Free-form surface lens design method and system for regulating and controlling light beams of expanded surface light source

Abstract

The invention discloses a free-form surface lens design method and a free-form surface lens design system for regulating and controlling light beams of an extended surface light source, and relates to the field of non-imaging optics. According to the method, an extended area light source is divided into a plurality of small-scale light sources which can be regarded as point light sources, and a day-ampere equation is constructed based on the Snell law and energy conservation; calculating the energy contribution of each segmented independent small-scale light source on the observation plane, and calculating illumination distribution according to the energy contribution of each small-scale light source; and establishing a free-form surface lens light beam regulation and control model for the extended surface light source, and carrying out numerical solution to obtain the free-form surface lens meeting the predetermined illumination requirement. According to the invention, the light beam distribution of the extended light source can be efficiently integrated, regulated and controlled, and a compact system structure is realized while the energy utilization rate is improved. The system can be widely applied to various optical application scenes including efficient illumination, optical sensing and other fields needing compact structures and accurate light beam control.

Description

Technical Field

[0001] The present invention relates to the field of non-imaging optics and extended light source technology, and in particular to a free-form surface lens design method and system for extended surface light source beam regulation. Background Art

[0002] Extended surface light sources are a type of light source with a certain luminous area and a variety of emitting light beam directions. Compared with point light sources, their emitted light distribution is more complex and their spatial coherence is lower, which increases the difficulty of precise light beam control. Extended surface light sources can achieve efficient utilization of light energy and compact and miniaturized optical systems. The beam control technology of this type of light source has broad application prospects in LED lighting, automotive lighting, display backlighting and visual inspection systems. However, the beam control of extended surface light sources is relatively complex, and traditional optical design methods based on the assumption of point light sources are difficult to directly apply. Its main challenges include: (1) The light source has a large luminous surface, resulting in a wide beam angle distribution, making it difficult to achieve high uniformity lighting through simple optical elements; (2) The luminous intensity and angle distribution of the light source are non-uniform, and it is necessary to construct an accurate light energy mapping relationship to meet the illumination requirements of the observation plane; (3) The design of free-form surfaces must take into account the compactness and efficiency of the optical system and the uniform control of the beam, while traditional analytical or empirical methods have limitations in high-precision free-form surface modeling. Therefore, for the free-form surface optical design of extended light sources, it is necessary to build a more accurate mathematical model to optimize the beam control and improve the performance of the optical system.

[0003] Among the free-form surface optical design methods for extended light sources in the prior art, patent CN202210607568 proposes a double free-form surface homogenizing lens design method, which improves the uniformity and energy utilization of the light beam by iteratively solving the discrete points of the free-form surface; patent CN202311344003 uses weighted superposition and feedback optimization, combined with particle swarm algorithm to optimize the lens generatrix weight factor, realizes automated optical system design, and improves computational efficiency and beam control accuracy; patent CN202410904784 uses snake optimization algorithm to optimize the free-form surface shape, achieving efficient light energy utilization and high uniformity lighting. These methods have made progress in beam control accuracy, optimization algorithm application and computational efficiency, but there is still room for optimization in large-scale optical free-form surface solution, nonlinear equation group computational stability and system compactness. Summary of the invention

[0004] The purpose of the present invention is to solve the technical deficiencies and provide a free-form surface lens design method and system for expanding the light beam control of a surface light source.

[0005] The present invention is achieved through the following technical solutions:

[0006] The present invention first provides a method for designing a free-form surface lens for regulating the light beam of an extended surface light source, wherein the free-form surface lens is used to regulate the light beam of a specified extended surface light source to achieve a preset target light intensity distribution on an observation plane; the method comprises the following steps:

[0007] 1) Divide the specified extended surface light source into several independent and non-overlapping small-scale light sources, and regard each small-scale light source as a point light source;

[0008] 2) According to Snell's law and energy conservation and the specified incident surface shape of the free-form lens, the Monge-Ampere equation is constructed. The Monge-Ampere equation is used to describe the energy distribution of the light beam during the deflection and regulation process of the free-form lens;

[0009] 3) According to the Monge-Ampere equation corresponding to each small-scale light source, calculate the energy contribution of each small-scale light source on the observation plane, and calculate the illumination distribution according to the energy contribution of each small-scale light source;

[0010] 4) According to the preset target light intensity distribution on the observation plane, a free-form surface lens beam control model for the extended surface light source is constructed, and the corresponding free-form surface lens output surface data points are obtained by numerical solution, and then the corresponding free-form surface lens is constructed.

[0011] In the above design process, the extended surface light source is pre-specified, the observation plane and the target light intensity distribution thereon are also pre-given, the incident surface of the free-form surface lens is pre-given, and the exit surface of the free-form surface lens is the free-form surface to be designed. The design method obtains the exit surface surface data points of the free-form surface lens that meet the above settings, and then constructs the corresponding free-form surface lens.

[0012] On the other hand, the present invention also provides a beam control system for an extended surface light source, which includes an extended surface light source, a free-form surface lens and an observation plane; the exit surface of the free-form surface lens is a free-form surface, and the free-form surface lens is used to control the beam of the extended light source to achieve a preset light intensity distribution on the observation plane; the free-form surface lens is designed using the aforementioned method.

[0013] Compared with the prior art, the present invention has the following advantages:

[0014] 1. Aiming at the characteristics of the extended light source, the present invention adopts a light source segmentation method to discretize it into multiple small-scale light sources, and explicitly introduces the spatial position information of the light source into the Monge-Ampere equation. This method can not only accurately describe the light energy distribution of the extended light source, but also effectively solve the problems of beam divergence and uneven energy transmission caused by the large light-emitting surface, making the free-form surface design more in line with the actual optical system requirements, thereby improving the beam control accuracy and system adaptability.

[0015] 2. The present invention establishes the global illumination distribution of the observation plane, and performs centroid interpolation calculation of the control points on the basis of segmented light sources, so that the energy contribution of each small-scale light source is more uniform in space, while reducing the calculation error caused by local energy mutation. Subsequently, the energy superposition strategy of multiple light sources is adopted to make the global illumination distribution more accurately match the brightness requirements of the observation plane, and combined with the free-form surface optimization solution, realize the design of an optical system with high uniformity and high energy utilization, thereby improving the stability of the free-form surface design and the beam control accuracy.

[0016] 3. The present invention constructs a large-scale Monge-Ampere equation group and solves it in combination with the Newton iteration method, which can make full use of the second-order partial derivative information and accelerate the convergence of the solution. Compared with the traditional optimization method, the present invention avoids the computational complexity of high-dimensional numerical integration, reduces local error accumulation through global illumination modeling and interpolation optimization, and significantly improves the convergence speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 The design principle diagram of the free-form surface lens used to expand the surface light source;

[0019] Figure 2 A schematic diagram of the barycenter interpolation calculation for obtaining the global illumination distribution model;

[0020] Figure 3 Schematic diagram of the principle of free-form surface beam control for extended light source;

[0021] Figure 4 is a free-form surface lens model in the embodiment;

[0022] Figure 5 This is a diagram of the illumination distribution on the illumination surface after the expanded light source beam is regulated in the embodiment. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention clearer and more complete, the present invention will be further described below in conjunction with the drawings of the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] In this document, the terms "comprises," "comprising," or any other variations thereof, are intended to cover a non-exclusive inclusion of elements other than those listed and may also include additional elements not expressly listed.

[0025] In this document, the directional words such as front, back, top, and bottom are defined by the positions of the components in the drawings and the positions of the components relative to each other, and are only for the sake of clarity and convenience in expressing the technical solution. It should be understood that the use of the directional words should not limit the scope of protection claimed in this application.

[0026] Figure 1 The free-form surface lens design principle diagram for extending the surface light source. The free-form surface lens design method for extending the surface light source beam control divides the extended surface light source into a number of independent and non-overlapping small-scale light sources during the modeling process, and ensures that all light source positions are covered and there is no overlapping area. The ratio of the distance between the incident surface of the free-form surface lens and the small-scale light source after segmentation to the maximum size of the small-scale light source is greater than 5, so as to ensure that the small-scale light source after segmentation can be approximated as a point light source. Figure 1 As shown, the extended surface light source 101 is divided into a plurality of independent and non-overlapping small-scale light sources, such as the sub-light source 102. The sub-light source satisfies the "five-fold rule" and can be regarded as a point light source. The light emitted by the light source is regulated by the free-form surface lens 103 and falls on the target illumination plane 104, and the landing point (t x1 ,t y1 ,0) acts at a specific illumination E(t x1 ,t y1 ). For each sub-light source, based on Snell's law and energy conservation, the Monge-Ampere equation is constructed to describe the deflection of a light beam by an optical free-form surface and its energy conservation and distribution.

[0027] The specific steps of the design method of the present invention are as follows:

[0028] 1) According to the division requirements introduced above, the specified extended surface light source is divided into a number of independent and non-overlapping small-scale light sources, and each small-scale light source is regarded as a point light source;

[0029] When the extended light sources are divided, the light-emitting positions of all extended surface light sources are covered by small-scale light sources, and no overlapping areas appear among the small-scale light sources.

[0030] 2) According to Snell's law and energy conservation and the specified incident surface shape of the free-form lens, the Monge-Ampere equation is constructed. The Monge-Ampere equation is used to describe the energy distribution of the light beam during the deflection and regulation process of the free-form lens;

[0031] Specifically, in this embodiment, step 2) can be implemented as follows:

[0032] 2.1) Coordinate system establishment: Establish a global rectangular coordinate system xyz and define the coordinates of each independent small light source S in the coordinate system xyz as (s x ,s y ,0); Set the coordinates of point P on the free surface as the lens exit surface in the coordinate system xyz to (p x ,p y ,p z ); Set the coordinates of point T on the observation plane in the global coordinate system xyz to (t x ,t y ,t z ), the coordinates in the local coordinate system x1y1z1 of the observation plane are (t x1 ,t y1 ,0); define the normal vector of the free-form surface at point P as O=(O x ,O y ,O z );

[0033] 2.2) Setting the observation plane equation: The observation plane is a preset plane in three-dimensional space. The equation of the plane in the global coordinate system is

[0034]

[0035] Where A=sinβcosα, B=sinβsinα, C=cosβ, D=-C×L, where β is the angle between the z1 axis in the local coordinate system x1y1z1 and the z axis in the global coordinate system xyz, α is the angle between the x1 axis in the local coordinate system x1y1z1 and the x axis in the global coordinate system xyz, and L is the distance from the intersection of the z axis of the local coordinate system x1y1z1 and the global coordinate system xyz to the origin;

[0036] 2.3) Light path calculation: According to Snell's law, set the light path equation from the light source point through the incident surface of the free-form lens to the point P on the exit surface and then to the target point T on the observation plane, and calculate the coordinates of point T in the global coordinate system xyz:

[0037]

[0038] 2.4) According to step 2.2) and step 2.3), point T must satisfy both the plane equation and the coordinate relationship equation. Further merge, simplify and transform the coordinate system to obtain the coordinates of the target point T in the local coordinate system x1y1z1:

[0039] Where E = cosα, F = sinα;

[0040] 2.5) According to the law of energy conservation, the energy emitted by the small-scale light source produces an illumination distribution on the observation plane after passing through the free-form surface lens. The integrated energy of the two remains consistent. Therefore, the energy constraint relationship of a ray from the small-scale light source falling on a point on the observation plane can be obtained;

[0041] Specifically, the energy constraint relationship is:

[0042]

[0043] in, is the brightness distribution of the small-scale light source, is the tilt angle in the spherical coordinate system, is the azimuth; |JT1| is the coordinate from the observation plane (t x1 ,t y1 ,0) to the coordinate transformation Jacobian matrix of the free-form surface lens; |JT2| is respectively the transformation from the light source position (s x ,s y ,0)) to the Jacobian matrix of the coordinate transformation of the free-form surface lens; E(t x1 ,t y1 ) is the small-scale light source at coordinate (t x1 ,t y1 ,0) where the illumination value is generated;

[0044] 2.6) The local coordinates (t x1 ,t y1 ,0), combined with the energy constraint relationship in step 2.5), calculate the energy from the light source position (s x ,s y ,0) after passing through the free-form surface lens, it falls on a point on the observation plane (t x1 ,t y1 ,0) at the illuminance value E(t x1 ,t y1 ), and further simplifying it to obtain the Monge–Ampere equation.

[0045] 3) According to the Monge-Ampere equation corresponding to each small-scale light source, calculate the energy contribution of each small-scale light source on the observation plane, and calculate the illumination distribution according to the energy contribution of each small-scale light source;

[0046] In this embodiment, the specific steps of step 3) are as follows:

[0047] 3.1) Data sampling: Based on the illuminance value of each independent small-scale light source, obtain the illuminance distribution data on the observation plane and define each independent light source S i The coordinate distribution of the falling point on the observation plane is (t xi ,t yi ,0);

[0048] 3.2) Control point setting: Taking the center position of the extended light source as the reference, ray tracing is performed on the discrete points (p x ,p y ,p z ) to the observation plane to obtain the control coordinate point (t xc ,t yc ,0), and serves as a reference point for subsequent interpolation calculations;

[0049] 3.3) Constructing space division grid: Based on independent light source S i The grid formed by the coordinates of the landing points (t xi ,t yi ) is used to divide the space, and the observation plane is divided into multiple non-overlapping grid cells, so that any reference point (t xc ,t yc ,0) falls into at least one grid cell. Figure 1 and 2 As shown, in this embodiment, the grid unit is selected as a triangle, but it should be noted that the grid unit type of the present invention can be a polygon such as a triangle, a quadrilateral, a pentagon, etc., and the subsequent embodiments will only be described in detail using a triangle as an example.

[0050] 3.4) Calculate interpolation weights: For each target control point (t xc ,t yc ,0), determine the vertex coordinates (tr1,tr2,tr3) of the triangle where it is located and the corresponding illumination value (E1,E2,E3), and calculate the centroid weight w of the reference point relative to the mesh vertex j. i,j

[0051] 3.5) Interpolation calculation: Use the area ratio weight method to calculate the illumination value of the control point:

[0052]

[0053] Each independent light source S is constructed i The illumination distribution E at the control point on the observation plane i (t xc ,t yc ).

[0054] Figure 2 Schematic diagram of the centroid interpolation calculation for obtaining the global illumination distribution model. Figure 3 Schematic diagram of the principle of free-form surface beam control for extended light source. Figure 3It can be seen in Figure 3 that after the extended light source 301 passes through the free-form surface lens 302, the light beams at different positions on the extended light source have different control effects, and the final control result is obtained by the combined action of the light beams at different positions. Therefore, it is necessary to calculate the energy contribution of each segmented small-scale light source on the observation plane and perform interpolation and superposition.

[0055] 4) According to the preset target light intensity distribution on the observation plane, a free-form surface lens beam control model for the extended surface light source is constructed, and the corresponding free-form surface lens output surface data points are obtained by numerical solution, and then the corresponding free-form surface lens is constructed.

[0056] In this embodiment, step 4) includes the following steps:

[0057] 4.1) Construction of global illumination distribution: based on multiple small-scale light sources S i The illumination rays on the observation plane establish the global illumination distribution E global (t xc ,t yc ):

[0058]

[0059] Where N is the total number of small-scale light sources divided from the extended surface light source. So far, E is calculated. global (t xc ,t yc ) is the global illumination distribution on the observation plane;

[0060] 4.2) Target illumination distribution setting: Set the expected illumination distribution E of the observation plane disire (t xc ,t yc ), and calculate the expected illumination distribution E corresponding to each light source based on the contribution of each small-scale light source to the global illumination d,i (t xc ,t yc ),satisfy:

[0061]

[0062] 4.3) Construction of nonlinear equations: According to the steps of calculating the illumination of the target point, for each light source S i The light control process on the free-form surface lens can be expressed as the linear transformation superposition of multiple Monge-Ampere equations.

[0063] The E calculated in step 4.2) d,i (t xc ,t yc ) is substituted into the above formula to obtain the equation that represents the deviation between the actual irradiance and the target irradiance:

[0064]

[0065] Combine the E obtained in step 4.2) i (t xc ,t yc ) and E d,i (t xc ,t yc ), accurately describe the light regulation process on the free-form surface lens, and finally form a large-scale Monge-Ampere equation group;

[0066] 4.4) Numerical solution: Newton iteration method or other numerical methods suitable for nonlinear elliptic equations are used to solve the above equations, calculate and update the free-form surface shape until the global error meets the convergence standard, and finally form the free-form surface shape for controlling the extended light source beam. Figure 4 is the free-form surface lens model in the embodiment. The boundary of the free-form surface is a rectangle, the size of the free-form surface lens is 18mm×18mm×4mm, the incident surface is a plane, the exit surface is the designed free-form surface, the extended light source is located 7mm directly below the free-form surface, and the extended light source is a 1.3mm×1.3mm surface light source. It is required that the extended light source beam generates a circular illumination spot with "Ω" on the observation plane after being regulated by the free-form surface lens. In the embodiment, the background is required to be uniformly illuminated, and the ratio between the letter pattern and the illumination is 3. The designed illumination distance is 250mm, and the diameter of the circular illumination spot after regulation is 250mm. The refractive index of the free-form surface lens is 1.49386, and the medium around the lens is air. The modeling and solution are performed as in the previous method, and finally a free-form surface lens that meets the design conditions and is suitable for an extended light source of 1.3mm×1.3mm and 7mm away from the lens is obtained, see Figure 4 .

[0067] Figure 5 This is the illuminance distribution diagram on the illumination surface after the extended light source beam is regulated in the embodiment. By performing Monte Carlo ray tracing on the free-form surface lens model, an illuminance distribution diagram is obtained on the observation plane, which clearly shows that an illumination spot with a ratio of letter illumination to uniform background illumination of 3 is achieved. The embodiment effectively realizes the free-form surface design for the regulation of the extended light source beam.

[0068] In summary, the present invention realizes the precise design of free-form surfaces and beam control for large-area surface light sources by constructing a large-scale nonlinear Monge-Ampere equation group suitable for extended light sources, and combining the comprehensive processing of light source segmentation, global illumination interpolation and boundary conditions. The embodiments show that the free-form surface lens designed by the present invention shows high efficiency and stability in meeting various lighting requirements (such as letter shapes, uniform light spots and different illumination ratios in the embodiments), and significantly improves the light energy utilization rate and lighting uniformity of the extended light source. Since the present invention has carried out targeted optimization in key links such as optical modeling, numerical iteration and physical constraints, it can also ensure rapid convergence and high-precision control in complex optical environments. It can be seen that the technical solution of the present invention has a wide range of applications and high reliability, and can effectively solve the design problems of large-area extended light sources that are difficult to handle based on traditional point light source methods, and has significant engineering application value and industrial promotion potential.

Claims

1. A free-form surface lens design method for extending the light beam control of a surface light source, characterized in that: The free-form surface lens is used to adjust the light beam of the specified extended surface light source to achieve a preset target light intensity distribution on the observation plane; the design method comprises the following steps: 1) Divide the specified extended surface light source into several independent and non-overlapping small-scale light sources, and regard each small-scale light source as a point light source; 2) According to Snell's law and energy conservation and the specified incident surface shape of the free-form lens, the Monge-Ampere equation is constructed. The Monge-Ampere equation is used to describe the energy distribution of the light beam during the deflection and regulation process of the free-form lens; 3) According to the Monge-Ampere equation corresponding to each small-scale light source, calculate the energy contribution of each small-scale light source on the observation plane, and calculate the illumination distribution according to the energy contribution of each small-scale light source; 4) According to the preset target light intensity distribution on the observation plane, a free-form surface lens beam control model for the extended surface light source is constructed, and the corresponding free-form surface lens output surface data points are obtained by numerical solution, and then the corresponding free-form surface lens is constructed.

2. The design method according to claim 1, characterized in that: When the extended light sources are divided in step 1), the light-emitting positions of all extended surface light sources are covered by small-scale light sources, and no overlapping areas appear among the small-scale light sources.

3. The design method according to claim 1, characterized in that: The ratio of the distance between the incident surface of the free-form surface lens and the segmented small-scale light source to the maximum size of the small-scale light source is greater than 5.

4. The design method according to claim 1, characterized in that: The step 2) comprises the following steps: 21) Establish a global rectangular coordinate system xyz and define the coordinates of each independent small-scale light source S in the coordinate system xyz as (s x ,s y ,0); Set the coordinates of point P on the free surface as the lens exit surface in the coordinate system xyz to (p x ,p y ,p z ); Set the coordinates of point T on the observation plane in the global coordinate system xyz to (t x ,t y ,t z ), the coordinates in the local coordinate system x1y1z1 of the observation plane are (t x1 ,t y1 ,0); define the normal vector of the free-form surface at point P as O=(O x ,O y ,O z ); 22) Set the observation plane equation. The observation plane is a preset plane in the three-dimensional space. The equation of the plane in the global coordinate system is: ； Among them, A, B, C, and D are the coefficients of the plane equation; 23) According to Snell's law, set the light path equation from the light source point through the incident surface of the free-form lens to the point P on the exit surface and to the target point T on the observation plane, and calculate the coordinates of point T in the global coordinate system xyz: ； 24) According to step 22) and step 23), point T must satisfy both the plane equation and the coordinate relationship equation. Further merge, simplify and transform the coordinate system to obtain the coordinates of the target point T in the local coordinate system x1y1z1 of the observation plane (t x1 ,t y1 ,0); 25) According to the law of energy conservation, the energy emitted by a small-scale light source passes through a free-form surface lens and then produces an illumination distribution on the observation plane. The integrated energy of the two remains consistent. Therefore, the energy constraint relationship of a ray from a small-scale light source falling on a point on the observation plane can be obtained; 26) The local coordinates (t x1 ,t y1 ,0), combined with the energy constraint relationship in step 25), calculate the energy from the light source position (s x ,s y ,0) after passing through the free-form surface lens, it falls on a point on the observation plane (t x1 ,t y1 ,0) at the illuminance value E(t x1 ,t y1 ), and further simplification gives the Monge–Ampere equation.

5. The design method according to claim 4, characterized in that α is the angle between the x1 axis in the local coordinate system x1y1z1 of the observation plane and the x axis in the global coordinate system xyz, β is the angle between the z1 axis in the local coordinate system x1y1z1 of the observation plane and the z axis in the global coordinate system xyz, and L is the distance from the origin to the intersection of the z axis of the local coordinate system x1y1z1 and the global coordinate system xyz; Then the coefficients of the plane equation in step 22) are A=sinβcosα, B=sinβsinα, C=cosβ, D=-C×L; In step 24), the coordinate values ​​satisfy: ； Among them, the coefficients E=cosα and F=sinα.

6. The design method according to claim 4, characterized in that: The energy constraint relationship in step 25) is: ； in, is the brightness distribution of the small-scale light source, is the tilt angle in the spherical coordinate system, is the azimuth; |JT1| is the coordinate from the observation plane (t x1 ,t y1 ,0) to the coordinate transformation Jacobian matrix of the free-form surface lens; |JT2| is respectively the transformation from the light source position (s x ,s y ,0)) to the Jacobian matrix of the coordinate transformation of the free-form surface lens; E(t x1 ,t y1 ) is the small-scale light source at coordinate (t x1 ,t y1 ,0) is the illumination value generated at the location.

7. The design method according to claim 1, characterized in that: In step 3), the calculation of the energy contribution of each small-scale light source on the observation plane includes the following steps: 31) Based on the illuminance values ​​of each independent small-scale light source, obtain the illuminance distribution data on the observation plane and define each independent light source S i The coordinate distribution of the falling point on the observation plane is (t xi ,t yi ,0); 32) Taking the center position of the extended light source as the reference, ray tracing is performed on the discrete points (p x ,p y ,p z ) to the observation plane to obtain the control coordinate point (t xc ,t yc ,0), and serves as a reference point for subsequent interpolation calculations; 33) Based on the coordinate distribution of the landing point (t xi ,t yi ) is used to divide the space, and the observation plane is divided into multiple non-overlapping grid cells, so that any reference point (t xc ,t yc ,0) falls into at least one grid cell; 34) For each reference point (t xc ,t yc ,0), determine the independent light source S i The coordinates of each vertex of the grid formed by the coordinates of the landing point tr i,j The corresponding illuminance value E i,j , where i in the following table represents an independent light source S i The subscript j represents the vertex number of the grid unit. The centroid weight w of the reference point relative to the grid vertex j is calculated. i,j ; 35) Calculate the illumination value of the reference point according to the center of gravity weight: ； Each independent light source S is constructed i The illumination distribution E at the control point on the observation plane i (t xc ,t yc ).

8. The design method according to claim 7, characterized in that: In step 33), the type of the grid unit is a triangle, a quadrilateral or a pentagon.

9. The design method according to claim 7, characterized in that: Step 4), comprising the following steps: 41) Based on multiple small-scale light sources S i The illumination light on the observation plane establishes the global illumination distribution E on the observation plane global (t xc ,t yc ): ； Where N is the total number of small-scale light sources divided from the extended surface light source; 42) Set the expected illumination distribution E of the observation plane disire (t xc ,t yc ), and calculate the expected illumination distribution E corresponding to each small-scale light source according to the contribution of each small-scale light source to the global illumination d,i (t xc ,t yc ),satisfy: ； 43) Each light source S i The light control process on the free-form surface lens is represented as a linear transformation superposition of multiple Monge-Ampere equations; The E calculated in step 42) d,i (t xc ,t yc ) is substituted into the above formula to obtain the equation that represents the deviation between the actual irradiance and the target irradiance: ； Combined with E obtained in step 42) i (t xc ,t yc ) and E d,i (t xc ,t yc ), accurately describe the light regulation process on the free-form surface lens, and finally form a large-scale Monge-Ampere equation group; 44) The above large-scale Monge-Ampere equations are solved, and the free-form surface shape is updated using the Newton iteration method, ultimately forming a free-form surface lens shape for controlling the expanded light source beam.

10. A beam control system for extending a surface light source, characterized in that: The system includes an extended surface light source, a free-form surface lens and an observation plane; the exit surface of the free-form surface lens is a free-form surface, and the free-form surface lens is used to regulate the light beam of the extended light source to achieve a preset light intensity distribution on the observation plane; the free-form surface lens is designed using the method described in any one of claims 1 to 9.

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