An evaluation method and a design method of a bifocal progressive addition lens

Abstract

The application discloses an evaluation method and a design method of a bifocal progressive multifocal lens, and the evaluation method comprises the following steps: arranging a plurality of discrete sample points P bi on the back surface of the lens; selecting n pairs of light ray starting points on the circumference of a pupil; determining two light rays of the first pair of light ray starting points to the back surface of the lens in the direction parallel to the center of the pupil to the sample point P bi , and obtaining two intersection points of the two light rays with the front surface of the lens and the outgoing vectors s1 and s2 from the two intersection points through ray tracing; obtaining the intersection point of the two outgoing light rays and the distance from the intersection point to the sample point, and taking the reciprocal of the distance as the surface power of the first pair of light ray starting points; obtaining the surface power of other pairs of light ray starting points corresponding to the same sample point; taking the difference between the maximum value and the minimum value of each surface power corresponding to the sample point as the astigmatism value of the sample point; and obtaining the astigmatism value corresponding to each sample point to simulate the astigmatism distribution of the lens. The application can more accurately reflect the visual effect when the lens is used.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical lenses, in particular to an evaluation method and a design method of a bifocal progressive lens. BACKGROUND

[0002] Progressive lenses, also known as progressive lenses, can solve the problem of using different diopter for viewing distant objects, medium distance objects and close distance objects, and are also an important choice for vision correction of young people. Accurate evaluation of progressive lenses is of great significance to their design and subsequent processing, and is the premise of obtaining lenses with the best visibility.

[0003] In the prior art, the method for evaluating progressive lenses is generally only applicable to measuring and evaluating the processed lenses, and the positional relationship between the lenses and the eyeballs is not considered in the evaluation process. The Chinese invention patent with publication number CN103123420 proposes to calculate the optical parameters of bifocal free-form lenses through the sagittal height distribution data of the front and back surfaces of the lenses, and finally deduces the optical power and astigmatism distribution of the combined lenses. Although the evaluation method proposed by the patent considers the positional relationship between the lenses and the eyeballs, and can accurately calculate the optical power and astigmatism distribution generated by the two surfaces of the lenses, the calculation method is complex and is not conducive to embedding into subsequent optimization algorithms.

[0004] The disclosure of the above background art content is only used to assist in understanding the inventive concept and technical solutions of the present application, and it does not necessarily belong to the prior art of the present patent application, nor does it necessarily provide technical teaching; in the absence of clear evidence that the above-mentioned content has been disclosed before the filing date of the present patent application, the above-mentioned background art should not be used to evaluate the novelty and inventiveness of the present application. SUMMARY

[0005] The purpose of the present application is to provide an evaluation method and a design method of a bifocal progressive lens, which simulates a plurality of pairs of light ray starting points at the pupil circumference position to calculate the astigmatism distribution of the lens, and more accurately reflects the visual effect when using the lens.

[0006] To achieve the above-mentioned purpose, the technical solutions adopted by the present application are as follows:

[0007] An evaluation method of a bifocal progressive lens, comprising the following steps:

[0008] determining the mirror surface structure of the front surface and the back surface of the lens to be analyzed, and the material refractive index of the lens to be analyzed;

[0009] a plurality of discrete sample points P bi are arranged on the back surface of the lens, where 1≤i≤j, j is the integer number of sample points;

[0010] Determine the center position of the pupil according to the preset relationship between the glasses and the eye; and determine the circumference of the pupil according to the preset pupil diameter;

[0011] Take n pairs of light source points on the circumference of the pupil, each pair of light source points is symmetrical about the center of the pupil, and n is the integer number of light source point pairs;

[0012] For each sample point P bi Its astigmatism is determined in the following way:

[0013] Parallel to the center of the pupil towards the sample point P bi The direction of the first pair of light rays is determined, and the two light rays from the origin of the first pair of light rays to the rear surface of the lens are obtained by ray tracing, and the intersection points P with the front surface of the lens are obtained respectively. fi-1 and P fi-2 and intersection point P fi-1 The outgoing vector s1 and the intersection point P fi-2 The outgoing vector s2 at that point;

[0014] Obtain the intersection point P of the two rays with outgoing vectors s1 and s2. cross-i1 The intersection point P is obtained. cross-i1 To the sample point P bi The distance is calculated, and the reciprocal of this distance is used as the sectional optical power of the starting point of the first pair of light rays.

[0015] Obtain the same sample point P bi Corresponding other sectional optical powers relative to the light source to

[0016] Determine the same sample point P bi The maximum and minimum optical power values ​​of each corresponding section are used, and the difference between them is taken as the sample point P. bi The corresponding astigmatism value Δx' bi ;

[0017] The astigmatism value corresponding to each sample point is obtained, the astigmatism distribution of the lens is simulated, and this is used as the basis for evaluating the lens.

[0018] Furthermore, following any one or a combination of the aforementioned technical solutions, a contour line with a preset astigmatism threshold is determined in the astigmatism distribution;

[0019] Estimate the area within the contour lines of the preset astigmatism threshold;

[0020] If the area within the contour line is smaller than a preset area threshold, the lens is deemed unqualified.

[0021] Furthermore, following any one or a combination of the aforementioned technical solutions, the intersection point P of the two rays of the outgoing vectors s1 and s2 is calculated using the following formula. cross-i1 :

[0022] Normal = s1 × s2,

[0023] Normal_1 = s1 × Normal,

[0024] Normal_2 = s2 × Normal,

[0025] P f-3 =P f-2 -P f-1 ,

[0026] P cross-i1 =P f-1 +s1·(P f-3 ·Normal_2) / (s1·Normal_2),

[0027] Where s1 is the emission vector of the first outgoing ray from the front surface of the lens, s2 is the emission vector of the second outgoing ray from the front surface of the lens, and Normal, Normal_1, and Normal_2 are intermediate calculation variables, P fi-1 P represents the point where the first emitted ray intersects the front surface of the lens. fi-2 The intersection point P represents the point where the second emitted ray intersects the front surface of the lens. f-2 to intersection point P f-1 The distance, P cross-i1 This represents the intersection of the outgoing vectors s1 and s2.

[0028] Furthermore, following any one or a combination of the aforementioned technical solutions, the intersection point P of the two rays from the origin of the first pair of rays to the rear surface of the lens and the front surface of the lens is obtained by ray tracing in the following manner. fi-1 and P fi-2 :

[0029] Draw the pupil center towards the sample point P bi The virtual light ray is generated, and a first ray and a second ray are drawn parallel to the virtual light ray, wherein the first ray and the second ray respectively pass through the first pair of light source points;

[0030] Based on the mirror structure of the rear surface of the lens, the intersection point P of the first ray and the rear surface is determined. bi-1 and the intersection point P bi-1 normal line And determine the intersection point P of the second ray and the rear surface. bi-2 and the intersection point P bi-2 normal line

[0031] Determine the direction of the refracted light after the first light ray enters the lens. and the direction of the refracted light after the second light enters the lens

[0032] Based on the mirror structure of the front surface of the lens, the intersection point P is determined. bi-1 Refracted light direction The intersection point P of the ray and the front surface fi-1 And determine the intersection point P bi-2 Refracted light direction The intersection point P of the ray and the front surface fi-2 .

[0033] Furthermore, following any one or a combination of the aforementioned technical solutions, the direction of the refracted ray after the first ray enters the lens is calculated according to the following formula.

[0034] in, Let I1 be the direction of the refracted ray after the first ray enters the lens, and let I1 be the refractive index of the lens material. The direction of the first ray passing through the origin of one of the rays. Let P be the intersection point. bi-1 The normal vector;

[0035] And calculate the direction of the refracted ray after the second ray enters the lens according to the following formula.

[0036] in, I1 represents the direction of the refracted ray after the second ray enters the lens, and I1 represents the refractive index of the lens material. The direction of the second ray that passes through the origin of another ray. Let P be the intersection point. bi-2 The normal vector.

[0037] Furthermore, based on any one or a combination of the aforementioned technical solutions, the intersection point P is determined in the following manner. fi-1 The outgoing vector s1 and the intersection point P fi-2 The outgoing vector s2 at that point;

[0038] Based on the mirror structure of the front surface of the lens, determine the intersection point P with the front surface. fi-1 normal line And determine the intersection point P with the front surface. fi-2 normal line

[0039] Determine the refractive index I2 of the medium surrounding the lens, and calculate the intersection point P using the following formula. fi-1 The outgoing vector s1 at point:

[0040] in, s1 is the intersection point P fi-1 The outgoing vector at the point, where I2 is the refractive index of the medium surrounding the lens. The direction of the refracted ray after the first ray enters the lens. Let P be the intersection point. fi-1 The normal vector;

[0041] The intersection point P is calculated using the following formula. fi-2 The outgoing vector s2 at point:

[0042] in, s2 is the intersection point P fi-2 The outgoing vector at the point, where I2 is the refractive index of the medium surrounding the lens. The direction of the refracted ray after the second ray enters the lens. Let P be the intersection point. fi-2 The normal vector.

[0043] Furthermore, based on any one or a combination of the aforementioned technical solutions, in obtaining the same sample point P... bi Optical power of the cross section at the origin of each pair of light rays to Then, the average value of the optical power of the section is calculated and used as the sample point P. bi The corresponding average optical power;

[0044] The average optical power corresponding to each sample point is obtained, the average optical power distribution of the lens is simulated, and this is used as a basis for auxiliary evaluation of the lens.

[0045] Furthermore, following any one or a combination of the aforementioned technical solutions, the average optical power value at a preset position in the average optical power distribution is determined. The preset position includes a distance use area and a near use area. If the average optical power of the near use area is 0 and the average optical power of the distance use area meets the design target optical power value, then the lens is evaluated as qualified.

[0046] Furthermore, following any one or a combination of the aforementioned technical solutions, the center of the pupil is taken as a point on the optical axis on the rear side of the lens that is a preset distance from the center of the rear surface of the lens.

[0047] determine a plane in which the pupil circumference lies in a direction perpendicular to the optical axis;

[0048] The pairs of light ray origins on the pupil circumference are more than six pairs, and more than 12 light ray origins are distributed equidistantly on the pupil circumference.

[0049] According to another aspect of the present application, the present application provides a design method of a bifocal progressive addition lens, wherein the lens is obtained by using the evaluation method according to any one of the technical solutions or the combination of the technical solutions.

[0050] According to the astigmatism distribution, the design parameters of the lens are adjusted until the astigmatism distribution of the lens meets the preset standard.

[0051] The technical solutions provided by the present application have the following beneficial effects: considering the actual wearing state of the user, a plurality of pairs of light ray origins are simulated at the positions of the pupil circumference, which is closer to the actual situation of observing an object by the eye, and thus the astigmatism distribution obtained can theoretically more accurately reflect the real visual effect of the user when using the lens, and the accuracy of the performance evaluation of the lens is improved. BRIEF DESCRIPTION OF DRAWINGS

[0052] In order to more clearly illustrate the technical solutions in the embodiments or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only illustrate some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0053] Figure 1 A flowchart of the evaluation method of the bifocal progressive addition lens is provided for an exemplary embodiment of the present application.

[0054] Figure 2 A schematic diagram of the pupil and the optical system of the lens when the eye wears the glasses is provided for an exemplary embodiment of the present application.

[0055] Figure 3 A schematic diagram of the pupil circumference provided with six pairs of light ray origins is provided for an exemplary embodiment of the present application.

[0056] Figure 4 A schematic diagram of the lens rear surface provided with a plurality of sampling points is provided for an exemplary embodiment of the present application.

[0057] Figure 5 A deflection schematic diagram of the incident light and the emergent light passing through the lens surface is provided for an exemplary embodiment of the present application.

[0058] Figure 6A schematic diagram of the optical path of two light rays passing through a lens, which are parallel to the center of the pupil and directed toward a sample point, provided as an exemplary embodiment of the present invention;

[0059] Figure 7 An astigmatism distribution map of a lens obtained by simulation using the conventional surface shape method is provided as an exemplary embodiment of the present invention.

[0060] Figure 8 In response to Figure 7 The astigmatism distribution map of the medium lens was obtained by simulation using the lens evaluation method provided in this invention.

[0061] Figure 9 In response to Figure 7 The optical power distribution map of the middle lens was obtained by simulation using the traditional surface shape method.

[0062] Figure 10 In response to Figure 7 The optical power distribution map of the medium lens was obtained by simulation using the lens evaluation method provided in this invention.

[0063] The reference numerals in the attached drawings include: 1-pupil, 2-lens, 21-rear surface of the lens, 22-front surface of the lens, 3-first ray, and 4-second ray. Detailed Implementation

[0064] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0065] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, apparatus, product, or device that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or devices.

[0066] In one embodiment of the present invention, an evaluation method for a two-sided progressive multifocal lens is provided, see [link to relevant documentation].Figure 1 The evaluation method comprises the following steps:

[0067] determining the mirror surface structure of the front surface and the back surface of the lens to be analyzed, and the material refractive index of the lens to be analyzed;

[0068] Referring to Figure 4 a plurality of discrete sample points P are arranged on the back surface of the lens bi , wherein 1≤i≤j, and j is the integer number of sample points;

[0069] determining the pupil center position according to a preset wearing eye-glasses eye relationship, and determining the pupil circumference according to a preset pupil diameter;

[0070] Referring to Figure 3 n pairs of light ray origins are taken on the pupil circumference, each pair of light ray origins is symmetrical about the pupil center, and n is the integer number of pairs of light ray origins;

[0071] For each sample point P bi , the astigmatism thereof is determined by the following manner:

[0072] As shown in Figure 6 , two light rays of the first pair of light ray origins to the back surface of the lens are determined in a direction parallel to the pupil center to the sample point P bi , and ray tracing is performed to obtain the intersection points P fi-1 and P fi-2 of the front surface of the lens and the exit vectors s1 at the intersection point P fi-1 and s2 at the intersection point P fi-2 respectively;

[0073] the intersection point P cross-i1 of the two light rays of the exit vectors s1 and s2 is obtained, the distance of the intersection point P cross-i1 to the sample point P bi is obtained, and the reciprocal of the distance is taken as the surface power of the first pair of light ray origins

[0074] the surface power of the other pairs of light ray origins corresponding to the same sample point P bi is obtained

[0075] the maximum value and the minimum value of each surface power corresponding to the same sample point P bi are determined, and the difference between the maximum value and the minimum value is taken as the astigmatism value △x’ bi of the sample point P bi ;

[0076] ​The astigmatism value corresponding to each sample point is obtained, the astigmatism distribution of the lens is simulated, and this is used as the basis for evaluating the lens.

[0077] The evaluation method for double-sided progressive multifocal lenses provided by this invention simulates several pairs of light origins at the circumference of the pupil and uses ray tracing to calculate the astigmatic distribution of the lens. This evaluation method takes into account the optical structure of the lens in actual use by the user and comprehensively evaluates the contributions of the front and rear surfaces of the lens to optical power and astigmatism. It can more accurately reflect the visual effect when using the lens, and its evaluation results can better reflect the real situation observed by the human eye.

[0078] In one embodiment of the present invention, the optical system between the pupil and the lens when the human eye wears glasses is as follows: Figure 2 As shown. The rear surface 21 of the lens has a concave structure, the front surface 22 has a planar structure, and the refractive index of the lens 2 is I. The pupil center is located at a point on the optical axis on the rear side of the lens 2, with a distance from the center of the rear surface of the lens equal to a preset lens-eye distance. Figure 2 As shown, the distance from the center of pupil 1 to the rear surface of lens 2 is 27mm; the coordinates of the pupil center can be set as (0,0,-27), and the intersection point of a ray passing through the pupil center and the rear surface of the lens is P. b The intersection point with the front surface of the lens is P. f .

[0079] The plane containing the pupil circumference is defined by a direction perpendicular to the optical axis. In this embodiment, a circle with a radius of 2 mm perpendicular to the optical axis is used as the pupil circumference. There are six or more pairs of light ray origins on the pupil circumference, and more than 12 light ray origins are evenly distributed on the pupil circumference.

[0080] In this embodiment, see Figure 3 Six pairs of light ray origins are taken on the circumference of the pupil, and each pair of light ray origins is symmetrical about the center of the pupil. Figure 3 The circle shown is the pupil circle, and 1 and 1- on it are a pair of light ray origins, 2 and 2- are a pair of light ray origins, 3 and 3- are a pair of light ray origins, 4 and 4- are a pair of light ray origins, 5 and 5- are a pair of light ray origins, and 6 and 6- are a pair of light ray origins.

[0081] See Figure 6 To a sample point P parallel to the center of the pupil bi The direction is determined by identifying the two light rays from the origin of the first pair of light rays to the rear surface 12 of the lens. Figure 6 The first ray 3 and the second ray 4 in the middle.

[0082] See Figure 6 To a sample point P parallel to the center of the pupil biThe direction is determined by identifying the two light rays from the origin of the first pair of light rays to the rear surface 12 of the lens. Figure 6 The first ray 3 and the second ray 4 in the middle.

[0083] Ray tracing involves two key steps: first, determining the location of the intersection point between the ray and the freeform surface; and second, determining the direction of the refracted ray. Chinese patent application CN113281903A discloses a fast iterative method for determining the intersection point of the ray and the freeform surface. Based on this method, the intersection point P of the two rays from the origin of the first pair of rays to the rear surface of the lens and the front surface 21 of the lens can be obtained. fi-1 and P fi-2 .

[0084] In this embodiment, the intersection point P of the two rays from the origin of the first pair of rays to the rear surface of the lens, namely the first ray 3 and the second ray 4, with the front surface 21 of the lens is obtained by ray tracing. fi-1 and P fi-2 :

[0085] Draw the pupil center towards the sample point P bi The virtual light ray is generated, and a first ray 3 and a second ray 4 are drawn parallel to the virtual light ray, wherein the first ray 3 and the second ray 4 respectively pass through the starting point of the first pair of light rays;

[0086] Based on the mirror structure of the rear surface of the lens, the intersection point P of the first ray and the rear surface is determined. bi-1 and the intersection point P bi-1 normal line And determine the intersection point P of the second ray and the rear surface. bi-2 and the intersection point P bi-2 normal line

[0087] Determine the direction of the refracted light after the first light ray enters the lens. and the direction of the refracted light after the second light enters the lens

[0088] Based on the mirror structure of the front surface of the lens, the intersection point P is determined. bi-1 Refracted light direction The intersection point P of the ray and the front surface fi-1 And determine the intersection point P bi-2 Refracted light direction The intersection point P of the ray and the front surface fi-2 .

[0089] In one embodiment of the present invention, see Figure 5The direction of the refracted ray after the first ray enters the lens is calculated according to the following formula.

[0090] in, Let I1 be the direction of the refracted ray after the first ray enters the lens, and let I1 be the refractive index of the lens material. The direction of the first ray passing through the origin of one of the rays. Let P be the intersection point. bi-1 The normal vector;

[0091] And calculate the direction of the refracted ray after the second ray enters the lens according to the following formula.

[0092] in, I1 represents the direction of the refracted ray after the second ray enters the lens, and I1 represents the refractive index of the lens material. The direction of the second ray that passes through the origin of another ray. Let P be the intersection point. bi-2 The normal vector.

[0093] In one embodiment of the present invention, the intersection point P is determined in the following manner. fi-1 The outgoing vector s1 and the intersection point P fi-2 The outgoing vector s2 at that point;

[0094] Based on the mirror structure of the front surface of the lens, determine the intersection point P with the front surface. fi-1 normal line And determine the intersection point P with the front surface. fi-2 normal line

[0095] Determine the refractive index I2 of the medium surrounding the lens, and calculate the intersection point P using the following formula. fi-1 The outgoing vector s1 at point:

[0096] in, s1 is the intersection point P fi-1 The outgoing vector at the point, where I2 is the refractive index of the medium surrounding the lens. The direction of the refracted ray after the first ray enters the lens. Let P be the intersection point. fi-1 The normal vector;

[0097] The intersection point P is calculated using the following formula. fi-2 The outgoing vector s2 at point:

[0098] in, s2 is the intersection point P fi-2 The outgoing vector at the point, where I2 is the refractive index of the medium surrounding the lens. The direction of the refracted ray after the second ray enters the lens. Let P be the intersection point. fi-2 The normal vector.

[0099] In one embodiment of the present invention, the intersection point P of the two rays of the outgoing vectors s1 and s2 is calculated using the following formula. cross-i1 :

[0100] Normal = s1 × s2,

[0101] Normal_1 = s1 × Normal,

[0102] Normal_2 = s2 × Normal,

[0103] P f-3 =P f-2 -P f-1 ,

[0104] P cross-i1 =P f-1 +s1·(P f-3 ·Normal_2) / (s1·Normal_2),

[0105] Where s1 is the emission vector of the first outgoing ray from the front surface of the lens, s2 is the emission vector of the second outgoing ray from the front surface of the lens, and Normal, Normal_1, and Normal_2 are intermediate calculation variables, P fi-1 P represents the point where the first emitted ray intersects the front surface of the lens. fi-2 The intersection point P represents the point where the second emitted ray intersects the front surface of the lens. f-2 to intersection point P f-1 The distance, P cross-i1 This represents the intersection of the outgoing vectors s1 and s2.

[0106] Calculate the intersection point P cross-i1 To sample point P bi The distance is calculated, and the reciprocal of this distance is used as the sectional optical power of the starting point of the first pair of light rays.

[0107] Repeat the above method to obtain the same sample point P. bi Corresponding other sectional optical powers relative to the light source to And determine the same sample point P biThe maximum and minimum optical power values ​​of each corresponding section are used, and the difference between them is taken as the sample point P. bi The corresponding astigmatism value Δx' bi ;Image divergence value △x' bi It can be expressed using the following formula:

[0108]

[0109] Then, the above method is repeated to obtain the astigmatism values ​​corresponding to other sample points. Based on the astigmatism values ​​corresponding to all sample points, the astigmatism distribution of the lens is simulated, such as... Figure 8 As shown, the criteria for evaluating the lens are as follows: A contour line representing a preset astigmatism threshold is determined in the astigmatism distribution; the area within the contour line of the preset astigmatism threshold is estimated; if the area within the contour line is less than a preset area threshold, the lens is deemed unqualified; if the area within the contour line is not less than the preset area threshold, the lens is deemed qualified. In typical evaluation rules, an astigmatism value within -0.5 is considered a valid area. Figure 8 For example, the area within the -0.5 astigmatism contour line is considered acceptable. The larger the area within the -0.5 astigmatism contour line, the better the lens performance. Different grades can also be assigned based on the area within the -0.5 astigmatism contour line to evaluate the lens grade.

[0110] In one embodiment of the present invention, the proposed evaluation method for a double-sided progressive multifocal lens not only includes determining the astigmatism value corresponding to each sample point, simulating the astigmatism distribution of the lens, and using this as the basis for evaluating the lens, but also includes determining the average optical power corresponding to each sample point, simulating the average optical power distribution of the lens, and using this as an auxiliary basis for evaluating the lens.

[0111] In this embodiment, when obtaining the same sample point P bi Optical power of the cross section at the origin of each pair of light rays to Then, the average value of the optical power of the section is calculated and used as the sample point P. bi The corresponding average optical power; obtain the average optical power corresponding to each sample point, and simulate the average optical power distribution of the lens, such as... Figure 10 As shown, this serves as a basis for supplementary evaluation of the lens. The following methods can be used to supplement the evaluation of the lens:

[0112] Determine the average optical power value at a preset position in the average optical power distribution. The preset position includes a central local area. If the average optical power at the lower part of the central local area is 0 and the average optical power at the upper part thereof meets the designed target optical power value, the lens is evaluated as qualified. For example, for a lens with a far vision area power of 2.0, a near vision area power of 0, and an ADD of 2.0, taking Figure 10 as an example, if it is determined that the optical powers of the far vision and near vision test points in the figure meet the design requirements, the lens is evaluated as qualified.

[0113] In a specific embodiment of the present invention, the evaluation method of the double-sided progressive multifocal lens is used to evaluate a lens with a curvature radius of 228 mm for the outer surface (i.e., the front surface of the lens) and a progressive surface for the inner surface (i.e., the back surface of the lens). In this embodiment, it is set that when wearing glasses, the distance between the pupil center and the back surface of the lens is 27 mm, and the pupil circumference radius is 2 mm.

[0114] In this embodiment, Figure 7 is the astigmatism distribution diagram obtained by simulating the lens using the traditional surface shape method. Figure 8 is the astigmatism distribution diagram obtained by simulating the lens using the lens evaluation method based on ray tracing provided by the present invention. Figure 9 is the optical power distribution diagram obtained by simulating the lens using the traditional surface shape method; Figure 10 is the optical power distribution diagram obtained by simulating the lens using the lens evaluation method based on ray tracing provided by the present invention. It can be seen from Figures 7 to 10 that the simulation results based on ray tracing are similar to those obtained by the surface shape method, but there are also obvious differences: Since the present application simulates several pairs of ray starting points at the pupil circumference position, which is closer to the actual situation of the eye observing an object, the astigmatism distribution obtained thereby can theoretically more accurately reflect the true visual effect when the user uses the lens.

[0115] In another embodiment of the present invention, a design method for a double-sided progressive multifocal lens is provided. The astigmatism distribution and average optical power distribution of the lens are obtained by using the evaluation method described in any of the above embodiments; and according to the astigmatism distribution and / or the average optical power distribution, the design parameters of the lens are adjusted until the astigmatism distribution of the lens meets the preset standard.

[0116] Applying the lens evaluation method provided by the present invention in the lens design process can directly evaluate the astigmatism and optical power conditions at each ray tracing position of the lens, and the lens evaluation method provided by the present invention is simple, and can be fed back to the optimization design according to the evaluation results, so as to be able to shorten the design cycle of the lens and facilitate industrial popularization and application.

[0117] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0118] The above description is only a specific embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A method for evaluating a double-sided progressive multifocal lens, characterized in that, Includes the following steps: Determine the mirror structure of the front and back surfaces of the lens to be analyzed, as well as the refractive index of the lens material; Multiple discrete sample points P are set on the rear surface of the lens. bi Where 1≤i≤j, and j is the integer number of sample points; Determine the center position of the pupil according to the preset relationship between the glasses and the eye; and determine the circumference of the pupil according to the preset pupil diameter; Take n pairs of light source points on the circumference of the pupil, each pair of light source points is symmetrical about the center of the pupil, and n is the integer number of light source point pairs; For each sample point P bi Its astigmatism is determined in the following way: Parallel to the center of the pupil towards the sample point P bi The direction of the first pair of light rays is determined, and the two light rays from the origin of the first pair of light rays to the rear surface of the lens are obtained by ray tracing, and the intersection points P with the front surface of the lens are obtained respectively. fi-1 and P fi-2 and intersection point P fi-1 The outgoing vector s1 and the intersection point P fi-2 The outgoing vector s2 at the point is obtained by ray tracing the intersection point P of the two rays from the origin of the first pair of rays to the rear surface of the lens and the front surface of the lens. fi-1 and P fi-2 : Draw the line from the pupil center to the sample point P bi A virtual ray is generated, and a first ray and a second ray are drawn parallel to this virtual ray, wherein the first ray and the second ray respectively pass through the starting point of a first pair of rays; based on the mirror structure of the rear surface of the lens, the intersection point P of the first ray and the rear surface is determined. bi-1 and the intersection point P bi-1 normal line And determine the intersection point P of the second ray and the rear surface. bi-2 and the intersection point P bi-2 normal line Determine the direction of the refracted light after the first light ray enters the lens. and the direction of the refracted light after the second light enters the lens Based on the mirror structure of the front surface of the lens, the intersection point P is determined. bi-1 Refracted light direction The intersection point P of the ray and the front surface fi-1 And determine the intersection point P bi-2 Refracted light direction The intersection point P of the ray and the front surface fi-2 ; Obtain the intersection point P of the two rays with outgoing vectors s1 and s2. cross-i1 The intersection point P is obtained. cross-i1 To the sample point P bi The distance is calculated, and the reciprocal of this distance is used as the sectional optical power of the starting point of the first pair of light rays. The intersection point P of the two rays, s1 and s2, can be calculated using the following formula. cross-i1 : Normal=s1×s2, Normal_1=s1×Normal, Normal_2=s2×Normal, P f-3 =P fi-2 -P fi-1 P cross-i1 =P fi-1 +s1·(P f-3 ·Normal_2) / (s1·Normal_2), where s1 is the exit vector of the first outgoing ray from the front surface of the lens, s2 is the exit vector of the second outgoing ray from the front surface of the lens, Normal, Normal_1, and Normal_2 are intermediate calculation variables, and P fi-1 P represents the point where the first emitted ray intersects the front surface of the lens. fi-2 P represents the point where the second emitted ray intersects the front surface of the lens. cross-i1 This represents the intersection point of the two rays emitted from vectors s1 and s2; Obtain the same sample point P bi The corresponding other optical power ￠ of the cross section at the origin of the light ray i-2 To ￠ i-n ; Determine the same sample point P bi The maximum and minimum optical power values ​​of each corresponding section are used, and the difference between them is taken as the sample point P. bi The corresponding astigmatism value Δx' bi ; The astigmatism value corresponding to each sample point is obtained, the astigmatism distribution of the lens is simulated, and this is used as the basis for evaluating the lens: a contour line with a preset astigmatism threshold is determined in the astigmatism distribution; the area within the contour line of the preset astigmatism threshold is estimated; if the area within the contour line is less than a preset area threshold, the lens is evaluated as unqualified.

2. The evaluation method for double-sided progressive multifocal lenses according to claim 1, characterized in that, The direction of the refracted ray after the first ray enters the lens is calculated using the following formula. : in, Let I1 be the direction of the refracted ray after the first ray enters the lens, and let I1 be the refractive index of the lens material. The direction of the first ray passing through the origin of one of the rays. Let P be the intersection point. bi-1 The normal vector; And calculate the direction of the refracted ray after the second ray enters the lens according to the following formula. : in, I1 represents the direction of the refracted ray after the second ray enters the lens, and I1 represents the refractive index of the lens material. The direction of the second ray that passes through the origin of another ray. Let P be the intersection point. bi-2 The normal vector.

3. The evaluation method for double-sided progressive multifocal lenses according to claim 1, characterized in that, The intersection point P is determined using the following method. fi-1 The outgoing vector s1 and the intersection point P fi-2 The outgoing vector s2 at that point; Based on the mirror structure of the front surface of the lens, determine the intersection point P with the front surface. fi-1 normal line And determine the intersection point P with the front surface. fi-2 normal line Determine the refractive index I2 of the medium surrounding the lens, and calculate the intersection point P using the following formula. fi-1 The outgoing vector s1 at point: in, s1 is the intersection point P fi-1 The outgoing vector at the point, where I2 is the refractive index of the medium surrounding the lens. The direction of the refracted ray after the first ray enters the lens. Let P be the intersection point. fi-1 The normal vector; The intersection point P is calculated using the following formula. fi-2 The outgoing vector s2 at point: in, s2 is the intersection point P fi-2 The outgoing vector at the point, where I2 is the refractive index of the medium surrounding the lens. The direction of the refracted ray after the second ray enters the lens. Let P be the intersection point. fi-2 The normal vector.

4. The evaluation method for double-sided progressive multifocal lenses according to claim 1, characterized in that, When obtaining the same sample point P bi Optical power of the cross section at the origin of each pair of light rays to Then, the average value of the optical power of the section is calculated and used as the sample point P. bi The corresponding average optical power; The average optical power corresponding to each sample point is obtained, the average optical power distribution of the lens is simulated, and this is used as a basis for auxiliary evaluation of the lens.

5. The evaluation method for a bifacial progressive multifocal lens according to claim 4, characterized in that, The average optical power value at a preset position in the average optical power distribution is determined. The preset position includes a distance use area and a near use area. If the average optical power of the near use area is 0 and the average optical power of the distance use area meets the design target optical power value, then the lens is evaluated as qualified.

6. The evaluation method for a bifocal progressive multifocal lens according to any one of claims 1 to 5, characterized in that, The center of the pupil is a point on the optical axis on the back side of the lens that is a preset distance from the center of the back surface of the lens. The plane containing the pupil circumference is determined by a direction perpendicular to the optical axis; There are six or more pairs of light ray origins on the circumference of the pupil, and more than 12 light ray origins are distributed at equal intervals on the circumference of the pupil.

7. A design method for a double-sided progressive multifocal lens, characterized in that, The astigmatism distribution of the lens is obtained using the evaluation method as described in any one of claims 1 to 6; Based on the astigmatism distribution, adjust the lens design parameters until the astigmatism distribution of the lens meets the preset standard.

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