A microlens array refractive power distribution modulation method, application, verification method and vision correction element

Abstract

The present application relates to a kind of microlens array refractive power distribution modulation method, application, verification method and vision correction element, comprising the following steps: constructing space weight modulation function to the refractive power of each microlens is dynamically modulated, the refractive power of each microlens from center to edge smooth transition, adjacent microlens curvature is continuous, adjacent microlens has continuous curved surface / step surface and refractive power at boundary;Wherein, the curved surface / step surface position between adjacent microlenses, curved surface / step surface slope and curved surface / step surface curvature smooth connection.The modulation method of the present application is dynamically modulated to the refractive power of each microlens, the refractive power of each lens in microlens array from center to edge smooth transition, and through single parameter adaptation different refractive power demand, user no longer perceives the sudden change of correction degree when scanning across lens boundary, and viewing experience is uniform and comfortable, belong to optical element design technical field.

Description

Technical Field

[0001] This invention relates to the field of optical element design technology, specifically to a method for modulating the refractive power distribution of a microlens array, its application, verification method, and a vision correction element. Background Technology

[0002] Microlens arrays (MLAs) have broad application prospects in the field of display technology, especially in the magnification coating of display screens. By attaching microlens arrays to the surface of a display screen, effects such as local or overall image magnification, viewing angle control, or light field modulation can be achieved. In such applications, the distribution of refractive power (i.e., optical power) of each microlens unit directly determines the uniformity of the magnification effect and visual comfort.

[0003] Ideally, to achieve a continuous, seamless magnification experience across different areas of the screen, the refractive power of each microlens should gradually change from its center to the edge, and the refractive power of adjacent lenses should maintain a smooth transition at the boundaries. However, existing microlens array designs often suffer from discontinuities in refractive power at the boundaries of adjacent lenses. Specifically, when the user's gaze sweeps across and crosses the lens boundaries, the human eye perceives a sudden change in screen magnification. This visual jump disrupts the continuity of viewing, causing visual fatigue or discomfort, and severely impacts the user experience and usability of such products. Figure 2 As shown in (a) of the diagram.

[0004] To address the aforementioned issues, existing technologies attempt to optimize the lens surface shape to achieve a smooth connection between the positions and slopes of adjacent lenses at the boundary, thereby reducing geometric abrupt changes. However, these methods primarily focus on the continuity of the first derivative-slope of the surface shape, neglecting the continuity of the second derivative-curvature, such as... Figure 2 As shown in (b) in the figure. Curvature directly corresponds to refractive power, so even if the position and slope are continuous, the step of curvature at the boundary still exists. The human visual system is quite sensitive to changes in curvature, and the sudden change in refractive power caused by such a curvature step can still be perceived by the human eye, thus failing to fundamentally eliminate visual discomfort during viewing.

[0005] In related optical design fields, progressive addition lenses (PAL) achieve a continuous and smooth transition of refractive power from the distance to the near field within a single sheet lens, effectively avoiding image jump. However, PAL technology is a scheme for gradual change in optical power across different fields of view within a single lens, and its design logic does not involve the boundary coordination issues between multiple discrete microlens units. Furthermore, the refractive power distribution of PAL is typically described by complex and non-parametric freeform surfaces, making it difficult to directly simplify or extend to the design of microlens arrays containing a large number of periodically or non-periodically arranged lens units.

[0006] In summary, current technologies lack a universal, parameterizable microlens array design method that can achieve a continuous transition of refractive power from the center to the edge of each lens within the array, while ensuring the continuity of curvature at the boundaries of adjacent lenses, and flexibly adapt to different target refractive power requirements using a single parameter. Therefore, developing a novel microlens array design method that can solve these problems has significant engineering application value and market potential. Summary of the Invention

[0007] To address the technical problems existing in the prior art, the purpose of this invention is to provide a method for modulating the refractive power distribution of a microlens array. This method dynamically modulates the refractive power of each microlens through a spatial weight modulation function, allowing the refractive power of each lens in the microlens array to smoothly transition from the center to the edge. Furthermore, it adapts to different refractive power requirements through a single parameter, so that users no longer perceive sudden changes in the degree of correction when scanning across the lens boundaries, resulting in a uniform and comfortable viewing experience.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A method for modulating the refractive power distribution of a microlens array includes the following steps:

[0010] A spatial weighted modulation function is constructed to dynamically modulate the refractive power of each microlens, so that the refractive power of each microlens transitions smoothly from the center to the edge, the curvature of adjacent microlenses is continuous, and adjacent microlenses have continuous curved / stepped surfaces and refractive power at the boundary.

[0011] Among them, the positions, slopes, and curvatures of the curved / step surfaces between adjacent microlenses are smoothly connected.

[0012] Preferably, the spatial weight modulation function is as follows: the refractive power is greatest at the center of the microlens, and the normalization ratio is 1;

[0013] The refractive power P0 at the center of each microlens is determined by the formula:

[0014] P0=(n-1) / R,

[0015] Where n is the refractive index of the lens material, and R is the radius of curvature of the microlens center.

[0016] The refractive power at the edge of the microlens is k times that at the center, where k is the edge attenuation coefficient, and the edge attenuation coefficient k satisfies 0. <k≤1;

[0017] During the transition of the microlens from the center to the edge, the refractive power and curvature change continuously, without abrupt changes at the edge;

[0018] The edge attenuation coefficient k is selected according to the refractive power at the center of the microlens. According to the refractive power at the center of different microlenses, the edge attenuation coefficient k is 0.60 - 0.98. Among them, when P0 ≤ 1.00 D, k takes a value from 0.60 to 0.80; when 1.00 D < P0 ≤ 4.00 D, k takes a value from 0.80 to 0.94; when P0 > 4.00 D, k takes a value from 0.94 to 0.98.

[0019] Preferably, when the microlens array is a two-dimensional rectangular array, the refractive power modulation is performed by the spatial weight modulation function in the row direction and the column direction respectively. The edge attenuation coefficients in each direction are denoted as k1 and k2 respectively, where k1 and k2 are set independently. The refractive power of the microlenses at the four corner positions of the two-dimensional rectangular array is P0 × k1 × k2.

[0020] Preferably, the shape of the microlens is circular or polygonal.

[0021] Preferably, the microlens is manufactured by precision turning, nanoimprinting, injection molding or grayscale lithography.

[0022] Preferably, when the microlens array is a Fresnel lens array, each Fresnel lens has a Fresnel zone structure, and the Fresnel zone structure of each Fresnel lens retains the curvature at the corresponding radial position.

[0023] Among them, the refractive power of each Fresnel lens is dynamically modulated by the spatial weight modulation function, so that the step surface position, step surface slope and step surface curvature between adjacent Fresnel lenses are smoothly connected.

[0024] Among them, the Fresnel zone structure of each Fresnel lens includes multiple zones. The step height between adjacent zones of the Fresnel lens is modulated by the spatial weight modulation function, so that the step height between adjacent zones gradually decreases from the center to the edge of the Fresnel lens, and the step height between adjacent zones changes according to the same smoothing principle from the center to the edge, so as to reduce the stray light of the Fresnel lens.

[0025] Preferably, when there is an optical path avoidance structure in the microlens array, the optical path avoidance structure in the microlens array is modulated by the spatial weight modulation function, and the edge attenuation coefficient k set in the area where the optical path avoidance structure is arranged in the microlens array is lower than the edge attenuation coefficient k in other areas.

[0026] The second object of the present invention is to provide an application of a method for modulating the refractive power distribution of a microlens array, which is applied to the phase distribution design of a metasurface optical element and the modulation of a toric microlens array. Among them, after the metasurface optical element is modulated, the phase of each unit of the metasurface optical element smoothly transitions from the center to the edge according to the spatial weight function, and the phase is continuous at the boundary of two adjacent units of the adjacent metasurface optical elements, eliminating the diffraction artifacts and stray light caused by the phase step.

[0027] To ensure a smooth transition of refractive power from the center to the edge of each lens in the microlens array, the following methods are provided for verification.

[0028] The third objective of this invention is to provide a verification method that uses a surface profiler to scan the surface of a microlens array modulated by the microlens array refractive power distribution modulation method, extracts the radius of curvature of each lens, and fits the refractive power distribution curve to achieve the detection and verification of the microlens array refractive power distribution modulation method.

[0029] The fourth objective of this invention is to provide a vision correction element obtained by a microlens array refractive power distribution modulation method.

[0030] In vision correction elements, the refractive power of each microlens transitions smoothly from the center to the edge, and the curvature of adjacent microlenses is continuous at the boundary.

[0031] Vision correction components include films and individual lenses;

[0032] Vision correction elements are applied to flat or curved transparent substrates.

[0033] In summary, the present invention has the following advantages:

[0034] 1. The modulation method of the present invention dynamically modulates the refractive power of each microlens through a spatial weight modulation function, so that the refractive power of each lens in the microlens array smoothly transitions from the center to the edge, and adapts to different refractive power requirements through a single parameter. When scanning through the lens boundary, the user no longer perceives a sudden change in the degree of correction, and the viewing experience is uniform and comfortable, solving the problem of the user perceiving a sudden change in the degree of correction when scanning through the lens boundary.

[0035] 2. The modulation method of the present invention modulates the Fresnel lens array through a spatial weighted modulation function, which eliminates dispersion problems (unlike diffraction Fresnel) and multi-level diffraction efficiency loss, and provides a consistent refractive correction effect across the entire visible light band.

[0036] 3. The modulation method of the present invention can be applied to planar or curved substrates. The curved substrates include spherical, aspherical, freeform, or complex curved surfaces, and are suitable for various curved optical products such as ski goggles, sports glasses, and helmet visors. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the spatial distribution curve of refractive power. The horizontal axis represents the normalized radius (0 to 1), and the vertical axis represents the spatial distribution value of refractive power. The curve shows the process of refractive power smoothly decreasing from the maximum value at the center to k times the central value at the edge. The solid line shows the spatial distribution curve of refractive power, and the dashed line shows the contrast curve that only ensures the slope is continuous (the curvature is discontinuous at the boundary).

[0038] Figure 2 This is a schematic diagram showing the contrast between different levels of refractive power transition at the boundary of adjacent microlenses. Figure 2 (a) in the figure is a curve of a step-type boundary - abrupt change in refractive power, and the stripes can be clearly perceived by the human eye. Figure 2 (b) is a curve with only continuous slope (i.e., no discontinuity in the first-order differential) – the surface is smooth and without bends, but the curvature can change abruptly, and the refractive power can still be perceived as changing. Figure 2 (c) is a curve of continuous curvature (Example 1) - the curvature also transitions smoothly, and the refractive power of adjacent lenses is basically equal at the boundary. There is no obvious discomfort when scanning across the boundary.

[0039] Figure 3 This is a schematic diagram of a lens array arrangement—showing a two-dimensional grid arrangement of M rows × N columns of microlenses and the relationship between adjacent lenses.

[0040] Figure 4 for Figure 3 A magnified view of a portion of the image.

[0041] Figure 5 This is a continuous refractive power spatial distribution curve. The horizontal axis is the normalized radius (0 to 1), and the vertical axis is the refractive power spatial distribution value. The center value, edge value, and continuity condition are marked.

[0042] Figure 6 This is a schematic diagram of the refractive Fresnel ring section, showing how N concentric rings translate the continuous refractive power distribution surface along the optical axis to remove excess sagittal material. Each ring retains the local slope of the original surface at the corresponding radial position, and the decreasing trend of the ring width and the step height are marked.

[0043] Figure 7 To compare the sagittal distribution of continuous curved surfaces, refractive power distribution curved surfaces, and Fresnel composite curved surfaces, the horizontal axis represents the radial distance, the vertical axis represents the sagittal height sag(r), and the sagittal thinning ratio is marked.

[0044] Figure 8 This is a schematic diagram comparing the phase distribution of each unit in a metasurface optical element. It shows the change of the phase distribution (solid line) after modulation by the spatial weight modulation function and the uniform phase distribution (dashed line) along the normalized radius of the metasurface. After modulation, the phase smoothly transitions from the center to the edge, eliminating the phase step at the unit boundary. Detailed Implementation

[0045] The present invention will now be described in further detail with reference to specific embodiments.

[0046] Example 1

[0047] like Figures 1-4As shown, this embodiment provides a method for modulating the refractive power distribution of a microlens array, which includes the following steps: constructing a spatial weight modulation function to dynamically modulate the refractive power of each microlens, so that the refractive power of each microlens smoothly transitions from the center to the edge, the curvature of adjacent microlenses is continuous, and adjacent microlenses have continuous curved / stepped surfaces and refractive power at the boundary.

[0048] In this embodiment, the surface positions, slopes, and curvatures of adjacent microlenses are smoothly connected. Through this smooth connection, the surface in the transition region between adjacent microlenses satisfies six endpoint constraints, achieving curvature continuity at the edges. This surface construction method, which satisfies six endpoint constraints, represents a different level of smoothness in physical essence compared to the existing technology that only guarantees position and slope continuity (four constraints). While ensuring only position and slope continuity results in a smooth, crease-free surface, curvature can abruptly change at the boundaries, manifesting as perceptible fluctuations in refractive power. The method in this embodiment, through six constraints, ensures a smooth curvature transition as well, with refractive power changes smoothed to below the human eye's perceptible threshold (approximately 0.25D), thus eliminating noticeable discomfort when scanning across lens boundaries. Furthermore, the aforementioned surface satisfying the six constraints can be uniquely determined using known interpolation methods.

[0049] The spatial weighting modulation function is as follows: the refractive power is greatest at the center of the microlens, and the normalization ratio is 1.

[0050] The refractive power at the edge of the microlens is k times that at the center, where k is the edge attenuation coefficient, and the edge attenuation coefficient k satisfies 0. <k≤1;

[0051] During the transition of a microlens from the center to the edge, the refractive power and curvature change continuously, with no abrupt changes at the edge.

[0052] The refractive power P0 at the center of each microlens is determined by the formula:

[0053] P0=(n-1) / R,

[0054] Where n is the refractive index of the lens material, and R is the radius of curvature of the microlens center.

[0055] The edge attenuation coefficient k is selected according to the absolute value P0 of the refractive power at the center of the microlens, and the value range of k is from 0.60 to 0.98. Specifically: when P0≤1.00D, k takes values from 0.60 to 0.80; when 1.00D<P0≤4.00D, k takes values from 0.80 to 0.94; when P0>4.00D, k takes values from 0.94 to 0.98. The lower the absolute value of the refractive power, the lower the value of k, to expand the smooth transition area and enhance the perception effect of the continuity of the boundary refractive power; the higher the absolute value of the refractive power, the higher the value of k, to ensure the central correction accuracy. Exemplarily, when the screen magnification film (P0≈0.50D), k≈0.65, when P0≈1.00D, k≈0.80, when P0≈2.00D, k≈0.88, when P0≈3.00D, k≈0.92, when P0≈6.00D, k≈0.98.

[0056] For example, when the microlens array is a two-dimensional rectangular array, the refractive power modulation is performed by the spatial weight modulation function in the row direction and the column direction respectively. The edge attenuation coefficients in each direction are denoted as k1 and k2 respectively, where k1 and k2 are set independently. The refractive power of the microlenses at the four corners of the two-dimensional rectangular array is P0×k1×k2. The refractive power at the edge of the row direction is P0×k_x, the refractive power at the edge of the column direction is P0×k_y, and the refractive power of the lenses at the four corners of the array is P0×k_x×k_y. Exemplarily, when k_x≈0.95 and k_y≈0.80, the refractive power at the edge of the row direction is P0×0.95, the refractive power at the edge of the column direction is P0×0.80, and the refractive power at the four corners is P0×0.76. Exemplarily, the spatial weight modulation function f(t) can adopt a monotonically decreasing function that satisfies the conditions of position, slope and curvature continuity at the center and the edge, where t is the normalized position parameter (0≤t≤1), t = 0 corresponds to the lens center, and t = 1 corresponds to the lens edge. The conditions that both the center and the edge satisfy the position, slope and curvature continuity are: the center takes the maximum value 1, and the change rate and the curvature change rate are zero; the edge takes the value of k, and the change rate and the curvature change rate are also zero. For a line array composed of a single row of N microlenses, the normalized position t_i of the i-th microlens is |i - c| / d, where c is the index of the central lens and d is the index distance between the edge lens and the central lens, and the refractive power P_i of this lens is P0×f(t_i). Exemplarily, taking a single-row array with N = 7 and k≈0.94 as an example, the refractive power of the central lens (t = 0) is P0, the refractive power of the outermost edge lens (t = 1) is P0×0.94, and the refractive powers of the intermediate lenses are determined by f(t) according to their respective normalized positions. The method can be directly applied to flat or curved transparent substrates, and the curved substrates include but are not limited to spherical, aspherical, free-form or compound-curved surfaces. When applied to a curved substrate, the spatial weight modulation function is defined on the curved surface, and during manufacturing, it is directly processed and formed on the curved surface mold or substrate by precision turning or nanoimprinting.

[0057] This embodiment provides the following application example, and the design steps are as follows:

[0058] a. Determine the radius of curvature of the microlens center R=(n-1) / P0 based on the target refractive power P0. For example, when n=1.52, R≈347mm when P0=+1.50D.

[0059] b. Select the edge attenuation coefficient k based on P0. For example, when P0 = +1.50D, k ≈ 0.92.

[0060] c. The surface of each lens is determined by its target refractive power and spatial weight modulation function, and the mold is processed according to this surface during manufacturing.

[0061] d. The microlens array is exemplarily arranged with a spacing of approximately 7 mm, forming a rectangular array of approximately 7 rows × 5 columns within a lens area of ​​approximately 52 mm × 34 mm. For example, taking a target refractive power of approximately -2.00 D and a refractive index of approximately 1.52 as an example, after modulation, the refractive power difference at the boundary of adjacent lenses does not exceed approximately 0.06 D, which is lower than the threshold perceptible to the human eye (approximately 0.25 D), and the user experiences no significant discomfort when scanning across the lens boundary.

[0062] Furthermore, an effect comparison was conducted using a target refractive power of approximately -6.00D and a spacing of approximately 7mm as an example. Existing continuous curved microlens arrays satisfy position and slope continuity (i.e., first-order continuity) at their boundaries, but curvature can abruptly change at these boundaries, resulting in a refractive power jump of approximately 0.5D, exceeding the human eye's perceptible threshold (approximately 0.25D). Users can perceive a sudden change in correction level when scanning across the lens boundaries. Using the modulation method of this embodiment, with k≈0.94, after modulation, adjacent lenses not only maintain position and slope continuity at their boundaries but also experience a smooth curvature transition (i.e., second-order continuity). The refractive power of adjacent lenses at the boundaries is essentially equal, with no refractive power jump. The visual quality remains uniform when the user scans across the entire microlens array, with VA changes not exceeding approximately one line, and no discomfort caused by abrupt refractive power changes.

[0063] The above effects can be quantitatively verified through optical theory. The test conditions are: microlens spacing p≈7mm, half-aperture a≈3.0mm (including the transition zone), human eye pupil diameter approximately 3mm (daytime standard illumination conditions), and human eye refractive power perceptible threshold ΔP_th≈0.25D. In a first-order continuous microlens array, the curvature jump Δκ at the boundary between adjacent lenses corresponds to a refractive power jump ΔP1=(n-1)×Δκ, where n≈1.52 is the refractive index of the lens material. This refractive power jump can reach approximately 0.5D, exceeding the human eye perceptible threshold ΔP_th≈0.25D. Using the modulation method of this embodiment, adjacent lenses at the boundary satisfy the constraint conditions of continuous position, slope, and curvature, with a curvature jump Δκ=0 and a refractive power jump ΔP2=0. When the pupil is covered by multiple lenses (approximately 6mm in low light conditions), the difference in refractive power between the sub-beams entering the pupil does not exceed approximately 0.06D, far lower than ΔP_th≈0.25D. The above theoretical calculations are based on the thin lens approximation and geometric optics principles. All parameters are derived from recognized standard values ​​in the field of optical design or published clinical data, allowing those skilled in the art to reproduce and verify the effects. In some embodiments, the microlenses are circular or polygonal in shape. That is, the modulation method of this embodiment is applicable to dynamic modulation of the refractive power of most types of microlenses, demonstrating strong versatility.

[0064] In some embodiments, the microlenses are formed using precision turning, nanoimprinting, injection molding, grayscale lithography, or other processes suitable for manufacturing microlens arrays. Microlenses processed using these methods ensure minimal manufacturing errors.

[0065] In some embodiments, the microlens array refractive power distribution modulation method can be applied to product forms such as mobile phone screen protectors, tablet screen protectors, automotive display screen protectors, near-eye display optical elements using folded optical paths in head-mounted displays, vision correction films or lens inserts for artificial intelligence glasses, vision correction films or lens inserts for virtual reality head-mounted displays, and vision correction films for everyday glasses. By applying the microlens array refractive power distribution modulation method to these product forms, users no longer perceive sudden changes in the degree of correction when scanning across the lens boundary when using the aforementioned optical elements, resulting in a uniform and comfortable viewing experience.

[0066] Example 2

[0067] like Figure 5-7As shown, the modulation method of this embodiment can be applied to the step height modulation of a Fresnel lens. Specifically, when the microlens array is a Fresnel lens array, each Fresnel lens has a Fresnel zone structure, and the Fresnel zone structure of each Fresnel lens retains the curvature at the corresponding radial position;

[0068] The Fresnel structure can significantly reduce the lens vertex height (the vertex height can be reduced by about 86% at 2.00D refractive power), and is suitable for use scenarios requiring ultra-thin thickness or high refractive power.

[0069] Among them, the refractive power of each Fresnel lens is dynamically modulated by a spatial weight modulation function, so that the step surface position, step surface slope, and step surface curvature between adjacent Fresnel lenses are smoothly connected; adjacent Fresnel lenses achieve continuous curvature transition by satisfying the interpolation method of six constraints.

[0070] Among them, the Fresnel zone structure of each Fresnel lens includes multiple zones. The step height between adjacent zones of the Fresnel lens is modulated by a spatial weight modulation function, so that the step height between adjacent zones gradually decreases from the center to the edge of the Fresnel lens, ensuring that adjacent Fresnel lenses have continuous surfaces and substantially equal refractive powers at the boundary. The step height between adjacent zones changes according to the same smoothing principle from the center to the edge to reduce the stray light of the Fresnel lens.

[0071] Exemplarily, the steps of the modulation method are as follows:

[0072] 1. According to the target refractive power P0 and the refractive index n of the lens material, calculate the radius of curvature R = (n - 1) / P0 of the continuous surface at this refractive power, and obtain the continuous surface vertex height distribution sag_cont(r) = R - √(R² - r²), where r is the radial distance from the center of the lens (0 ≤ r ≤ a, a is the semi-aperture of the lens).

[0073] 2. Apply continuous refractive power distribution modulation - superimpose a continuous refractive power spatial distribution on the continuous surface to obtain the enveloped continuous surface vertex height distribution. The refractive power spatial distribution is such that: the maximum value is taken as 1 at the center, k times the center value is taken at the edge (0 < k ≤ 1), and there is a smooth slope transition at both the center and the edge, and the curvature is continuous at the edge.

[0074] 3. Fresnel zone segmentation - divide the enveloped continuous surface into N concentric zones along the radial direction (N is a positive integer not less than 2). Each zone retains the local slope of the original enveloped surface at the corresponding radial position, and is translated along the optical axis direction to cut off the excess vertex height material to form a refractive Fresnel zone structure.

[0075] 3. Determine N and k – Based on the lens half-aperture a, the target refractive power P0, and the manufacturing process capability, select the number of rings N and the edge attenuation coefficient k to achieve a balance between the reduction in sag and the manufacturing complexity.

[0076] Medium refractive power setting N=8 rings: Taking a typical electronic display screen area size as an example (half-aperture example approximately 10.85mm), refractive index 1.58. The continuous surface sagitta is approximately 268μm, and after continuous refractive power distribution (k≈0.92), the envelope sagitta is approximately 156μm. N=8 ring Fresnel segmentation: Each ring retains the local slope of the envelope surface, and the sagitta is cut off by translation along the optical axis, with a maximum step height of approximately 21μm. The ring width decreases from the center to the edge.

[0077] High refractive power setting N=12 ring: The continuous curved surface sagitta is approximately 305μm, exceeding the film thickness limit. After continuous refractive power distribution (k≈0.94) and N=12 Fresnel ring segmentation, the maximum step is approximately 28μm, and the envelope sagitta is approximately 170μm, allowing this refractive power lens to be manufactured within the limited film thickness. The ring width decreases from the center to the edge, with a minimum ring width of approximately 0.5mm, suitable for single-point diamond turning with micron-level tools.

[0078] Low refractive power setting N=4 ring: The continuous curved surface has a low sag. After being divided by the continuous refractive power distribution (k≈0.96) and the N=4 Fresnel ring, the maximum step is about 8μm. The ring is relatively wide, easy to manufacture, and suitable for cost-sensitive applications.

[0079] For example, the step height of the Fresnel lens, after modulation, compared to an existing uniform Fresnel lens array:

[0080] (1) The refractive power at the boundary of adjacent Fresnel lenses is continuously transitioned, eliminating visual jumps at the boundary;

[0081] (2) The height of the ring step gradually decreases from the center to the edge, reducing stray light scattering. Taking a target refractive power of about 2.00D as an example, the sag height can be reduced by about 80% to about 86%.

[0082] (3) No dispersion problem (unlike diffractive Fresnel lenses), providing consistent refractive correction effect across the entire visible light spectrum;

[0083] (4) Compared with continuous curved surface microlens arrays, it significantly reduces the total thickness of the components while maintaining second-order continuity, making it suitable for ultra-thin applications.

[0084] The parts not mentioned in this embodiment are the same as in Embodiment 1.

[0085] Example 3

[0086] The modulation method of this embodiment can be applied to optical path avoidance design. When an optical path avoidance structure is provided in the microlens array, the optical path avoidance structure in the microlens array is modulated by a spatial weight modulation function. The edge attenuation coefficient k in the area where the optical path avoidance structure is set in the microlens array is lower than the edge attenuation coefficient k in other areas. After modulation, the refractive power in the optical path avoidance area changes smoothly, avoiding extra stray light from entering the optical path due to abrupt changes in refractive power, while not affecting the correction accuracy of other areas.

[0087] The parts not mentioned in this embodiment are the same as in Embodiment 1.

[0088] Example 4

[0089] like Figure 8 As shown, this embodiment provides an application of a microlens array refractive power distribution modulation method for the phase distribution design of metasurface optical elements. After modulation, the phase of each unit of the metasurface optical element smoothly transitions from the center to the edge according to a spatial weighting function, and the phase is continuous at the boundary between two units of adjacent metasurface optical elements, eliminating diffraction artifacts and stray light caused by phase steps. Compared with existing metasurfaces with uniform phase distribution, the metasurface modulated by this method can reduce stray light and improve imaging contrast over a wide wavelength range.

[0090] The parts not mentioned in this embodiment are the same as in Embodiment 1.

[0091] Example 5

[0092] To ensure a smooth transition of refractive power from the center to the edge of each lens in the microlens array, the following methods are provided for verification.

[0093] This embodiment provides a verification method. The verification method uses a surface profiler to scan the surface of a microlens array modulated by the microlens array refractive power distribution modulation method, extracts the radius of curvature of each lens, and fits the refractive power distribution curve to realize the detection and verification of the microlens array refractive power distribution modulation method. Compared with the existing detection method that only measures the radius of curvature of a single lens, this verification method uses a surface profiler to perform a full-field scan of the microlens array, which can simultaneously extract the radius of curvature of all microlenses, fit the overall refractive power spatial distribution curve, and verify whether each microlens meets the preset spatial weight modulation function relationship. This achieves a systematic evaluation of the refractive power distribution quality of the entire array, significantly improves detection efficiency, and allows for quantitative evaluation of modulation accuracy.

[0094] The parts not mentioned in this embodiment are the same as in Embodiment 1.

[0095] Example 6

[0096] This embodiment provides a vision correction element, which is obtained by a microlens array refractive power distribution modulation method;

[0097] In vision correction elements, the refractive power of each microlens transitions smoothly from the center to the edge, and the curvature of adjacent microlenses is continuous at the boundary.

[0098] Vision correction elements include forms such as films, stand-alone lenses, or embedded other optical components;

[0099] Vision correction elements are applied to flat or curved transparent substrates.

[0100] The parts not mentioned in this embodiment are the same as in Embodiment 1.

[0101] Example 7

[0102] The modulation method of this embodiment can be applied to toric microlens arrays. A toric microlens array is formed when the radii of curvature R1 and R2 of each microlens in the two orthogonal directions are not equal, where the cylindrical refractive power CYL = |(n-1) / R2-(n-1) / R1|. The two orthogonal directions are independently modulated using a spatial weighting modulation function, and the edge attenuation coefficients k1 and k2 are independently set. For example, k1≈k2≈0.97.

[0103] In a complex surface microlens array, each microlens has a local optical center, and the local optical centers of adjacent microlenses are independent of each other; the axis of the cylindrical lens is a global directional field property of the array, which does not depend on the local optical center of a single microlens, and the axis remains unchanged after translation.

[0104] During manufacturing, the mold is machined to a preset cylindrical lens axis direction (e.g., 0°). After rotating the substrate to the axis angle in the optometry prescription, it is pressed into shape, and the axis is locked on the substrate. Different axis finished products can be obtained by rotating the same mold at different angles.

[0105] For example, taking a spherical lens of approximately -2.50D, a cylindrical lens of approximately -0.75D, and a refractive index of approximately 1.52 as an example, R1≈208mm (axis direction) and R2≈160mm (vertical direction). After the substrate is rotated 15° and then imprinted, the axis of the finished product is 15°.

[0106] The parts not mentioned in this embodiment are the same as in Embodiment 1.

[0107] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for modulating the refractive power distribution of a microlens array, characterized in that, It includes the following steps: Construct a spatial weight modulation function to dynamically modulate the refractive power of each microlens, making the refractive power of each microlens smoothly transition from the center to the edge, with continuous curvature of adjacent microlenses, and adjacent microlenses having continuous curved surfaces / step surfaces and refractive powers at the boundaries; Among them, the positions, slopes, and curvatures of the curved surfaces / step surfaces between adjacent microlenses are smoothly connected.

2. The microlens array refractive power distribution modulation method according to claim 1, characterized in that, The specific form of the spatial weight modulation function is: the refractive power at the center of the microlens is the largest, and the normalized ratio is 1; The refractive power P0 at the center of each microlens is determined by the formula, and the formula is: P0=(n - 1) / R, where n is the refractive index of the lens material and R is the radius of curvature at the center of the microlens; The refractive power at the edge of the microlens is k times the refractive power at the center, where k is the edge attenuation coefficient, and the edge attenuation coefficient k satisfies 0 < k ≤ 1; During the transition of the microlens from the center to the edge, the refractive power and curvature change continuously without mutation at the edge; The edge attenuation coefficient k is selected according to the refractive power at the center of the microlens. According to the refractive power at the center of different microlenses, the edge attenuation coefficient k is 0.60 - 0.98; among them, when P0 ≤ 1.00D, k takes values from 0.60 to 0.80; when 1.0,D < P0 ≤ 4.00D, k takes values from 0.80 to 0.94; when P0 > 4.00D, k takes values from 0.94 to 0.

98.

3. The method for modulating the refractive power distribution of a microlens array according to claim 2, characterized in that, When the microlens array is a two-dimensional rectangular array, the refractive power modulation is performed separately in the row direction and the column direction through the spatial weight modulation function. The edge attenuation coefficients in each direction are denoted as k1 and k2 respectively, where k1 and k2 are set independently, and the refractive power of the microlenses at the four corner positions of the two-dimensional rectangular array is P0 × k1 × k2.

4. The method for modulating the refractive power distribution of a microlens array according to claim 1, characterized in that, The shape of the microlens is circular or polygonal.

5. The method for modulating the refractive power distribution of a microlens array according to claim 1, characterized in that, The microlens is manufactured by precision turning, nanoimprinting, injection molding or grayscale lithography.

6. The method for modulating the refractive power distribution of a microlens array according to claim 1, characterized in that, When the microlens array is a Fresnel lens array, each Fresnel lens has a Fresnel zone structure, and the Fresnel zone structure of each Fresnel lens retains the curvature at the corresponding radial position; Among them, the refractive power of each Fresnel lens is dynamically modulated through the spatial weight modulation function to make the positions, slopes, and curvatures of the step surfaces between adjacent Fresnel lenses smoothly connected; Among them, the Fresnel zone structure of each Fresnel lens includes multiple zones. The step height between adjacent zones of the Fresnel lens is modulated through the spatial weight modulation function, so that the step height between adjacent zones gradually decreases from the center to the edge of the Fresnel lens, and the step height between adjacent zones changes according to the same smoothing principle from the center to the edge to reduce the stray light of the Fresnel lens.

7. The method for modulating the refractive power distribution of a microlens array according to claim 2, characterized in that, When there is an optical path avoidance structure in the microlens array, the optical path avoidance structure in the microlens array is modulated through the spatial weight modulation function, and the edge attenuation coefficient k set in the area where the optical path avoidance structure is arranged in the microlens array is lower than the edge attenuation coefficient k in other areas.

8. The application of the microlens array refractive power distribution modulation method according to any one of claims 1-7, characterized in that, This technology is applied to the phase distribution design of metasurface optical elements and the modulation of complex toroidal microlens arrays. After modulation, the phase of each unit of the metasurface optical element smoothly transitions from the center to the edge according to the spatial weighting function. The phase is continuous at the boundary between two units of adjacent metasurface optical elements, eliminating diffraction artifacts and stray light caused by phase steps.

9. A verification method, characterized in that, The verification method involves scanning the surface of a microlens array modulated by the microlens array refractive power distribution modulation method according to any one of claims 1-7 using a surface profiler, extracting the radius of curvature of each lens and fitting the refractive power distribution curve, thereby realizing the detection and verification of the microlens array refractive power distribution modulation method.

10. A vision correction element, characterized in that, The vision correction element is obtained by the microlens array refractive power distribution modulation method according to any one of claims 1-7; In vision correction elements, the refractive power of each microlens transitions smoothly from the center to the edge, and the curvature of adjacent microlenses is continuous at the boundary. Vision correction components include films and individual lenses; Vision correction elements are applied to flat or curved transparent substrates.

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