CN-122018146-A - Uniform light distribution lens system based on free curved surface and design method thereof

CN122018146ACN 122018146 ACN122018146 ACN 122018146ACN-122018146-A

Abstract

The invention provides a uniform light distribution lens system based on a free-form surface and a design method thereof, and relates to the technical field of lens design, wherein the lens system comprises the steps of acquiring a light intensity distribution diagram of a target surface under a lens sample, and identifying a region to be improved in the light intensity distribution diagram based on a uniform light distribution standard; the invention relates to a method for optimizing a free-form surface lens, which comprises the steps of dividing control points on the free-form surface into an optimized control point and a reference control point according to types based on an area to be improved, randomly perturbing thickness values of the control points based on the types of the control points, taking the uniformity degree of light intensity distribution of a maximized target surface and the smoothness of the free-form surface as optimization targets, and determining an optimal three-dimensional mathematical model by adopting a simulated annealing algorithm.

Inventors

GAO SHUANGHONG
WANG XIAODONG
WEI JIANGEN

Assignees

深圳市朗一曼光学有限公司

Dates

Publication Date: 20260512
Application Date: 20260130

Claims (10)

1. A method of designing a free-form lens comprising the steps of: S1, modeling a lens sample containing a free curved surface to generate a three-dimensional mathematical model thereof, inputting the three-dimensional mathematical model into optical simulation software to obtain a light intensity distribution map of a target surface, and identifying areas to be improved with uneven light intensity distribution in the light intensity distribution map based on uniform light distribution standards; S2, analyzing the area to be improved based on a ray tracing algorithm, dividing control points arranged on the free curved surface into an optimized control point and a reference control point according to types, and performing subtraction processing on the reference control point; S3, after random disturbance is carried out on the thickness value of the control point based on the type of the control point, a three-dimensional mathematical model is reconstructed by combining a double interpolation algorithm, secondary simulation is carried out based on optical simulation software, the light intensity distribution uniformity degree of the target surface and the smoothness of the free curved surface are maximized as optimization targets, and an optimal three-dimensional mathematical model is determined by adopting a simulated annealing algorithm.
2. The method of designing a free-form lens according to claim 1, wherein the logic for identifying the area to be modified is as follows: 1) Determining the size of the evaluation grids based on the height and the width of the light intensity distribution map, and further generating an evaluation network covering the light intensity distribution map, wherein the evaluation network consists of a plurality of evaluation grids, and the area of the light intensity distribution map falling into each evaluation grid is independently used as an evaluation sub-area; 2) And presetting a uniform light distribution standard consisting of a minimum light intensity constraint condition, a light intensity extremum ratio constraint condition and a light intensity variation degree constraint condition, judging whether each judging subarea meets the three constraint conditions one by one, if so, judging the subarea as a qualified area, and otherwise, judging the subarea as an area to be improved.
3. The method of claim 2, wherein the logic for dividing the intensity profile into a plurality of evaluation sub-regions is as follows: 1.1 Presetting a scaling factor which is a positive decimal, calculating the product of the height value of the light intensity distribution map and the scaling factor to be used as a judging grid height value, and calculating the product of the width value of the light intensity distribution map and the scaling factor to be used as a judging grid width value, so as to determine the size of the judging grid; 1.2 Paving a first judging grid on the light intensity distribution map, wherein the geometric center of the judging grid coincides with the geometric center of the light intensity distribution map, so as to determine the initial paving position of the judging grid; 1.3 Taking the latest laid evaluation grid as a central grid, and executing the evaluation grid laying based on the following rules: A first rule is that whether a light intensity distribution map area which is not covered by the existing evaluation grid exists right above the central grid is judged, if so, a new evaluation grid is paved right above the central grid, and the paving position of the evaluation grid is the same as the position of the central grid shifted upwards by one evaluation grid height value; a second rule is used for judging whether a light intensity distribution map area which is not covered by the existing judging grid exists right below the central grid, if so, a new judging grid is paved right below the central grid, and the paving position of the judging grid is the same as the position of the central grid after being shifted downwards by a judging grid height value; Thirdly, judging whether a light intensity distribution map area which is not covered by the existing judging grid exists right left of the central grid, if so, paving a new judging grid right left of the central grid, wherein the paving position of the judging grid is the same as the position of shifting the central grid leftwards by one judging grid width value; a fourth rule, judging whether a light intensity distribution map area which is not covered by the existing judging grid exists right of the central grid, if so, paving a new judging grid right of the central grid, wherein the paving position of the judging grid is the same as the position of shifting the central grid rightwards by one judging grid width value; 1.4 Repeating the step 1.3) until a new evaluation grid cannot be paved, so that an evaluation network covering the light intensity distribution map is generated, and then the area of the light intensity distribution map falling into each evaluation grid is independently used as an evaluation sub-area.
4. The method for designing a free-form surface lens according to claim 2, wherein the minimum light intensity constraint condition is that the light intensity value at each position of the evaluation sub-region is not less than a minimum light intensity threshold value; The constraint condition of the light intensity extremum ratio is that the ratio of the light intensity maximum value to the light intensity minimum value in the judging subarea is not higher than an extremum ratio threshold value, and the extremum ratio threshold value is larger than one; The constraint condition of the light intensity variation degree is that the ratio of the standard deviation of the light intensity to the average value of the light intensity in the judging subarea is not higher than a light intensity variation threshold, and the light intensity variation threshold is a positive decimal less than one.
5. The method of claim 2, wherein the logic for setting control points on the free-form surface is to uniformly sample the plane of the lens sample at fixed sampling intervals to generate a plurality of sampling points, and for each sampling point, the projection position of the sampling point on the free-form surface along the direction perpendicular to the plane is used as one control point on the free-form surface.
6. The method according to claim 5, wherein the classifying logic is that, for any control point, the position of the light beam incident on the light intensity distribution map after passing through the control point is simulated by the ray tracing function in the optical simulation software, if the position is located in the area to be improved, the control point is used as an optimized control point, otherwise the control point is used as a reference control point; The logic for reducing the reference control points is that the sampling points corresponding to the reference control points are defined as reference sampling points, one reference sampling point is randomly selected from all the reference sampling points on the plane, all the reference sampling points with the distance smaller than the reduction radius from the reference sampling points are removed, and the iteration is carried out until the distance between the rest reference sampling points on the plane is not smaller than the reduction radius, the reference control points corresponding to the rest reference sampling points on the plane one by one are reserved, and the reduction radius is larger than the sampling interval.
7. The method of designing a free-form surface lens according to claim 6, wherein the logic for determining the optimal three-dimensional mathematical model is as follows: 1) Setting an initial temperature, a final temperature and a cooling rate; 2) Taking the thickness value of each control point in the lens sample as an initial solution, and combining the light intensity distribution diagram of the target surface under the initial solution to determine the energy value of the initial solution, wherein the energy value is generated by weighting and fusing the uniform light distribution index representing the adaptation degree of the light intensity distribution diagram of the target surface to the uniform light distribution standard and the smoothness index representing the smoothness of the free curved surface; 3) And taking the initial solution as a current solution of the first round of annealing optimization, randomly perturbing the thickness values of all control points in the current solution based on the type of the control points to generate a new solution, comparing the energy values of the current solution and the new solution to determine the current solution of the next round of annealing optimization, repeating iteration until the annealing temperature is not more than the termination temperature, taking the current solution of the last round of annealing optimization as an optimal solution, and determining an optimal three-dimensional mathematical model based on the optimal solution.
8. The method for designing the free-form surface lens according to claim 7, wherein the calculation logic of the corresponding uniform light distribution index is that, for an initial solution, in a target surface light intensity distribution map corresponding to the initial solution, suitability analysis is carried out on each judgment subarea and three constraint conditions in a uniform light distribution standard one by one to obtain the adaptation value of each judgment subarea relative to each constraint condition, and the adaptation values of the same judgment subarea relative to each constraint condition are subjected to weighted fusion to obtain the suitability index of the judgment subarea relative to the uniform light distribution standard, and the suitability index average value of all judgment subareas is taken as the uniform light distribution index corresponding to the initial solution; For the initial solution, the corresponding smoothness index calculation logic is used for calculating the standard deviation and the average value of the thickness values of all control points in the initial solution, and taking the ratio of the standard deviation and the average value of the thickness values as a smoothness index.
9. The method of claim 7, wherein for the current solution under any round of annealing optimization, the logic based on which a new solution is generated is as follows: 1) Calculating the ratio of the annealing temperature to the initial temperature under the annealing optimization of the round, and taking the product of the ratio and the initial value of the disturbance amplitude as the disturbance amplitude under the annealing optimization of the round, wherein the initial value of the disturbance amplitude is a positive decimal less than one; 2) Multiplying the disturbance amplitude under the annealing optimization of the round by a scaling factor which is a positive decimal to generate a reference disturbance amplitude under the annealing optimization of the round, taking the reference disturbance amplitude as an upper limit value, taking the product of the reference disturbance amplitude and-1 as a lower limit value to construct a reference disturbance interval, multiplying the thickness value of any control point belonging to a reference control point in the current solution under the annealing optimization of the round by a random value in the reference disturbance interval under the annealing optimization of the round to obtain the thickness disturbance value of the control point under the annealing optimization of the round, and summing the thickness value and the thickness disturbance value of any control point belonging to the reference control point in the current solution of the annealing optimization of the round to be used as the thickness value of the control point in the new solution under the annealing optimization of the round; 3) Taking the disturbance amplitude under the annealing optimization of the current round as an upper limit value, taking the product of the disturbance amplitude under the annealing optimization of the current round and-1 as a lower limit value to construct an optimized disturbance interval, multiplying any control point belonging to the optimized control point in the current solution under the annealing optimization of the current round by the reference thickness value, if the distance between the sampling point corresponding to the reference control point and the sampling point corresponding to the reference control point is smaller than a searching radius, taking the reference control point as a reference control point, searching the radius to be larger than a reducing radius, determining the attenuation weight of each reference control point relative to the sampling point based on a Gaussian function, weighting and fusing the thickness value of each reference control point based on the attenuation weight to obtain the reference thickness value of the control point, multiplying the reference thickness value by a random value in the optimized disturbance interval under the annealing optimization of the current round, obtaining the thickness disturbance value of the control point under the annealing optimization of the current round, and taking the sum of the thickness value and the disturbance value of the control point belonging to the optimized control point in the current solution of the annealing optimization of the current round as the thickness value in the annealing optimization of the new round.
10. A free-form surface based uniform light distribution lens system, comprising a free-form surface lens manufactured by the design method of any one of claims 1-9, and further comprising a light source for providing illumination, a bracket for fixing the light source, and a light intensity adjusting device for adjusting the brightness of the light source.

Description

Uniform light distribution lens system based on free curved surface and design method thereof Technical Field The invention relates to the technical field of lens design, in particular to a uniform light distribution lens system based on a free curved surface and a design method thereof. Background The beam shaping is the regulation and control of the spatial intensity distribution of the light beam, and has wide application space in the fields of uniform illumination and laser processing. The design method of the optical shaping element is mainly divided into two types, namely, adopting Fourier optics to carry out algorithm design of a diffraction element for optical shaping, and calculating the curved surface type of the transmission type or reflection type optical element required by beam shaping according to the energy distribution of an incident beam and the energy distribution of a target beam and the Snell law and the energy conservation law. Compared with the traditional optical surfaces (spherical surfaces, aspherical surfaces, paraboloids and the like), the optical free-form surface is higher in optical design freedom and more flexible in space layout, and can be applied to an illumination optical system, so that the optical system structure can be simplified, and meanwhile, more accurate light beam regulation and control capability can be given to the optical free-form surface, and the design method of the free-form surface lens is more and more paid attention to related technicians. In the prior art, a design method and a system of a free-form surface light distribution lens with a publication number of CN116381930A are disclosed, wherein a virtual plane is firstly arranged at a position vertical to an optical axis, the required illuminance distribution on a three-dimensional target surface is converted into the virtual plane through a self-built mathematical model to obtain a virtual illuminance distribution, then a beam regulation mathematical model is constructed through an energy conservation law, boundary constraint and integrality conditions, and the free-form surface light distribution lens is designed to realize the illuminance distribution on the virtual plane. However, the prior art still has a great problem, such as that when the free-form surface lens design is optimized, the positions of all points on the free-form surface are updated and changed uniformly blindly, so that when the actual iteration update is performed, the reasonable point positions are updated to the unreasonable point positions, and when the unreasonable point positions are updated, the blindness is caused, the stability of the new solution quality is seriously affected, and the optimization efficiency is low. The above information disclosed in the background section is only for enhancement of understanding of the background of the disclosure and therefore it may include information that does not form the prior art that is already known to a person of ordinary skill in the art. Disclosure of Invention The invention aims to provide a uniform light distribution lens system based on a free-form surface and a design method thereof, so as to solve the problems in the background art. In order to achieve the above purpose, the present invention provides the following technical solutions: a design method of a free-form surface lens comprises the following steps: S1, modeling a lens sample containing a free curved surface to generate a three-dimensional mathematical model thereof, inputting the three-dimensional mathematical model into optical simulation software to obtain a light intensity distribution map of a target surface, and identifying areas to be improved with uneven light intensity distribution in the light intensity distribution map based on uniform light distribution standards; S2, analyzing the area to be improved based on a ray tracing algorithm, dividing control points arranged on the free curved surface into an optimized control point and a reference control point according to types, and performing subtraction processing on the reference control point; S3, after random disturbance is carried out on the thickness value of the control point based on the type of the control point, a three-dimensional mathematical model is reconstructed by combining a double interpolation algorithm, secondary simulation is carried out based on optical simulation software, the light intensity distribution uniformity degree of the target surface and the smoothness of the free curved surface are maximized as optimization targets, and an optimal three-dimensional mathematical model is determined by adopting a simulated annealing algorithm. Further, the logic for identifying the area to be improved is specifically as follows: 1) Determining the size of the evaluation grids based on the height and the width of the light intensity distribution map, and further generating an evaluation network covering the light intensity distribution