Microstructure myopia prevention and control lens and design method thereof

Abstract

The application belongs to the technical field of eye optics, and relates to a microstructure myopia prevention lens and a design method thereof. The microstructure myopia prevention lens comprises a parent lens and a negative microlens array. The parent lens comprises a central clear area and a regulation area. The negative microlens array is arranged on the surface of the regulation area of the parent lens and comprises a plurality of even aspheric negative lenses arranged in an array. The main curvature of each even aspheric negative lens changes from a negative value to a positive value from the center to the edge. The microstructure lens with the even aspheric negative lens designed in the application can improve the light deflection angle of most areas around the center of the microstructure, increase the aberration of the medium and small aperture light passing through the microstructure, further improve the inhibition effect of the lens on the retinal imaging contrast in the low frequency band, realize the maximization of the retinal imaging contrast under the same microstructure sag, and thus achieve the best effect of inhibiting the progression of myopia.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of eye optics, in particular to a microstructure myopia prevention lens and a design method thereof. BACKGROUND

[0002] Research shows that the effectiveness of myopia control frame glasses based on contrast theory and myopia control treatment methods based on peripheral defocus are related to changes in retinal contrast. Myopia control frame glasses based on contrast principle can effectively slow down the deepening of myopia degree by designing special microstructures on the lens to reduce the contrast of retinal imaging.

[0003] At present, most of the glasses designed based on the principle of reducing retinal contrast add a spherical positive lens microstructure array on the surface of the lens, but the spherical positive lens microstructure focuses the incident light in front of the retina, forming an effect similar to peripheral defocus. With the passage of time, the myopia prevention ability will gradually weaken. The patent with application number 2025106271950 studies the inhibition effect of spherical negative lens microstructure lenses with different sag changes on retinal contrast, and finds that the lens with spherical negative lens microstructure has better effect on reducing retinal contrast. However, since the spherical negative lens has aberration, when parallel light passes through the spherical negative lens, the central light near the optical axis can diverge along the ideal refraction path for imaging and focus on the center of the image plane due to the small incident angle, while the edge light far from the optical axis will deviate from the ideal path due to the large incident angle, and focus at any position between the center and the circumference of the image plane. This aberration will appear as a diffused spot with a bright center and a surrounding halo on the image plane, that is, the spherical negative lens has poor ability to diverge light, and the effect of inhibiting the contrast of retinal imaging is limited, resulting in rapid deepening of the myopia degree of the wearer. SUMMARY

[0004] Therefore, the technical problem to be solved by the present application is that the existing lens based on spherical negative lens microstructure has limited effect on inhibiting the contrast of retinal imaging, resulting in rapid deepening of the myopia degree of the wearer.

[0005] To solve the above technical problems, the present application provides a microstructure myopia prevention lens, comprising:

[0006] A mother lens comprising a central clear zone and a control zone;

[0007] A negative microlens array arranged on the surface of the control zone of the mother lens, comprising a plurality of even aspheric negative lenses arranged in an array, and the main curvature of each even aspheric negative lens changes from negative to positive from the center to the edge.

[0008] The microstructure myopia prevention lens provided in the application comprises a mother lens and a negative microlens array composed of even aspheric negative lenses, wherein the mother lens comprises a central clear vision zone and a regulation zone; the negative microlens array is arranged on the surface of the regulation zone of the mother lens and comprises a plurality of even aspheric negative lenses arranged in an array, and the main curvature of each even aspheric negative lens changes from a negative value to a positive value from the center to the edge. Since the effect of reducing the retinal contrast of the lens with the spherical negative lens microstructure is better than that of the lens with the spherical positive lens microstructure, the lens with the negative microlens microstructure is still considered in the application. As a commonly used aspheric surface in optical design, the even aspheric surface has a nonlinear change in the main curvature of the curved surface with the increase of the aperture, which can increase the deflection angle of the light incident from the microstructure region, thereby greatly reducing the retinal imaging contrast, and therefore the lens with the even aspheric negative lens is considered in the application. Further, it is found through a large number of comparison experiments that not all even aspheric negative lenses can greatly reduce the retinal imaging contrast compared with the spherical negative lens. Only when the main curvature changes from a negative value to a positive value from the center to the edge, the deflection angle of the light around the center in most regions of the microstructure can be increased, so that the aberration of the medium and small aperture light passing through the microstructure is increased, and the inhibitory effect of the lens on the retinal imaging contrast in the low frequency band is further improved. Therefore, the microstructure lens with the even aspheric negative lens having the curvature radius changing from a negative value to a positive value from the center to the edge designed in the application can maximize the reduction of the retinal imaging contrast under the same microstructure height condition, thereby achieving the best effect of inhibiting the progression of myopia. BRIEF DESCRIPTION OF DRAWINGS

[0009] In order to make the content of the application more easily understood, the application will be further described in detail below according to specific embodiments of the application and in conjunction with the drawings, in which:

[0010] Figure 1 A structural schematic diagram of a microstructure myopia prevention lens provided in the application;

[0011] Figure 2 A schematic diagram of the arrangement of even aspheric negative lenses in a first negative microlens array provided in the application;

[0012] Figure 3 A schematic diagram of the arrangement of even aspheric negative lenses in a second negative microlens array provided in the application;

[0013] Figure 4 A schematic diagram of the arrangement of even aspheric negative lenses in a third negative microlens array provided in the application;

[0014] Figure 5 A flowchart of a microstructure myopia prevention lens design method provided in the application;

[0015] Figure 6 The position of the center of the inscribed circle of the hexagonal grid on the projection of the vertex section of the mother mirror is provided for the embodiment of the present application when the even-order aspheric negative lens is arranged in a hexagonal grid pattern;

[0016] Figure 7 The principle diagram of the curvature center calculation step of the even-order aspheric negative lens is provided for the embodiment of the present application;

[0017] Figure 8 The optical path diagram of the mother mirror and the model eye is provided for the embodiment of the present application;

[0018] Figure 9 The schematic diagram of the microstructure lens physical model is provided for the embodiment of the present application;

[0019] Figure 10 The MTF curve comparison diagram of the microstructure lens with different even-order aspheric negative micro-lens arrays and spherical negative micro-lens arrays under three different sagittal height variation amounts is provided for the present application; wherein, Figure 10 (a) in the above (a) is the sagittal height variation amount of 2 μm, Figure 10 (b) in the above (b) is the sagittal height variation amount of 6 μm, Figure 10 (c) in the above (c) is the sagittal height variation amount of 8 μm;

[0020] Figure 11 The principal curvature diagram of the surface of the negative lens with different surface types when the sagittal height variation amount is 6 μm is provided for the embodiment of the present application; wherein, Figure 11 (a) in the above (a) is the principal curvature diagram of the spherical surface, Figure 11 (b) in the above (b) is the principal curvature diagram of the aspheric surface 1, Figure 11 (c) in the above (c) is the principal curvature diagram of the aspheric surface 2;

[0021] Figure 12 The MTF curve comparison diagram of the microstructure lens with different even-order aspheric negative micro-lens arrays and spherical negative micro-lens arrays under five different sagittal height variation amounts is provided for the embodiment of the present application;

[0022] Figure 13 The MTF curve diagram of the microstructure lens with different even-order aspheric negative micro-lens arrays with different high-order term coefficients when the sagittal height variation amount is 6 μm and the high-order term number is 2 is provided for the embodiment of the present application;

[0023] Figure 14 The MTF curve diagram of the microstructure lens with different even-order aspheric negative micro-lens arrays with different high-order term coefficients when the sagittal height variation amount is 8 μm and the high-order term number is 2 is provided for the embodiment of the present application;

[0024] Figure 15The MTF curve schematic diagram of the microstructure lens of the even aspheric negative lens array with different high order term coefficients when the sagittal height variation is 6 μm and the high order term frequency is 3 and 4 is provided for the embodiment of the application;

[0025] Figure 16 The actual data and fitting straight line of the high order term coefficient threshold and the vertex curvature threshold under different sagittal height variations when the high order term frequency is 2 are provided for the embodiment of the application; wherein, Figure 16 (a) in the above is the fitting effect of the high order term coefficient and the sagittal height variation, Figure 16 (b) in the above is the fitting effect of the vertex curvature and the sagittal height variation;

[0026] Figure 17 The cross-sectional view of the even aspheric negative lens when the sagittal height variation is 10 μm and the high order term coefficient takes the upper limit value under different high order term frequencies is provided for the embodiment of the application; wherein, Figure 17 (a) in the above is the high order term frequency is 2, Figure 17 (b) in the above is the high order term frequency is 3;

[0027] Figure 18 The MTF curve and the drop amount schematic diagram of the microstructure lens of the even aspheric negative lens and the spherical negative lens with different high order term coefficients when the sagittal height variation is 6 μm and the high order term frequency is 2 are provided for the embodiment of the application;

[0028] Figure 19 The fitting curve of the different high order term coefficients and the MTF drop amount when the sagittal height variation is 6 μm and the high order term frequency is 2 is provided for the embodiment of the application;

[0029] Figure 20 The cross-sectional view of the spherical negative lens and the even aspheric negative lens determined by the three-fraction median method when the sagittal height variation is 6 μm is provided for the embodiment of the application;

[0030] Figure 21 The MTF curve under different high order term coefficients when the sagittal height variation is 8 μm and the high order term frequency is 2 is provided for the embodiment of the application;

[0031] Figure 22 The fitting curve of the different high order term coefficients and the MTF drop amount when the sagittal height variation is 8 μm and the high order term frequency is 2 is provided for the embodiment of the application;

[0032] Figure 23 The cross-sectional view of the spherical negative lens and the even aspheric negative lens determined by the three-fraction median method when the sagittal height variation is 8 μm is provided for the embodiment of the application;

[0033] The description of the drawings is as follows: 10, mother mirror; 100, central clear zone; 110, regulation zone; 20, negative microlens array; 200, even aspheric negative lens. DETAILED DESCRIPTION

[0034] The application will be further described below in conjunction with the drawings and specific embodiments, so that those skilled in the art can better understand the application and implement it. The embodiments are not intended to limit the application.

[0035] As Figure 1 The microstructure myopia prevention lens structure provided by the application is shown in the schematic diagram, which specifically includes a mother mirror 10 and a negative microlens array 20.

[0036] The mother mirror 10 includes a central clear zone 100 and a regulation zone 110. Specifically, in some embodiments of the application, the mother mirror 10 is a meniscus spherical lens for correcting refractive errors, and the diameter of the central clear zone 100 is 6mm-12mm.

[0037] The negative microlens array 20 is arranged on the surface of the regulation zone 110 of the mother mirror 10, and includes a plurality of even aspheric negative lenses 200 arranged in an array. The main curvature of each even aspheric negative lens 200 changes from negative to positive from the center to the edge. Specifically, in some embodiments of the application, the radial diameter of each even aspheric negative lens 200 is 0.5mm-2mm, and the sagittal height variation of each even aspheric negative lens is 1μm-15μm.

[0038] Optionally, the plurality of even aspheric negative lenses 200 can be arranged in a hexagonal grid array, an orthogonal grid array or a diamond grid array on the surface of the regulation zone 110 of the mother mirror 10. As Figure 2 The arrangement pattern of the even aspheric negative lens in the first negative microlens array provided by the application is shown in the schematic diagram, and the plurality of even aspheric negative lenses 200 are arranged in a circular ring shape; Figure 3 The arrangement pattern of the even aspheric negative lens in the second negative microlens array provided by the application is shown in the schematic diagram, and the plurality of even aspheric negative lenses 200 are arranged in an orthogonal grid shape; Figure 4 The arrangement pattern of the even aspheric negative lens in the third negative microlens array provided by the application is shown in the schematic diagram, and the plurality of even aspheric negative lenses 200 are arranged in a prismatic grid.

[0039] Further, the conic coefficient of each even aspheric negative lens 200 is 0; each even aspheric negative lens 200 only contains one high-order term coefficient. When the high-order term number is 2, the value range of the high-order term coefficient is (0, 16H); when the high-order term number is 3, the value range of the high-order term coefficient is (0, 32H); wherein H represents the sagittal height variation.

[0040] As preferred, when the high order term degree is 2, the high order term coefficient is 8H; and / or, when the high order term degree is 3, the high order term coefficient is 16H.

[0041] The embodiment of the present application also provides a method for designing the microstructure myopia prevention and control lens, as shown in the figure, the method specifically comprises: Figure 5 As shown in the figure, the method specifically comprises:

[0042] S100: based on a plurality of preset sag change amounts, calculating the structure parameters of the spherical negative microlens array to construct a microstructure lens three-dimensional model under the spherical negative microlens array.

[0043] S101: based on a plurality of preset sag change amounts, taking the sag of the even aspherical surface monotonously increasing with the radial distance as a constraint, calculating the structure parameters of each even aspherical surface negative microlens array with different high order term coefficients to construct a microstructure lens three-dimensional model under each even aspherical surface negative microlens array.

[0044] S102: obtaining the MTF curve of the combination of each microstructure lens three-dimensional model and the eye model, and taking the MTF curve of the microstructure lens under the spherical negative microlens array as a standard curve; comparing the MTF curves of the microstructure lenses under each even aspherical surface negative microlens array with the standard curve respectively.

[0045] S103: taking the even aspherical surface negative microlens with the MTF curve lower than the standard curve in the preset frequency band as a target surface type, obtaining the variation rule of the principal curvature of the even aspherical surface negative lens based on the high order term coefficient of the even aspherical surface negative lens in the target surface type, and setting the principal curvature of the even aspherical surface negative lens on the surface of the parent lens control area in the microstructure myopia prevention and control lens to change from negative to positive from the center to the edge.

[0046] Specifically, the acquisition process of the parent lens structure parameters comprises:

[0047] Based on the spherical power and the preset parent lens front surface power, the parent lens back surface power is calculated;

[0048] Based on the refractive index of the parent lens material, the parent lens front surface power and the parent lens back surface power, the parent lens front surface curvature radius and the parent lens back surface curvature radius are calculated.

[0049] The acquisition process of the structure parameters of the spherical / even aspherical surface negative microlens array under the preset sag change amount comprises:

[0050] Based on the preset sag change amount and the parent lens sag, the sag of the spherical / even aspherical surface negative lens in the negative microlens array is calculated, and the curvature radius of the spherical / even aspherical surface negative lens is calculated based on the sag of the spherical / even aspherical surface negative lens.

[0051] arranging the aspherical negative microlens array based on the preset aspherical negative lens arrangement type;

[0052] arranging the mother lens and the spherical / aspherical negative microlens array to obtain a position parameter of a center point of the negative microlens array; and calculating a curvature center position and an inclination angle of the spherical / aspherical negative lens in the spherical / aspherical negative microlens array based on the curvature center of the mother lens and the position parameter of the center point of the spherical / aspherical negative microlens array.

[0053] Further, after obtaining the variation law of the principal curvature radius of the aspherical negative lens, the method further comprises:

[0054] S104: constructing a relationship function of a sag of the aspherical negative lens and a vertex curvature, a radial distance and a high-order term coefficient of the aspherical negative lens, and a derivative function with respect to the radial distance, with a constraint that the aspherical negative lens contains only one high-order term coefficient and a quadratic surface coefficient is equal to 0. Specifically, the relationship function of the sag of the aspherical negative lens and the vertex curvature, the radial distance and the high-order term coefficient of the aspherical negative lens is expressed as:

[0055] ,

[0056] wherein, represents the sag of the aspherical negative lens; represents the radial distance of the aspherical negative lens; represents the vertex curvature of the aspherical negative lens; represents the high-order term coefficient corresponding to the high-order term of n.

[0057] S105: substituting the maximum radial distance of the negative lens into the relationship function to obtain a maximum sag relationship of the aspherical negative lens; and obtaining a relationship analytical expression of the high-order term coefficient of the aspherical negative lens and the vertex curvature of the aspherical negative lens based on the difference between the maximum sag of the aspherical negative lens and the variation amount of the sag and the sag of the mother lens.

[0058] Specifically, the maximum sag relationship of the aspherical negative lens is expressed as:

[0059] ,

[0060] wherein, represents the maximum sag of the aspherical negative lens; represents the maximum radial distance of the negative lens;

[0061] The relationship analytical expression of the high-order term coefficient of the aspherical negative lens and the vertex curvature of the aspherical negative lens is expressed as:

[0062] ,

[0063] wherein, represents the sag change amount; represents the sag of the primary mirror.

[0064] S106: sampling a plurality of sag change amounts in the first preset interval, for each sag change amount, sampling a plurality of vertex curvatures in the second preset interval, and inputting the current sag change amount, each vertex curvature, the sag of the primary mirror and the preset high order term number into the relationship analysis formula to obtain the high order term coefficient value corresponding to each vertex curvature value under the current sag change amount.

[0065] S107: based on each vertex curvature value and its corresponding high order term coefficient value under each sag change amount, a relationship curve of vertex curvature and high order term number under the current sag change amount is drawn; the vertex curvature value and the high order term coefficient value at the extreme point in the relationship curve under each sag change amount are obtained.

[0066] S108: fitting the vertex curvature value and the high order term coefficient value at the extreme point under all sag change amounts to obtain the first relationship formula of the high order term coefficient of the even order aspheric negative lens and the sag change amount, the second relationship formula of the vertex curvature and the sag change amount under the preset high order term number, thereby obtaining the high order term coefficient value range of the even order aspheric negative lens under the preset high order term number.

[0067] Specifically, when the preset high order term number is 2, the first relationship formula of the high order term coefficient of the even order aspheric negative lens and the sag change amount is represented as:

[0068] ,

[0069] wherein, represents the high order term coefficient corresponding to the high order term number 2; represents the sag change amount;

[0070] The second relationship formula of the vertex curvature and the sag change amount is represented as:

[0071] ;

[0072] The high order term coefficient value range of the even order aspheric negative lens is (0, 16H).

[0073] The even aspheric negative lens is composed of a quadratic surface and an even as high order term part. It is found in the application that when the even aspheric negative lens only contains one high order term, the greater the high order term coefficient, the better the contrast reduction effect. However, with the continuous increase of the high order term coefficient, the aspheric surface may appear reverse curvature (i.e. the surface slope has different signs at different apertures), causing processing difficulties or unattractive appearance, etc. Therefore, by limiting the value range of the high order term coefficient of the even aspheric negative lens, the application avoids the reverse curvature of the negative lens surface, so that the even aspheric negative lens with better contrast reduction effect can be obtained, and the problems of processing difficulty and unattractive appearance of the lens can be avoided.

[0074] Further, after obtaining the value range of the high order term coefficient of the even aspheric negative lens under the preset high order term number, the following steps are further included:

[0075] S109: sampling in the value range of the high order term coefficient of the even aspheric negative lens to obtain a plurality of candidate high order term coefficient values.

[0076] S110: based on the parent lens structure parameters, the preset sagittal height variation, the arrangement pattern of the microstructure array and the maximum radial distance of the negative lens, calculating the structure parameters of each candidate even aspheric negative micro-lens array, so as to construct the three-dimensional model of the candidate micro-structure lens under each candidate even aspheric negative micro-lens array.

[0077] S111: obtaining the MTF curve of the combination of the three-dimensional model of each candidate micro-structure lens and the eye model, and calculating the decline amount of the MTF curve of each candidate micro-structure lens in the preset frequency band compared with the standard curve.

[0078] S112: binary fitting the relationship between the plurality of candidate high order term coefficient values and the maximum decline amount, obtaining the quantitative relationship between the high order term coefficient and the maximum decline amount, and obtaining the optimal value of the high order term coefficient of the even aspheric negative lens based on the quantitative relationship by using the three-point median method. Specifically, when the high order term number is 2, the optimal value of the high order term coefficient is 8H; and / or, when the high order term number is 3, the optimal value of the high order term coefficient is 16H.

[0079] Although the upper limit of the range of the high-order term coefficient can obtain the maximum contrast reduction effect under the same sag change amount, the present application also finds in the design process that when the high-order term coefficient takes the maximum value in the range of values, the slope of the edge part of the even aspheric negative lens changes too fast, which makes the wearer easily observe the microstructure of the even aspheric negative lens on the surface of the lens, and subjective over-attention and rejection are caused, and the lens aesthetics and subjective prevention and control effect are also affected. Therefore, in order to avoid the above situation, the value of the high-order term coefficient needs to be reduced as much as possible under the upper limit value benchmark, and as many contrast reduction effects as possible need to be retained. Therefore, the present application quantitatively analyzes the relationship between the MTF of the lens with different high-order term coefficients and the maximum reduction effect of the sphere, and determines a best value from the range of values of the high-order term coefficient, so as to maximize the inhibition effect of the lens on the retinal imaging contrast, the imaging quality, the lens aesthetics and the processing difficulty and other indicators.

[0080] The microstructure myopia prevention and control lens design method provided by the present application is further explained and described below through multiple embodiments.

[0081] The microstructure myopia prevention and control lens design method provided by the present application specifically includes the following steps:

[0082] S1: calculating the structure parameters of the mother lens according to the spherical degree of the lens wearer;

[0083] Specifically, the spherical degree of a certain myopic eye is known to be -3D, and the pre-set front surface power F1 of the mother lens 10 is 2D, so the back surface power F2 of the mother lens is in combination with the refractive index 1.56 of the mother lens material, the front surface curvature radius R1 of the mother lens is determined to be 280 mm, the back surface curvature radius R2 of the mother lens is determined to be 112 mm, and the shape is a meniscus lens. It should be noted that the positive curvature radius means that the curved surface is bent to the left, and the negative curvature radius means that the curved surface is bent to the right.

[0084] S2: obtaining the structure parameters of the negative microlens array under a plurality of pre-set sag change amounts, which specifically includes:

[0085] S20: based on the pre-set diameter 6 mm of the central clear zone and the full aperture D1=6 mm of the central clear zone, the control zone is determined to be the area outside the main optical axis 3 mm.

[0086] S21: taking the value range 0.5 mm~2 mm of the diameter of the even aspheric negative lens in the negative microlens array as a constraint, the diameter D200 of the even aspheric negative lens is determined to be 1 mm; taking the value range 1 μm~15 μm of the sag change amount of the even aspheric negative lens as a constraint, the pre-set sag change amount H is selected to be 2 μm, 6 μm and 8 μm.

[0087] In particular, the sag variation H refers to the distance from the vertex of the arc surface of the mother mirror to the vertex of the arc surface of the spherical or even aspheric negative lens in the negative microlens array, and thus wherein, represents the sag of the mother mirror, represents the sag of the spherical or even aspheric negative lens.

[0088] S22: When the negative lens surface type in the negative microlens array is spherical, the curvature c, the radial distance r, and the sag z1 / z2 of the mother mirror / negative lens are related as follows:

[0089] ,

[0090] ,

[0091] wherein, when the sag z1 of the mother mirror is calculated, represents the sag of the spherical negative lens. represents the sag of the spherical negative lens; r represents the radial distance, and the maximum radial distance of the negative lens . The above formula represents a convex spherical surface with the vertex at the zero position , if a concave spherical negative lens with the vertex at the zero position is to be represented, the value of the radius of curvature r1 of the spherical negative lens relative to the convex spherical surface is reversed, and will also become negative, since z2 is defined to be always positive, when a concave spherical surface is represented, z2 is represented in the form of an absolute value;

[0092] Based on the radius of curvature R1 of the mother mirror 10, the sag is obtained, and then based on , the sag of the spherical negative lens is obtained, and the curvature c of the spherical negative lens can be obtained from z2, and then the radius of curvature is calculated.

[0093] S23: When the negative lens surface type in the negative microlens array is even aspheric, the sag z2 introduced by the even aspheric negative lens is composed of the quadratic surface part and the even high-order term part, and at this time, the sag z2, the curvature c, the radial distance r, and the quadratic surface coefficient k are related as follows:

[0094] ,

[0095] wherein, c=1 / R, R is the vertex radius of curvature r1 of the even aspheric negative lens, is the high-order term number, is the high-order term coefficient; similarly, the above formula represents a convex aspheric surface with the vertex at the zero position , if a concave aspheric surface with the vertex at the zero position is to be represented, r1, k, and The numerical value of the relative convex aspherical surface is reversed, It will also become negative, because the z2 is defined as positive, so when the concave aspherical surface is represented, z2 is represented in the form of absolute value.

[0096] It should be noted that in the embodiment, the quadratic surface coefficient k of the even aspherical negative lens is set to 0, and the high-order term n is 2, that is, the even aspherical negative lens only contains This high-order term coefficient, further, under the constraint condition that z2 increases monotonously with the increase of the radial distance r in the range of the maximum radial distance of the negative lens, selects The maximum radial distance of the negative lens =0.5mm is substituted into the formula, and the action amount of the even high-order term part on the sag is ; Because the sag z2 introduced by the even aspherical negative lens is obtained, the sag z21 generated by the quadratic surface part can be obtained according to the quadratic surface equation. The vertex curvature radius r1 of the even aspherical negative lens can be obtained by calculation.

[0097] Specifically, according to the above calculation process, the structural parameters of the spherical surface, two kinds of even aspherical surfaces (the aspherical surface 1 The aspherical surface 2 with the same sign And the aspherical surface 2 with opposite signs) with the sag change amount H=2μm, 6μm and 8μm are calculated respectively, and the calculation results are shown in Tables 1-3. Table 1

[0098]

[0099] Table 2

[0100]

[0101] Table 3

[0102]

[0103] In Tables 1-3, r1 and

[0104] are given in the form of concave aspherical surface, and z2 is given in the form of absolute value. S24: Select the grid type and grid center point position parameters used. In the embodiment, hexagonal grids are selected to arrange the spherical surface and two kinds of aspherical surfaces to obtain a spherical negative microlens array, a first aspherical negative microlens array and a second aspherical negative microlens array, and the distance d between adjacent grid center points is D2=1mm.

[0105]

[0106] ​Specifically, the main optical axis of the mother mirror is the Z axis, the horizontal direction perpendicular to the Z axis is the X axis, and the vertical direction is the Y axis, to establish a three-dimensional XYZ rectangular coordinate system. The vertex (0, 0, 0) of the mother mirror is taken as the tangent plane z = 0, and the positions of the center points of a hexagonal grid in the plane and the central clear area are as shown in Figure 6 , the hexagonal grid is represented by its inscribed circle, and the radius of the inscribed circle is 0.5 mm. The center point of the hexagonal grid, i.e. the center of the inscribed circle of the hexagonal grid.

[0107] Let the center point coordinates of the grid inscribed circle be (x0, y0, 0), and the distances of each center point along the X and Y axis directions to the Z axis be hx = x0 and hy = y0, respectively. The coordinates of each grid center point can be further plotted in Figure 6 .

[0108] If the grid inscribed circle is not in the central clear area, the grid center point can be used as the layout position of the negative lens in the negative microlens array, such as points 1-6 and H-M marked in Figure 6 .

[0109] Select an array unit directly above the central clear area, such as the grid inscribed circle represented by the numerical designations 1-6 in Figure 6 , which is used for coordinate calculation and optical modeling analysis. The subsequent H-M no longer refers to the center point in Figure 6 .

[0110] S25: According to the positions of the grid center points on the tangent plane, the vertex curvature center positions of the negative lenses in the corresponding negative microlens array located in each hexagonal grid are calculated for final modeling.

[0111] Let the curvature center of the mother mirror be P, and the calculation steps are represented by the movement process from A to B to C in Figure 7 . Specifically, the position of point A in the figure corresponds to the center of a grid inscribed circle in Figure 6 . Project the grid along the Z axis to the front surface of the mother mirror. If the center of a grid inscribed circle is A (x0, y0, 0), and the translation distance along the Z axis is z, then the coordinates of the vertex B of the grid inscribed circle on the front surface of the mother mirror are (x0, y0, z), and the translation process is shown in Figure 7 step 1.

[0112] For the negative lenses in the spherical or aspherical negative microlens array, let the vertex curvature center corresponding to the vertex be C (x0', y0', z'), and since C, the vertex B of the front surface of the mother mirror, and the curvature center P of the mother mirror are collinear, then B is translated outward along the extension of BP by a distance to obtain C, and the translation distance is the absolute value of the negative lens vertex curvature radius r1 minus the maximum change H of the sag, and the translation process is shown in Figure 7 step 2.

[0113] A set of similar triangles can be obtained by drawing a perpendicular line from the vertex curvature center C of the negative lens and the vertex B of the front surface of the mother lens to the main optical axis . Then we have:

[0114] ,

[0115] wherein, , Given R1, r1, H, and the coordinates of the center of the inscribed circle (x0, y0, 0), the coordinates of the vertex curvature center of the negative lens (x0', y0', z') can be calculated.

[0116] Through the above calculation process, the coordinates of points A, B, and C related to numbers 1-6 in Table 2 are obtained as shown in Table 4: Figure 6

[0117] Table 4

[0118]

[0119] S26: Calculate the tilt angle of the corresponding negative lens according to the position of the center of the inscribed circle. Specifically, the angle between the main optical axis of the negative lens and the main optical axis of the mother lens in different coordinate directions is the tilt angle of the negative lens. The angle between the main optical axis of the negative lens and the y=0 plane (X tilt) is denoted as α, and the direction of increasing y coordinate is denoted as positive. The angle between the main optical axis of the negative lens and the x=0 plane (Y tilt) is denoted as β, and the direction of decreasing x coordinate is denoted as positive. The two are equivalent to the components of the angle between the BP line and the main optical axis of the mother lens in the X and Y axis directions. The selected negative lens surface is a rotationally symmetric structure, and there is no need to calculate the Z tilt. The calculation formulas for X tilt and Y tilt are as follows:

[0120] , ,

[0121] Taking the spherical surface in Table 2 as an example, the required parameters for modeling the negative lens corresponding to numbers 1-6 in Table 2 are calculated as shown in Table 5: Figure 6

[0122] Table 5

[0123]

[0124] S3: According to the parameters of each part in steps S1 and S2, use the optical design software Zemax to complete the modeling of the mirror-eye optical system containing the negative micro-structure lens three-dimensional model, and the specific steps are as follows:

[0125] ​​S31: Model the eye model and the parent lens: select an appropriate optical simulation eye model, and model it using the sequence mode of ZEMAX software. Set the wavelength of the optical system to 0.55 μm, and the field of view to 0°, -8° and -16°. Then, model the parent lens P1 in the non-sequence mode according to Table 1, with the distance from the back surface of the lens to the front surface of the cornea being 12 mm. Temporarily select the pupil radius to be 1.5 mm under the constraint of the pupil radius being 1-3 mm, and focus optimize the vitreous thickness of the eye model in the sequence mode. At this time, the optical path diagram of the parent lens and the eye model is as shown in Figure 8 .

[0126] S32: Model the negative microlens array based on the modeling data of the negative lens under different sag height variation amounts (H = 2 μm, 6 μm, 8 μm), and take the spherical microlens in Table 2 as an example for illustration:

[0127] Input the six spherical positive lenses shown in Table 6 in the non-sequence editor: use a plano-convex lens, as shown in MNKDJ in Figure 7 , take the coordinate of the vertex curvature center C point as the coordinate of the positioning point of the front surface center, take the curvature radius r1 as the thickness CD and the back surface curvature radius, and substitute the tilt angle, take the half aperture CM of the plano-convex lens to be slightly larger than the half aperture used for calculation, i.e. EF / 2 = D200 / 2 = 0.5 mm, take CM = 0.6 mm, and thus obtain the positive lenses P2-P7 that can be used for structure cutting.

[0128] Use Boolean objects to subtract, and thus obtain the lens of cutting off the six positive lenses P2-P7 on the parent lens P1, and thus obtain a spherical negative microlens array. The Boolean object expression is: The modeling of the two kinds of even aspherical negative microlens arrays for comparison is the same as the modeling of the spherical surface, and the cutting is realized by using a positive lens with a plane front surface and an even aspherical back surface.

[0129] The lens entity model containing a negative microlens array is as shown in Figure 9 , for the convenience of analyzing the influence of the microstructure unit, adjust the maximum field of view in the system to -16.5°, and the pupil radius to 1.4 mm, at this time, the light rays of the maximum field of view can completely cover the six negative lenses built, and then re-focus optimize and fix the vitreous thickness of the Liou model eye.

[0130] According to the data in Tables 2-4, repeat the above steps to complete the modeling of the optical systems of all nine negative lens microstructure lenses.

[0131] S4: Select a field of view that completely covers a microstructure unit, obtain the modulation transfer function (MTF) curves of the nine lens-eye systems under different sag height variation amounts, take the average of the meridional and sagittal directions of the function as the MTF, and compare them.

[0132] Figure 10 MTF curves of micro-structured lenses with different even aspheric negative microlens arrays and spherical negative microlens arrays under three sag height variation amounts are compared; Figure 11 For the sag height variation amount of 6 μm, the principal curvature graphs of the sphere and two aspheres are drawn by selecting the data in Table 2. Combined with the MTF curves of the three kinds of negative microlens arrays, it can be seen that Figure 10 and Figure 11 Under the same sag height variation amount and diameter, compared with the spherical negative microlens structure, the asphere 2 with the principal curvature changing from negative to positive from the center to the edge can make the MTF have more decline in the low frequency part, and the maximum decline rates under three sag height variation amounts are 42%, 24% and 15% respectively, while the asphere 1 with the principal curvature changing from negative to negative from the center to the edge makes the MTF increase.

[0133] In order to explore the universality of the phenomenon that the even asphere with the principal curvature changing from negative to positive from the center to the edge can make the MTF have more decline in the low frequency part than the sphere, this embodiment further increases the calculation, modeling and MTF analysis of the structure parameters of the spherical and two aspheric negative microlenses under the sag height variation amounts of H = 4, 5, 7, 9 and 10 μm, and the same phenomenon is found, Figure 12 The MTF comparison graphs of the three kinds of surface types in the low frequency part under the above five sag height variation amounts are given.

[0134] In order to analyze the reason for this result, the deflection angles of parallel light at different radial distances r of the three negative lens surface types under the sag height variation amount of 6 μm are analyzed according to the data in Table 2, and the calculation results are shown in Table 6. As shown in Table 6, the deflection angles of light within 0~0.35 radial distance (within 70% aperture) are asphere 2> sphere> asphere 1. According to the relationship between the aperture and contrast, the increase of the deflection angles of light around the center of the microstructure makes the aberration of the light passing through the microstructure increase, which further reduces the contrast of the retinal imaging in the low frequency band compared with the spherical negative lens. The deflection angles calculated according to the negative lens surface types in Table 1 and Table 3 are similar to those in Table 6.

[0135] Table 6

[0136]

[0137] In the above analysis, the surface type of the negative lens is determined as the even asphere with the principal curvature changing from negative to positive from the center to the edge. According to the principal curvature characteristics of this surface type, it can be seen that the even aspheres with the quadratic coefficient all have the characteristic of the principal curvature changing from negative to positive from the center to the edge, so the contrast of the even aspheric negative lens microstructure within the range of is directly discussed.

[0138] To explore the universality of the conclusion that the even aspherical negative lens microstructure in the range of For H = 6 μm, The structure parameters calculation, modeling and MTF analysis are carried out for the negative microstructure from 0.02 to 0.08 at an interval of 0.02, Figure 13 The corresponding MTF curves are given, in which The corresponding spherical negative microstructure is from Figure 13 It can be seen that, compared with the spherical surface, The even aspherical negative lens microstructure in the range of The greater the H is, the more the MTF curve drops. In addition, for H = 8 μm, The negative lens microstructure from 0.02 to 0.08 at an interval of 0.02 is also analyzed, and the results are shown in Figure 14 From the figure, the same conclusion as when H = 6 μm can be drawn.

[0139] At the same time, for higher order terms of n > 2, the even aspherical surface in the range of The even aspherical surface in the range of The even aspherical surface in the range of The sign and the change trend of the principal curvature are consistent with Here, the spherical surface of H = 6 μm and the two even aspherical surfaces of The negative micro-lens structures of the two even aspherical surfaces of The corresponding MTF curves are shown in Figure 15 The results are consistent with the above conclusion.

[0140] The above embodiment 1 draws the conclusion that the even aspherical negative lens in the range of The conclusion that the even aspherical negative lens in the range of The greater the value is, the better the contrast reduction effect is, but Too large, it may cause the aspherical surface to appear reverse curvature (i.e. the surface slope at different apertures has different signs), causing processing difficulties or unsightly appearance, etc. In order to avoid the reverse curvature of the micro-lens surface, the structure parameters of the even aspherical surface are limited in the embodiment 2, further narrowing the range of the even aspherical surface structure that can better reduce the contrast effect obtained in the embodiment 1.

[0141] For ease of calculation and analysis, this embodiment uses vertices at position zero. Threshold calculations of even-order aspherical surface shape parameters are performed on convex aspherical surfaces. Except for the conclusion, the formulas used and the signs of the parameters are consistent with those for convex aspherical surfaces, i.e., r1>0, c>0. <0.

[0142] The method in this embodiment includes the following steps:

[0143] S1: List the surface slope formula and constraints:

[0144] For an even-order aspherical positive lens containing only one higher-order term and with a quadratic surface coefficient k of 0, the derivative (slope form) of its surface profile elevation z with respect to the radial distance r is as follows:

[0145] ,

[0146] Meanwhile, the sag constraint set by the requirements The specific form is as follows:

[0147] ,

[0148] In this example, Then it can be obtained through the formula. The analytical expression for c is as follows:

[0149] ,

[0150] Because the solution can prevent even-order aspherical microlenses from exhibiting inversion. The analytical solution is very difficult. The following uses a numerical solution to represent the specific change in elevation H and the target higher-order term n. .

[0151] S2: Determine whether to use numerical solution to obtain the coefficients of higher-order terms. The method for determining the upper and lower limits (thresholds) of vertex curvature c, and the Matlab code for implementing the method.

[0152] S21: Determine the numerical analysis process: For a given change in elevation H, increase the vertex curvature c at regular intervals starting from 0, according to S21... The analytical calculation of c corresponds to (Represented as An in the program), then calculate the derivative values ​​(slopes) at checkpoints distributed at certain radial intervals along the generatrix of the surface. If the derivative at each checkpoint on the generatrix does not change sign, then the current vertex curvature c meets the requirement, and the next increased c is verified. Repeat the above process until a sign change occurs and an inflection point appears, and record the current vertex curvature c and the corresponding... .

[0153] S22: Complete the writing of Matlab code according to S21: encapsulate the function of checking whether the derivative of the curvature c of a vertex and the corresponding derivative of the generatrix of the corresponding surface changes sign as a function check_derivative, the function file of the first part of the corresponding code, and store it in a new m file.

[0154] In the command line window, define the target height variation H, the height z1 introduced by the mother mirror, and the target high order number n; limit the upper and lower limits and the variation interval of the vertex curvature c, and call the function to check one by one. If it does not meet the requirements, display the upper limit of the current parameters.

[0155] The following Matlab algorithm can be used to check the vertex curvature c and the derivative of the generatrix of the corresponding surface from 0 to 1E-04 interval one by one, from the center of the microlens surface to the maximum radial distance to find the c and corresponding that meet the no-kink condition.

[0156] % Function file

[0157] function error = check_derivative(c, H, n)

[0158] An = (H - (1 - sqrt(1 - (c * 0.5)^2)) / c) / (0.5^(2*n));

[0159] dzdr = @(r) (c * r). / sqrt(1 - (c * r).^2) + 2 * n * An * r.^(2*n - 1);

[0160] r_samples = linspace(1e-6, 0.5, 1000); % Ignore r=0

[0161] vals = dzdr(r_samples);

[0162] if any(diff(sign(vals)) ~= 0)

[0163] error = 1; % There is a sign change, which does not meet the condition

[0164] else

[0165] error = 0; % No sign change, meet the condition

[0166] end

[0167] end

[0168] % call analysis

[0169] n=2;% define target high order number n

[0170] H=2e-3;% define target sag change H, unit: mm

[0171] H=H-0.446429e-3;% subtract the primary mirror sag z1, corresponding to z1 in Table 2, unit: mm

[0172] c_min=1e-6;% vertex curvature lower limit, unit: mm-1

[0173] c_max=2-1e-6;% vertex curvature upper limit, limited by microlens aperture, unit: mm-1

[0174] c_interval=1e-4;% vertex curvature search interval, unit: mm-1

[0175] for c=c_min: c_interval:c_max

[0176] if check_derivative(c,H,n) % check if the derivative changes sign within the interval

[0177] An = (H - (1 - sqrt(1 - (c * 0.5)^2)) / c) / (0.5^(2*n));

[0178] disp(['c=',num2str(c)]);

[0179] disp(['An=',num2str(An)]);

[0180] break;% only find the first An that does not satisfy from 0

[0181] end

[0182] end

[0183] S23: Determine the target high order number n and the target sag change H according to the requirements, change the variable n and H code in the call analysis section, and execute the program. The program will output the corresponding high order coefficient and the threshold value of vertex curvature c.

[0184] S3: Repeat the numerical solution calculation of S2, count the calculation results and perform fitting to obtain the high order coefficient ​and the relationship between the threshold value of vertex curvature c and the sag change H.

[0185] In this embodiment, the sag change H = 0.5-15 μm is used, and H is traversed at intervals of 0.5 μm, and the corresponding high-order coefficient is counted The threshold value of vertex curvature c is fitted and analyzed in the array. Table 7 is the calculation result at several typical sag changes H of n = 2.

[0186] Table 7

[0187]

[0188] According to the fitting analysis, when n = 2, the The actual data of c and the univariate fitting effect are as shown in Figure 16 , wherein Figure 16 (a) in and the fitting effect of H, Figure 16 (b) in is the fitting curve, and the point represents the actual data.

[0189] When n = 2, the regression coefficients of the fitting results are all , and the fitting formula is as follows:

[0190] ,

[0191] ,

[0192] The above operation is repeated to complete the fitting when n = 3, and the result is also the regression coefficient , which conforms to the following fitting formula:

[0193] ,

[0194] ,

[0195] It should be noted that when the aspheric surface with is solved, other high-order coefficients are all 0, and when the aspheric surface with is solved, other high-order coefficients are also all 0.

[0196] From the above formula, it can be known that the lower limit of the vertex curvature c corresponds to the curvature of the sphere under the same sag change H , , and the upper limit of the vertex curvature c is 0, which also corresponds to the sphere. In order to distinguish from the vertex curvature radius of the aspheric surface, the following uses represents the radius of curvature of the sphere under the sag height variation H. Since the research object is a negative lens microstructure, the above research result is taken as the opposite number and appropriately rounded, and the value range of the higher order term of the even aspherical surface is simplified as follows (conclusion):

[0197] ,

[0198] ,

[0199] It should be noted that in the above fitting formula and simplified formula, only the value of H in mm unit is substituted, and the unit of c is mm -1 . In addition, the two parameters in the simplified formula have correlation and cannot be taken independently at the same time. From the simplified formula, it can be seen that when the lower limit value is taken, c is the upper limit value, and at this time the surface type is spherical; and when the upper limit value is taken, c is the lower limit value, corresponding to the even aspherical surface with reverse curvature at the edge of the lens.

[0200] According to the above simplified formula, the sag height variation H is selected as an example, the corresponding and the cross-sectional view of the even aspherical surface with reverse curvature at the edge of the lens are drawn for n=2 and n=3, as shown in Figure 17 (a) and (b) of the figure, wherein the solid line is the sphere under the same sag height. As can be seen from the figure, the slope of the aspherical surface continuously changes from the center of the lens to the edge of the lens, and tends to 0 at the edge of the lens, but there is no reverse curvature on the whole curve, which meets the design requirements.

[0201] Using the same way, the threshold interval of the higher order term coefficient of the even aspherical surface can be obtained, and after the value range of the higher order term coefficient of the even aspherical surface and the vertex curvature c is simplified, the threshold of and c does not need to be obtained by using the program any more, and can be directly obtained by the selected sag height variation H and the simplified formula. The embodiment further reduces the selection range of the surface type parameters of the even aspherical surface which can better reduce the contrast compared with the spherical surface, guarantees that there is no reverse curvature on the micro-lens surface type, basically meets the requirements of lens processing and appearance, makes the even aspherical surface in the structure parameter value range more easily used in engineering, and further improves the design efficiency.

[0202] Figure 17 In the embodiment 2, the value range of the higher order term coefficient of the even aspherical surface micro-lens with no reverse curvature and better reducing the contrast compared with the spherical surface is obtained; from the embodiment 1, it is known that the greater the higher order term coefficient, the better the effect of reducing the contrast, so that the upper limit of the value range of the higher order term coefficient under the same sag height variation can obtain the maximum effect of reducing the contrast. However, from , it can be seen that when H=10μm,As can be seen from the cross-sectional curve at the upper limit, the slope of the edge of the negative lens changes too quickly, which still presents problems in processing and appearance. This may make it easier for the wearer to observe the microstructure, causing excessive attention and rejection subjectively, affecting the aesthetics of the lens and the subjective control effect, while also increasing the processing difficulty.

[0203] To avoid the above situation, the value should be minimized as much as possible within the upper limit benchmark. To achieve the desired contrast reduction while preserving as much of the contrast reduction effect of even-order aspherical surfaces as possible compared to spherical surfaces, Embodiment 3 of this application quantifies the relationship between the maximum contrast reduction effect of lenses with different higher-order coefficients compared to spherical surfaces. Based on this quantification, a "three-part median" method is proposed to determine an optimal value from the range of higher-order coefficients. The specific explanation of this method is as follows:

[0204] S1: The maximum decrease in MTF of even-order aspherical microstructure lenses with different higher-order terms compared to spherical microstructure lenses was statistically analyzed: an even-order aspherical lens with H=6μm and n=2 higher-order terms was selected as the negative lens surface type for MTF analysis of the lens system. As shown in Example 2, the range of easily manufactured higher-order term coefficients is... (H is a numerical value in mm), that is We selected 0.01 as the coefficient analysis interval, and used 0.01, 0.02, 0.03, ..., 0.09 as the coefficients of higher-order terms. The analysis series was modeled and optically simulated using the method described in Example 1. All other modeling data not listed here are the same as in Example 1.

[0205] The corresponding optical models for the above-described series of high-order term coefficient analysis were completed using the method of Example 1, and MTF values ​​were statistically analyzed. Since this application aims to reduce contrast, and the region of MTF decrease is mainly concentrated in the low-frequency range, the statistical region for MTF was set to the spatial frequency range of 0~10 lp / mm with intervals of 0.5 lp / mm. For ease of observation, only the following are listed: MTF curves for 0.01, 0.03, 0.05, 0.07, and 0.09, as shown below. Figure 18 As shown, the horizontal axis of the curve represents spatial frequency (in lp / mm), and the vertical axis represents MTF value.

[0206] To compare the descent effect, the MTF reduction of even-order aspherical microstructures compared to spherical microstructures is calculated using the following formula:

[0207] ,

[0208] Calculations revealed that for different The maximum value of the decrease of the negative microstructure with the change of spatial frequency is defined as the maximum decrease, i.e.:

[0209] ,

[0210] The maximum decrease is obtained when the independent variable spatial frequency f takes the value of

[0211] It can be seen from Figure 18 that the maximum decrease of the negative microstructure of different occurs before the first fluctuation of the MTF curve and is contained in the statistical spatial frequency interval; secondly, the maximum decrease as a numerical value is more convenient for comparison than the array form of the decrease, and therefore, the maximum decrease is suitable as the quantitative object of analysis.

[0212] The maximum decrease of the negative microstructure of the even aspheric surface with different high-order coefficients is calculated by statistically analyzing the MTF data, as shown in Table 8. Figure 18 The maximum decrease of 40% of =0.09 is marked in the figure, and the MTF value of the sphere at the spatial frequency corresponding to the maximum decrease of 100% (the denominator in the formula).

[0213] Table 8

[0214]

[0215] S2: Binary fitting (quantification) of the relationship between the high-order coefficient and the maximum decrease: The high-order coefficients and the corresponding maximum decreases listed in Table 8 are fitted. It is observed from Table 8 that the statistical data as a whole conforms to the rising trend of the power function, and therefore, the fitting is performed using , wherein a, b, and c are the coefficients to be fitted, E represents the maximum decrease, and A2 represents the high-order coefficient . The final fitting result is as follows:

[0216] ,

[0217] The correlation coefficient of the fitting formula is 0.9805, and the fitting effect is good. The fitting result is shown in Figure 19 , the solid line is the fitting result, the dots represent the actual data, the abscissa is the high-order coefficient, and the ordinate is the maximum decrease in percentage form.

[0218] S3: According to the quantitative relationship between the high-order coefficient and the maximum decrease, an optimal value is determined from the range of the high-order coefficient of the surface without reverse curvature by the "three-fraction median" method:

[0219] As the target requirements indicate, to balance the requirements of microstructured lenses in terms of shape, use, and processing, a maximum reduction should be achieved with the smallest possible coefficient for higher-order terms. (Observation) Figure 19 If the maximum achievable descent effect is considered, as shown in Table 8... The difference between the maximum decrease of 0.09 and 0.01 As the baseline, set to 100%, then... When the analysis series reaches its midpoint at 0.05, the maximum decrease in the fitted value is approximately 30%, as shown below. Figure 19 (Mid-level dashed line), the first half contributed about 70% ( The extreme descent effect of the second half contributed approximately 30% ( ). The limiting descent effect of ) . The coefficients of higher-order terms When the value is set to the median of the analysis series (0.05), compared to setting it to the maximum value (0.09), the coefficients of higher-order terms decrease significantly by 50%, but the limiting effect on MTF reduction only decreases by 30%. For example... Figure 20 The figure shows The cross-sectional view of the microlens when the value is set to the median of 0.05 shows the slope change at the upper edge compared to... Taking the upper limit makes things much smoother; the above is the explanation of the "three points" in the "three-point median" method.

[0220] Considering the analysis series Scope The range of values ​​included in Example 2 The amount of higher-order terms discarded before and after The midpoint of the analysis series, 0.05, is approximately equal to the midpoint of the processing range, 0.048. Therefore, the midpoint of the analysis series is equivalent to the midpoint of the range of higher-order coefficients in Example 2. This is the explanation of the midpoint of the "three-part median" method. By abandoning the 30% MTF reduction effect in the latter half, the optimal higher-order coefficient is set as the midpoint of the range of higher-order coefficients for surfaces without curvature. With the higher-order coefficient value significantly reduced by 50% compared to the threshold, a maximum MTF reduction effect of 70% is obtained. The slope change of the even-order aspherical surface is relatively gentle, which not only makes it easier to process and makes the appearance more acceptable to the wearer, but also has a better contrast reduction effect, achieving the best balance between appearance, processing difficulty, and visual effect of the microstructure.

[0221] Based on the range of values ​​for the higher-order coefficients of the surface without inflection obtained in Example 2, the optimal values ​​for the higher-order coefficients of even-order aspherical surfaces determined by the "three-part median" method are:

[0222] ,

[0223] ,

[0224] S4: Verify the MTF decline effect corresponding to the optimal value of the higher order coefficient using other sag change values:

[0225] Select the higher order coefficient of H=8 μm, n=2 0.01, 0.02, …, 0.11 are the verification series of the final conclusion, and the modeling and optical simulation of the microstructure lens are carried out according to the method of embodiment 1. The MTF curves of different higher order coefficient microstructure lenses are obtained, and compared with the MTF curves of the spherical microstructure lens under the same conditions, the maximum decline is calculated, and the results are shown in Table 9. For easy observation, the MTF curves of a2=0 (the curve corresponding to the spherical surface in the figure) are listed in Figure 21 0.01, 0.03, 0.05, 0.07, 0.09, 0.11 (the curve corresponding to a2=0 in the figure corresponds to the spherical surface).

[0226] Table 9

[0227]

[0228] For the statistical data of this series, the function can be well fitted, where p1, p2, p3, p4, q1, q2, q3 are the fitted coefficient values. The final results are as follows:

[0229] ,

[0230] The correlation coefficient is 0.9946, and the fitting effect is good, and the fitting results are shown in Figure 22 Similarly, taking the middle position 0.06 of the verification series as the boundary, the maximum decline difference between 0.11 and 0.01 is taken as the reference quantity, set to 100%, and the same conclusion in S3 is found: the first half contributes about 70% of the limit decline effect, and the second half contributes about 30% of the limit decline effect. Figure 23 is The micro-lens cross-section graph at the middle value 0.06 is taken, and the slope change of the edge part of the graph is relatively gentle, thus the phenomenon of the "third median" method is verified, which can be directly used in actual use.

[0231] By analyzing the quantitative relationship between the higher order coefficient and the maximum decline effect of MTF, and combining the "third median" method, the optimal value of the higher order coefficient in the design of the microstructure surface can be effectively determined. Moreover, using the method proposed in this embodiment, it can be applied to different ​The high-order coefficient of the microstructure is determined based on the maximum MTF reduction effect quantification model of the high-order coefficient (n>2) of the aspherical surface, and the optimal value of the high-order coefficient of the microstructure is determined.

[0232] The above embodiments 1-3 draw the following conclusions: 1. Under the same variation of the lenticule sag height and diameter, the even aspherical negative microstructure with the high-order coefficient The even aspherical negative microstructure with the high-order coefficient in the range can make the MTF have more reduction in the low frequency part than the spherical negative microstructure; 2. On the basis of conclusion 1, the upper and lower limit ranges of the high-order coefficient or the vertex curvature c of the aspherical surface without reverse curvature are given, wherein one side is a constant and the other side is only related to the variation of the sag height H; 3. On the basis of conclusion 2, the middle value is determined as the optimal value from the high-order coefficient value range by the “three-fraction median” method, the high-order coefficient value is reduced by 50% compared with the upper limit, the maximum MTF reduction effect of 70% at the upper limit value is obtained, and the best balance between the appearance, processing difficulty and the MTF reduction effect of the microstructure is achieved. According to the above conclusions, when the surface profile of the even aspherical negative lens microstructure is designed to reduce the contrast, the repeated modeling and simulation of the overall microstructure lens are not needed, and the structure design of the even aspherical negative lens surface profile can be directly performed to obtain the even aspherical negative lens microstructure lens which meets the appearance and processing requirements of the lens and can reduce the retinal contrast as much as possible.

[0233] Obviously, the above embodiments are only examples for clearly illustrating the present application, and are not intended to limit the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. All the embodiments do not need to be exhausted, and the obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A method for designing a microstructure myopia control lens, characterized in that, The method is used for designing a microstructure myopia prevention lens, the microstructure myopia prevention lens comprising a base lens and a negative microlens array, the base lens comprising a central clear zone and a regulation zone; the negative microlens array is arranged on the surface of the regulation zone of the base lens and comprises a plurality of even aspheric negative lenses arranged in an array, the main curvature of each even aspheric negative lens changes from a negative value to a positive value from the center to the edge; the design method comprises: based on a plurality of preset sag variation amounts, calculating the structure parameters of the spherical negative microlens array to construct a three-dimensional model of the microstructure lens under the spherical negative microlens array; based on a plurality of preset sag variation amounts, calculating the structure parameters of each even aspheric negative microlens array with different high-order coefficients as a constraint that the sag of the even aspheric surface monotonously increases with the increase of the radial distance to construct a three-dimensional model of the microstructure lens under each even aspheric negative microlens array; obtaining the MTF curve of the combination of each three-dimensional model of the microstructure lens and the eye model, and taking the MTF curve of the microstructure lens under the spherical negative microlens array as a standard curve; comparing the MTF curves of the microstructure lens under each even aspheric negative microlens array with the standard curve respectively; taking the surface shape of the even aspheric negative lens with the MTF curve lower than the standard curve in the preset frequency band as a target surface shape, obtaining the variation rule of the main curvature of the even aspheric negative lens based on the high-order coefficient of the target surface shape, and setting the main curvature of the even aspheric negative lens on the surface of the regulation zone of the base lens of the microstructure myopia prevention lens to change from a negative value to a positive value from the center to the edge.

2. The microstructure myopia prevention lens design method according to claim 1, wherein: the quadratic surface coefficient of each even aspheric negative lens is 0; each even aspheric negative lens only contains one high-order coefficient, when the high-order term is 2, the value range of the high-order coefficient is (0, 16H), and when the high-order term is 3, the value range of the high-order coefficient is (0, 32H); wherein H represents the sag variation amount.

3. The microstructure myopia prevention lens design method according to claim 2, wherein: when the high-order term is 2, the high-order coefficient is 8H; and / or when the high-order term is 3, the high-order coefficient is 16H.

4. The microstructure myopia prevention lens design method according to claim 1, wherein: the base lens is a meniscus spherical or aspherical lens for correcting refractive errors; and / or the diameter of the central clear zone is 6mm-12mm; and / or the radial diameter of the even aspheric negative lens is 0.5mm-2mm, and the sag variation amount is 1μm-15μm.

5. The microstructure myopia control lens design method of claim 1, wherein, After obtaining the variation rule of the main curvature of the even aspheric negative lens, the method further comprises: constructing the relationship function of the sag of the even aspheric negative lens with the vertex curvature, the radial distance and the high-order coefficient of the even aspheric negative lens, and the derivative function with respect to the radial distance, under the constraint that the even aspheric negative lens only contains one high-order coefficient and the quadratic surface coefficient is equal to 0. The maximum radial distance of the negative lens is substituted into the relationship function to obtain a maximum sag relationship of the even aspheric negative lens; based on the maximum sag of the even aspheric negative lens being equal to the difference between the sag variation and the sag of the parent lens, an analytical expression of the relationship between the high-order term coefficient of the even aspheric negative lens and the vertex curvature thereof is obtained; A plurality of sag variations are obtained by sampling in a first preset interval, and for each sag variation, a plurality of vertex curvature values are obtained by sampling in a second preset interval, and the current sag variation, each vertex curvature value, the sag of the parent lens and the preset high-order term number are input into the analytical expression to obtain the high-order term coefficient value corresponding to each vertex curvature value under the current sag variation; Based on each vertex curvature value and the corresponding high-order term coefficient value under each sag variation, a relationship curve of the vertex curvature and the high-order term number under the current sag variation is drawn; the vertex curvature value and the high-order term coefficient value at the extreme point in the relationship curve under each sag variation are obtained; The vertex curvature values and the high-order term coefficient values at the extreme points under all sag variations are fitted to obtain a first relationship between the high-order term coefficient of the even aspheric negative lens and the sag variation and a second relationship between the vertex curvature and the sag variation under the preset high-order term number, so that the high-order term coefficient value range of the even aspheric negative lens under the preset high-order term number is obtained.

6. The microstructure myopia control lens design method of claim 5, wherein, After obtaining the high-order term coefficient value range of the even aspheric negative lens under the preset high-order term number, the following steps are further included: A plurality of candidate high-order term coefficient values are obtained by sampling in the high-order term coefficient value range of the even aspheric negative lens; Based on the structure parameters of the parent lens, the preset sag variation, the arrangement pattern of the microstructure array and the maximum radial distance of the negative lens, the structure parameters of each candidate even aspheric negative micro-lens array are calculated to construct a three-dimensional model of a candidate micro-structured lens under each candidate even aspheric negative micro-lens array; The MTF curves of each candidate micro-structured lens after the three-dimensional model is combined with an eye model are obtained, and the maximum decline of the MTF curve of each candidate micro-structured lens compared with a standard curve in a preset frequency band is calculated; A binary fitting is performed on the relationship between the plurality of candidate high-order term coefficient values and the maximum decline to obtain a quantitative relationship between the high-order term coefficient and the maximum decline, and the ternary median method is used to obtain the optimal value of the high-order term coefficient of the even aspheric negative lens based on the quantitative relationship.

7. The microstructure myopia control lens design method of claim 5, wherein, The relationship function of the sag of the even aspheric negative lens and the vertex curvature, the radial distance and the high-order term coefficient thereof is represented as: ， wherein, represents the sag of the even aspherical negative lens; represents the radial distance of the even aspherical negative lens; represents the vertex curvature of the even aspherical negative lens; represents the high order term coefficient corresponding to the high order term of n. The maximum sag relationship of the even aspheric negative lens is represented as: ， wherein, represents the maximum sag of the even aspheric negative lens; represents the maximum radial distance of the negative lens; The analytical expression of the relationship between the high-order term coefficient of the even aspheric negative lens and the vertex curvature thereof is represented as: ， wherein, represents the change in sag; represents the primary mirror sag.

8. The microstructure myopia control lens design method of claim 5, wherein, When the preset high-order term number is 2, the first relationship between the high-order term coefficient of the even aspheric negative lens and the sag variation is represented as: ， wherein, represents the high-order term coefficient corresponding to the high-order term with the order of 2; represents the change amount of the sag. The second relationship between the vertex curvature and the sag variation is represented as: ； The high-order term coefficient value range of the even aspheric negative lens is (0, 16H).

9. The microstructure myopia control lens design method of claim 5, wherein, When the preset high-order term number is 3, the first relationship between the high-order term coefficient of the even aspheric negative lens and the sag variation is represented as: ， wherein, represents the high-order term coefficient corresponding to the high-order term with the order of 3; represents the change in the sag. The second relationship between the vertex curvature and the sag variation is represented as: ； The high-order term coefficient value range of the even aspheric negative lens is (0, 32H).

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