CN117742005B - Ophthalmic lens with microstructure and design method thereof - Google Patents

Abstract

The application discloses an ophthalmic lens with microstructure and a design method thereof, comprising the following steps: the lens body is provided with a bright visual area and a regulating and controlling area surrounding the bright visual area; a microstructure located in the regulatory region, the microstructure comprising a plurality of microlenses; a plurality of microlenses are coupled to the optic body and configured to form a blur-state diffuse speckle with the optic body on any of the retina, the pre-retinal, and the post-retinal. The application forms fuzzy state diffuse spots within the acceptable imaging signal range of human eyes and can not form convergent imaging, so that the light rays passing through the microstructure do not stimulate the human eyes to regulate or adapt to functions in a defocusing signal mode. When the MTF is less than or equal to 0.05 and less than 1, modulating a modulation transfer function curve of partial region imaging in the pupil glancing range, and quantitatively reducing the contrast sensitivity of retina imaging, thereby achieving the effect of inhibiting myopia progression.

Description

A spectacle lens with microstructure and design method thereof

Technical Field

The present application belongs to the field of ophthalmic optics technology, and specifically relates to a spectacle lens with a microstructure and a design method thereof.

Background technique

Currently, microstructured lenses used to delay the progression of myopia in adolescents can be divided into lenses based on the principle of myopia defocus or lenses based on the principle of higher-order aberrations. The adjustment effect of lenses based on the principle of myopia defocus will gradually weaken as the wearing time increases; while the evaluation of the effect of myopia prevention and control by lenses based on the principle of higher-order aberrations is somewhat indirect. With the current data accumulation, it is difficult to directly link the quantitative evaluation of specific items and indicators of higher-order aberrations with the effect of myopia prevention and control. Therefore, it is necessary to provide a lens that can be more intuitively linked to the quantitative effect of myopia prevention and control.

Summary of the invention

Purpose of the invention: The embodiment of the present application provides a spectacle lens with a microstructure and a design method thereof, so that the light passing through the microstructure can neither form a clear image on the retina nor affect the clear vision adjustment of the human eye system in any defocus form, thereby achieving the effect of inhibiting the progression of myopia.

The present invention discloses a spectacle lens with a microstructure, comprising:

A lens body, wherein the lens body has a clear vision area and a control area surrounding the clear vision area;

A microstructure, the microstructure is located in the control area, the microstructure includes a plurality of microlenses; the plurality of microlenses are connected to the lens body and are configured to cooperate with the lens body to form a blurred diffuse spot on the retina, in front of the retina, or behind the retina;

The off-axis field of view passes through at least one of the microlenses in the control area, and the average value of the modulation transfer function generated on the retina is MTF, which satisfies: 0.05≤MTF＜1.

In some embodiments, the modulation transfer function average MTF further satisfies: MTF=B ₀ +B ₁ lnH+B ₂ lnF;

Among them, H is the maximum vector height of the microlens included in the microstructure, in μm; F is the spatial frequency corresponding to the modulation transfer function, in lp/mm; _B0 is a constant term, and _{0.860≤B0≤0.894} ; _B1 is the regression coefficient of the maximum vector height, and _{-0.036≤B1≤} -0.022; _B2 is the regression coefficient of the spatial frequency, and _{-0.224≤B2≤} -0.216.

In some embodiments, the modulation transfer function average MTF further satisfies: ;

Among them, H is the maximum vector height of the microlens included in the microstructure, in μm; F is the spatial frequency corresponding to the modulation transfer function, in lp/mm; _B0 is a constant term, and _{1.032≤B0≤1.094} ; _B1 is the regression coefficient of the maximum vector height, and _{-0.037≤B1≤} -0.029; _B2 is the regression coefficient of the spatial frequency, and _{-0.104≤B2≤} -0.100.

In some embodiments, the surface shape of the microlens is selected from at least one of an aspherical surface and a free-form surface; and/or

The surface shape of the microlens is selected from at least one of a coaxial region and an off-axis region; and/or

The shape of the microlens is selected from at least one of a circle, an ellipse, and a polygon.

In some embodiments, the eyeglasses further satisfy at least one of the following features:

a) 1 μm ≤ H ≤ 10 μm;

b) 0 lp/mm＜F≤45 lp/mm.

In some embodiments, the range in front of the retina or behind the retina includes all focal planes that can form a clear visual area through virtual adjustment of the human eye between -10D and +10D.

In some embodiments, the aspheric surface and/or the free-form surface includes a convex area, a concave area, and a flat area between the convex area and the concave area; wherein the curvature of the convex area is greater than zero, the curvature of the concave area is less than zero, and the curvature of the flat area is equal to zero.

In some embodiments, the shape of the microlens is circular and the diameter of the microlens is 0.5-3 mm; or

The shape of the microlens is elliptical, and the major axis of the microlens is 1-6 mm, and the minor axis is 0.5-3 mm.

In some embodiments, a plurality of said microlenses are connected to each other; or

The plurality of microlenses are arranged spaced apart from each other; or

The microlenses are circular in shape and there are at least three of them. The at least three microlenses are arranged in the microstructure in the form of a polygonal inscribed circle.

In some embodiments, the center of the clear vision zone coincides with the optical center of the lens body, the clear vision zone is located in an area 3-6 mm away from the optical center, and the control zone is located in an area 3-35 mm away from the optical center; the RMS radius value of the diffusion spot ranges from 15 to 200 μm.

In some embodiments, the present application further provides a method for designing a spectacle lens with a microstructure, comprising the following steps:

A lens body is provided, and a three-dimensional coordinate system is defined according to the lens body; wherein the optical center of the lens body is taken as the origin O of the three-dimensional coordinate system, two directions along the radial direction of the lens body from the origin O are respectively the X axis and the Y axis of the three-dimensional coordinate system, and the direction along the axial direction of the lens body from the origin O is the Z axis of the three-dimensional coordinate system, and the X axis, the Y axis and the Z axis are perpendicular to each other;

Providing a microlens, and determining the coordinates of the center of the microlens (21) on the symmetrical YOZ plane in the three-dimensional coordinate system and the angle around the X-axis according to the structural parameters of the microlens and in combination with the arrangement of the microstructure (2);

According to the structural parameters of the microlens (21) and in combination with the arrangement of the microstructure (2), the coordinates of the center of the microlens (21) on the asymmetric YOZ plane in the three-dimensional coordinate system and the tilt angles around the X-axis, the Y-axis and the Z-axis are determined;

According to the obtained coordinate and angle data of each microlens, the microlens is arranged in the control area of the lens body to form a microstructure, and the microstructure and the lens body are combined to obtain the eyeglass lens.

In some embodiments, in the step of determining the coordinates of the center of the microlens on the asymmetric YOZ plane in the three-dimensional coordinate system and the tilt angles around the X-axis, the Y-axis, and the Z-axis according to the structural parameters such as the shape, surface type, and sagittal height of the microlens and in combination with the arrangement of the microstructure:

The angle of the microlens on the asymmetric YOZ plane around the Z axis is α, and the calculation formula is:

;

The angle of the microlens on the asymmetric YOZ plane around the X-axis is β, and the calculation formula is:

;

The angle of the microlens on the asymmetric YOZ plane around the Y axis is γ, and the calculation formula is:

;

Wherein, x is the x-coordinate value of the center of the microlens, y is the y-coordinate value of the center of the microlens, z is the z-coordinate value of the center of the microlens, and _R1 is the radius of curvature of the lens body.

Beneficial effects: Compared with the prior art, the present invention provides a spectacle lens with a microstructure, comprising: a lens body, the lens body having a clear vision area and a control area surrounding the clear vision area; a microstructure, the microstructure is located in the control area, and the microstructure includes a plurality of microlenses; the plurality of microlenses are connected to the lens body, and are configured to cooperate with the lens body to form a blurred diffuse spot on the retina, in front of the retina, or behind the retina; wherein the off-axis field of view passes through at least one microlens in the control area, and the average value of the modulation transfer function generated on the retina is MTF, satisfying: 0.05≤MTF＜1. The microstructure of the present invention forms a blurred diffuse spot within the acceptable imaging signal range of the human eye and cannot be converged for imaging, so that the light passing through the microstructure does not stimulate the adjustment or adaptive function of the human eye in the form of a defocused signal. Therefore, the light passing through this microstructure can neither form a clear image on the retina nor converge in front of or behind the retina to form a clear myopic defocus or hyperopic defocus signal; when 0.05≤MTF＜1 is satisfied, the modulation transfer function curve of the imaging of part of the area within the pupil scanning range is modulated to quantitatively reduce the contrast sensitivity of retinal imaging, thereby achieving the effect of inhibiting the progression of myopia.

The design method of the present application evaluates the quality of microstructure imaging through point array diagrams and MTF curves. The spectacle lenses allow the pupil to scan the microstructure area while covering the microlens and the lens body as much as possible. Such spectacle lenses can send a signal to delay myopia progression by reducing contrast, and are completely different from the principle or mechanism of myopia defocus of microlenses in the past and can be quantitatively evaluated. It can relatively easily achieve a balance between the wearer's compliance with the glasses and the functionality of the lenses through testing and design adjustments, and may provide optometrists with new and better functional products when the long-term use efficacy of myopia defocus products declines.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

FIG1 is a front view of a front surface of a spectacle lens with microstructures provided in an embodiment of the present application;

FIG2 is a partial schematic diagram of the microstructure of the regulatory region provided in an embodiment of the present application;

FIG3 is a diagram showing the morphology of diffuse spots of the maximum field of view of a lens-eye system having only a lens body provided by an embodiment of the present application;

FIG4 is an MTF diagram of the maximum field of view of the lens-eye system when only the lens body is provided in an embodiment of the present application and the spatial frequency is 0-100 lp/mm;

FIG5 is an MTF diagram of the maximum field of view of the lens-eye system when the spatial frequency is 0-100 lp/mm for a micro-lens with a maximum sag height of 2 microns provided in an embodiment of the present application;

FIG6 is a schematic diagram showing the positional relationship between two parabolas of a saddle-face micro-lens and a lens body on a symmetrical YOZ plane provided in an embodiment of the present application;

FIG7 is a diagram showing the positional relationship between a symmetrical YOZ plane saddle-face sub-microlens and a horizontally adjacent saddle-face sub-microlens and a lens body provided in an embodiment of the present application;

FIG8 is a projection diagram of a saddle-faced microlens on an asymmetric YOZ plane and its vertex normal on the YOZ plane provided by an embodiment of the present application;

FIG9 is a projection diagram of the J reference plane of the saddle-face microlens on the asymmetric YOZ plane on the XOZ plane provided by an embodiment of the present application;

FIG10 is a diagram showing the diffuse spot morphology of the maximum field of view of the lens-eye system corresponding to the microlens in the control area at different vector heights provided in an embodiment of the present application;

FIG11 is a graph showing the average MTF of the maximum field of view of the lens-eye system corresponding to the microlens in the control area at different sag heights provided in an embodiment of the present application;

FIG12 is a morphological diagram of the diffuse spots formed by the maximum field of view of the lens-eye system corresponding to different sagittal heights in a certain range in front of or behind the retina of the human eye provided by the microlens in the control area of the embodiment of the present application;

FIG13 is a front view of the front surface of another spectacle lens with microstructures provided in an embodiment of the present application;

The serial numbers in the figure are: 1-lens body, 10-clear vision area, 11-regulation area, 2-microstructure, 21-microlens.

Detailed ways

The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

In the description of the present application, it should be understood that the terms "upper", "lower", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In the description of the present application, "plurality" means two or more, and at least one means one, two or more, unless otherwise clearly and specifically defined.

The applicant found that the microstructure lenses currently on the market for delaying the deepening of myopia in adolescents can be roughly divided into three categories, namely, based on the principle of myopia defocus, based on the principle of higher-order aberrations or based on the principle of contrast. In clinical verification, the effect of lenses based on the principle of myopia defocus has been verified to a certain extent, but it has also exposed defects, that is, as the wearing time of the glasses increases, the effect seems to be weakened. However, the evaluation of the effect of myopia prevention and control based on the principle of higher-order aberrations is somewhat indirect, that is, with the current data accumulation, it is difficult to directly link the quantitative evaluation of the specific items and indicators of higher-order aberrations with the effect of myopia prevention and control. In contrast, the microstructure lenses based on the contrast principle are relatively intuitive by quantitatively linking the reduction of contrast with the effect of myopia prevention and control. There is no need to consider the various indicators of higher-order aberrations, and it can be completed by evaluating through the MTF curve. At present, the lenses based on the contrast principle on the market mainly consider the use of non-transparent microstructures to block the passage of part of the light, so as to reduce the contrast around the lens. This type of method is relatively difficult to quantitatively evaluate the contrast using optical quantitative indicators.

Referring to Figures 1 and 2, this embodiment provides an eyeglass lens with a microstructure, including: a lens body 1 and a microstructure 2; the lens body 1 has a clear vision area 10 and a control area 11 surrounding the clear vision area; the microstructure 2 is located in the control area 11, and the microstructure includes a plurality of microlenses 21 connected to each other; the plurality of microlenses 21 are connected to the lens body 1, and are configured to cooperate with the lens body 1 to form a blurred diffuse spot on the retina, in front of the retina, or behind the retina; wherein the off-axis field of view passes through at least one microlens 21 in the control area 11, and the average value of the modulation transfer function generated on the retina is MTF, which satisfies: 0.05≤MTF＜1.

In some embodiments, the modulation transfer function average MTF further satisfies: MTF=B ₀ +B ₁ lnH+B ₂ lnF; wherein H is the maximum vector height of the microlens 21 included in the microstructure 2, in μm; F is the spatial frequency corresponding to the modulation transfer function, in lp/mm; B ₀ is a constant term, and 0.860≤B ₀ ≤0.894; B ₁ is the regression coefficient of the maximum vector height, and -0.036≤B ₁ ≤-0.022; B ₂ is the regression coefficient of the spatial frequency, and -0.224≤B ₂ ≤-0.216.

In some embodiments, the modulation transfer function average MTF further satisfies: ; Wherein, H is the maximum vector height of the microlens 21 included in the microstructure 2, in μm; F is the spatial frequency corresponding to the modulation transfer function, in lp/mm; _B0 is a constant term, and _{1.032≤B0≤1.094} ; _B1 is the regression coefficient of the maximum vector height, and _{-0.037≤B1≤} -0.029; _B2 is the regression coefficient of the spatial frequency, and _{-0.104≤B2≤} -0.100.

It can be understood that in the eyeglasses of the present application, the lens body 1 has the function of clear imaging; the microlens 21 is configured to cooperate with the lens body 1 so that the light passing through the microstructure within the pupil range forms a blurred diffuse spot on the retina of the human eye and a certain range in front and behind it. The eyeglasses of this embodiment can cover the microlens 21 and the lens body 1 as much as possible when the pupil scans the microstructure area, so that the light passing through the microstructure 2 can neither form a clear image on the retina, nor converge on the retina, and the front or back of the retina to form a clear myopia defocus or hyperopia defocus signal, that is, it cannot affect the clear vision adjustment of the human eye system in any form of defocus, so as to achieve the effect of inhibiting the progression of myopia.

The spectacle lens of the present application has a lens body 1 for correcting the refractive error symptoms of the wearer and a microstructure 2 attached to the surface of the lens body 1 and causing the light passing through the structure to form a blurred diffuse spot on the human eye retina and a certain range in front and behind it, that is, the light passing through the microstructure 2 can neither form a clear image on the retina nor affect the clear vision adjustment of the human eye system in any defocus form. There is a correlation between the blurred diffuse spots generated by the structure and the inhibition of axial growth. The above-mentioned parameter relationship of 0.05≤MTF＜1 is set to modulate the modulation transfer function curve of the imaging of a part of the area within the pupil scanning range, and quantitatively reduce the contrast sensitivity of retinal imaging, thereby achieving the effect of inhibiting the progression of myopia. In addition, a fitting relationship between the average value of the modulation transfer function and the maximum height and spatial frequency is established. By changing the structural parameters of the microstructure, the blurred diffuse spots can be effectively controlled, providing a stimulus factor for inhibiting axial growth and slowing down the rate of myopia development.

Furthermore, the off-axis field of view passes through the microlens and generates a modulation transfer function value on the retina, which is preferably obtained on a myopia simulation eye, which can characterize the regulation and focusing of light during image transmission. The microlens 21 is an optical element with a specific shape, which can change the direction of light during light transmission. When light passes through the microlens 21, due to the convex and concave surface or shape change of the microlens 21, the light will be refracted to form a new light beam. This new light beam is modulated compared to the light before passing through the microlens, that is, the intensity, phase and wavefront shape of the light have changed. The modulation transfer function value describes the modulation effect of the microlens 21 on light, which is conducive to studying the perception of different light signals and the understanding of visual sensation in the off-axis field of view.

In some embodiments, the off-axis field of view through at least one microlens 21 in the control zone 11 can be a plurality of microlenses 21 closest to the control zone 11, and the control zone 11 closest to the clear vision zone 10 can be understood as the area where the microstructure 2 close to the clear vision zone 10 and the control zone 11 intersects and belongs to the control zone is located.

In some embodiments, a plurality may be understood as a number of at least two or more.

In some embodiments, the surface type of the microlens 21 is selected from at least one of an aspherical surface and a free-form surface; an aspherical surface refers to a surface with uneven curvature, and a free-form surface refers to a surface without a specific geometric shape, and its shape and curvature are not restricted.

In some embodiments, the surface shape of the microlens 21 is selected from at least one of the coaxial region and the off-axis region of the aspheric surface; the coaxial region of the aspheric surface refers to the region with the rotational symmetry axis of the aspheric surface as the center of the surface shape. In these regions, the shape of the lens can adjust the divergence and convergence behavior of light by changing the curvature. The off-axis region of the aspheric surface refers to the region that does not take the rotational symmetry axis of the aspheric surface as the center of the surface shape, and may or may not contain the rotational symmetry axis. In these regions, the shape of the lens will have more irregular effects on the divergence or convergence of the incident light.

In some embodiments, the shape of the microlens 21 is selected from at least one of a circle, an ellipse, and a polygon.

In some embodiments, the maximum sag H of the microlens 21 satisfies: 1 μm≤H≤10 μm. For example, the sag H may be any value of 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, or a range between any two values.

In some embodiments, the spatial frequency F satisfies: 0 lp/mm＜F≤45 lp/mm. For example, the spatial frequency F may be any one of 0.2 lp/mm, 0.3 lp/mm, 0.4 lp/mm, 0.5 lp/mm, 0.6 lp/mm, 0.7 lp/mm, 0.8 lp/mm, 0.9 lp/mm, 1.0 lp/mm, 2.0 lp/mm, 3.0 lp/mm, 4.0 lp/mm, 5.0 lp/mm, 6.0 lp/mm, 7.0 lp/mm, 8.0 lp/mm, 9.0 lp/mm, 10 lp/mm, 15 lp/mm, 20 lp/mm, 25 lp/mm, 30 lp/mm, 35 lp/mm, 40 lp/mm, and 45 lp/mm, or a range between any two of the values.

In some embodiments, for the fitting relationship of MTF=B ₀ +B ₁ lnH+B ₂ lnF, the constant term B ₀ is preferably 0.877; the regression coefficient of the vector height B ₁ is preferably -0.029; the regression coefficient of the spatial frequency B ₂ is preferably -0.220; that is, the preferred relationship satisfies: MTF = 0.877-0.029lnH-0.220lnF.

In some embodiments, for The fitting relationship is as follows: the constant term _B0 is preferably 1.063; the regression coefficient _B1 of the vector height is preferably -0.033; the regression coefficient _B2 of the spatial frequency is preferably -0.102; that is, the preferred relationship satisfies:/> .

In some embodiments, the range in front of the retina or behind the retina includes all focal planes that can form a clear visual area through virtual accommodation of the human eye between -10D and +10D.

In some embodiments, the aspheric surface and/or free-form surface includes a convex area, a concave area, and a flat area between the convex area and the concave area; wherein the curvature of the convex area is greater than zero, the curvature of the concave area is less than zero, and the curvature of the flat area is equal to zero. It can be understood that the microlens 21 has an aspheric surface or a free-form surface with alternating positive and negative curvatures, and curvature is a concept that describes the degree of curvature of the surface. Positive curvature means that the lens surface is more prominent at this position, similar to a convex surface, and in these areas, the lens can converge light. Negative curvature means that the lens surface is more concave at this position, similar to a concave surface, and in these areas, the lens will disperse light and make it diverge.

In some embodiments, the microlens 21 having an aspherical surface or a free-form surface with alternating positive and negative curvatures has one or more positive curvatures, negative curvatures, and planes at the same time.

In some embodiments, the distribution of the microstructures 2 on the lens body 1 includes any one of a honeycomb type, a rotationally symmetric radial type, a ring type, and a polygonal grid array.

In some embodiments, the lens body 1 includes a front surface and a back surface opposite to each other, the front surface is away from the human eye, and the back surface is close to the human eye, and the microstructure is arranged on either the front surface or the back surface.

In some embodiments, the microlens 21 is circular in shape and has a diameter of 0.5-3 mm. For example, the diameter may be any one of 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, and 3 mm, or a range between any two values.

In some embodiments, the shape of the microlens 21 is elliptical and the major axis of the microlens 21 is 1-6 mm and the minor axis is 0.5-3 mm.

In some embodiments, referring to FIG. 1 , a plurality of micro lenses 21 are connected to each other.

In some embodiments, referring to FIG. 13 , the plurality of micro lenses 21 may also be spaced apart from each other.

In some embodiments, the shape of the microlens 21 is circular and there are at least three of them, and at least three microlenses 21 are arranged in the form of polygonal inscribed circles in the microstructure 2. It can be understood that, taking FIG. 2 as an example, the microlens 21 is circular, and the microlenses 21 are arranged in the form of regular hexagonal inscribed circles, that is, the shape of each microlens can be regarded as the inscribed circle of a regular hexagon. Of course, in some other structures, the regular polygon can also be other shapes such as a square, a regular pentagon, a regular octagon, etc.

In some embodiments, further referring to FIG. 1 , the center of the clear vision zone 10 coincides with the optical center of the lens body 1 , the clear vision zone 10 is located in an area 3-6 mm from the optical center, and the control zone 11 is located in an area 3-35 mm from the optical center.

In some embodiments, the RMS radius of the diffuse spot ranges from 15 to 200 μm.

In some embodiments, the spectacle lenses can be cast or injection molded by metal molds, or cast and molded by glass molds into the required prescription diopter or semi-finished products, and the semi-finished products are then processed by a workshop to obtain the required prescription diopter. In some embodiments, the spectacle lenses can also be made into the required prescription diopter or semi-finished products by metal and glass molds using UV light curing technology, and the semi-finished products are then processed by a workshop to produce the spectacle lenses required by the wearer, or spectacle lenses or spectacle lens blanks produced by a bonding process.

In some embodiments, the material of the lens body 1 includes a polymer material or an inorganic non-metal material. The polymer material includes a thermoplastic resin or a thermosetting resin, and the inorganic non-metal material includes glass, etc. Thermoplastic resins include polycarbonate or polymethyl methacrylate; thermosetting resins include any one of acrylic resin, episulfide resin, thiourethane resin, allyl resin, and polyurethane.

In some embodiments, a coating film is formed on the surface of at least one side of the lens body 1, and the coating film includes a transparent coating film that increases the transmittance of the lens, a hard coating film that increases the durability of the lens, a reflective film that blocks harmful light, an anti-reflection and anti-reflection film that realizes imaging visibility, a polarizing film with a color-changing function, or other color-changing films doped with ultraviolet-sensitive materials, etc. The coating film itself can have different colors, and the visual color under the reflection condition can be green, blue, yellow, purple, etc., or other colors.

In some embodiments, the eyeglass lens is directly prepared by a mold, and the mold may include an upper mold base and a lower mold base. The working surface of the upper mold base is a concave surface, which is used to shape the first optical surface and the second optical surface respectively.

In some embodiments, the spectacle lenses obtained by the above process can be combined with the spectacle frames to further obtain glasses, and the shape of the spectacle lenses can be round, square, elliptical or other special-shaped structures. It should be noted that the shape of the spectacle lenses can be roughly the above shapes and is not limited to a perfect geometric shape.

In some embodiments, this embodiment further provides a method for designing a spectacle lens with a microstructure, comprising the following steps:

A lens body 1 is provided, and a three-dimensional coordinate system is defined according to the lens body 1; wherein the optical center of the lens body 1 is taken as the origin O of the three-dimensional coordinate system, two radial directions from the origin O along the lens body 1 are respectively the X axis and the Y axis of the three-dimensional coordinate system, and the direction from the origin O along the axial direction of the lens body 1 is the Z axis of the three-dimensional coordinate system, and the X axis, the Y axis and the Z axis are perpendicular to each other;

Provide a microlens 21, and determine the coordinates of the center of the microlens 21 on the symmetrical YOZ plane in a three-dimensional coordinate system and the angle around the X-axis according to structural parameters such as the shape, surface shape and sagittal height of the microlens 21 and in combination with the arrangement of the microstructure 2;

According to the shape, surface type and sagittal height of the microlens 21 and the arrangement of the microstructure 2, the coordinates of the center of the microlens 21 on the non-YOZ plane in the three-dimensional coordinate system and the tilt angles around the X-axis, the Y-axis and the Z-axis are determined;

According to the obtained coordinate and angle data of each microlens 21 , the microlens 21 is arranged in the control area 11 of the lens body 1 to form a microstructure 2 , and the microstructure 2 and the lens body 1 are combined to obtain an eyeglass lens.

In some embodiments, the angle of the microlens 21 around the Z axis on the asymmetric YOZ plane is α, and the calculation formula is: The angle of the microlens 21 around the X-axis on the asymmetric YOZ plane is β, and the calculation formula is: The angle of the microlens 21 around the Y axis on the asymmetric YOZ plane is γ, and the calculation formula is: ; wherein x is the x-coordinate value of the center of the microlens 21, y is the y-coordinate value of the center of the microlens 21, z is the z-coordinate value of the center of the microlens 21, and _R1 is the curvature radius of the lens body 1.

It can be understood that the spectacle lens with microstructure of the present embodiment comprises a lens body 1 composed of a meniscus lens capable of correcting refractive errors having front and rear surfaces and a microstructure 2 located in a control area 11 and cooperating with the lens body 1 to provide contrast modulation; the structural parameters of the front and rear surfaces of the lens body 1 are determined according to the prescription of the wearer and the refractive index of the selected lens material; the surface shape and structural parameters of the microlens 21 in the control area 11 are determined, and added to the front surface of the lens body 1, so that the light passing through the structure forms a blurred diffuse spot in the human eye retina and a certain range in front and behind it; the relationship between the structural parameters of the microlens 21 or the grid arrangement of the microlens 21 and the modulation transfer function (MTF for short) is obtained by changing the structural parameters of the microlens 21 or the grid arrangement of the microlens 21, so as to adjust the size of the MTF average value, so as to determine the final structural parameters of the microlens 21 in the control area or the grid arrangement of the microlens 21.

The specific design process is as follows:

Assume that the prescription of the wearer is S-3.00D, set the diameter of the lens body 1 to 60 mm, the material refractive index to 1.56, the center thickness of the lens body 1 to 1.3 mm, and the shape to be a curved moon lens.

St1: According to the wearer's eye test degree -3D, the average optical focal length of the front surface of the lens body 1 is set to 2 diopters (abbreviated as D), and the average optical focal length of the back surface is -5D; combined with the refractive index of the lens material 1.56, the curvature radius of the front surface of the lens body 1 is determined to be R1=280mm, and the curvature radius of the back surface is determined to be R2=112mm.

St2: Select an appropriate optical simulated eye model, insert the lens body 1 obtained according to the calculation results into the simulated eye model, set the distance between the lens and the front surface of the cornea to 12mm, set the pupil diameter of the simulated eye to 2.8mm, the system wavelength to 0.55μm, and the full field of view to ±16.5°; use optical simulation software to optimize the simulated eye model so that the on-axis light passing through the lens body 1 is focused on the retina of the simulated eye model, and record the diffuse spot size and MTF data on the retina under the maximum off-axis field of view at this time. The diffuse spot size is expressed by RMS radius and GEO radius, where the RMS radius is the radius of a circle centered at the reference point that only contains relatively concentrated light, and is the root mean square radial size, and the GEO radius is the radius of a circle centered at the reference point and containing all light. The above data are shown in Table 1, the diffuse spot morphology is shown in Figure 3, and the MTF data is shown in Figure 4.

Table 1

St31: According to the constraint that the diameter or short axis length of the microlens 21 is between 0.5mm and 3mm, the microlens 21 is selected to be circular, with a diameter D1 of 1.0mm; the control area 11 is selected to be distributed in the area outside the 3mm semi-diameter of the center of the lens, that is, the diameter of the central blank area of the front surface of the lens body 1 is at least 6mm; the microlenses 21 of the control area 11 are connected and distributed with the exposed lens body 1 to form a regular hexagonal grid arrangement and attached to the front surface of the lens body 1. The microlenses 21 exist in the form of regular hexagonal inscribed circles in the microstructure 2, and the central area of each regular hexagonal grid is the exposed lens body 1. The front view of the front surface of the lens body with the control area 11 added is shown in Figure 1, and the partial schematic diagram of the microstructure 2 of the control area is shown in Figure 2.

St32: Determine the structural parameters of the microlenses 21 in each area of the control area. According to the constraint that the surface of the microstructure 2 has an aspheric or free-form surface with alternating positive and negative curvatures, the surface type of the microstructure 2 is selected as a saddle surface, and the structural parameters of the saddle surface microlens 21 of the symmetrical YOZ plane are first determined. According to the definition of the saddle surface, the parabola with an opening downward is set in the YOZ plane, and the vertex normal of the parabola faces the center of the sphere on the front surface of the lens body 1; the other parabola with an opening upward is located in the H plane perpendicular to the YOZ plane and passing through the vertex normal of the parabola with an opening downward (each sub-microlens 21 is set to have a corresponding H plane); in order to calculate the structural parameters of the saddle surface, the distance between the vertex of the parabola in the YOZ plane and the intersection of the vertex normal of the parabola and the front surface of the lens body 1 (vertex sag) is set to 1 micron, and the maximum sag of the H plane parabola, that is, the distance between the edge point of the parabola and the intersection of the vertex normal of the parabola and the front surface of the lens body 1 in the normal direction is set to 2 microns. The vertex curvature radii of the two parabolas are calculated based on the above data. The optical structure data of the saddle surface microlens 21 is shown in Table 2.

Table 2

The microstructure 2 is constructed by using the eccentricity and inclination of the standard saddle surface. For modeling purposes, the position of the center of the saddle surface sub-microlens is first determined, that is, the coordinates of the vertices (saddle points) of the two parabolas in the YOZ plane and on the H plane. Since the radial diameter of the inscribed circle of the lens body 1 exposed in the microstructure 2 is the same as the radial diameter of the saddle surface microlens 21, the center distance between any saddle surface microlens 21 and its radially adjacent part of the lens body 1 or the same saddle surface microlens 21 is approximately equal to 2 mm. Therefore, according to the arrangement of the microlenses 21 in FIG. 2, the radial distance h from the intersection of the center normal of the saddle surface microlens 21 of the symmetrical YOZ plane and the front surface of the lens body 1 to the optical axis can be determined first. According to the radial distance h, the radial diameter of the saddle-surface microlens 21, the vertex sagittal height of the parabola in the YOZ plane of 1 micron, and the constraint that the direction of the center normal of the saddle-surface microlens 21 should be toward the center of the surface curvature of the lens body 1, the vertex coordinates (x, y, z) of the parabola of each saddle-surface sub-microlens on the YOZ plane, that is, the position of the saddle surface center, can be calculated; and then the inclination angle "X inclination" of the saddle surface around the X axis is determined according to the vertex normal of the parabola toward the center of the front surface of the lens body 1 (Y inclination and Z inclination are both 0). The positional relationship between the parabola of the saddle-surface microlens on the YOZ plane and the lens body 1 in the YOZ optical axis section is shown in (a) of Figure 6, and the positional relationship between the parabola of the H plane and the lens body 1 is shown in (b) of Figure 6, where the Z axis is the optical axis. The positions and inclination angles of the centers of each saddle-surface microlens on the symmetrical YOZ plane obtained above are shown in Table 3.

table 3

Secondly, determine the center coordinates and tilt angle of the microlens 21 of the asymmetric YOZ plane in Figure 1. Use the above-mentioned method for establishing the saddle-face sub-microlens reference plane of the symmetrical YOZ plane to establish a new coordinate system, and draw a schematic diagram similar to (a) and (b) in Figure 6 for the plane where the two parabolas of the saddle surface are located. According to the arrangement of the regular hexagonal grid array of the microlenses, the positional relationship between the saddle-face sub-microlens with serial number 1 on the YOZ optical axis section in Table 3 and the saddle-face sub-microlens closest in the horizontal direction can be obtained, and the center coordinates are obtained according to the positional relationship; in order to ensure that the parabola with its opening downward on the saddle surface of the microlens 21 that is not symmetrical in the YOZ plane is always in the radial direction of the lens, the saddle-face microlens 21 is set with a Z tilt. To calculate the tilt angle, a reference plane K is made through the center of the saddle-surface microlens, the center of the front surface of the lens body 1 and the center of the sphere of the front surface of the lens body 1 (the reference plane must be perpendicular to the XOY plane, and each saddle surface that is not symmetrical in the YOZ plane has a corresponding modeling reference plane K), and it is projected onto the XOY plane, as shown in FIG7 . The distance from the center of the saddle-surface microlens 21 to the YOZ plane is the x-coordinate of the center of the saddle-surface microlens 21 . Then, according to the y-coordinate of the center of the saddle-surface microlens 21 , the angle α between the reference plane K and the Y axis (i.e., the tilt angle of the saddle-surface microlens 21 around the Z axis, Z tilt) can be calculated. The calculation formula is as follows: .

The above-mentioned non-YOZ plane symmetric microlens 21 together with its central normal is projected onto the YOZ plane, as shown in FIG8 . According to the y coordinate and z coordinate of the center of the saddle surface microlens 21 in the figure, and the curvature radius R1 of the lens body, the angle β between the central normal of the saddle surface microlens and the Z axis (i.e., the inclination angle of the saddle surface microlens around the X axis, X inclination) can be calculated by the following formula: .

Then, a reference plane J is made through the center of the saddle surface microlens 21 and the center of the front surface of the lens body 1 and perpendicular to the reference plane K (the reference plane must be perpendicular to the XOZ plane, and each saddle surface that is not symmetrical in the YOZ plane also has a modeling reference plane J), and it is projected to the XOZ plane, as shown in FIG9 . The distance from the center of the saddle surface microlens 21 to the XOY plane in the figure is the z coordinate of the center of the saddle surface microlens. Then, according to the curvature radius R1 of the front surface of the lens body 1 and the x coordinate of the center point O of the saddle surface microlens, the angle γ between the reference plane M and the Z axis (i.e., the inclination angle of the vertex normal of the saddle surface microlens 21 around the Y axis, Y inclination) can be calculated, and the calculation formula is as follows: .

According to the above method, the center coordinates and tilt angles of the two left and right saddle surface microlenses closest to the saddle surface microlens No. 1 in the horizontal direction of the symmetric YOZ plane in Table 3 can be obtained, see Table 4.

Table 4

By repeating the above process of solving the structural parameters of the sub-microlenses that are not symmetrical in the YOZ plane, the reference plane K and the angle α between it and the Y axis, the reference plane H and the angle β between it and the Z axis, and the reference plane M and the angle γ between it and the Z axis of all saddle-surface sub-microlenses with the same y coordinate can be calculated; similarly, the α angle, β angle, γ angle of the saddle-surface microlenses with other Y coordinates not listed in Table 3 and the center coordinates of the saddle-surface microlenses can also be calculated using the above method.

St4: Perform three-dimensional modeling based on the calculation results of steps St31-St32, add the saddle-surface microlenses 21 in the control area to the front surface of the lens body 1, and record the size, shape, and MTF value of the blurred diffuse spots formed on the retina of the human eye and within a certain range in front and behind it under the maximum off-axis field of view under the lens eye model through optical simulation software, where the MTF graph is shown in Figure 5.

St5: Keep the diameter D1 of the saddle-surface microlens 21 constituting the control area and the vertex sagitta of the parabola with the opening downward unchanged, gradually increase the maximum sagitta of the parabola with the opening upward of the saddle-surface microlens 21 in the control area, and take the maximum sagitta of the saddle-surface microlens 21 in the control area not exceeding 10 microns as a constraint, repeat steps St3-St4, and record the size and morphology of the blurred diffuse spot formed on the retina under the maximum off-axis field of view in the eye model through modeling and optical simulation. The RMS and GEO radius data of the diffuse spot radius are shown in Table 5, and the morphology of the diffuse spot is shown in Figure 10; at the same time, contrast evaluation is performed in combination with MTF, and the MTF diagram is shown in Figure 11 (only the 0-10lp/mm part where the MTF change is more obvious is listed).

table 5

It can be seen from Table 5 that the surface parameters of the saddle-surface microlens in the control area will affect the size of the diffuse spot formed on the retina of the human eye. When the maximum vector height of the saddle-surface microlens in the control area is larger, the RMS radius value of the generated diffuse spot is larger, and the two show a positive correlation. Comparing the data in Table 5 with the RMS radius of the lens body 1 in Table 1, it can be seen that the RMS radius of the eyeglass with the saddle-surface microstructure is significantly higher than the RMS radius of the lens body 1, indicating that the eyeglass with the saddle-surface microstructure can form a larger blurred diffuse spot, which helps to reduce the imaging quality.

At the same time, the blurred diffuse spots formed by the saddle-surface microstructure spectacle lenses with different maximum sagittal heights in a certain range in front of or behind the retina under the maximum off-axis field of view in the eye model are recorded, and the diffuse spots are shown in Figure 12. From the above simulation results, it can be seen that the light passing through the saddle-surface microstructure 2 within the pupil size range forms a large blurred diffuse spot on the retina of the human eye and in a certain range in front and behind it.

According to the above simulation, the MTF size of the eyeglass with the saddle-shaped sub-microlens 21 under the maximum off-axis field of view can be obtained, and the monotonically decreasing 1-43lp/mm interval of the MTF average value (defined as the average value of the MTF in the meridian direction and the sagittal direction) is taken out, and the MTF average value data with spatial frequencies of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 40, 43lp/mm and maximum sagittal heights of 2, 4, 6, 8 and 10um are listed in Table 6.

Table 6

It can be seen from Table 6 that when the spatial frequency is 43lp/mm, the MTF average values at each vector height value are all greater than 0.05, which is still within the range that the human eye can normally respond to. Therefore, Excel software is used to perform multivariate nonlinear regression and establish an equation such as MTF= _B0 + _B1lnH + _B2lnF . The maximum vector height H of the microlens 21 and the spatial frequency F are used as independent variables, and the MTF average values of the frequency of 0-43lp/mm at each vector height value are used as the dependent variable for multivariate nonlinear regression analysis. The results are shown in Table 7.

Table 7

According to Table 7, the empirical formula for the maximum sagittal height of the saddle-surface microlens in the control area and the average MTF at the specified spatial frequency is as follows: MTF = 0.877-0.029lnH-0.220lnF. From Table 7 and the above empirical formula, it can be seen that the correlation coefficient ^R2 between the actual data and the fitting function is 0.924, which is greater than 0.9, indicating that the effect of the matching curve is good; when a certain spatial frequency in the range of 0~43lp/mm is selected, the surface parameters of the control area will affect the average MTF of the lens-eye system at this spatial frequency. When the maximum sagittal height of the saddle-surface microlens in the control area is larger, the average MTF of the lens-eye system at this spatial frequency is smaller; it can be concluded that the maximum sagittal height of the saddle-surface microlens in the control area is negatively correlated with the average MTF.

In order to improve the fitting effect of the curve, other types of functions were selected to perform multivariate nonlinear regression again, and the following The results are shown in Table 8.

Table 8

The empirical formula obtained from Table 8 for the maximum sag height of the saddle-surface microlens in the control area and the average MTF value at the specified spatial frequency is as follows: From Table 8 and the above empirical formula, we can see that the correlation coefficient R ² between the actual data and the fitting function is 0.939, which is larger than 0.924 of the previous multivariate nonlinear regression formula and closer to 1. The residual square Q and standard deviation σ of the regression equation are both smaller, indicating that the curve fitted by this function is better. (The above coefficient range: 1.032≤B ₀ ≤1.094; -0.037≤B ₁ ≤-0.029; -0.104≤B ₂ ≤-0.100).

St6: According to the contrast reduction value at the specified spatial frequency, the structural parameters of the saddle surface microlens 21 in the control area are solved according to the empirical formula obtained in step St5.

In order to compare the imaging effects of the saddle-surface microstructure 2 and the spherical microstructure under conditions of relatively close light transmittance, the method in this embodiment is used to create a lens with a saddle-surface microstructure 2 with a downward-opening parabola vertex sagitta of 0.9 μm and a maximum sagitta of an upward-opening parabola of 1 μm, and a lens with a spherical microstructure with a maximum sagitta of 1 μm. The MTF average values of the lenses are compared with those of the lens with only the lens body 1 at the maximum off-axis field of view and the specified spatial frequency (10lp/mm). The analysis results are shown in Table 9.

Table 9

From the results, it can be seen that in the simulation, the two microstructures have the situation that not all the light reaches the image surface, and the spherical microstructure has a greater light loss; secondly, the MTF average values of the spectacle lenses with the two microstructures are significantly lower than the MTF average values of the spectacle lenses with only the lens body 1, and the MTF average value of the saddle surface microstructure is lower than that of the spherical microstructure. This shows that when the light loss is relatively small, the saddle surface microstructure is better than the spherical microstructure spectacle lenses in reducing contrast and is more helpful in reducing visual quality.

In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

The above is a detailed introduction to a kind of eyeglass lens with microstructure and its design method provided in the embodiment of the present application, and the principle and implementation method of the present application are explained by applying specific examples. The description of the above embodiments is only used to help understand the technical solution and its core idea of the present application; ordinary technicians in this field should understand that: it is still possible to modify the technical solutions recorded in the aforementioned embodiments, or to replace some of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the present application.

Claims (8)

1. An ophthalmic lens with microstructures comprising:

A lens body (1), the lens body (1) having a bright vision zone (10) and a regulatory region (11) surrounding the bright vision zone;

-a microstructure (2), said microstructure (2) being located in said regulatory region (11), said microstructure comprising a plurality of microlenses (21); a plurality of microlenses (21) are connected with the lens body (1) and are configured to form a fuzzy diffuse spot on any one of retina, pre-retina and post-retina in cooperation with the lens body (1);

Wherein an off-axis field passes through at least one of said microlenses (21) in said regulatory region (11) and produces a modulation transfer function MTF on the retina, the average of which satisfies: MTF is more than or equal to 0.05 and less than 1;

The average value of the modulation transfer function MTF further satisfies: mtf=b ₀+B₁lnH+B₂ lnF; wherein H is the maximum sagittal height of the micro-lenses (21) comprised by the microstructure (2), in μm; f is the spatial frequency corresponding to the modulation transfer function, and the unit is lp/mm; b ₀ is a constant term, B ₀≤0.894;B₁ is a maximum sagittal regression coefficient, B ₁≤-0.022;B₂ is a spatial frequency regression coefficient, B ₂ is more than or equal to-0.224 and less than or equal to-0.216; or alternatively

The average value of the modulation transfer function MTF further satisfies: ; wherein H is the maximum sagittal height of the micro-lenses (21) comprised by the microstructure (2), in μm; f is the spatial frequency corresponding to the modulation transfer function, and the unit is lp/mm; b ₀ is a constant term, B ₀≤1.094;B₁ is a maximum sagittal regression coefficient, B ₁≤-0.029;B₂ is a spatial frequency regression coefficient, B ₂ is greater than or equal to-0.104 and less than or equal to-0.100.

2. An ophthalmic lens with microstructure according to claim 1, characterized in that the surface shape of the micro-lenses (21) is chosen from at least one of aspherical surfaces, free-form surfaces; and/or

The surface shape of the microlens (21) is selected from at least one of a coaxial region and an off-axis region; and/or

The microlens (21) has a shape selected from at least one of a circle, an ellipse, and a polygon.

3. The microstructured ophthalmic lens of claim 1 wherein the pre-retinal or post-retinal range comprises: all focal planes of the clear vision region can be formed by virtual accommodation between the human eye-10D and +10d.

4. An ophthalmic lens with microstructures as claimed in claim 2 wherein the aspherical surface and/or the free-form surface comprises a convex region, a concave region and a flat region between the convex region and the concave region; wherein the curvature of the convex region is greater than zero, the curvature of the concave region is less than zero, and the curvature of the flat region is equal to zero.

5. An ophthalmic lens with microstructure according to claim 2, characterized in that the center of the photopic region (10) coincides with the optical center of the lens body (1), the photopic region (10) being located in a region 3-6mm from the optical center, the accommodation region (11) being located in a region 3-35mm from the optical center; the RMS radius value range of the diffuse spots generated by the off-axis vision field passing through the microstructure area of the spectacle lens is 15-200 mu m;

Wherein the shape of the micro lens (21) is round, and the diameter of the micro lens (21) is 0.5-3 mm; or alternatively

The shape of the micro lens (21) is elliptical, the long axis of the micro lens (21) is 1-6 mm, and the short axis of the micro lens is 0.5-3 mm; or alternatively

A plurality of the microlenses (21) are connected to each other; or alternatively

A plurality of microlenses (21) disposed at intervals from each other; or alternatively

The microlenses (21) are circular in shape and at least three, and at least three microlenses (21) are arranged in the microstructure (2) in a polygonal inscribed circle.

6. The microstructured ophthalmic lens of claim 1 wherein the ophthalmic lens further satisfies at least one of the following characteristics:

a）1 μm≤H≤10 μm；

b）0 lp/mm＜F≤45 lp/mm。

7. A method of designing an ophthalmic lens with a microstructure according to any one of claims 1 to 6, comprising the steps of:

providing a lens body (1), defining a three-dimensional coordinate system according to the lens body (1); the optical center of the lens body (1) is taken as an origin O of a three-dimensional coordinate system, two directions along the radial direction of the lens body (1) from the origin O are respectively an X axis and a Y axis of the three-dimensional coordinate system, the directions along the axial direction of the lens body (1) from the origin O are Z axes of the three-dimensional coordinate system, and the X axis, the Y axis and the Z axis are perpendicular to each other;

Providing a micro lens (21), and determining the coordinates of the center of the micro lens (21) on a symmetrical YOZ plane in the three-dimensional coordinate system and the angle around the X axis according to the structural parameters of the micro lens (21) and in combination with the arrangement mode of the micro structure (2);

according to the structural parameters of the micro lenses (21) and in combination with the arrangement mode of the micro structures (2), determining the coordinates of the centers of the micro lenses (21) on the asymmetric YOZ plane in the three-dimensional coordinate system and the angles of inclination around the X axis, the Y axis and the Z axis;

according to the obtained coordinates and angles of each micro lens (21), the micro lenses (21) are arranged in the regulating area (11) of the lens body (1) to form a micro structure (2), and the micro structure (2) and the lens body (1) are combined to obtain the spectacle lens.

8. The method of designing an ophthalmic lens with microstructure according to claim 7, wherein the step of determining the coordinates of the center of the microlens (21) on the asymmetric YOZ plane in the three-dimensional coordinate system and the angles of inclination around the X-axis, the Y-axis and the Z-axis according to the structural parameters of the microlens (21) in combination with the arrangement of the microstructures (2):

the angle of the micro lens (21) on the asymmetric YOZ plane around the Z axis is alpha, and the calculation formula is:

；

the angle of the micro lens (21) on the asymmetric YOZ plane around the X axis is beta, and the calculation formula is:

；

The angle of the micro lens (21) on the asymmetric YOZ plane around the Y axis is gamma, and the calculation formula is as follows:

；

wherein x is an x coordinate value of the center of the micro lens (21), y is a y coordinate value of the center of the micro lens (21), z is a z coordinate value of the center of the micro lens (21), and R ₁ is a curvature radius of the lens body (1).