eye lenses to divide the irradiation surface at the field lens. The irradiation surface at the field lens of the integrator is divided by the sub-eye lenses, which eliminates the spherical aberration and coma outside the aperture axis, prevents the deformation of the segmented image, and also prevents it from falling into the non-corresponding projection image channel. After being processed by the sub-eye lenses, the irradiation distribution in each sub-eye lens is better than the uniformity at the light inlet of the integrator. The segmented images divided by the sub-eye lenses are then superimposed by the sub-eye lenses corresponding to the integrator projection lens group and incident on the telecentric mapping system. The telecentric mapping system uses its special optical structure and principle to map the image ratio of the dimming LCOS into the imaging LCOS, so that the grayscale adjustment dimension of the imaging LCOS is expanded from one dimension to two dimensions. Under ideal optical conditions, it is only necessary to adjust the grayscale of any pixel that makes up the simulated star point in the two LCOS to achieve precise control of the energy center position of any star point in the star map, greatly improving the accuracy and flexibility of star point position simulation.

[0070] The free-form surface focusing system includes a first lens and a second lens, wherein one side of the first lens is a plane and the other side is a free-form surface, and both sides of the second lens are free-form surfaces. The use of two lenses ensures that light uniformity and collimation are achieved while collecting light, which makes it easier to calculate the surface shape, aperture, thickness and shape of the lens of the free-form surface focusing system, so that the free-form surface focusing system has both light collection and collimation characteristics.

[0071] Step S2, based on the scalar diffraction theory, establish the light intensity distribution function model of each sub-eye of the light integrator field lens and the projection lens, analyze the main factors affecting the grayscale resolution of the dimming LCOS and establish the optimization design principle of the focusing system.

[0072] Specifically, if Figure 3 As shown in the figure, due to the mismatch between the focusing system and the integrator in the architecture, the irradiance distribution superimposed on the dimming LCOS surface presents a distribution state of high in the center and low at the edge. This non-uniform irradiance distribution reduces the grayscale adjustment capability of the simulated star point located in the central field of view, and may even cause the grayscale resolution of some areas of the dimming LCOS to be lost. Therefore, it is necessary to analyze the main factors affecting the matching degree between the focusing system and the integrator based on the working principle of the integrator, and determine the optimization design principle of the focusing system.

[0073] Furthermore, based on the scalar diffraction theory, the light intensity distribution function model of each sub-eye of the light integrator field lens and the projection lens is established, including:

[0074] Under the paraxial approximation, the field of a plane diffraction wave at a point (x, y) in space at a distance z can be expressed by the Fresnel diffraction formula:

[0075]

[0076] Where j is the imaginary part, z is the propagation distance of the wave, k is the wave number, U(x0,y0) is the field distribution on the input plane, x0 and y0 are the coordinates of the input plane, and x and y are the coordinates of the output plane.

[0077] The Fourier transform form of the Fresnel diffraction formula is:

[0078]

[0079] Where F{} is the Fourier transform.

[0080] Furthermore, the Fresnel diffraction formula can also be viewed as The Fourier transform of .

[0081] If only the spatial phase distribution of the incident light wave by the lens can be considered, the simplified formula of its complex amplitude transmittance is:

[0082]

[0083] Among them, t i (x,y) is the complex amplitude transmittance, k is the wave number, f is the focal length of the lens, and x and y are the spatial coordinates.

[0084] Therefore, for an integrator composed of N sub-eye lenses, the aperture of the sub-eye lens is d=p, and the focal length is f. Since the lens array is composed of many lens units with the same structural parameters arranged closely, this lens array with a theoretical filling rate of 100% is a phase modulation element, so its transmittance function is the convolution of the transmittance function of the lens unit and the comb function. The transmittance function in one-dimensional direction is:

[0085]

[0086] Among them, t m (y) is the transmittance function of the integrator in one-dimensional direction, N is the number of sub-eye lenses, n is the summation variable, δ(y-np) is a comb function used to represent the array arrangement of sub-eye lenses, p is the spacing of sub-eye lenses, is a rectangular function, which represents the aperture function of the sub-eye lens, k is the wave number, f is the focal length of the sub-eye lens, is the convolution operation, is the phase function. k is the wave number ( λ is the wavelength of light), and f is the focal length of the sub-eye lens.

[0087] Assume that the complex amplitude distribution of a monochromatic plane wave with an incident wavelength of λ is represented by U0(y), and the wavefront incident on the rear surface of the field mirror is represented by:

[0088]

[0089] Among them, U1(y1) is the wavefront incident on the rear surface of the field mirror, U0(y0) is the complex amplitude distribution of the monochromatic plane wave with incident wavelength, and t m1 is a quantity related to transmittance, y1 is the coordinate of the rear surface of the field lens, δ(y1-np) is a comb function used to indicate the array arrangement of sub-eye lenses, p is the spacing of sub-eye lenses, is a rectangular function, which means the aperture function of the sub-eye lens; is the phase function. k is the wave number ( λ is the wavelength of light), and f is the focal length of the sub-eye lens.

[0090] Specifically, the wavefront formula incident on the rear surface of the field lens describes the wavefront change of the incident light after passing through the field lens, which is the product of the incident light distribution and the transmittance function.

[0091] According to the imaging principle, the interval between the field lens and the projection lens is d1 = f1, and the light field distribution incident on the projection lens is expressed as:

[0092]

[0093] Among them, U 1-2 (y2) is the light field distribution incident on the projection mirror, d1 is the interval between the field mirror and the projection mirror, and d1=f1, y2 is the coordinate at the projection mirror, i is the imaginary unit, and F{} is the Fourier transform.

[0094] Specifically, the formula for representing the distribution of the light field incident on the projection mirror is based on the imaging principle. Through operations such as integration and Fourier transform, an expression for the distribution of the light field from the field mirror to the projection mirror is given, showing the changes and distribution of the light field during the propagation process.

[0095] The wavefront expression formula corresponding to the plane behind the integrator projection mirror is:

[0096]

[0097] Among them, U2(y2) is the wavefront corresponding to the plane behind the integrator projection mirror, t m2 is a quantity related to transmittance.

[0098] Specifically, the formula indicates that the wavefront of the plane behind the projection mirror is the product of the light field distribution incident on the projection mirror and a term including a comb function, a rectangular function and a phase function, which describes the wavefront change after the light passes through the projection mirror.

[0099] The light field emitted from the projection mirror reaches the focusing system. According to the Fresnel diffraction formula, its complex amplitude distribution is expressed as:

[0100]

[0101] Among them, U 2-F (y F ) is the complex amplitude distribution of the light field emitted from the projection mirror when it reaches the focusing system, d L is the distance from the projection mirror to the front surface of the focusing system, y F is the coordinate of the focusing system.

[0102] Specifically, based on the Fresnel diffraction formula, this formula gives an expression for the complex amplitude distribution of the light field emitted from the projection mirror when it reaches the focusing system. It includes operations such as integration and Fourier transform, and describes the diffraction and distribution of light during propagation.

[0103] The light field distribution formula after the incident light is emitted by the relay system is:

[0104]

[0105] Among them, U F (y F ) is the light field distribution of the incident light after it is emitted by the relay system, P(y) is the pupil function of the relay system, and f F is the focal length of the relay system.

[0106] Specifically, this formula indicates that the light field distribution of the incident light after it is emitted from the relay system is the product of the light field distribution emitted from the projection lens to the focusing system, the pupil function of the relay system, and a phase term. It describes the change of the light field after the light passes through the relay system, where the pupil function reflects the restriction and modulation effect of the relay system on the light.

[0107] The light field distribution of the outgoing light from the relay system on the dimming LCOS surface is expressed as:

[0108]

[0109] Among them, U'(y H ) is the light field distribution of the outgoing light of the relay system on the dimming LCOS surface, z is the propagation distance of the wave, y H are the coordinates of the dimming LCOS surface.

[0110] Specifically, the formula gives an expression for the light field distribution of the outgoing light of the relay system on the dimming LCOS surface through operations such as integration and Fourier transform, and describes the distribution of the light field when it propagates to the dimming LCOS surface.

[0111] The light intensity distribution formula on the dimming LCOS is:

[0112] I(y H )=U(y H ) * (y H)=|U(y H )| 2

[0113] Among them, I(y H ) is the light intensity distribution on the dimming LCOS, U * (y H ) is U(y H ) is the conjugate function of .

[0114] Specifically, the formula shows that the light intensity distribution on the dimming LCOS is equal to the product of the light field distribution on the dimming LCOS surface and its complex conjugate, that is, the light intensity is the square of the light field amplitude. This is the basic expression for the relationship between light intensity and light field in optics, and is used to describe the energy distribution of light on the dimming LCOS.

[0115] By reorganizing the above formulas and discarding the constant phase factor, we can get the following formula:

[0116]

[0117] Where I is the light intensity on the dimming LCOS, y H is the coordinate of the dimming LCOS surface, m is the summation variable, p is the spacing of the sub-eye lenses (clear aperture), λ is the wavelength of light, is a comb function, which is used to represent the array arrangement of sub-eye lenses. is the Sigmund function, which is related to the propagation and diffraction of light. is a rectangular function representing the limiting or distribution characteristics associated with the sub-eye lens aperture, etc.

[0118] It can be concluded from the above formula that the irradiance distribution on the dimming LCOS surface is mainly composed of the field lens and projection lens related functions and the sub-eye lens arrangement function. The convolution term has the same propagation effect as the single channel of the sub-eye lens, so the irradiance uniformity on the dimming LCOS surface can be improved by changing the irradiance uniformity on the front surface of the field lens. The comb function is mainly affected by the sub-eye aperture and wavelength. Since the aperture of the sub-eye is much larger than the wavelength, the diffraction phenomenon only occurs at the edge of the sub-eye. Therefore, the edge irradiance of the dimming LCOS surface can be improved by controlling the aperture angle of the incident light of each sub-eye and adjusting the diffraction intensity of the sub-eye.

[0119] In summary, by improving the uniformity of the irradiated surface of the field mirror and controlling the incident light aperture angle of its sub-eye, the matching degree between the focusing system and the integrator can be improved, thereby improving the irradiation uniformity of the dimming LCOS surface.

[0120] In step S3, the coordinates of discrete points are preprocessed by the straight line thinning method, the discrete point interval is divided based on the Bezier curve control point setting and parameter iteration rules, an irradiation evaluation model with uniformity and collimation weights is constructed, and the Bezier curve of the free-form surface light collection system is optimized using the simulated annealing algorithm.

[0121] Specifically, considering that the free-form surface light collection system has both light collection and collimation characteristics, using only a single lens may make it difficult to control the surface shape, aperture, thickness and shape of the lens during calculation. Therefore, the free-form surface light collection system includes a first lens and a second lens, one side of the first lens is a plane and the other side is a free-form surface, and both sides of the second lens are free-form surfaces, ensuring that light uniformity and collimation are achieved while collecting light.

[0122] Let the center of the light source be located at the origin of the coordinate system, and the light incident on the target surface through the light collecting system is a circle with a radius of r, such as Figure 4 As shown. Figure 4 It can be seen that the light emitted by the light source is refracted by the two lenses of the free-form surface light collection system in sequence and then incident on the circle with a radius of r on the target surface. In the figure, d0, d2, and d4 represent the air intervals, and d1 and d3 represent the thickness of the two lenses of the light collection system. in represents the divergence angle of the light emitted by the light source, a0 represents the incident angle of the first surface, a1, a2, and a3 represent the angles between the optical axis and the tangent of the sampling point, a4 represents the angle between the incident light and the target surface, and b0, b1, b2, and b3 represent the angles between the emitted light of each surface and the optical axis.

[0123] Depend on Figure 4 From the geometric relationship in, we can see that r also satisfies the following relationship formula:

[0124] r=d0tanθ in +(x1-d0)tanβ0+(x2-x1)tanβ1

[0125] +(x3-x2)tanβ2+(d0+d1+d2+d3+d4-x3)tanβ3

[0126] Where r is the radius of the circle incident on the target surface through the light collection system, d0, d2, d4 are the air intervals, that is, the thickness of the air layer between the lenses or between the lens and other components, d1 and d3 are the thickness of the two lenses of the light collection system, θ in is the divergence angle of the light emitted by the light source, x1, x2, and x3 are the horizontal coordinates of the light path on the three free-form surfaces, and tanβ0, tanβ1, tanβ2, and tanβ3 are the tangent values ​​related to the angles of the light at different positions, which are used to describe the change in direction of the light when it passes through the free-form surface light collection system.

[0127] The following will take the free-form surface I in the first lens of the free-form surface light collection system as an example to illustrate the design process. For any sampling point P1 (x1, y1) on the free-form surface I of the first lens, the relationship between its coordinates and the divergence angle of the light source is expressed as follows:

[0128] y1=d0tanθ in +(x1-d0)tanb0

[0129] Wherein, y1 is the ordinate of any sampling point on the free-form surface I of the first lens, x1 is the abscissa of the sampling point, and tan b0 is the tangent value of the angle b0.

[0130] According to the definition of slope, the slope expression formula of sampling point 1 is:

[0131]

[0132] in, is the slope of the sampling point, that is, the derivative of the ordinate with respect to the abscissa, tan a1 is the tangent of angle a1, n is the refractive index of the lens, cosb0 is the cosine of angle b0, sin b0 is the sine of angle b0, cosb1 is the cosine of angle b1, and sinb1 is the sine of angle b1.

[0133] Combining the above equations, the coordinate x1 of the free surface Ⅰ of the first lens and the angle θ of the light source in The formula is:

[0134]

[0135] The initial condition of the above equation is θ in =0 and x1=d0+d1, the free-form surface shape of lens II can be determined by iterating the above formula.

[0136] Similarly, the coordinates x2 of the free surface II of the second lens and the angle θ of the light source can be calculated: in The relationship is expressed as:

[0137]

[0138] Similarly, the relationship between the coordinate 3 of the free surface III of the second lens and the angle of the light source can be calculated as follows:

[0139]

[0140] The linear sparse method is used to pre-process the coordinates of the three sets of discrete points, including: setting points P1 and P i There are i-2 discrete points between them; use the point-to-line distance formula to determine the distance between i-2 discrete points and the line P1P i The distance d max If dmax Less than the maximum allowable error ε, points P1 and P i There are i-2 discrete points between them, separated by the straight line P1P i Replacement, thereby completing the preprocessing of three sets of discrete point coordinates.

[0141] The formula for the nth-order Bessel function controlled by n+1 points is:

[0142]

[0143] Among them, t is a parameter, t∈(0,1), P i is the control point of the Bezier curve, B i,n (t) is a Bernstein polynomial of order n.

[0144] Let point P on the Bezier curve point set be i The corresponding parameter t value is t i , then the curve point set matrix P is expressed as:

[0145]

[0146] Among them, P(t i ) is a point on the Bezier curve point set, and the corresponding parameter value t is t i The point coordinates at time t i is the parameter value corresponding to each point on the Bezier curve point set, P i is the control point of the Bezier curve, b i is the element in the matrix, and matrix b is the control point coordinate matrix, which is used to store the coordinate information of the control points.

[0147] Furthermore, the curve parameter t i It is obtained by the following iterative formula:

[0148]

[0149] In order to increase the influence of the control points in the Bezier curve, the following steps are used to complete the division of the discrete point interval of the Bezier curve:

[0150] Step S31, select a Bezier curve with n+1 control points, set P n-1 , P n , P n+1 is the set of control points that make up the curve.

[0151] Step S32, when line segment P n-1 P n and line segment P n P n+1 The angle β between the two should be smaller than the target value βtargate, and When P n+1Belongs to the control point set.

[0152] Step S33, after calculating each set of curve point sets, determine whether the number of points is less than the target control point number n+1. If the number is less than n+1, it is regarded as a regular line segment point set.

[0153] Since the free-form surface light collection system not only has the function of uniform light, but also its outgoing light divergence angle should be consistent with the theoretical value θ of the integrator design t Therefore, the light-inlet end face of the integrator is meshed, and the uniformity and collimation at the light-inlet of the field lens are combined in a weighted ratio to establish an irradiation evaluation model.

[0154] The calculation formula of the irradiation evaluation model is:

[0155]

[0156] Where D is the evaluation function value of the irradiation evaluation model, y r is the uniformity weight, y d is the weight of the collimation, a and b are the longitude and latitude coordinates of the grid, m and n are the longitude and latitude boundaries of the grid, E(a, b) is the normalized irradiance, is the normalized irradiance target value, ΔE(a,b) is the normalized irradiance tolerance, A(a,b) is the absolute value of the maximum incident angle of the integrator light-entering end face, is the collimation target value, and ΔA(a,b) is the collimation target value tolerance.

[0157] like Figure 5 As shown in FIG. 1 , the Bezier curve is optimized by using the simulated annealing algorithm. The optimization process includes: setting the initial annealing temperature to T initial , the termination temperature is T final , calculate the optimization parameters of the initial Bezier curve, and the evaluation function is D. The simulated annealing algorithm will iterate M times at each temperature to fully search the solution space. During the search process, if the current solution D m+1 The evaluation function of is less than the previous solution D m If the evaluation function is m+1 ; If the current solution is D m+1 The evaluation function of the solution D is greater than the previous solution D m When the evaluation function is used, a solution acceptance probability k related to temperature is generated. According to the preset probability function, it is determined whether to use the new solution as the solution of the free surface light collection system. As the temperature decreases, the probability of accepting a solution worse than the original one decreases, gradually changing from searching the breadth of the solution space to searching the depth of the solution space until the optimal solution is selected.

[0158] Step S4, compare the star point position cascade modulation device of the focusing system using a spherical surface, before optimization, and after optimization for simulation verification, by setting a receiving surface on the front end surface of the field mirror and the imaging LCOS surface to monitor the light propagation and irradiation, and calculate the correction accuracy of the simulated star point position based on the energy distribution principle.

[0159] Specifically, if Figure 6 As shown in the figure, the lightools software is used to simulate the star point position cascade modulation architecture using the spherical focusing system and the free-form surface focusing system before and after optimization. Among them, a receiving surface is set on the front face of the field mirror and the imaging LCOS surface to verify the correctness of the free-form surface focusing system optimization method and the star point position cascade modulation architecture establishment method.

[0160] Depend on Figure 6 From the enlarged schematic diagram in , we can see that after the incident light is emitted from the optimized free-form surface, as the aperture increases, the surface shape gradually shrinks, the contour line is relatively low at a small aperture angle, and the contour line is relatively high at a large aperture angle. This makes the emitted light with a smaller aperture angle projected on the dimming LCOS with a higher height value, and the emitted light with a larger aperture angle projected on the dimming LCOS with a lower height value, ensuring the uniformity and collimation of the irradiance distribution of the dimming LCOS.

[0161] Optical simulations were performed on the spherical focusing system and the free-form surface focusing system before and after optimization. The simulation results are shown in the figure. Figure 7 As shown in the figure, after using three focusing systems, the irradiation uniformity of the corresponding field lens light inlet is 62%, 71%, and 82%, respectively, and the collimation is 5.4°, 7.8°, and 4.6°, respectively. From the simulation results, it can be seen that compared with the spherical focusing system, the irradiation uniformity of the optimized free-form surface focusing system is improved by 32%, and the collimation is improved by 22%.

[0162] Based on the energy distribution principle, the correction accuracy of the simulated star point in the meridian and sagittal directions is expressed as follows:

[0163] Δx=x-x0

[0164] Δy=y-x0

[0165] Among them, Δx is the correction accuracy of the simulated star point in the meridian direction, that is, the deviation between the actual position of the simulated star point in the meridian direction and the theoretical position; Δy is the correction accuracy of the simulated star point in the sagittal direction, that is, the deviation between the actual position of the simulated star point in the sagittal direction and the theoretical position; x is the actual position coordinate of the simulated star point in the meridian direction, y is the actual position coordinate of the simulated star point in the sagittal direction, x0 is the theoretical position coordinate of the simulated star point in the meridian direction, and y0 is the theoretical position coordinate of the simulated star point in the sagittal direction.

[0166] Assume that the simulated star point is represented by 3×3 pixels. (x0, y0) is the position coordinate of the simulated star point after grayscale reconstruction. The position coordinate representation formula of the simulated star point after grayscale reconstruction is:

[0167]

[0168] Among them, F(x, y) is the gray value of a single pixel at the theoretical position (x, y) of the simulated star point, and m and n are summation variables used to traverse the 3×3 pixel area.

[0169] m ranges from 1 to 9, and n also ranges from 1 to 9. The position coordinates of the simulated star point after grayscale reconstruction are determined by summing up the grayscale values ​​of the pixels in the entire 3×3 pixel area.

[0170] Comparison of LCOS irradiance distribution in the star point position cascade modulation architecture after using three focusing systems Figure 8 As shown in the figure, the irradiation uniformity is 76%, 84% and 96% respectively. It can be found that after using the optimized free-form surface focusing system, the irradiation uniformity of the imaging LCOS surface is improved by 26.3%.

[0171] The central field of view, half field of view and full field of view of the imaging LCOS are sampled in a three-ring six-arm manner, and the correction accuracy of the simulated star point position is calculated using the correction accuracy expression formula and the position coordinate expression formula of the simulated star point after grayscale reconstruction. The results are as follows: Fig. 9 As shown. Fig. 9 It can be seen that after adopting the star point position cascade modulation architecture of three focusing systems, the simulated star point correction distances are 8.2μm, 5.2μm, and 3.4μm respectively, and the simulated star point correction accuracy is improved by 62%.

[0172] A second embodiment of the present invention provides a method for cascading star point position modulation of a weak starlight simulator, comprising: sequentially setting a free-form surface focusing system, an integrator, a relay system and a telecentric cascade system, wherein the free-form surface focusing system comprises a first lens and a second lens, one side of the first lens is a plane and the other side is a free-form surface, and both sides of the second lens are free-form surfaces; based on the scalar diffraction theory, a light intensity distribution function model of each sub-eye of the light integrator field lens and the projection lens is established, the main factors affecting the grayscale resolution of the dimming LCOS are analyzed, and the optimization design principle of the focusing system is established; the coordinates of discrete points are pre-processed by a linear thinning method, the discrete point intervals are divided based on the Bezier curve control point setting and parameter iteration rules, an irradiation evaluation model containing uniformity and collimation weights is constructed, and the Bezier curve of the free-form surface light collection system is optimized by using a simulated annealing algorithm; a star point position cascade modulation device using a spherical focusing system before and after optimization is compared for simulation verification, and the light propagation and irradiation are monitored by setting a receiving surface on the front face of the field lens and the imaging LCOS surface, and the correction accuracy of the simulated star point position is calculated based on the energy distribution principle. Based on the imaging principle of proportional mapping of a telecentric system, the present invention proportionally maps the image of a dimming LCOS to the surface of an imaging LCOS, realizes the superposition of two LCOS grayscales, and improves the correction accuracy of the simulated star point position; based on the scalar diffraction theory, a light intensity distribution function model of each sub-eye in an integrator field lens and a projection lens is established, the light intensity distribution law inside the optical system is deeply analyzed, and it is accurately determined that the uniformity and collimation of the focusing system and the mismatch of the integrator are the main factors affecting the grayscale resolution of the imaging LCOS; an evaluation model for the irradiation characteristics of the focusing system is established in a weighted matching manner, and combined with the simulated annealing method, a free-form surface optimization design of the focusing system is performed, and key performance indicators such as the irradiation uniformity and collimation of the focusing system are fully considered, thereby realizing the precise optimization of the focusing system.

[0173] Third embodiment:

[0174] A third embodiment of the present invention provides a network side server, such as Fig.10 As shown, it includes at least one processor 301; and a memory 302 that is communicatively connected to the at least one processor 301; wherein the memory 302 stores commands that can be executed by at least one processor 301, and the instructions are executed by at least one processor 301, so that at least one processor 301 can execute the above-mentioned data processing method.

[0175] The memory 302 and the processor 301 are connected in a bus manner, and the bus may include any number of interconnected buses and bridges, and the bus connects various circuits of one or more processors 301 and the memory 302 together. The bus can also connect various other circuits such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art and are therefore not further described herein. The bus interface provides an interface between the bus and the transceiver. The transceiver can be one element or multiple elements, such as multiple receivers and transmitters, providing a unit for communicating with various other devices on a transmission medium. The data processed by the processor 301 is transmitted on a wireless medium through an antenna, and further, the antenna also receives data and transmits the data to the processor 301.

[0176] The processor 301 is responsible for managing the bus and general processing, and can also provide various functions, including timing, peripheral interfaces, voltage regulation, power management and other control functions. The memory 302 can be used to store data used by the processor 301 when performing operations.

[0177] Fourth embodiment:

[0178] The fourth embodiment of the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the star point position cascade modulation method of the faint starlight simulator in the second embodiment.

[0179] That is, those skilled in the art can understand that all or part of the steps in the above-mentioned embodiment method can be completed by instructing the relevant hardware through a program, and the program is stored in a storage medium, including several instructions to enable a device (which can be a single-chip microcomputer, chip, etc.) or a processor to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0180] The above is only an embodiment of the present invention. The common sense such as the known specific structure and characteristics in the scheme is not described in detail here. The ordinary technicians in the relevant field know all the common technical knowledge in the technical field of the invention before the application date or priority date, can obtain all the existing technologies in the field, and have the ability to apply the conventional experimental means before that date. The ordinary technicians in the relevant field can improve and implement this scheme in combination with their own abilities under the enlightenment given by this application. Some typical known structures or known methods should not become obstacles for ordinary technicians in the relevant field to implement this application. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several deformations and improvements can be made, which should also be regarded as the protection scope of the present invention, which will not affect the effect of the implementation of the present invention and the practicality of the patent. The protection scope required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

[0181] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A cascade modulation device for star point position of a weak starlight simulator, characterized in that: include: A free-form surface focusing system, an integrator, a relay system and a telecentric cascade system; the free-form surface focusing system comprises a first lens and a second lens, wherein one side of the first lens is a plane and the other side is a free-form surface, and both sides of the second lens are free-form surfaces; The free-form surface focusing system is used to collect and preliminarily process the light emitted by the light source, so that the light converges to the light inlet of the integrator to form a small-angle and relatively uniform radiation distribution; The integrator is located after the free-form surface focusing system, and the integrator is used to homogenize the light; The relay system is located after the integrator, and is used to achieve stable transmission of light, ensuring that the light processed by the integrator can be accurately transmitted to the telecentric cascade system to maintain the transmission characteristics and energy distribution of the light; The telecentric cascade system is used to proportionally map the image of the dimming LCOS into the imaging LCOS.

2. The star point position cascade modulation device of the weak starlight simulator according to claim 1, characterized in that: The other side of the first lens is a free-form surface and the shapes of the two free-form surfaces of the second lens are based on the geometric relationship between the light source and the optical path. The relationship formula between the coordinates of each free-form surface of the lens and the divergence angle of the light emitted by the light source is derived and determined through iterative calculation.

3. A cascade modulation method for the star point position of a weak starlight simulator, characterized in that: Applied to the star point position cascade modulation device of the weak starlight simulator described in claim 1, the method comprises: S1, sequentially setting a free-form surface focusing system, an integrator, a relay system and a telecentric cascade system, wherein the free-form surface focusing system comprises a first lens and a second lens, one side of the first lens is a plane and the other side is a free-form surface, and both sides of the second lens are free-form surfaces; S2, based on scalar diffraction theory, establish the light intensity distribution function model of each sub-eye of the light integrator field lens and projection lens, analyze the main factors affecting the grayscale resolution of dimming LCOS and establish the optimization design principle of the focusing system; S3, the coordinates of discrete points are preprocessed by the straight line thinning method, the discrete point interval is divided based on the Bezier curve control point setting and parameter iteration rules, an irradiation evaluation model with uniformity and collimation weights is constructed, and the Bezier curve of the free-form surface light collection system is optimized using the simulated annealing algorithm; S4, a simulation verification is carried out by comparing the star point position cascade modulation device of the focusing system using a spherical surface, before and after optimization. The light propagation and irradiation conditions are monitored by setting receiving surfaces on the front end surface of the field mirror and the imaging LCOS surface, and the correction accuracy of the simulated star point position is calculated based on the energy distribution principle.

4. The method for cascading star point position modulation of a weak starlight simulator according to claim 3, characterized in that: In S2, the complex amplitude distribution of a monochromatic plane wave with an incident wavelength of λ is represented by U0(y), and the wavefront incident on the rear surface of the field mirror is represented by: Among them, U1(y1) is the wavefront incident on the rear surface of the field mirror, U0(y0) is the complex amplitude distribution of the monochromatic plane wave with incident wavelength, and t m1 is a quantity related to transmittance, y1 is the coordinate of the rear surface of the field lens, δ(y1-np) is a comb function used to indicate the array arrangement of sub-eye lenses, p is the spacing of sub-eye lenses, is a rectangular function, which means the aperture function of the sub-eye lens; is the phase function. k is the wave number ( λ is the wavelength of light), f is the focal length of the sub-eye lens, N is the number of sub-eye lenses, and n is the summation variable; According to the imaging principle, the interval between the field lens and the projection lens is d1 = f1, and the light field distribution incident on the projection lens is expressed as: Where f1 is the focal length of the lens, U 1-2 (y2) is the light field distribution incident on the projection mirror, d1 is the interval between the field mirror and the projection mirror, and d1=f1, y2 is the coordinate at the projection mirror, i is the imaginary unit, F{} is the Fourier transform, j is the imaginary part, z is the propagation distance of the wave, and k is the wave number.

5. The method for cascading star point position modulation of a weak starlight simulator according to claim 4, characterized in that: In S3, the use of a straight line sparse method to pre-process the coordinates of discrete points includes: setting points P1 and P i There are i-2 discrete points between them; use the point-to-line distance formula to determine the distance between i-2 discrete points and the line P1P i The distance d max If d max Less than the maximum allowable error ε, points P1 and P i There are i-2 discrete points between them, separated by the straight line P1P i Replacement, thereby completing the preprocessing of three sets of discrete point coordinates.

6. The method for cascading star point position modulation of a weak starlight simulator according to claim 1, characterized in that: In S3, the discrete point interval division based on Bezier curve includes: Step S31, select a Bezier curve with n+1 control points, set P n-1 , P n , P n+1 is the set of control points that make up the curve. Step S32, when line segment P n-1 P n and line segment P n P n+1 The angle β between the two should be smaller than the target value βtargate, and When P n+1 Belongs to the control point set. Step S33, after calculating each set of curve point sets, determine whether the number of points is less than the target control point number n+1. If the number is less than n+1, it is regarded as a regular line segment point set.

7. The method for cascading star point position modulation of a weak starlight simulator according to claim 3, characterized in that: In S3, the calculation formula of the irradiation evaluation model is: Where D is the evaluation function value of the irradiation evaluation model, y r is the uniformity weight, y d is the weight of the collimation, a and b are the longitude and latitude coordinates of the grid, m and n are the longitude and latitude boundaries of the grid, E(a, b) is the normalized irradiance, is the normalized irradiance target value, ΔE(a,b) is the normalized irradiance tolerance, A(a,b) is the absolute value of the maximum incident angle of the integrator light-entering end face, is the collimation target value, and ΔA(a,b) is the collimation target value tolerance.

8. The star point position cascade modulation device of the weak starlight simulator according to claim 7, characterized in that: In S3, the use of the simulated annealing algorithm to optimize the Bezier curve of the free-form surface light collection system includes: setting the initial annealing temperature to T initial , the termination temperature is T final , calculate the optimization parameters of the initial Bezier curve, the evaluation function is D; the simulated annealing algorithm will iterate M times at each temperature to fully search the solution space; during the search process, if the current solution D m+1 The evaluation function of is less than the previous solution D m If the evaluation function is m+1 ; If the current solution is D m+1 The evaluation function of the solution D is greater than the previous solution D m When the evaluation function is used, a probability k of accepting a solution related to temperature will be generated at this time; according to the preset probability function, it is determined whether the new solution is used as the solution of the free surface light collecting system; as the temperature decreases, the probability of accepting a solution worse than the original one continues to decrease, gradually changing from searching the breadth of the solution space to searching the depth of the solution space until the optimal solution is selected.

9. A network side server, characterized in that: include: at least one processor; as well as, a memory communicatively connected to the at least one processor; wherein, The memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the star point position cascade modulation method of a faint starlight simulator according to any one of claim 3.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the star point position cascade modulation method of a faint starlight simulator according to any one of claim 3 is implemented.

Images