A method and device for optimizing a free-form surface light collecting mirror assembly of a solar spectrum simulator

Abstract

The present invention provides a method and device for optimizing a free-form surface light collecting mirror group of a solar spectrum simulator. The method comprises: respectively calculating the discrete point coordinates of a first free-form surface, a second free-form surface and a third free-form surface of the free-form surface light collecting mirror group under the condition that the free-form surface light collecting mirror group only has a uniform light function and under the condition that the free-form surface light collecting mirror group only has a collimation function; obtaining a first Bezier curve, a second Bezier curve and a third Bezier curve based on Bezier function fitting; establishing a uniformity and collimation joint evaluation function in a weighted matching manner; optimizing the free-form surface light collecting mirror group by a simulated annealing method to obtain a free-form surface light collecting mirror group solution; modifying preset variables of the simulated annealing method, completing multiple optimizations of the free-form surface light collecting mirror group, and selecting the optimal solution structure based on the free-form surface light collecting mirror group solution after multiple optimizations. A joint evaluation model is constructed in a weighted matching manner, and the Bezier curve and the simulated annealing method are combined to realize the LCG feedback optimization of the free-form surface of the solar spectrum simulator, thereby improving the uniformity of the irradiation surface of the solar spectrum simulator.

Description

Technical Field

[0001] The present invention relates to the technical field of solar spectrum simulators, and in particular to a method and device for optimizing a free-form surface light collecting mirror group of a solar spectrum simulator. Background Art

[0002] The irradiation uniformity of the solar spectrum simulator is an important factor affecting the measurement of photovoltaic cell conversion efficiency, multi-cell splicing, and the accuracy of cell surface defect detection. However, due to the mismatch between the light collecting mirror group (LCG) and the beam smoothing system (BSS) in the solar spectrum simulator, the induced system sidelobe effect reduces the irradiation uniformity of the existing solar spectrum simulator, restricting the application of the solar spectrum simulator in photovoltaic cell feature detection experiments. To solve the above problems, methods such as changing the curvature of the ellipsoidal parabolic reflector in the light collecting mirror group and adding a Fresnel lens at the light outlet of the light collecting mirror group are often used to reduce the divergence angle of the light collecting mirror group to reduce the impact of the sidelobe effect on uniformity. However, in order to improve the accuracy of spectral simulation, integrating spheres with built-in multi-spectrum LEDs are often used as alternative light sources for traditional solar spectrum simulators. The volume of the integrating sphere not only restricts the application of the existing reflective light collecting mirror group, but also due to the accumulation of various errors such as the processing and manufacturing errors of the integrating sphere shell, the geometric position of the internal baffle, the actual thickness of the diffuse reflection coating, the geometric position of the internal light source, etc., it reduces the collimation and uniformity of the BSS light input position and aggravates the influence of the sidelobe effect on the irradiation uniformity of the solar spectrum simulator.

[0003] The above problems need to be solved urgently. Summary of the invention

[0004] The present invention aims to overcome at least one of the above-mentioned disadvantages of the prior art. On the one hand, a method for optimizing a free-form surface light-collecting mirror group of a solar spectrum simulator is provided, wherein the free-form surface light-collecting mirror group comprises two lenses, wherein the first lens comprises a first free-form surface, and the second lens comprises a second free-form surface and a third free-form surface. The method comprises: respectively calculating the coordinates of discrete points of the first free-form surface, the second free-form surface and the third free-form surface of the free-form surface light-collecting mirror group under the condition that only the uniform light function is provided; respectively calculating the coordinates of discrete points of the first free-form surface, the second free-form surface and the third free-form surface of the free-form surface light-collecting mirror group under the condition that only the collimation function is provided; and respectively calculating the coordinates of discrete points of the first free-form surface, the second free-form surface and the third free-form surface of the free-form surface light-collecting mirror group under the condition that only the collimation function is provided based on the Bessel function. The discrete point coordinates of the first free-form surface under the condition of uniform light function and only with the collimation function, the discrete point coordinates of the second free-form surface and the discrete point coordinates of the third free-form surface are fitted by generatrix to obtain the first Bezier curve, the second Bezier curve and the third Bezier curve respectively; a joint evaluation function of uniformity and collimation is established in a weighted ratio manner; the free-form surface light collecting mirror group is optimized by combining the first Bezier curve, the second Bezier curve, the third Bezier curve and the joint evaluation function using a simulated annealing method to obtain a solution of the free-form surface light collecting mirror group; the preset variables of the simulated annealing method are modified to complete multiple optimizations of the free-form surface light collecting mirror group; and the light collecting mirror group structure is selected based on the optimal solution.

[0005] Further, the discrete point coordinates of the first free-form surface, the second free-form surface and the third free-form surface of the free-form surface light collecting mirror group under the condition that only the light homogenization function is provided are calculated respectively, including: using the light flux model of the point light source and the light flux model within the target surface ring to calculate the light flux formula; combining the light flux formula with the principle of vector light propagation to calculate the discrete point coordinates of the first free-form surface, the second free-form surface and the third free-form surface of the free-form surface light collecting mirror group under the condition that only the light homogenization function is provided;

[0006] Among them, the point light source luminous flux model is:

[0007]

[0008] Where I(θ) is the luminous intensity at each angle at the outlet of the integrating sphere, θ is the effective luminous angle of the integrating sphere, Ω is the solid angle, and θ max and θ min The upper and lower limits of the effective luminous angle of the integrating sphere;

[0009] Assume that the light distribution curve of the integrating sphere outlet meets the Lambert distribution condition, integrate formula (1) and calculate each sub-interval Δθ=θ i+1 -θ i The luminous flux inside,

[0010]

[0011] The luminous flux in each sub-interval Δθ is mapped to the target surface through the free surface (R i ,R i+1 ) on the ring, the luminous flux E in the ring on the target surface i It is expressed as:

[0012]

[0013] In the formula, e 0 is the ideal illumination on the preset wooden surface, r i and r i+1 is the target surface (R i ,R i+1 ) the ordinate on the ring;

[0014] Let formula (2) and (3) be equal to obtain the luminous flux formula:

[0015]

[0016] In the formula, i represents dividing the irradiated surface into m parts, and i is the i-th part.

[0017] Further, the discrete point coordinates of the first free-curved surface, the second free-curved surface and the third free-curved surface of the free-curved surface light collecting lens group under the condition of only having the collimation function are calculated respectively, including: calculating the coordinate x of the first free-curved surface 1 Angle θ with light source in The first free-form surface shape is obtained based on the first expression; the second free-form surface coordinate x is calculated 2 Angle θ with light source in The second free-form surface shape is obtained based on the second expression; the third free-form surface coordinate x is calculated 3 Angle θ with light source in A third expression of the invention; based on the third expression, a third free-form surface shape is obtained; based on the first free-form surface shape, the second free-form surface shape and the third free-form surface shape, the discrete point coordinates of the first free-form surface, the second free-form surface and the third free-form surface of the free-form surface collecting lens group under the condition of only having the collimation function are obtained.

[0018] Furthermore, the first expression is:

[0019]

[0020] In the formula, the initial condition is θ in =0,x 1 =d 0 +d 1 , d 0 represents the air interval, d 1 represents the thickness of the first lens, θin represents the divergence angle of the light emitted by the integrating sphere, b 1 represents the angle between the outgoing light of the first free-form surface and the optical axis, n 1 represents the refractive index of the first lens;

[0021] The first free-form surface shape is obtained by iterating formula (9);

[0022] The second expression is:

[0023]

[0024] In the formula, the initial condition is θ in =0,x 1 =d 0 +d 1 +d 2 , d 2 represents the air gap, b 2 represents the angle between the outgoing light of the second free-form surface and the optical axis, n 2 represents the refractive index of the second lens;

[0025] The second free-form surface shape is obtained by iterating formula (10);

[0026] The third expression is:

[0027]

[0028] In the formula, the initial condition is θ in =0,x 1 =d 0 +d 1 +d 2 +d 3 , d 3 represents the thickness of the second lens, d 3 represents the angle between the outgoing light of the third free-form surface and the optical axis, n 2 represents the refractive index of the second lens;

[0029] The third free-form surface shape is obtained by iterating formula (11);

[0030] Solving formulas (9) to (11) we can obtain the coordinates of the discrete points on the three free-form surfaces under the collimation condition.

[0031] Further, the generatrix discrete point model of the first free-form surface with only the homogenization function and the generatrix discrete point model of the second free-form surface and the generatrix discrete point model of the third free-form surface are respectively fitted based on the Bessel function to obtain the first Bessel curve, the second Bessel curve and the third Bessel curve respectively, including: pre-processing the three groups of discrete point coordinates respectively by using the straight line sparse method, wherein the first group of discrete point coordinates includes the discrete point coordinates of the first free-form surface with only the homogenization function and the discrete point coordinates of the first free-form surface with only the collimation function. point coordinates, the second group of discrete point coordinates includes the discrete point coordinates of the second free-form surface under the condition of only having the even light function and the discrete point coordinates of the second free-form surface under the condition of only having the collimation function, the third group of discrete point coordinates includes the discrete point coordinates of the third free-form surface under the condition of only having the even light function and the discrete point coordinates of the third free-form surface under the condition of only having the collimation function; based on the Bessel function, the three groups of preprocessed discrete point coordinates are respectively fitted to obtain the first Bessel curve, the second Bessel curve and the third Bessel curve; the discrete point interval is divided to increase the influence proportion of the control points in the Bessel curve.

[0032] Furthermore, the use of the straight line sparse method to pre-process the three sets of discrete point coordinates includes: setting point P 1 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 P 1 P i The distance d max If d max Less than the maximum allowable error ε, point P 1 and P i The i-2 discrete points between them are separated by the straight line P 1 P i Replacement, thereby completing the preprocessing of the three sets of discrete point coordinates; the fitting of the three sets of discrete point coordinates after preprocessing based on the Bessel function to obtain the first Bessel curve, the second Bessel curve and the third Bessel curve includes: the n-order Bessel function controlled by n+1 points is expressed as:

[0033]

[0034] Where t∈(0,1), P i is the control point of the Bezier curve, B i,n (t) is the n-order Bernstein polynomial; let point P on the Bezier curve point set i The corresponding parameter t value is t i , then the curve point set matrix P is expressed as:

[0035]

[0036] In the formula, matrix b is the control point coordinate matrix, and curve parameter t is i It is obtained by iterating the following formula:

[0037]

[0038] The dividing of discrete point intervals to increase the influence ratio of the control points in the Bezier curve includes:

[0039] The Bezier curve has n+1 control points, let P n-1 , P n , P n+1 is the set of control points that make up the curve;

[0040] 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 β targate ,and When P n+1 Belongs to the control point set;

[0041] After calculating each set of curve points, 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.

[0042] Furthermore, the establishment of a uniformity and collimation joint evaluation function in a weighted ratio manner includes:

[0043] Meshing the target surface of the free-form surface light collecting lens group;

[0044] The linear weighted method based on the evaluation function combines uniformity and collimation in a weighted ratio to obtain a joint evaluation function:

[0045]

[0046] In the formula, y r and d represents the weight of uniformity and collimation, a and b represent the longitude and latitude coordinates of the grid, e and f represent the longitude and latitude boundaries of the grid, and E(a, b) represents the normalized irradiance. represents the normalized irradiance target value, ΔE(a,b) represents the normalized irradiance tolerance, A(a,b) represents the absolute value of the maximum incident angle of the light-entering end face of the beam smoothing system, represents the collimation target value, and ΔA(a,b) represents the collimation target value tolerance.

[0047] Furthermore, the method of optimizing the free-form surface light collecting mirror group by using a simulated annealing method in combination with the first Bezier curve, the second Bezier curve, the third Bezier curve and the joint evaluation function to obtain a solution of the free-form surface light collecting mirror group includes:

[0048] S510: taking the first Bezier curve, the second Bezier curve and the third Bezier curve as an initial structure;

[0049] S520: Optimizing the free-form surface light collecting mirror group by combining the joint evaluation function to obtain the solution of the free-form surface light collecting mirror includes:

[0050] S5201: applying random perturbations to the initial structure so that the joint evaluation function generates a new solution;

[0051] S5202: Determine whether the new solution generated by the joint evaluation function is smaller than the solution before random perturbation is applied to the initial structure;

[0052] S5203: In response to the new solution generated by the joint evaluation function being smaller than the solution before random perturbation is applied to the initial structure, using the new solution generated by the joint evaluation function as the solution of the free-form surface light collecting mirror;

[0053] S5204: In response to the new solution generated by the joint evaluation function being greater than the solution before random perturbation is applied to the initial structure, determining whether to use the new solution as the solution of the free-form surface light collecting mirror according to a preset probability function;

[0054] Among them, the probability function is:

[0055]

[0056] Where, T c Indicates the current temperature, D V+1 Indicates A V+1 The corresponding evaluation function, k is the number of evaluations, when t = t V When the vth optimization is performed, the matrix A of the angles between the tangent lines of the control points of the three Bezier curves and the optical axis is V It is expressed as:

[0057]

[0058] In the formula, each row represents the angles between the tangents of all control points corresponding to the three free-form surfaces and the optical axis, and each column represents the angles between the tangents of n control points corresponding to the same free-form surface and the optical axis. During the optimization process, the relationship between the v+1th variable value and the vth variable value is expressed as:

[0059] A v+1 =A v +QU; (18)

[0060] In the formula, each parameter of the matrix U is expressed as a random variable matrix that obeys the [-1,1] distribution, and Q is a diagonal matrix, which represents the threshold value satisfied by the angle between the tangent line of the control point and the optical axis.

[0061] Furthermore, after the steps S5203 and S5204, the following steps are further included:

[0062] S5205: Determine whether the number of iterations has been reached;

[0063] S5206: In response to reaching the number of iterations, using simulation software to calculate whether the uniformity of the irradiation surface of the solar spectrum simulator reaches a target condition;

[0064] S5207: In response to the solar spectrum simulator irradiation surface uniformity reaching the target condition, output the solution of the free-form surface light collecting mirror group currently calculated as a condition for subsequent selection of the light collecting mirror group structure;

[0065] S5208: In response to the uniformity of the irradiation surface of the solar spectrum simulator not reaching the target condition, go to step S6 and reset the preset variables of the simulated annealing method.

[0066] In a second aspect, the present invention provides a free-form surface light collecting mirror group optimization device for a solar spectrum simulator, wherein the free-form surface light collecting mirror group includes two lenses, wherein the first lens includes a first free-form surface, and the second lens includes a second free-form surface and a third free-form surface, and the device includes: a first calculation unit, adapted to respectively calculate the discrete point coordinates of the first free-form surface, the second free-form surface and the third free-form surface of the free-form surface light collecting mirror group under the condition that only the uniform light function is provided; a second calculation unit, adapted to respectively calculate the discrete point coordinates of the first free-form surface, the second free-form surface and the third free-form surface of the free-form surface light collecting mirror group under the condition that only the collimation function is provided; a fitting unit, adapted to respectively calculate the discrete point coordinates of the first free-form surface, the second free-form surface and the third free-form surface of the free-form surface light collecting mirror group under the condition that only the collimation function is provided; and a fitting unit, adapted to respectively calculate the discrete point coordinates of the first free-form surface, the second free-form surface and the third free-form surface of the free-form surface light collecting mirror group based on the uniform light function. The Bessel function is used to fit the discrete point coordinates of the first free-form surface, the discrete point coordinates of the second free-form surface and the discrete point coordinates of the third free-form surface under the condition of only having the uniform light function and only having the collimation function, respectively, to obtain the first Bessel curve, the second Bessel curve and the third Bessel curve; a uniformity and collimation joint evaluation function unit is established, which is suitable for establishing the uniformity and collimation joint evaluation function in a weighted ratio manner; a first optimization unit is suitable for optimizing the free-form surface light collecting mirror group by combining the first Bessel curve, the second Bessel curve, the third Bessel curve and the joint evaluation function with the simulated annealing method to obtain the solution of the free-form surface light collecting mirror group;

[0067] The second optimization unit is suitable for modifying the preset variables of the simulated annealing method and completing multiple optimizations of the free-form surface light collecting mirror group;

[0068] The selection unit is suitable for selecting the optimal solution structure based on the free-form surface light collecting mirror group solution after multiple optimizations.

[0069] On the other hand, the present invention also provides a computer-readable storage medium, wherein one or more instructions are stored in the computer-readable storage medium, and the computer instructions are used to enable the computer to execute the above-mentioned free-form surface light collecting mirror group optimization method of the solar spectrum simulator.

[0070] On the other hand, the present invention provides an electronic device, comprising: a memory and a processor; the memory stores at least one program instruction; the processor implements the above-mentioned free-form surface light collecting mirror group optimization method of the solar spectrum simulator by loading and executing the at least one program instruction.

[0071] The beneficial effects of the present invention are as follows: the present invention provides a method for optimizing a free-form surface light-collecting mirror group of a solar spectrum simulator, wherein the free-form surface light-collecting mirror group comprises two lenses, wherein the first lens comprises a first free-form surface, and the second lens comprises a second free-form surface and a third free-form surface, and the method comprises: respectively calculating the discrete point coordinates of the first free-form surface, the second free-form surface and the third free-form surface of the free-form surface light-collecting mirror group under the condition that only the light-homogenizing function is provided; respectively calculating the discrete point coordinates of the first free-form surface, the second free-form surface and the third free-form surface of the free-form surface light-collecting mirror group under the condition that only the collimating function is provided; and respectively calculating the discrete point coordinates of the first free-form surface, the second free-form surface and the third free-form surface of the free-form surface light-collecting mirror group under the condition that only the light-homogenizing function is provided based on the Bessel function. The discrete point coordinates of the first free-form surface, the discrete point coordinates of the second free-form surface and the discrete point coordinates of the third free-form surface under the collimation function condition are fitted by the generatrix to obtain the first Bezier curve, the second Bezier curve and the third Bezier curve respectively; a joint evaluation function of uniformity and collimation is established in a weighted ratio manner; the free-form surface light collecting mirror group is optimized and calculated by combining the first Bezier curve, the second Bezier curve, the third Bezier curve and the joint evaluation function using the simulated annealing method to obtain the solution of the free-form surface light collecting mirror group; the preset variables of the simulated annealing method are modified to complete multiple optimizations of the free-form surface light collecting mirror group; based on the free-form surface light collecting mirror group solution after multiple optimizations, the optimal solution structure is selected. A joint evaluation model of LCG uniformity and collimation is constructed in a weighted ratio manner, and the feedback optimization of the transmission free-form surface LCG of the solar spectrum simulator is realized by combining the Bezier curve and the simulated annealing method, thereby improving the uniformity of the irradiation surface of the solar spectrum simulator. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0073] Figure 1 It is a flow chart of a method for optimizing a free-form surface light collecting mirror assembly of a solar spectrum simulator provided by an embodiment of the present invention.

[0074] Figure 2It is a schematic diagram of energy mapping between the light outlet of an integrating sphere and the target surface provided in an embodiment of the present invention.

[0075] Figure 3 It is a schematic diagram of the light path when the free-form surface light collecting mirror provided by an embodiment of the present invention has only a collimating function.

[0076] Figure 4 It is a method flow chart corresponding to step S5 provided in an embodiment of the present invention.

[0077] Figure 5a It is a schematic diagram comparing the contours of the free-form surface light collecting mirror before and after optimization provided by an embodiment of the present invention.

[0078] Figure 5b This is a schematic diagram of the radiation distribution of the free-form surface before optimization provided by an embodiment of the present invention.

[0079] Figure 5c It is a schematic diagram of the radiation distribution of the free-form surface after optimization provided by an embodiment of the present invention.

[0080] Figure 6a It is a schematic diagram of the divergence angle of the free-form surface light collecting mirror before optimization provided in an embodiment of the present invention.

[0081] Figure 6b It is a schematic diagram of the divergence angle of the optimized free-form surface light collecting mirror provided in an embodiment of the present invention.

[0082] Figure 7a This is a ray tracing diagram of the optimized solar spectrum simulator provided in an embodiment of the present invention.

[0083] Figure 7b It is a schematic diagram of the irradiance distribution of the solar spectrum simulator before optimization provided in an embodiment of the present invention.

[0084] Figure 7c It is a schematic diagram of the irradiance distribution of the optimized solar spectrum simulator provided in an embodiment of the present invention.

[0085] Figure 8 It is a schematic structural diagram of a free-form surface light collecting mirror group optimization device of a solar spectrum simulator provided by an embodiment of the present invention.

[0086] Fig. 9 It is a partial block diagram of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0087] 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.

[0088] 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.

[0089] 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.

[0090] Example 1

[0091] See also Figure 1 , a flow chart of a method for optimizing a free-form surface light collecting mirror group of a solar spectrum simulator provided in an embodiment of the present invention.

[0092] In order to facilitate subsequent understanding, the overall inventive concept of the present invention is described here:

[0093] The present invention proposes a method for optimizing the free-form surface light collecting mirror group of a solar spectrum simulator. First, a discrete point model of the free-form surface light collecting mirror busbar is constructed with uniformity and collimation as the goals respectively. Then, the calculation results are fitted into Bezier curves and a joint evaluation function of uniformity and collimation is established. Finally, a multi-parameter synchronous optimization process is constructed in combination with the simulated annealing method to achieve synchronous iterative optimization of each optical surface of the free-form surface light collecting mirror group. The present invention is suitable for the optimization of the light collecting mirror group of a solar spectrum simulator with any index. Since the standard photovoltaic cell size is 20mm×20mm, the present invention uses a solar spectrum simulator with an irradiation surface size better than Taking the irradiation uniformity better than 98% and the integrating sphere outlet diameter of 6 mm as an example, the specific implementation process of the optimization of the transmission-type free-form surface light collecting lens group is explained.

[0094] The specific embodiments are as follows:

[0095] As an example, the method includes:

[0096] S1: respectively calculating the coordinates of discrete points of the first free-curved surface, the second free-curved surface and the third free-curved surface of the free-curved surface light collecting lens group under the condition that only the light homogenization function is provided.

[0097] S2: respectively calculating the coordinates of discrete points of the first free-curved surface, the second free-curved surface and the third free-curved surface of the free-curved surface light collecting lens assembly under the condition that it only has the collimation function.

[0098] S3: Based on the Bessel function, the discrete point coordinates of the first free-form surface under the condition of only having the uniform light function and the discrete point coordinates of the second free-form surface and the discrete point coordinates of the third free-form surface are respectively fitted with the mother line to obtain the first Bessel curve, the second Bessel curve and the third Bessel curve.

[0099] S4: Establish a joint evaluation function of uniformity and collimation in a weighted manner.

[0100] S5: Optimizing the free-form surface light collecting mirror group by combining the first Bezier curve, the second Bezier curve, the third Bezier curve and the joint evaluation function using a simulated annealing method to obtain a solution for the free-form surface light collecting mirror group.

[0101] S6: Modify the preset variables of the simulated annealing method and complete multiple optimizations of the free-form surface light collecting mirror group;

[0102] S7: Based on the free-form surface light collecting mirror group solution after multiple optimizations, select the optimal solution structure.

[0103] Preferably, combined Figure 2 As shown, the step S1 includes:

[0104] The luminous flux formula is calculated using the point light source luminous flux model and the luminous flux model within the target surface ring;

[0105] The luminous flux formula is combined with the principle of vector light propagation to calculate the coordinates of discrete points on the first free-form surface, the second free-form surface and the third free-form surface of the free-form surface light collecting lens group under the condition of only having the light homogenization function;

[0106] Among them, the point light source luminous flux model is:

[0107]

[0108] Where I(θ) is the luminous intensity at each angle at the outlet of the integrating sphere, θ is the effective luminous angle of the integrating sphere, Ω is the solid angle, and θ max and θ min The upper and lower limits of the effective luminous angle of the integrating sphere;

[0109] Assume that the light distribution curve of the integrating sphere outlet meets the Lambert distribution condition, integrate formula (1) and calculate each sub-interval Δθ=θ i+1 -θ i The luminous flux inside,

[0110]

[0111] The luminous flux in each sub-interval Δθ is mapped to the target surface through the free surface (R i ,R i+1 ) on the ring, the luminous flux E in the ring on the target surface i It is expressed as:

[0112]

[0113] In the formula, e 0 is the ideal illumination on the preset wooden surface, r i and r i+1 is the target surface (R i ,R i+1 ) the ordinate on the ring;

[0114] Let formula (2) and (3) be equal to obtain the luminous flux formula:

[0115]

[0116] In the formula, i represents dividing the irradiated surface into m parts, and i is the i-th part.

[0117] Preferably, step S2 includes: calculating the first free-form surface coordinate x 1 Angle θ with light source in The first free-form surface shape is obtained based on the first expression; the second free-form surface coordinate x is calculated 2 Angle θ with light source in The second free-form surface shape is obtained based on the second expression; the third free-form surface coordinate x is calculated 3 Angle θ with light source in A third expression of the invention; based on the third expression, a third free-form surface shape is obtained; based on the first free-form surface shape, the second free-form surface shape and the third free-form surface shape, the discrete point coordinates of the first free-form surface, the second free-form surface and the third free-form surface of the free-form surface collecting lens group under the condition of only having the collimation function are obtained.

[0118] Wherein, the first expression is:

[0119]

[0120] In the formula, the initial condition is θ in =0,x1 =d 0 +d 1 , d 0 represents the air interval, d 1 represents the thickness of the first lens, θ in represents the divergence angle of the light emitted by the integrating sphere, b 1 represents the angle between the outgoing light of the first free-form surface and the optical axis, n 1 represents the refractive index of the first lens;

[0121] The first free-form surface shape is obtained by iterating formula (9);

[0122] The second expression is:

[0123]

[0124] In the formula, the initial condition is θ in =0,x 1 =d 0 +d 1 +d 2 , d 2 represents the air gap, b 2 represents the angle between the outgoing light of the second free-form surface and the optical axis, n 2 represents the refractive index of the second lens;

[0125] The second free-form surface shape is obtained by iterating formula (10);

[0126] The third expression is:

[0127]

[0128] In the formula, the initial condition is θ in =0,x 1 =d 0 +d 1 +d 2 +d 3 , d 3 represents the thickness of the second lens, b 3 represents the angle between the outgoing light of the third free-form surface and the optical axis, n 2 represents the refractive index of the second lens;

[0129] The third free-form surface shape is obtained by iterating formula (11);

[0130] Solving formulas (9) to (11) we can obtain the coordinates of the discrete points on the three free-form surfaces under the collimation condition.

[0131] Specifically, when the free-form surface light collecting lens group (hereinafter referred to as LCG) has only the collimation function, its optical path diagram is as follows: Figure 3As shown, let the center of the light outlet of the integrating sphere be located at the origin of the coordinate system, and the light incident on the target surface through the LCG is a circle with a radius of r. Figure 2 As can be seen from the figure, the light emitted from the integrating sphere is refracted by the two lenses of the LCG in sequence and then incident on a circle with a radius of r on the target surface. 0 ,d 2 ,d 4 represents the air interval, d 1 ,d 3 Respectively represent the thickness of the two LCG lenses. in represents the divergence angle of the light emitted by the integrating sphere, a 0 is the incident angle of the first surface, a 1 、a 2 、a 3 They represent the angle between the optical axis and the tangent line of the sampling point, a 4 represents the angle between the incident light and the target surface, b 0 、b 1 、b 2 、b 3 Respectively represent the angle between the emitted light of each surface and the optical axis. The radius of the target surface r should satisfy the following relationship:

[0132] r=d 0 tanθ in +(x 1 -d 0 )tanb 0 +(x 2 -x 1 )tanb 1 +(x 3 -x 2 )tanb 2 +

[0133] (d 0 +d 1 +d 2 +d 3 +d 4 -x 3 )tanb 3 ; (5)

[0134] For any sampling point P on the first free-form surface of the first lens 1 (x 1 ,y 1 ), the relationship between its coordinates and the divergence angle of the light emitted by the integrating sphere can be expressed as

[0135] y 1 =d 0 tanθ in +(x 1 -d 0 )tanb 0; (6)

[0136] Where b 0 Satisfies Snell's law, sina 0 =nsinb 0 , where θ in =a 0 .

[0137] From Snell's law we can get:

[0138]

[0139] According to the definition of slope, the sampling point P 1 The slope of can be expressed as:

[0140]

[0141] Combining equations (5) to (8), the first free-form surface coordinate x of the first lens is 1 Angle θ with light source in It can be expressed as the above formula (9), and the above formulas (10) and (11) can be obtained similarly.

[0142] In the above embodiment, it is considered that the free-form surface light collecting mirror group ensures collimation and uniformity while having certain light collecting characteristics. Using only a single lens may make the surface shape, aperture, thickness and shape of the lens difficult to control during calculation. Therefore, two lenses are used to ensure uniform light and collimation while collecting light. In order to simplify the design and facilitate lens adjustment, the first surface of the light collecting mirror group is set to a plane, and the rest are free-form surfaces. According to formula (5), the law of geometric optics propagation and the optimization target of the irradiation surface of the solar spectrum simulator, the minimum semi-aperture D of the transmission free-form surface light collecting mirror group is 1 <13mm, divergence angle better than 5°, uniformity better than 80%. Combining formulas (4)(9)(10)(11), the Runge-Kutta method can be used to obtain two initial structures of the free-form surface light collecting mirror group under the conditions of uniformity and collimation.

[0143] Preferably, step S3 includes: preprocessing three groups of discrete point coordinates respectively using a straight line thinning method, wherein the first group of discrete point coordinates includes the discrete point coordinates of the first free-form surface with only the even light function and the discrete point coordinates of the first free-form surface with only the collimation function, the second group of discrete point coordinates includes the discrete point coordinates of the second free-form surface with only the even light function and the discrete point coordinates of the second free-form surface with only the collimation function, and the third group of discrete point coordinates includes the discrete point coordinates of the third free-form surface with only the even light function and the discrete point coordinates of the third free-form surface with only the collimation function; fitting the three groups of preprocessed discrete point coordinates based on the Bessel function to obtain the first Bessel curve, the second Bessel curve and the third Bessel curve; dividing the discrete point interval to increase the influence proportion of the control points in the Bessel curve.

[0144] The method of preprocessing the three groups of discrete point coordinates by using the straight line thinning method comprises:

[0145] Set point P 1 and P i There are i-2 discrete points between them;

[0146] Use the point-to-line distance formula to determine the distance from i-2 discrete points to the line P 1 P i The distance d max ;

[0147] If d max Less than the maximum allowable error ε, point P 1 and P i The i-2 discrete points between them are separated by the straight line P 1 P i Substitution, thereby completing the preprocessing of three sets of discrete point coordinates;

[0148] The method of fitting the three groups of preprocessed discrete point coordinates based on the Bezier function to obtain the first Bezier curve, the second Bezier curve and the third Bezier curve comprises:

[0149] The n-order Bessel function controlled by n+1 points is expressed as:

[0150]

[0151] Where t∈(0,1), P i is the control point of the Bezier curve, B i,n (t) is the nth-order Bernstein polynomial;

[0152] 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:

[0153]

[0154] In the formula, matrix b is the control point coordinate matrix, and curve parameter t is i It is obtained by iterating the following formula:

[0155]

[0156] The dividing of discrete point intervals to increase the influence ratio of the control points in the Bezier curve includes:

[0157] The Bezier curve has n+1 control points, let P n-1 , P n , P n+1 is the set of control points that make up the curve;

[0158] When line segment P n-1 P m and line segment P n P n+1 The angle β between the two should be smaller than the target value β targate ,and When P n+1 Belongs to the control point set;

[0159] After calculating each set of curve points, 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.

[0160] In the above embodiment, the highest order of the Bezier curve is set to 3rd order, and the maximum allowable error of sparseness ε is 0.1 mm. Suppose the maximum value of the change in the tangent direction of any two control points β targate =20° and The control points that meet the requirements are divided into the same point set. At the same time, in order to reduce the difficulty of fitting and fit the third-order Bezier curve, it is stipulated that the tangent direction change angle of each group of curve points is not greater than 90°. Finally, the four control point coordinate matrices [b 0 b 1 b 2 b 3 ] T Calculation.

[0161] Preferably, the step S4 comprises: meshing the target surface of the free-form surface light collecting lens group;

[0162] The linear weighted method based on the evaluation function combines uniformity and collimation in a weighted ratio to obtain a joint evaluation function:

[0163]

[0164] In the formula, y r and d represents the weight of uniformity and collimation, a and b represent the longitude and latitude coordinates of the grid, e and f represent the longitude and latitude boundaries of the grid, E(a,b) represents the normalized irradiance (independent variable), represents the normalized irradiance target value, ΔE(a,b) represents the normalized irradiance tolerance, A(a,b) represents the absolute value of the maximum incident angle of the light-entering end face of the beam smoothing system (independent variable), represents the collimation target value, and ΔA(a,b) represents the collimation target value tolerance.

[0165] Specifically, since the transmission free-form surface light collector not only has the function of light homogenization, but also its outgoing light divergence angle should be consistent with the theoretical value θ designed by the BSS system. t Therefore, the LCG target surface is meshed, and the uniformity and collimation are combined in a weighted ratio based on the linear weighted method of the evaluation function.

[0166] Preferably, Figure 4 As shown, the step S5 includes: S510: taking the first Bezier curve, the second Bezier curve and the third Bezier curve as the initial structure; S520: optimizing the free-form surface light collecting mirror group in combination with the joint evaluation function to obtain the solution of the free-form surface light collecting mirror group, including: S5201: applying random perturbation to the initial structure so that the joint evaluation function generates a new solution; S5202: judging whether the new solution generated by the joint evaluation function is smaller than the solution before the random perturbation is applied to the initial structure; S5203: in response to the new solution generated by the joint evaluation function being smaller than the solution before the random perturbation is applied to the initial structure, taking the new solution generated by the joint evaluation function as the solution of the free-form surface light collecting mirror group; S5204: in response to the new solution generated by the joint evaluation function being larger than the solution before the random perturbation is applied to the initial structure, judging whether to take the new solution as the solution of the free-form surface light collecting mirror group according to a preset probability function;

[0167] Among them, the probability function is:

[0168]

[0169] Where, T c Indicates the current temperature, D V+1 Indicates A V+1 The corresponding evaluation function, k is the number of evaluations, when t = t V When the vth optimization is performed, the matrix A of the angles between the tangent lines of the control points of the three Bezier curves and the optical axis is V It is expressed as:

[0170]

[0171] In the formula, each row represents the angles between the tangents of all control points corresponding to the three free-form surfaces and the optical axis, and each column represents the angles between the tangents of n control points corresponding to the same free-form surface and the optical axis. During the optimization process, the relationship between the v+1th variable value and the vth variable value is expressed as:

[0172] A v+1 =A v +QU; (18)

[0173] In the formula, each parameter of the matrix U is expressed as a random variable matrix that obeys the [-1,1] distribution, and Q is a diagonal matrix, which represents the threshold value satisfied by the angle between the tangent line of the control point and the optical axis.

[0174] After the steps S5203 and S5204, the method further includes: S5205: determining whether the number of iterations has been reached; S5206: in response to the number of iterations being reached, using simulation software to calculate whether the uniformity of the irradiated surface of the solar spectrum simulator has reached the target condition; S5207: in response to the uniformity of the irradiated surface of the solar spectrum simulator reaching the target condition, outputting the solution of the free-form surface light collecting mirror group obtained by the current calculation as a condition for the subsequent selection of the light collecting mirror group structure;

[0175] S5208: In response to the uniformity of the irradiation surface of the solar spectrum simulator not reaching the target condition, go to step S6 and initialize the number of iterations.

[0176] Step S6 includes modifying the preset variables of the simulated annealing method, and completing multiple optimizations of the free-form surface light-collecting mirror group. Specifically, the annealing temperature is adjusted, the LCG evaluation function under different annealing temperature conditions is calculated, the individuals are sorted according to the size of the evaluation function value, and the individual with the smallest evaluation function value is recorded. The simulation software is used to calculate whether the uniformity of the irradiation surface of the solar spectrum simulator reaches the target. If the condition is not met, the annealing temperature is adjusted and re-optimized; if the target condition has been reached, the light-collecting mirror group with the smallest evaluation function value during the optimization process is selected, and the simulation software is used to calculate the uniformity of the irradiation surface of the solar spectrum simulator. That is, the evaluation function result obtained by the optimization calculation in step S5 is further optimized through step S6.

[0177] Specifically, in combination with steps S5 and S6, the annealing temperature is set to T in , the termination temperature is T fIn , the angle a between the tangent line corresponding to the control point and the optical axis in the initial three Bezier curves I The matrix A V , the evaluation function corresponding to the vth optimization is D V, the number of evaluations is k. During the optimization process, if the evaluation function of the current solution is greater than the evaluation function of the previous solution, the new solution is accepted. Otherwise, a probability function P related to temperature is generated, and the current result is judged based on the probability result to determine whether it is acceptable. Set the initial temperature T in = 2000K, the preset value of the number of iterations k = 200, the estimated probability P = 0.5, random perturbations are applied to the initial structure to generate new solutions, and the changes in the evaluation function value D are calculated. According to formula (16), it is decided whether the solution is accepted according to probability. When the preset value of the number of iterations k is reached but the output condition is not met, T in Each time, the optimization is performed by reducing 20K and resetting the number of iterations k. The optimization is then performed again. The contour and irradiation distribution of the transmission free-form surface light collector before and after optimization are compared in Figure 5. As shown in Figure 5(a), after the initial structure is optimized, the overall contour is easy to process, and the distance between the two lenses is moderate, which is convenient for subsequent adjustment. The transmission free-form surface light collector before and after optimization is modeled using Lightools software, and 2 million light rays are traced using the Monte Carlo method. The irradiation distribution results are shown in Figure 5(b)(c). As can be seen from the figure, compared with before optimization, the illumination distribution of the meridian and sagittal slices of the receiving surface of the transmission free-form surface light collector after optimization is consistent. This phenomenon indicates that the rotational symmetry of the irradiation distribution of the transmission free-form surface light collector has not been changed before and after optimization. The simulation results show that after optimization, the irradiation non-uniformity of the receiving surface is reduced from 4.6% to 3.1%. Nine sampling points were selected in the irradiation surface of the LCG before and after optimization in a three-ring six-arm manner, and the irradiation uniformity and collimation were measured respectively. The sampling results are shown in Figure 6. The horizontal axis is the sampling point number, and the vertical axis is the divergence angle. It can be seen from the figure that after the optimization of the transmission free-form surface light collector, the maximum divergence angle is reduced from 7.2° to 4.8°, and the collimation is increased by 1.5 times, which meets the BSS requirement that the incident light aperture angle is better than 5°.

[0178] Since the profile features of LCG are similar before and after optimization, only the ray tracing results of the solar spectrum simulator using the optimized LCG are shown in this paper, as shown in Figure 7(a). As shown in Figure 7(b)(c), the irradiation distribution of the solar spectrum simulator before and after optimization is compared. It can be seen from Figure 7(b)(c) that the solar spectrum simulator before optimization produces irradiation separation and unevenness in the meridian and sagittal directions. This is because the optical extension tolerance of the LCG before optimization is low, resulting in asymmetric intersections between the beams in the meridian and sagittal directions and the target surface, leading to irradiation separation. At the same time, the divergence angle of the LCG before optimization is too large, resulting in the edge image height in the BSS sub-eye exceeding its aperture. This part of the light forms stray light and enters other sub-eyes, causing the irradiation uniformity of the target surface to deviate from the theoretical value. Sampling points are selected on the irradiation surface according to the three-ring six-arm method, and the irradiance of the LCG before and after optimization is measured and compared, and the uniformity is calculated. The results show that the non-uniformity of the irradiation surface of the optimized solar spectrum simulator is reduced from 2.18% to 1.13%, and the uniformity is improved by 1.93 times, indicating that the method proposed in the present invention can effectively suppress the influence of the sidelobe effect on the irradiation uniformity.

[0179] In the above embodiment, suitable free-form surfaces are designed for different surfaces of the light collecting mirror group, and the structural differences between the free-form surfaces are utilized to ensure the uniformity of the target surface while ensuring the collimation of the light collecting mirror group, thereby improving the irradiation uniformity of the solar spectrum simulator.

[0180] Example 2

[0181] See also Figure 8 , this embodiment provides a schematic structural diagram of a free-form surface light collecting mirror group optimization device for a solar spectrum simulator.

[0182] As an example, the device comprises:

[0183] The first calculation unit 810 is adapted to respectively calculate the coordinates of discrete points of the first free-curved surface, the second free-curved surface and the third free-curved surface of the free-curved surface light collecting lens assembly under the condition that only the light homogenization function is provided.

[0184] The second calculation unit 820 is adapted to respectively calculate the coordinates of discrete points of the first free-curved surface, the second free-curved surface and the third free-curved surface of the free-curved surface light collecting lens assembly under the condition that it only has the collimation function.

[0185] The fitting unit 830 is adapted to perform generatrix fitting on the discrete point coordinates of the first free-form surface under the condition of only having the uniform light function and only having the collimation function, the discrete point coordinates of the second free-form surface, and the discrete point coordinates of the third free-form surface, respectively, based on the Bessel function, to obtain the first Bessel curve, the second Bessel curve, and the third Bessel curve, respectively.

[0186] The unit 840 for establishing a uniformity and collimation joint evaluation function is adapted to establish a uniformity and collimation joint evaluation function in a weighted manner.

[0187] The first optimization unit 850 is adapted to optimize the free-form surface light collecting mirror group by using a simulated annealing method in combination with the first Bezier curve, the second Bezier curve, the third Bezier curve and a joint evaluation function to obtain a solution of the free-form surface light collecting mirror group;

[0188] The second optimization unit 860 is adapted to modify the preset variables of the simulated annealing method and perform multiple optimizations on the free-form surface light collecting mirror group;

[0189] The selection unit 870 is adapted to select an optimal solution structure based on the free-form surface light collecting mirror group solution after multiple optimizations.

[0190] Example 3

[0191] The embodiment of the present invention further proposes a storage medium, on which a method for optimizing a free-form surface light collecting mirror group of a solar spectrum simulator is stored, and when the free-form surface light collecting mirror group optimization program of the solar spectrum simulator is executed by a processor, the steps of the method for optimizing a free-form surface light collecting mirror group of a solar spectrum simulator as described above are implemented. Since the storage medium adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be described one by one here.

[0192] Example 4

[0193] See also Fig. 9 An embodiment of the present invention further provides an electronic device, comprising: a memory and a processor; the memory stores at least one program instruction; the processor loads and executes the at least one program instruction to implement the free-form surface light collecting mirror group optimization method of the solar spectrum simulator provided in Example 1.

[0194] The memory 602 and the processor 601 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 601 and the memory 602 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 601 is transmitted on a wireless medium via an antenna, and further, the antenna also receives data and transmits the data to the processor 601.

[0195] The processor 601 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 602 can be used to store data used by the processor 601 when performing operations.

[0196] 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 know 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 scope of protection of the present invention, which will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection 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.

Claims

1. A method for optimizing a free-form surface light collecting lens group of a solar spectrum simulator, wherein the free-form surface light collecting lens group comprises two lenses, wherein the first lens comprises a first free-form surface, and the second lens comprises a second free-form surface and a third free-form surface, wherein: The method comprises: Calculating the coordinates of discrete points of the first free-curved surface, the second free-curved surface and the third free-curved surface of the free-curved surface light collecting lens group under the condition that only the light homogenization function is provided; Calculating the coordinates of discrete points of the first free-curved surface, the second free-curved surface and the third free-curved surface of the free-curved surface light collecting lens group under the condition that it only has a collimation function; Based on the Bessel function, the coordinates of the discrete points of the first free-form surface, the discrete points of the second free-form surface and the discrete points of the third free-form surface are respectively fitted with the generatrix under the condition of only having the uniform light function and only having the collimation function to obtain the first Bessel curve, the second Bessel curve and the third Bessel curve respectively; The uniformity and collimation joint evaluation function is established in a weighted ratio manner; The free-form surface light collecting mirror group is optimized and calculated by using a simulated annealing method in combination with a first Bezier curve, a second Bezier curve, a third Bezier curve and a joint evaluation function to obtain a solution of the free-form surface light collecting mirror group; Modify the preset variables of the simulated annealing method and complete multiple optimizations of the free-form surface light collecting mirror group; Based on the free-form surface light collecting mirror group solution after multiple optimizations, the optimal solution structure is selected.

2. The method for optimizing the free-form surface light collecting mirror assembly of the solar spectrum simulator according to claim 1, characterized in that: The discrete point coordinates of the first free-form surface, the second free-form surface and the third free-form surface of the free-form surface light collecting lens group respectively calculated under the condition that only the light homogenization function is provided include: The luminous flux formula is calculated using the point light source luminous flux model and the luminous flux model within the target surface ring; The luminous flux formula is combined with the principle of vector light propagation to calculate the coordinates of discrete points on the first free-form surface, the second free-form surface and the third free-form surface of the free-form surface light collecting lens group under the condition of only having the light homogenization function; Among them, the point light source luminous flux model is: Where I(θ) is the luminous intensity at each angle at the outlet of the integrating sphere, θ is the effective luminous angle of the integrating sphere, Ω is the solid angle, and θ max and θ min The upper and lower limits of the effective luminous angle of the integrating sphere; Assume that the light distribution curve of the integrating sphere outlet meets the Lambert distribution condition, integrate formula (1) and calculate each sub-interval Δθ=θ i+1 -θ i The luminous flux inside, The luminous flux in each sub-interval Δθ is mapped to the target surface through the free surface (R i ,R i+1 ) on the ring, the luminous flux E in the ring on the target surface i It is expressed as: Where e0 is the preset ideal illumination on the target surface, r i and r i+1 is the target surface (R i ,R i+1 ) the ordinate on the ring; Let formula (2) and (3) be equal to obtain the luminous flux formula: In the formula, i represents dividing the irradiated surface into m parts, and i is the i-th part.

3. The method for optimizing the free-form surface light collecting mirror assembly of the solar spectrum simulator according to claim 1, characterized in that: The step of respectively calculating the coordinates of discrete points on the first free-form surface, the second free-form surface and the third free-form surface of the free-form surface light collecting lens group under the condition that it only has a collimation function comprises: Calculate the first free-form surface coordinate x1 and the light source angle θ in The first expression of Obtaining a first free-form surface shape based on the first expression; Calculate the coordinates of the second free-form surface x2 and the light source angle θ in The second expression of Obtaining a second free-form surface shape based on the second expression; Calculate the third free surface coordinate x3 and the light source angle θ in The third expression of Obtaining a third free-form surface shape based on the third expression; Based on the first free-curved surface shape, the second free-curved surface shape and the third free-curved surface shape, the discrete point coordinates of the first free-curved surface, the second free-curved surface and the third free-curved surface of the free-curved surface light collecting lens group under the condition of only having the collimation function are obtained.

4. The method for optimizing the free-form surface light collecting mirror assembly of the solar spectrum simulator according to claim 3, characterized in that: The first expression is: In the formula, the initial condition is θ in =0, x1=d0+d1, d0 represents the air space, d1 represents the thickness of the first lens, θ in represents the divergence angle of the outgoing light from the integrating sphere, b1 represents the angle between the outgoing light from the first free-form surface and the optical axis, and n1 represents the refractive index of the first lens; The first free-form surface shape is obtained by iterating formula (9); The second expression is: In the formula, the initial condition is θ in =0, x1=d0+d1+d2, d2 represents the air gap, b2 represents the angle between the outgoing light of the second free-form surface and the optical axis, and n2 represents the refractive index of the second lens; The second free-form surface shape is obtained by iterating formula (10); The third expression is: In the formula, the initial condition is θ in =0, x1=d0+d1+d2+d3, d3 represents the thickness of the second lens, b3 represents the angle between the output light of the third free-form surface and the optical axis, and n2 represents the refractive index of the second lens; The third free-form surface shape is obtained by iterating formula (11); Solving formulas (9) to (11) we can obtain the coordinates of the discrete points on the three free-form surfaces under the collimation condition.

5. The method for optimizing the free-form surface light collecting mirror assembly of the solar spectrum simulator according to claim 1, characterized in that: The method of performing generatrix fitting on the generatrix discrete point model of the first free-form surface, the generatrix discrete point model of the second free-form surface and the generatrix discrete point model of the third free-form surface respectively under the condition of only having the homogenization function and only having the collimation function based on the Bessel function to obtain the first Bessel curve, the second Bessel curve and the third Bessel curve respectively comprises: The three groups of discrete point coordinates are preprocessed respectively by using a straight line thinning method, wherein the first group of discrete point coordinates includes the discrete point coordinates of the first free-form surface under the condition of only having a uniform light function and the discrete point coordinates of the first free-form surface under the condition of only having a collimation function, the second group of discrete point coordinates includes the discrete point coordinates of the second free-form surface under the condition of only having a uniform light function and the discrete point coordinates of the second free-form surface under the condition of only having a collimation function, and the third group of discrete point coordinates includes the discrete point coordinates of the third free-form surface under the condition of only having a uniform light function and the discrete point coordinates of the third free-form surface under the condition of only having a collimation function; Based on the Bezier function, the three groups of discrete point coordinates after preprocessing are fitted to obtain a first Bezier curve, a second Bezier curve and a third Bezier curve; The discrete point intervals are divided to increase the influence ratio of the control points in the Bezier curve.

6. The method for optimizing the free-form surface light collecting mirror assembly of the solar spectrum simulator according to claim 5, characterized in that: The method of preprocessing the three groups of discrete point coordinates by using the straight line thinning method comprises: Set points P1 and P i There are i-2 discrete points between them; Use the point-to-line distance formula to determine the distance from i-2 discrete points to 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 Substitution, thereby completing the preprocessing of three sets of discrete point coordinates; The method of fitting the three groups of preprocessed discrete point coordinates based on the Bezier function to obtain the first Bezier curve, the second Bezier curve and the third Bezier curve comprises: The n-order Bessel function controlled by n+1 points is expressed as: Where t∈(0,1), P i is the control point of the Bezier curve, B i,n (t) is the nth-order Bernstein polynomial; 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: In the formula, matrix b is the control point coordinate matrix, and curve parameter t is i It is obtained by iterating the following formula: The dividing of discrete point intervals to increase the influence ratio of the control points in the Bezier curve includes: The Bezier curve has n+1 control points, let P n-1 , P n , P n+1 is the set of control points that make up the curve; 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 β targate ,and When P n+1 Belongs to the control point set; After calculating each set of curve points, 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 optimizing the free-form surface light collecting mirror assembly of the solar spectrum simulator according to claim 1, characterized in that: The method of establishing a uniformity and collimation joint evaluation function in a weighted ratio manner includes: Meshing the target surface of the free-form surface light collecting lens group; The linear weighted method based on the evaluation function combines uniformity and collimation in a weighted ratio to obtain a joint evaluation function: In the formula, y r and d represents the weight of uniformity and collimation, a and b represent the longitude and latitude coordinates of the grid, e and f represent the longitude and latitude boundaries of the grid, and E(a, b) represents the normalized irradiance. represents the normalized irradiance target value, ΔE(a,b) represents the normalized irradiance tolerance, A(a,b) represents the absolute value of the maximum incident angle of the light-entering end face of the beam smoothing system, represents the collimation target value, and ΔA(a,b) represents the collimation target value tolerance.

8. The method for optimizing the free-form surface light collecting mirror assembly of the solar spectrum simulator according to claim 1, characterized in that: The method of optimizing the free-form surface light collecting mirror group by using the simulated annealing method in combination with the first Bezier curve, the second Bezier curve, the third Bezier curve and the joint evaluation function to obtain the solution of the free-form surface light collecting mirror group includes: S510: taking the first Bezier curve, the second Bezier curve and the third Bezier curve as an initial structure; S520: Optimizing the free-form surface light collecting mirror in combination with the joint evaluation function to obtain a solution of the free-form surface light collecting mirror group includes: S5201: applying random perturbations to the initial structure so that the joint evaluation function generates a new solution; S5202: Determine whether the new solution generated by the joint evaluation function is smaller than the solution before random perturbation is applied to the initial structure; S5203: In response to the new solution generated by the joint evaluation function being smaller than the solution before random perturbation is applied to the initial structure, using the new solution generated by the joint evaluation function as the solution of the free-form surface light collecting mirror assembly; S5204: In response to the new solution generated in response to the joint evaluation function being greater than the solution before random perturbation is applied to the initial structure, determining whether to use the new solution as a solution of the free-form surface light collecting lens assembly according to a preset probability function; The probability function is: Where, T c Indicates the current temperature, D V+1 Indicates A V+1 The corresponding evaluation function, k is the number of evaluations, when t = t V When the vth optimization is performed, the matrix A of the angles between the tangent lines of the control points of the three Bezier curves and the optical axis is V It is expressed as: In the formula, each column represents the angle between the tangent of n control points and the optical axis corresponding to the same free surface. During the optimization process, the relationship between the v+1th variable value and the vth variable value is expressed as: HAS v+1 =A v +WHAT; (18) In the formula, each parameter of the matrix U is expressed as a random variable matrix that obeys the [-1,1] distribution, and Q is a diagonal matrix, which represents the threshold value satisfied by the angle between the tangent line of the control point and the optical axis.

9. The method for optimizing the free-form surface light collecting mirror assembly of the solar spectrum simulator according to claim 8, characterized in that: After steps S5203 and S5204, the method further includes: S5205: Determine whether the number of iterations has been reached; S5206: In response to reaching the number of iterations, using simulation software to calculate whether the uniformity of the irradiation surface of the solar spectrum simulator reaches a target condition; S5207: In response to the solar spectrum simulator irradiation surface uniformity reaching the target condition, output the solution of the free-form surface light collecting mirror group currently calculated as a condition for subsequent selection of the light collecting mirror group structure; S5208: In response to the uniformity of the irradiation surface of the solar spectrum simulator not reaching the target condition, go to step S6 and reset the preset variables of the simulated annealing method.

10. A free-form surface light collecting lens group optimization device for a solar spectrum simulator, wherein the free-form surface light collecting lens group comprises two lenses, wherein the first lens comprises a first free-form surface, and the second lens comprises a second free-form surface and a third free-form surface, characterized in that: The device comprises: A first calculation unit is adapted to respectively calculate the coordinates of discrete points of the first free-curved surface, the second free-curved surface and the third free-curved surface of the free-curved surface light collecting lens group under the condition that only the light homogenization function is provided; The second calculation unit is adapted to respectively calculate the coordinates of discrete points of the first free-curved surface, the second free-curved surface and the third free-curved surface of the free-curved surface light collecting lens group under the condition that it only has a collimation function; A fitting unit is adapted to perform generatrix fitting on the discrete point coordinates of the first free-form surface, the discrete point coordinates of the second free-form surface and the discrete point coordinates of the third free-form surface under the condition of only having the uniform light function and only having the collimation function, respectively, based on the Bessel function, to obtain the first Bessel curve, the second Bessel curve and the third Bessel curve respectively; A unit for establishing a uniformity and collimation joint evaluation function is used to establish a uniformity and collimation joint evaluation function in a weighted ratio manner; The first optimization unit is adapted to optimize the free-form surface light collecting mirror group by using a simulated annealing method in combination with the first Bezier curve, the second Bezier curve, the third Bezier curve and a joint evaluation function to obtain a solution of the free-form surface light collecting mirror group; The second optimization unit is suitable for modifying the preset variables of the simulated annealing method and completing multiple optimizations of the free-form surface light collecting mirror group; The selection unit is suitable for selecting the optimal solution structure based on the free-form surface light collecting mirror group solution after multiple optimizations.

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