Free-form surface and aspheric surface beam shaping device and method

Abstract

The invention discloses a free-form surface beam shaping device and method, and belongs to the technical field of light distribution regulation and control. The free-form surface beam shaping method provided by the invention comprises the following steps: firstly, generating a standardized incident and emergent surface grid distribution diagram, then respectively mapping the standardized incident and emergent surface grid distribution diagram to a free-form surface and a target surface, and then calculating normal vectors of corresponding sampling points on the free-form surface according to the directions of incident light and emergent light, sampling points on the free-form surface are calculated based on normal vectors, and the method can design a free-form surface optical element to regulate and control light distribution. By integrating the designed free-form surface optical elements into the optical element array, light distribution regulation and control can be carried out on multiple light beams. The design method has very strong universality, can design free-form surface light distribution regulation and control aiming at multiple light sources and multiple light beams, realizes application in a high-power application scene, and can realize accurate regulation and control on non-zero expansion quantity light beams.

Description

Technical Field

[0001] The invention relates to a free-form surface light beam shaping device and method, and belongs to the field of light distribution control. Background Art

[0002] With the continuous development of science and technology, the use of light has expanded from traditional fields such as lighting and display to many cutting-edge fields such as optical communications, optical computing, precision manufacturing, and biomedicine.

[0003] However, the beam directly output by the light source is often difficult to be used directly due to its irradiance distribution or the shape of the spot. For example, the irradiance distribution of the beam directly emitted by the laser is generally Gaussian, which will lead to uneven energy distribution, the center intensity is far higher than the threshold required for practical applications, and the intensity of the edge area is lower than the threshold, resulting in energy waste, and the two wings of the Gaussian distribution beam may cause damage to areas outside the target area, expanding the heat affected zone; for this reason, many application scenarios require the irradiance of the output beam to be uniformly distributed, such as laser processing, industrial lighting, and biomedical information collection; in addition, the shape of the laser output beam spot is generally circular or elliptical, which makes beam shaping more difficult, and in many application scenarios, the spot shape is required to be square or rectangular, and in many application scenarios, the spot shape is required to be square or rectangular, such as solar cell laser scribing processing, laser micromachining, and high-precision dimensional measurement or surface detection. Another typical light source LED directly outputs a beam with a Lambertian distribution, which leads to low light utilization, uneven lighting, and increases the complexity of optical design; these problems exist in many application fields, such as LED street lighting, reading light lighting, etc.

[0004] The above problems can be solved by light distribution control technology, which mainly involves precise control of the irradiance distribution and wavefront of the light field to achieve advanced operations on beam propagation and transformation; by controlling the output of the light source, the required light distribution and spot shape can be achieved, so that the application scenarios of these light sources can be expanded. There are many optical elements that can achieve light distribution control, such as metasurfaces, free-form optical elements, spatial light modulators, digital micromirror devices, etc.; free-form optical elements are widely used because of their high light efficiency, the ability to precisely control light distribution, and relatively low processing costs. Although there are various methods for designing free-form surfaces for beam shaping, they all have certain limitations. For example, the literature [Y.Yue, K.Iwasaki, B.-Y.Chen, Y.Dobashi, and T.Nishita, "Poisson-Based Continuous Surface Generation for Goal-BasedCaustics," ACM Trans.Graph.33, 1–7 (2014).] proposed a method for designing free-form surfaces to produce a specific irradiance distribution on the target surface. This method is only designed for transmissive free-form surfaces. The incident beam aperture is rectangular, and the incident beam distribution is a uniform irradiance distribution. However, in many applications, the incident beam is a circular aperture, and the incident beam distribution may also be a Gaussian beam, etc., so the use of this method will be limited. Other methods also have various limitations. Although free-form surface light distribution control has certain applications, the following problems are still faced in this field:

[0005] (1) Existing design methods have requirements for the incident light beam. Currently, the design of free-form surface optical elements for light distribution control usually requires the incident light beam to have a Gaussian distribution or a Lambertian distribution. If the incident light beam has an arbitrary irradiance distribution, the existing methods will be difficult to apply.

[0006] (2) The design schemes for transmissive free-form surfaces and reflective free-form surfaces are not universal; since the light distribution control of transmissive free-form surfaces mainly involves a coaxial optical system, while the light distribution control of reflective free-form surfaces is mainly an off-axis system, and there are currently few methods that can design both transmissive free-form surface light distribution control and reflective free-form surface light distribution control components.

[0007] (3) Existing methods mainly focus on designing free-form surface optical elements for single light source or single light beam to achieve light distribution control, but there are no reports on designing free-form surface light distribution control systems for multiple light sources and multiple light beams. Designing free-form surface light distribution control systems for multiple light sources and multiple light beams is more practical in high-power application scenarios.

[0008] (4) Most of the existing free-form surface design methods for beam shaping are for the case where the optical etendue is zero. For the case where the optical etendue is not zero, the situation is more complicated and difficult to implement.

[0009] (5) It is currently difficult to design free-form surfaces for beam shaping with special aperture shapes. Summary of the invention

[0010] In order to solve at least one of the above problems, the present invention provides a free-form surface and aspheric beam shaping device and method; the design method provided by the present invention can design optical free-form surface elements and aspheric elements to achieve light distribution control.

[0011] The free-form surface optical element has no restrictions on the irradiance distribution of the incident light beam and is applicable to various types of incident light beam apertures; the method proposed in the present application can design both transmissive free-form surface light distribution control and reflective free-form surface light distribution control elements. In addition, the present application also provides a free-form surface optical element array design method and related devices. The free-form surface optical element array can be applied to the light distribution control of multiple light sources and multiple light beams, and is particularly suitable for application scenarios of high-power light distribution control.

[0012] In view of the situation that the incident light beam has a circular aperture, and the illumination distribution of the incident light beam is rotationally symmetric, and the illumination of the light spot on the target surface is also rotationally symmetric, the present invention also provides a non-spherical beam shaping element to regulate the rotationally symmetric light distribution. For some specific application scenarios, it is required that the light beam can not only output a specific illumination distribution after passing through the shaping system, but also that the output light beam is a collimated light beam. The present application designs a lens group composed of two free-form surface lenses, a reflector group composed of two free-form surface reflectors, and an aspheric lens group. The aspheric lens group is mainly aimed at the situation that the output light beam after the incident light beam passes through the shaping system is a collimated light beam, and the target surface is a circular uniform light spot.

[0013] The key optical elements used for the control of the beam shaping device are optical free-form surface elements and aspheric elements. The design idea of ​​the optical free-form surface element is to divide the free-form surface mirror and the target surface into grids, control the energy of the incident light beam on a grid on the free-form surface, and after reflection or refraction by the free-form surface, it is incident on the corresponding grid on the target surface. The grids on the free-form surface mirror are evenly spaced, and the irradiance distribution required on the target surface is mainly achieved by optimizing and adjusting the target surface grid. How to make the light corresponding to the input plane grid incident on the corresponding grid on the target surface requires control through the surface shape of the free-form surface. The design process is to find the optimal vector height of each point on the free-form surface so that it produces a predetermined irradiance distribution on the target surface.

[0014] The first object of the present application is to provide a single free-form surface transmission or reflection shaping optical element, and the technical solution adopted is as follows:

[0015] Step 1: Set and divide the initial grid;

[0016] Step 2: Optimize the target surface mesh;

[0017] Step 3: Calculate the normal vector of the corresponding sampling point on the free surface according to the directions of the incident light and the outgoing light to obtain the normal vector field;

[0018] Step 4: Calculate the free-form surface sagittal height based on the normal vector field;

[0019] Step 5: Build a solid model of the free-form surface transmission or reflection element and perform ray tracing to verify the results.

[0020] The second object of the present application is to provide a design method for a single aspheric lens, comprising:

[0021] Step S1: Perform initial meshing on the input plane and the target surface; the input plane is circular and the target surface is rectangular; when performing initial meshing, first perform ring-shaped division, and then perform radial division from the center to the surrounding to obtain the initial mesh;

[0022] Step S2: Optimizing the target surface mesh;

[0023] Step S3: Calculate the normal vector of the corresponding sampling point on the aspherical generatrix according to the directions of the incident light and the outgoing light to obtain the normal vector field;

[0024] Step S4: Calculate the vector height of each point on the aspheric generatrix based on the normal vector field;

[0025] Step S5: Rotate the generatrix to construct an aspherical optical element.

[0026] The third object of the present application is to provide a free-form surface beam shaping system, comprising a free-form surface lens group consisting of two free-form surface lenses or a reflector group consisting of two free-form surface reflectors.

[0027] The technical solution of the free-form surface beam shaping system is a simple repetition of the above-mentioned steps for preparing the single free-form surface transmission or reflection shaping optical element, which will not be elaborated here.

[0028] A fourth object of the present application is to provide an aspheric beam shaping system, comprising an aspheric lens group consisting of two aspheric lenses.

[0029] The technical solution of the aspheric beam shaping system is a simple repetition of the above-mentioned single aspheric lens preparation steps, which will not be described in detail here.

[0030] The fifth purpose of the present application is to provide a free-form surface reflector array, which includes multiple free-form surface reflectors, and can individually control the irradiance distribution generated by each reflector on the target surface. The irradiance distributions generated by different reflectors are superimposed to generate a uniform irradiance distribution on the target surface.

[0031] The sixth object of the present application is to provide a comprehensive beam shaping optical system, including a shaping element, a beam expansion system or a collimating lens, and the combination of the shaping element and the beam expansion or collimating lens is selected according to the type of light source, the aperture of the incident beam, the spot size of the target surface, etc.

[0032] The beneficial results of the present invention are

[0033] The present invention provides a free-form surface beam shaping device and method, designs optical free-form surface elements to achieve control of light distribution, and has no restrictions on the irradiance distribution of the incident light beam. The method can design both transmission-type free-form surface light distribution control and reflection-type free-form surface light distribution control elements. By providing a free-form surface optical element array design method and related devices, it can be applied to the light distribution control of multiple light sources and multiple light beams, and can achieve precise control of non-zero expansion beams. The present invention can control not only the irradiance distribution of the target surface of the output light beam by designing a free-form surface lens group or a free-form surface reflector group, but also control the output light beam to be a collimated light beam. The shaping element or element group in the present invention, in combination with other systems such as a beam expansion system, can be applicable to the requirements of incident beam apertures of different sizes and different spot sizes on the target surface. In addition, the method proposed in the present invention is also applicable to the design of aspheric surfaces. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. 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 creative work.

[0035] Figure 1 It is a schematic diagram of a collimated beam single free-form surface lens shaping device;

[0036] Figure 2 It is a schematic diagram of a divergent beam single free-form surface lens shaping device;

[0037] Figure 3 It is a schematic diagram of a collimated beam single free-form surface reflector shaping device;

[0038] Figure 4It is a schematic diagram of a divergent beam single free-form surface reflector shaping device;

[0039] Figure 5 It is a schematic diagram of a collimated beam multi-free-form surface lens shaping device;

[0040] Figure 6 It is a schematic diagram of a divergent beam multi-free-form surface lens shaping device;

[0041] Figure 7 It is a schematic diagram of a collimated beam shaping device with multiple free-form surface reflectors;

[0042] Figure 8 It is a schematic diagram of a divergent beam multi-free-form surface reflector shaping device;

[0043] Fig. 9 It is a schematic diagram of a reflective free-form surface shaping system;

[0044] Fig.10 It is a schematic diagram of a transmission-type free-form surface shaping system;

[0045] Fig.11 is a schematic diagram of the grid division of the steering symbol and the target surface in an embodiment of the present invention;

[0046] Fig.12 Schematic diagram of the corresponding discrete data of image pixels and grid points;

[0047] Fig.13 It is the meshing flow chart during the target surface mesh optimization process;

[0048] Fig.14 It is a schematic diagram of the initial shape and mesh of the calculated free-form surface;

[0049] Fig.15 It is a schematic diagram of grid division when the aperture of the incident light beam is circular or elliptical;

[0050] Fig.16 It is a schematic diagram of the calculation of the aspheric shaping system;

[0051] Fig.17 It is a schematic diagram of a free-form surface transmission laser shaping system that simultaneously controls the output irradiance and beam collimation;

[0052] Fig.18 It is a schematic diagram of a free-form surface reflective laser shaping system that simultaneously controls the output irradiance and beam collimation;

[0053] Fig.19 It is a schematic diagram of an aspheric shaping lens group for simultaneously controlling the output irradiance and beam collimation;

[0054] Fig. 20 It is a schematic diagram of the light path of the aspheric shaping lens group;

[0055] Fig.21 is a schematic diagram of a free-form surface reflector array and an optical path;

[0056] Fig. 22 It is a schematic diagram of the superposition of irradiance distribution of free-form surface reflector array;

[0057] Fig.23 This is the shaping result diagram of the aspheric lens group;

[0058] Fig.24 It uses a beam with complex irradiance distribution to produce a uniform illumination distribution on the target surface through a shaping system;

[0059] Fig.25 A beam with an elliptical aperture and a Gaussian irradiance distribution is transformed into a uniform irradiance distribution diagram through a shaping system. DETAILED DESCRIPTION

[0060] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0061] First, a typical free-form surface laser shaping device is introduced as follows:

[0062] Typical free-form surface laser shaping devices such as Figure 1-8 As shown, it usually includes a collimation system or a beam expansion system and a shaping system, wherein: Figure 1 and Figure 2 Schematic diagrams of single free-form lens shaping devices for collimated and divergent beams respectively; Figure 3 and Figure 4 Schematic diagrams of single free-form mirror shaping devices for collimated and divergent beams, respectively; Figure 5 and Figure 6 Schematic diagram of the double free-form surface lens shaping device for collimated light beam and divergent light beam respectively; Figure 7 and Figure 8 Schematic diagram of the double free-form mirror shaping device for collimated light beam and divergent light beam respectively.

[0063] If the light source emits a collimated beam, a beam expansion system (or beam reduction system) is usually required, such as Figure 1 , Figure 3 , Figure 5 and Figure 7 As shown, the light source emits a collimated light beam, and the diameter of the light beam emitted through the beam expansion system (or beam reduction system) is consistent with the incident aperture of the shaping system.

[0064] If the light source emits a divergent beam, a collimation system is usually required for collimation, such as Figure 2 , Figure 4 , Figure 6 and Figure 8 As shown, the light source emits a divergent light beam, which is collimated by the collimation system and then enters the shaping system. The focal length of the collimation system is determined by the incident aperture of the shaping system. The aperture of the light beam emitted by the light source after passing through the collimation system must be equal to the incident aperture of the shaping system.

[0065] If the irradiance distribution of the target surface is rotationally symmetric, you can use Figure 1 or Figure 2 To create a device, one only needs to replace the free-form surface lens with the corresponding aspherical lens.

[0066] If the irradiance distribution of the target surface is rotationally symmetric and the output beam is to be controlled to be a collimated beam, you can use Figure 5 and Figure 6 To create a device, you only need to replace two of the free-form surface lenses with two corresponding aspherical lenses.

[0067] like Fig. 9 , 10 As shown, taking parallel incident light as an example, the working principle of the reflection / transmission free-form surface shaping system is as follows: light is incident on the reflection / transmission free-form surface through the input plane, and after being reflected / transmitted by the designed free-form surface, it is irradiated on the target surface, and the required irradiance or spot distribution can be obtained.

[0068] Embodiment 1

[0069] This embodiment provides a single free-form surface reflection shaping optical element, and its design scheme is as follows:

[0070] Step 1: Set up and divide the initial grid;

[0071] The division and setting of the initial mesh are mainly for the mesh of the input plane and the mesh of the target surface. The number of meshes of the free-form surface is consistent with the number of meshes of the target surface, and the initial mesh of the target surface is also kept as a mesh with equal area distribution. Fig.11 If the target surface is to generate the illumination distribution shown in Fig.11 In the image shown in (a), the target surface is divided into grids as follows Fig.11 As shown in (b), how to transform the initial target surface grid with equal area distribution into the final Fig.11 This is a very critical step.

[0072] Assume that the grid point coordinates on the input plane and the target plane are represented as p(x ij ,y ij )、q(u ij ,vij ), further shortened to p ij and q ij i,j∈[1,n]×[1,n], where n is the number of rows and columns of grid points.

[0073] The irradiance distribution on the input plane and the target surface is denoted as I(x,y) and I'(u,v), respectively, where (x,y)∈Ω0 and (u,v)∈Ω1, where domains Ω0 and Ω1 represent the range of the input plane and the target surface, respectively.

[0074] The irradiance distribution of the input plane is known in advance, which is mainly determined by the incident beam used, such as Gaussian beam, uniform beam, Lambertian beam, etc. The irradiance distribution of the collected beam cross section is the irradiance distribution diagram of the input plane. Fig.11 As shown, the ideal irradiance distribution that the target surface hopes to produce. Fig.11 In (a), the output beam irradiance is set, and the entire image is distinguished by two different gray values ​​A1 and A2, which divide the image into different regions with their own gray values. Then I(u,v) can be expressed as formula (1), where A1 and A2 are two fixed values, representing different irradiances in domains a1 and a2.

[0075]

[0076] The irradiance distribution on the input plane and the target surface can be viewed as a digital image, where each grid point represents a corresponding pixel. The sum of the grayscale values ​​of all pixels in each image is equal to 1. Each pixel is associated with a corresponding grayscale value, which represents the irradiance value at the point where the pixel is located.

[0077] Step 2: Optimize the target surface mesh;

[0078] The irradiance values ​​of the grid points in the i-th row and j-th column on the input plane and the target surface are represented by I ij and I' ij The irradiance value of any grid on the input plane and the target plane is calculated by formula (2) as the average of the irradiance values ​​of the corresponding four grid points. Fig.12 As shown, the area of ​​the incident surface and the target surface corresponding to each grid are represented by S ij and S' ij The area of ​​each grid is usually determined by dividing it into two triangles, the sum of their areas represents the total area of ​​the grid.

[0079]

[0080] In formula (2), I(p ij )、I(p i+1j )、I(pij+1 ) and I(p i+1j+1 ) is the irradiance value of the four grid points in the i-th row and j-th column of the input plane; I'(q ij ), I'(q i+1j ), I'(q ij+1 ) and I'(q i+1j+1 ) is the irradiance value of the four grid points in the i-th row and j-th column of the target surface.

[0081] The grid of the input plane and the light intensity distribution of the input plane are fixed, so the energy of each grid on the input plane is fixed. The design of the free-form surface is to control the energy of the grid of the input plane to be incident on the corresponding grid on the target surface. The light intensity of each grid on the target surface is pre-set, such as Fig.12 As shown in the figure, in order to make the energy of the grid on the input plane equal to the energy of the corresponding grid on the target surface, it is necessary to adjust the grid area of ​​the output plane, which is an optimization process for the target surface grid. Because the light intensity distribution on the target surface is predetermined, according to the energy of the input plane grid and the energy of the corresponding target surface grid are equal, that is, I ij S ij =I' ij S' ij , which is used as the basis for whether the final target surface meshing is completed; because the mesh of the input plane remains unchanged, the mesh distribution of the target surface needs to be adjusted.

[0082] The detailed design process of target surface mesh distribution is as follows: Fig.13 As shown:

[0083] In the initial state, the input plane and target surface meshes are uniform, and the condition that the energy of the input plane mesh is equal to the energy of the corresponding target surface mesh cannot be met, that is:

[0084] I ij S ij =I' ij S' ij (3)

[0085] The target surface mesh needs to be optimized.

[0086] The optimization techniques of the mesh on the target surface mainly include:

[0087] First, construct the objective function as shown in formula (4):

[0088]

[0089] where f ij represents the difference between the energy of the input plane grid and the energy of the corresponding grid on the target surface. The purpose of optimizing the grid is to make |fij | is close to 0, let D ij =f ij .

[0090] The mesh of the target surface is optimized using the Poisson mesh optimization algorithm:

[0091] The mathematical relationship between the scalar field φ and the parameter D can be expressed by Poisson's equation (5). The scalar field φ is related to the grid coordinates on the target surface as shown in equation (6). By using equations (5) and (6), the optimization of the target surface grid points can be achieved, gradually reducing the difference D.

[0092]

[0093] in, represents the area of ​​the mesh on the target surface at the mth iteration, Represents the energy difference between the input plane and the target plane after m iterations. Approaching 0, the target surface meshing is completed, and the coordinates of the grid points on the target surface are

[0094] During the process of mesh control, the mesh on the free-form surface remains unchanged. By controlling the mesh of the target surface, the sampling points of the mesh on the free-form surface are always kept uniform, which facilitates the subsequent calculation of the vector height of the free-form surface.

[0095] Step 3: Calculate the normal vector of the corresponding sampling point on the free surface according to the directions of the incident light and the outgoing light to obtain the normal vector field;

[0096] Take the calculation of the vector height of a reflective free-form surface as an example to illustrate:

[0097] Initially, the z coordinate (sagittal) of the free-form surface is the data to be calculated, so the initial free-form surface reflection surface is replaced by a plane. The grid of the input plane is mapped to the initial plane. The coordinates of any grid point on the reflection surface are p = (p x ,p y ,p z ), the corresponding grid point coordinates on the target surface are q=(q u ,q v ,q z ). The x and y coordinates on the reflection surface remain unchanged, while the z coordinate reaches the optimal value through continuous iteration.

[0098] like Fig.14 As shown in the figure, the incident light passes through each grid point of the free-form surface, is reflected on the free-form surface, and is finally directed to the corresponding grid point on the target surface. The unit vector of the incident light is represented by In = [0, 0, 1], and the unit vector of the outgoing light is represented by Out:

[0099]

[0100] The outgoing light unit vector Out and the incident light unit vector In are obtained.

[0101] For the transmission free-form surface, equation (8) is used, and for the reflection free-form surface, equation (9) is used to calculate the normal vector of each sampling point on the free-form surface:

[0102]

[0103] where n t is the refractive index of the lens;

[0104]

[0105] It should be noted that since the z coordinate of the free-form surface is unknown, the outgoing light vector is calculated by using approximate coordinates. For a transmissive free-form surface, the coordinates of the initial free-form surface are directly replaced by the grid coordinates of a plane parallel to the substrate. For a reflective free-form surface, a plane is also used instead, but the reflective plane must have a certain inclination angle. The method for determining the inclination angle between the plane and each coordinate axis is as follows:

[0106] like Fig.14 As shown in the figure, the position of the initial point of the free-form surface is fixed G. The light incident on the initial point of the free-form surface reaches the corresponding grid point G1 on the target surface after being reflected by the point. According to the light incident on the point and the light reflected at the point, the normal vector through the point can be calculated. The initial reflection surface is a plane, and the normal vectors of each point on the reflection surface are the same. The coordinates of each point on the initial plane can be calculated:

[0107]

[0108] According to the initial reflection surface coordinates and equation (7), the initial outgoing light vector can be obtained and the normal vector can be calculated.

[0109] Step 4: Calculate the free-form surface sagittal height based on the normal vector field;

[0110] According to the normal vector field calculated in step 3, the vector height of the free surface can be calculated. The methods that can be used include discrete cosine transform, finite difference method, finite element method, and Fourier series method.

[0111] Take the discrete cosine transform (DCT) as an example:

[0112]

[0113] In formula (10), dct2( ) and idct2( ) are discrete cosine transform and inverse discrete cosine transform, h'k ' ,l represents the thickness in the frequency domain, and h k,l Indicates the vector height at the (k, l)th sampling point on the free surface m and n represent the total number of sampling points in the x and y directions.

[0114] The calculated vector height is iterated multiple times to obtain the optimal vector height; the iterative process can be described as follows:

[0115] First, after obtaining the normal vector, the vector height can be calculated h (1) is the vector height of all sampling points on the free-form surface obtained by the first calculation; Then the point cloud coordinates of the free-form surface are updated as Next, these updated coordinates can be used to calculate the new outgoing light vector Out (1) =p (1) -q, and recalculate the normal vector Using this normal vector, according to formula (10), the sagittal height on the free-form surface is calculated: h (2) is the vector height of all sampling points on the free-form surface obtained by the second calculation; Then the point cloud coordinates of the free-form surface are updated as Next, these updated coordinates can be used to calculate the new outgoing light vector Out (2) =p (2) -q, and recalculate the normal vector Using this normal vector, according to formula (10), the sagittal height on the free-form surface is calculated: Repeat the above process about 3-4 times to get a better free-form surface height.

[0116] Step 5: Build a solid model of the free-form surface transmission or reflection element and perform ray tracing to verify the results.

[0117] Beam shaping is achieved based on the prepared free-form surface reflection shaping optical element.

[0118] The preparation steps of the transmission-type free-form surface beam shaping element are the same as above and will not be repeated here.

[0119] The above-mentioned incident beam is rectangular, and the generated target surface is also rectangular. If the incident beam aperture is circular and the target surface is rectangular, the mesh division of the input plane and the target surface is as follows: Fig.15 As shown, Fig.15 (a) is the mesh division of the input plane. Fig.15 (b) in the figure is the mesh division of the target surface. Fig.15(c) is a schematic diagram of the input plane mesh being divided into two triangles. Fig.15 (d) is a schematic diagram of the target surface mesh being divided into two triangles. Fig.15 (e) shows the division of the input plane grid when the incident beam is an elliptical spot; when calculating the area of ​​each grid, each grid is also divided into two triangles, such as Fig.15 If the incident beam is an elliptical spot and the target surface is a rectangle, then Fig.15 The incident surface is divided as shown in (e), and the target surface is still Fig.15 The division is shown in (b).

[0120] Embodiment 2

[0121] This embodiment provides a single aspheric reflective shaping optical element, and its design scheme is as follows: the aspheric surface is a rotationally symmetric surface, and it is sufficient to design and calculate the generatrix, and the aspheric surface can be obtained by rotating the generatrix around the central axis. The design schematic diagram is shown in Figure (16).

[0122] Step 1: Set up and divide the initial mesh of the input and target surfaces, usually into concentric rings.

[0123] Step 2: Optimize the target surface mesh;

[0124] like Fig.16 As shown, the irradiance distribution of the input plane is I(r), the expected irradiance distribution of the target surface is E(r), and the energy difference of the annulus corresponding to the input surface and the target surface is:

[0125]

[0126] Initially, the annular areas of the input plane and the target plane are equal, so the energy difference is not zero, which requires optimizing the annular radius on the target plane. The energy difference is related to the radius of the target plane through the following formula.

[0127]

[0128] in, It means that after the mth iteration, the actual energy of the kth ring is different from the predetermined energy of the ring. When it approaches 0, the optimal radius distribution on the standardized target surface is obtained.

[0129] Step 3: Calculate the normal vector of the corresponding sampling point on the aspherical surface according to the directions of the incident light and the outgoing light to obtain the normal vector field;

[0130] With an initial plane P v Instead of the coordinate data of the aspherical surface, plane P vThe coordinates of each sampling point are known, and x is the size of the corresponding radius. Represents the z coordinate, which changes with subsequent optimization iterations. k Coordinates of the point The incident light refracts through this point to the target surface Q k (X k ,Z k ), the incident light vector In = [0,1], the outgoing light vector According to the law of refraction, the vector form can be obtained through P k Normal vector of a point Note that P k A point refers to any point on the aspherical surface, not a fixed point, so what is obtained is the normal vector field.

[0131] Step 4: Calculate the coordinates of each point on the aspherical surface based on the normal vector field;

[0132] According to the normal vector field, the discrete cosine transform (DCT) method is used to find any sampling point on the aspherical surface. Using this new coordinate point, we can find and the normal vector Using the updated normal vector Can be found After 3-4 iterations, the final z coordinates obtained are the coordinates of each point on the aspherical surface. After several iterations, the optimal coordinate points can be obtained, and these coordinate points can be fitted into a curve and rotated to obtain the aspherical surface.

[0133] Embodiment 3

[0134] This embodiment proposes a design for simultaneously controlling the irradiance distribution and collimation of the output light beam. There are many application scenarios that require not only controlling the irradiance distribution of the light beam on the target surface, but also requiring the emitted light beam to be a collimated light beam, so that the target surface can still maintain a predetermined irradiance distribution when placed at different distances from the optical system. In order to simultaneously control the irradiance distribution and collimation of the output light beam, two shaping optical elements are required, which can be a free-form surface lens group, or a free-form surface reflector group and an aspherical shaping lens group.

[0135] (1) The specific design scheme of the free-form surface lens group is as follows:

[0136] like Fig.17 As shown, the free-form surface lens group shaping system includes two free-form surface lenses, and each free-form surface lens includes a plane, a free-form surface and a side surface.

[0137] Among them, surface P and surface M are the free-form surfaces to be solved, P vand Mv are virtual planes, serving as the initial planes of the free-form surface. The first surface of lens P is a plane, and the second surface of lens M is a plane. The light beam incident on lens P is a collimated light beam, and the light beam emitted through lens M is also a collimated light beam, so P v The grid distribution of the input plane is the same as that of the Mv plane, and the grid distribution of the target plane is the same. The irradiance distribution of the incident beam and the irradiance distribution of the target plane are calculated according to the grid optimization method described in the first embodiment. v The mesh of the Mv surface and the target surface after optimization is the same, that is, the virtual plane P v The initial x, y coordinates on Mv are already known, and the parameter that needs to be obtained is the vector height, that is, the z coordinate. The method for obtaining the coordinates of the first free-form surface is the same as that in Example 1, except that the Mv surface is used as the target surface reached by the light beam after being emitted from the lens P. In this way, the z coordinates of all sampling points on the free-form surface P can be calculated according to the method recorded in Case 1. Once the free-form surface P is obtained, the light vector incident on the free-form surface M can be calculated based on the coordinate points on the free-form surface P and the initial coordinate points of Mv. The light incident on the free-form surface M is refracted by the free-form surface M and then emitted horizontally. Based on the incident light and the outgoing light vector, the normal vector corresponding to each sampling point on the second free-form surface M can be calculated, and the Z coordinate point of each sampling point on M can be calculated based on the normal vector field. In this process, the sampling points on P and M can be calculated to update the light vector emitted from the free-form surface P and the light vector incident on the free-form surface, thereby updating the normal vector field on the two free-form surfaces, and further calculating the z coordinates on the updated free-form surfaces P and M. Generally, this process can be repeated 3-4 times to obtain relatively good results.

[0138] (2) The specific design scheme of the reflective laser shaping system is as follows:

[0139] like Fig.18 As shown, the reflective laser shaping system transforms the incident Gaussian beam into a beam with uniform irradiance distribution after passing through the shaping system, and the outgoing beam is a collimated beam. Through the above method, the grid of the incident surface is divided and the grid of the target surface is optimized. Plane S and plane T are the input plane and target plane respectively, and the corresponding grid points on these two planes are S ij and T ij , a ray is emitted from each grid point on plane S as a sampling ray, and these rays are parallel and perpendicular to plane S. In addition, the emitted collimated beam is incident on the corresponding grid point on the target surface T. Reflective free-form surface laser shaping system, the shaping system includes two free-form surface reflectors, each of which includes a base, a free-form surface reflective surface and a side surface, and there is no restriction on the shape of the base. Establish the first point P of the reflector P, M 11and M 11 Incident on P 11 The light from point P 11 After reflection at point, it hits M 11 point, passing M 11 The light reflected from the point is incident on the corresponding grid point T on the target surface. 11 According to P 11 The incident and outgoing rays of the point can be obtained by 11 The normal vector of the point is obtained, so as to obtain 11 The tangent plane of point. Similarly, according to the incident M 11 The light of point P 11 M 11 and from M 11 Point outgoing ray M 11 T 11 , we can obtain M 11 The normal vector of the point is obtained, so as to obtain 11 For the free-form surface P, the position of the initial reflection surface is the same as that of the point P. 11 The tangent plane positions of the points are consistent. The sampling rays emitted from each grid point on the incident surface S hit the first initial plane. Each ray has an intersection with the initial plane and can be calculated P ij (1) For the second free-form surface M, the position of the initial reflection surface is 11 The intersection of the reverse extension of the light incident on the target surface and the initial plane of M

[0140] Because the coordinates S of the four faces ij , P ij , M ij , T ij All known, at this time P ij , M ij It is just the coordinates of the sampling points on the initial plane, which are used to approximately replace the coordinates of the free-form surface. In this way, the incident light and the outgoing light incident on any point on the free-form surfaces P and M can be obtained. According to the incident light and the outgoing light, the normal vector of any point on the free-form surfaces P and M can be calculated.

[0141] The incident light and refracted light S incident on any point on the free surface P ij P ij and P ij M ij , the incident light and the refracted light S incident on any point on the free surface M ij P ij and P ij M ij, in this way, the normal vector field N1 on the free-form surface P and the normal vector field N2 on the free-form surface M can be obtained. According to formula (10), the vector height of any point on the free-form surface can be calculated, that is, a new set of coordinates is obtained on P and M Recalculate a set of incoming and outgoing light vectors based on the new coordinates, and recalculate a set of normal vector fields and According to this new set of normal vector fields, the vector height of any point on the free surface is recalculated using formula (10), that is, a set of updated coordinates are obtained on P and M Repeat the above process, usually after 3-4 iterations, a relatively good set of free-form surface reflection surfaces can be obtained.

[0142] (3) Aspheric plastic lens group

[0143] like Fig.19 , 20 As shown, there are some applications such as shaping a Gaussian distributed laser beam into a flat-top distributed laser beam. The light spots on the incident surface and the target surface are both circular, but the outgoing beam is required to be a collimated beam. In this case, an aspheric lens group can be used to achieve this. The design of the aspheric group is explained below:

[0144] like Fig.19 , 20 As shown, the lens group includes two aspheric lenses, each of which includes a plane and an aspheric surface. Initially, the shape of the aspheric surface is unknown, and a virtual plane is used, P v The input plane and the target plane are both distributed in a ring-shaped manner. The input plane is divided into grids of equal area. The target plane is obtained by the optimization method described in Example 2. According to (1) in Example 3, it can be known that the input target plane and P v The grid distribution of the surface is the same, the grid distribution of the target surface is the same as that of the Mv surface, and the aspheric surface is a rotationally symmetric surface, so it is only necessary to calculate the generatrix contour, and the aspheric surface can be obtained by rotational symmetry around the axis.

[0145] Initially, P v and Mv coordinates are known, the incident light In 1k Incident on P k Point passing through P k After point refraction, the outgoing light ray Out 1k , we can calculate P k The z coordinate of the point, at this time P k Coordinates of the point Using the calculated P k The z coordinate of the point, recalculated based on and Out 2kWe can find out M k Normal vector of a point After obtaining the normal vector field, M can be obtained k Coordinates of the point According to P k Coordinates of the point and M k Coordinates of the point Can be recalculated P can be calculated k The z coordinate of the point, at this time P k Coordinates of the point According to the updated P k Recalculate the coordinates of the point based on and Out 2k We can find out M k Normal vector of a point After obtaining the normal vector field, M can be obtained k Coordinates of the point Generally, the final P can be obtained after 3-4 iterations. k Dot and M k The coordinates of the point.

[0146] Embodiment 4

[0147] This embodiment proposes a free-form surface reflector array design for light distribution control. The free-form surface reflector can be made of metal materials. Therefore, the free-form surface reflective shaping system can achieve high-power laser shaping. Using the free-form surface reflector array, each free-form surface reflector in the array can independently control the irradiance distribution of each beam of light on the target surface. Multiple beams are superimposed on the target surface to produce a uniform irradiance distribution, such as Fig.21 As shown, because multiple light beams are superimposed on the target surface, a high-power laser distribution can be generated on the target surface.

[0148] Assume that there is a reflector array consisting of k free-form surface reflectors. The 1st to (k-1)th free-form surface reflectors are designed for collimated beams, that is, beams with zero optical etendue, to produce uniform irradiance distribution on the target surface. Apply non-zero optical etendue beams to these reflectors. These (k-1) non-zero optical etendue beams pass through each free-form surface reflector and are incident on the target surface. After superposition, the irradiance distribution is generated as follows: Fig. 22 As shown in (a), the irradiance distribution is uneven at this time. The kth light beam uses a collimated light beam. The collimated light beam can be designed with a free-form surface according to the method described in Example 1 to produce a precise light distribution, that is, a compensation pattern, such as Fig. 22 As shown in (b). The uniform irradiance distribution produced by the superposition of all array beams on the target surface is shown in Fig. 22 As shown in (c), for a high-power array shaping system, a uniform irradiance distribution can be generated by superimposing (k-1) high-power non-zero optical etendue beams with 1 low-power optical etendue beam.

[0149] Some steps in the embodiments of the present invention may be implemented using software, and the corresponding software program may be stored in a readable storage medium, such as a CD or a hard disk.

[0150] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A free-form surface beam shaping method, characterized in that: The method is used to shape a light beam with arbitrary irradiance distribution into a desired irradiance distribution through a free-form surface lens or a reflector. The design method of the free-form surface lens or the reflector includes: Step 1: Determine the initial conditions and initialization parameters; Step 2: Optimize the initial mesh of the target surface; The optimization criterion is that the input plane mesh energy is equal to the corresponding target surface mesh energy, and the method used for optimizing the target surface mesh is the Poisson-based polygonal mesh optimization algorithm; Step 3: Calculate the normal vector of the corresponding sampling point on the free surface according to the directions of the incident light and the outgoing light to obtain the normal vector field; The unit vector of the incident light is In = [0, 0, 1], and the unit vector of the outgoing light is Out, and the expression is: Where p is the coordinate of any grid point on the input plane, and q is the coordinate of the corresponding grid point on the target plane; Then the calculation formula for the normal vector of each sampling point on the transmission free-form surface is: The calculation formula for the normal vector of each sampling point on the reflective free-form surface is: Among them, n t is the refractive index of the lens material; Step 4: Calculate the free-form surface sagittal height based on the normal vector field obtained in step 3; The discrete cosine transform is used to calculate the vector height of the free surface. The calculation formula is: h k,l =idct2(h" k,l ) Where N is the normal vector calculated in step 3, dct2() and idct2() are discrete cosine transform and inverse discrete cosine transform, and h" k,l represents the thickness in the frequency domain, h k,l represents the vector height at the (k, l)th sampling point on the free surface, m and n represent the total number of sampling points in the x and y directions; Step 5: Build a solid model of the free-form surface transmission or reflection element and perform ray tracing to verify the results.

2. The method according to claim 1, characterized in that The step 1 comprises: The input plane and the target surface are divided into grids with equal area distribution. The number of grids on the input plane and the target surface is consistent. The grid points on the input plane and the target surface are represented by p ij and q ij , i, j ∈ [1, n] × [1, n], n is the number of grid rows and columns, the irradiance distribution on the input plane and the target surface is expressed as I(x, y) and I'(u, v), (x, y) ∈ Ω0, (u, v) ∈ Ω1, where the domain Ω0, Ω1 represents the range of the input plane and the target surface respectively; Then the irradiance I of each grid on the input plane is ij And the irradiance value I' of each grid on the target surface ij The expressions are: I ij =(I(p ij )+I(p i+1j )+I(p ij+1 )+I(p i+1j+1 )) / 4 I' ij =(I'(q ij )+I'(q i+1j )+I'(q ij+1 )+I'(q i+1j+1 )) / 4 Among them, I(p ij )、I(p i+1j )、I(p ij+1 ) and I(p i+1j+1 ) is the irradiance value of the four grid points in the i-th row and j-th column of the input plane; I'(q ij ), I'(q i+1j ), I'(q ij+1 ) and I'(q i+1j+1 ) are the irradiance values ​​of the four grid points in the i-th row and j-th column of the target surface; The initial meshing of the input surface and the target surface includes three cases: When the incident beam aperture is rectangular and the target surface is rectangular, the initial grids of both the input surface and the target surface are divided into multiple rectangular grid cells; When the incident beam aperture is circular and the target surface is rectangular, the input surface is first divided into concentric rings, and then the concentric rings are further divided by radial lines; the target surface is first divided into concentric rectangular frames, and then multiple lines radiate from the center to further divide the rectangular frames; When the incident beam aperture is elliptical and the target surface is rectangular, the input surface is first divided into concentric elliptical rings, and then multiple lines radiate from the center to further separate the elliptical rings; the target surface is first divided into concentric rectangular frames, and then multiple lines radiate from the center to further separate the rectangular frames.

3. A transmission-type free-form surface laser shaping system, characterized in that: The projection-type free-form surface laser shaping system comprises two free-form surface lenses, each of which is composed of a plane, a free-form surface and a side surface; The free-form surface to be solved is represented by surface P and surface M. v and M v represents a virtual plane, P v and M v As the initial plane of the free-form surface; P v and M v The mesh distribution of the input plane and the target surface is the same; The input plane and the target surface are meshed in equal areas to obtain the initial mesh distribution; According to the irradiance distribution of the incident light beam and the irradiance distribution of the target surface, the target surface mesh is optimized by the optimization method in claim 1, and the optimal mesh of the target surface is obtained, that is, M v Grid, and P v The grid of the input plane has the same distribution as the grid of the input plane; calculate the vector height on the virtual plane, that is, the z coordinate; According to the determined grid distribution, the coordinate points on the free-form surface P and the coordinates of the sampling points on the free-form surface M are obtained by using steps 3 and 4 in claim 1; and the free-form surfaces of the two lenses are determined based on the obtained coordinate points on the free-form surface P and the coordinates of the sampling points on the free-form surface M.

4. A reflective free-form surface laser shaping system, characterized in that: The reflective free-form surface laser shaping system comprises two free-form surface reflectors P and M, each of which is composed of a substrate, a free-form surface reflective surface and a side surface, and there is no restriction on the shape of the substrate; The input plane S and the target plane T are divided into grids, and the corresponding grid points are S ij and T ij ; A light beam is emitted from each grid point on the input plane S as a sampling light beam, and the sampling light beams are parallel to each other and perpendicular to the plane S; in addition, the emitted collimated light beam is incident on the corresponding grid point on the target surface T; Establish the first grid point P on the free surface of the reflector P and M 11 and M 11 , incident on P 11 The light from point P 11 After reflection at point M 11 point, passing M 11 The light reflected from the point is incident on the corresponding grid point T on the target surface. 11 ; According to P 11 The incident and outgoing rays of the point P are obtained. 11 The normal vector of the point is obtained, so as to obtain 11 The tangent plane of point; similarly, according to the incident M 11 The light of point P 11 M 11 and from M 11 Point outgoing ray M 11 T 11 , and get M 11 The normal vector of the point is obtained, so as to obtain 11 Tangent plane of a point; For the free-form surface of the reflector P, the position of the initial reflective surface is 11 The tangent plane positions of the points are consistent, and the sampling rays emitted from each grid point on the incident surface S hit the first initial plane. Each ray has an intersection with the initial plane and is calculated. For the second free-form surface M, the position of the initial reflection surface is 11 The tangent plane position of the point is consistent; the intersection of the reverse extension line of the light incident on the target surface and the initial plane of M When the coordinates S on the four faces are obtained ij , P ij , M ij , T ij The incident light and the outgoing light incident on any point on the free-form surfaces P and M can be obtained, and a new set of coordinates on the free-form surfaces P and M can be calculated according to steps 3 and 4 described in claim 1. Recalculate a set of incident and outgoing light vectors based on the new coordinates, and again calculate a set of updated coordinates on P and M according to steps 3 and 4 of claim 1 Repeat the above process 3-4 times to iterate and obtain the free-form surface reflection surface.

5. A method for aspheric beam shaping, characterized in that: The aspheric beam shaping method is used to shape a beam with a rotationally symmetrical irradiance distribution into a desired irradiance distribution through an aspheric lens. The design method of the aspheric lens includes: Step S1: Initially mesh the input plane and the target surface; the input plane is a circle, and the target surface is a circle; both the input plane and the target surface are divided into ring zones, and initially the input plane and the target surface are divided into ring zones with equal areas; Step S2: Optimizing the radius of the target surface ring; The optimization criterion is the energy difference D between the annulus corresponding to the input surface and the target surface k is zero; The irradiance distribution of the input plane is represented by I(r), the expected irradiance distribution of the target surface is represented by E(r), and the energy difference D between the kth corresponding rings of the input plane and the target surface is k for: Among them, E k is the kth ring irradiance distribution of the input plane, R k is the radius of the kth ring in the input plane, I k is the irradiance distribution of the kth ring on the target plane, r k is the radius of the kth ring on the target plane; Initially, the annular areas of the input plane and the target plane are equal, and their energy difference is not zero. The energy difference between the two is made zero by optimizing the annular radius on the target plane. The energy difference is related to the radius of the target plane by the following formula: in, It means that after the mth iteration, the actual energy of the kth ring is different from the predetermined energy of the ring. k When it approaches 0, the optimal radius distribution on the standardized target surface is obtained; Step S3: Calculate the normal vector of the corresponding sampling point on the busbar according to the directions of the incident light and the outgoing light to obtain the normal vector field; Step S4: Calculate the vector height of each point on the busbar based on the normal vector field; Step S5: construct an aspheric lens by rotating the generatrix.

6. The method according to claim 5, characterized in that In the step S3, the normal vector field is obtained according to the normal vectors of the corresponding sampling points on the busbar according to the directions of the incident light and the outgoing light; With an initial plane P v Instead of the coordinate data of the aspherical surface, plane P v The coordinates of each sampling point are known, and x is the size of the corresponding radius. represents the z coordinate, which changes with the optimization iteration; P k Coordinates of the point The incident light refracts through this point to the target surface Q k (X k ,Z k ), the incident light vector In = [0,1], the outgoing light vector According to the law of refraction, the vector form can be obtained through P k Normal vector of a point Note that P k The point refers to any point on the aspherical surface, not a fixed point, so what is obtained is the normal vector field; The step S4 calculates the coordinates of each point on the busbar based on the normal vector field; Find any sampling point on the aspherical surface based on the normal vector field Using this new coordinate point, we can find and the normal vector Using the updated normal vector Find The final z coordinate obtained after 3-4 iterations is the coordinate of each point on the aspherical surface; the optimal coordinate points are obtained through iteration, and these coordinate points can be fitted into a curve and rotated to obtain the aspherical surface.

7. A method for beam shaping using an aspherical lens assembly, characterized in that: The method is used to shape a light beam with a rotationally symmetrical irradiance distribution into a uniform irradiance distribution through an aspheric lens group, and the outgoing light beam remains collimated; the aspheric lens group includes two aspheric lenses, each of which includes a plane and an aspheric surface; the shape of the aspheric surface is not known at the initial stage, so a virtual plane P is used v and Mv; optimize the meshes of the input plane and the target surface and map them to P respectively v The aspheric surface is a rotationally symmetric surface, so we only need to calculate the generatrix profile, and the aspheric surface can be obtained by rotational symmetry around the axis; Incident light In 1k Incident on P k Point passing through P k After point refraction, the outgoing light ray Out 1k , calculate P k The z coordinate of the point, at this time P k Coordinates of the point Using the calculated P k The z coordinate of the point, recalculated based on and Out 2k Find the M k Normal vector of a point After obtaining the normal vector field, we can find M k Coordinates of the point According to P k Coordinates of the point and M k Coordinates of the point Recalculate Calculate P k After the z coordinate of the point is determined, P k Coordinates of the point According to the updated P k Recalculate the coordinates of the points based on and Out 2k Find the M k Normal vector of a point After obtaining the normal vector field, M can be obtained k Coordinates of the point The final P is obtained through 3-4 iterations k Dot and M k The coordinates of the point.

8. A free-form surface reflector array, characterized in that: The free-form surface reflector array independently controls the irradiance distribution of each reflector on the target surface, and finally superimposes all the irradiance distributions on the target surface to generate a uniform irradiance distribution; Assume that the reflector array is composed of k free-form surface reflectors, and the 1st to (k-1)th free-form surface reflectors are designed for collimated beams, that is, beams with zero optical extension, so that they produce uniform irradiance distribution on the target surface; beams with non-zero optical extension are applied to these reflectors; these (k-1) non-zero optical extension beams are incident on the target surface through each free-form surface reflector respectively, and the irradiance produced after superposition is uneven; the kth beam uses a collimated beam, and the collimated beam calculates the free-form surface according to the method according to claim 1 to produce accurate light distribution, and all array beams produce uniform irradiance distribution after superposition on the target surface; uniform irradiance distribution is produced by superimposing (k-1) high-power non-zero optical extension beams with 1 low-power optical extension beam.

9. An optical system for free-form surface beam shaping, characterized in that: The optical system comprises: A light source, a light source with a divergent angle or a light source outputting a collimated light beam; Collimation system or beam expansion system, when the light source is a light source with a divergence angle, it is used in conjunction with the collimation system; when the light source is a light source that outputs a collimated beam, it is used in conjunction with the beam expansion system, and the beam expansion ratio of the beam expansion system is greater than 1 or less than 1; A free-form surface shaping optical element designed by the design method of claim 1; The light beam emitted by a single free-form surface shaping optical element is collimated by a collimating lens, and the size of the collimated light spot is achieved using different lens focal lengths; The light beam emitted after passing through the free-form surface lens system is scaled by a beam expansion system to scale the spot size so that the spot size on the target surface matches the required spot size on the target surface.

10. An optical system for aspheric beam shaping, characterized in that: The optical system comprises: A light source, a light source with a divergence angle or a light source outputting a collimated light beam, the aperture of the light beam is circular, and the irradiance distribution of the light beam is rotationally symmetrical; Collimation system or beam expansion system, when the light source is a light source with a divergence angle, it is used in conjunction with the collimation system; when the light source is a light source that outputs a collimated beam, it is used in conjunction with the beam expansion system, and the beam expansion ratio of the beam expansion system is greater than 1 or less than 1; An aspheric plastic lens designed by the method according to any one of claims 5 to 7; The light beam emitted from a single aspheric shaping lens is collimated by a collimating lens, and the size of the collimated light spot is achieved by using lenses with different focal lengths; The light beam emitted after the aspheric shaping system is scaled by a beam expansion system to make the light spot on the target surface match the required light spot size on the target surface.

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