A progressive multifocal lens based on meridional optimization and its design method

Abstract

This invention relates to a progressive multifocal lens based on meridional optimization and its design method. The front surface of the lens is a progressive surface, and the rear surface is a standard spherical surface. Based on the wearer's needs, after determining the optical power of the rear surface of the lens, the meridional lines on the front surface of the lens are optimized using a logistic function. By adjusting the translation factor and curvature adjustment factor in the meridional optimization function, the rate of change of optical power along the meridional lines can be flexibly adjusted, thereby controlling the astigmatic distribution of the lens. This invention designs contour lines orthogonal to the meridional lines that meet design requirements, spreading the optical power distribution along the meridional lines to the entire surface of the lens, and calculating the sagittal data of each point on the lens. The design scheme provided by this invention simplifies the lens design steps, reduces the computational load, and effectively controls the optical power and astigmatic distribution in the distance vision zone, near vision zone, and progressive channel of the lens, keeping astigmatism within 90% of the added power.

Description

Technical Field

[0001] This invention relates to a progressive multifocal lens based on meridional optimization and its design method, belonging to the field of optical design technology. Background Technology

[0002] Traditional single-vision glasses, due to their fixed power, cannot simultaneously address near, far, and intermediate vision. While bifocals solve the patient's needs for both near and far vision, they are unclear for intermediate objects, and the dividing line in the middle of the lens affects aesthetics and visual field. Progressive multifocal lenses, with their continuously varying power, can clearly focus objects at any distance onto the retina, gradually becoming the best choice for correcting the progression from myopia to presbyopia.

[0003] The surface shape of progressive multifocal eyeglass lenses is one of the important factors affecting the quality of eyeglass lenses, and the meridian of the eyeglass lens is the primary step in surface shape design. Chinese invention patent CN113253482A proposes a two-segment meridian design for progressive multifocal eyeglass lenses. While this method can flexibly obtain different meridian power variation curves to design progressive multifocal lenses that meet user requirements, it requires solving different high-order partial differential equations before designing each different meridian, resulting in a large computational load. Summary of the Invention

[0004] This invention addresses the shortcomings of existing technologies by providing a progressive multifocal lens and its design method based on meridional optimization, which requires less computation, effectively controls the power distribution in the distance vision zone, near vision zone, and progressive channel of the lens, and keeps astigmatism within 90% of the added power.

[0005] The technical solution to achieve the objective of this invention is to provide a design method for a progressive multifocal lens based on meridional optimization. The lens includes a distance vision zone, a near vision zone, a transition zone, and a peripheral astigmatism zone. The rear surface of the lens is spherical. The design method for the front surface of the lens includes the following steps: (1) The optical power D on the meridian of the front surface of the lens. f (u) is set to: D f (u)=Dd+(Dr-Dd) / (1+e (-k(u-x0) )) Where Dd is the focal length of the distance vision zone, Dr is the focal length of the near vision zone; k is the curvature adjustment factor; x0 is the translation factor; and u is the distance from any point on the meridian to the center of the lens. (2) In the coordinate system, construct the correspondence between any point (x,y) on the front surface of the lens and u using the contour line expression, and express the optical power D along the meridian. f(u) The distribution diffuses to the front surface of the lens, resulting in the power distribution D at various points on the front surface of the lens. f The outline expression is as follows: Where, x d x is the distance from the focal point of the distance vision zone to the center of the lens. n The distance between the focal point of the near vision zone and the center point of the lens; the coordinate system is a Cartesian rectangular coordinate system constructed with the center point of the front surface of the lens as the origin O, the positive direction of the x-axis is horizontal to the right along the arc direction of the front surface of the lens, the positive direction of the y-axis is vertically upward along the meridian direction of the front surface of the lens, and the z-axis is perpendicular to the xoy plane and satisfies the right-hand rule with the x-axis and y-axis; (3) Calculate the radius of curvature r(u) corresponding to each point on the front surface of the lens: r(u)=(n-1) / D f Where n is the refractive index of the lens material; (4) Calculate the coordinates of the curvature centers corresponding to each point on the front surface of the lens. ξ(u)=ur(u)sinθ η(u)=0 Where θ is the angle between the line connecting each point on the lens to its corresponding center of curvature and the z-axis; (5) The sag z1(x,y) corresponding to each point on the front surface of the lens is calculated:

[0006] The technical solution of the present invention also includes a progressive multifocal lens obtained according to the above design method.

[0007] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0008] 1. Traditional design methods determine the meridional power variation curve of a progressive multifocal lens by solving the coefficients of various terms of a higher-order polynomial. Different higher-order polynomials need to be solved for different meridional power variation curves. The progressive multifocal lens provided by this invention does not require solving higher-order polynomials during the design process. Different meridional power variation curves can be obtained by changing the curvature adjustment factor and the translation factor, resulting in a smaller computational load during the design process.

[0009] 2. The technical solution of the present invention can control the optical power distribution along the meridional line of the progressive multifocal lens by adjusting the curvature adjustment factor and the translation factor, thereby controlling the optical power distribution in the distance vision zone, the near vision zone and the progressive channel.

[0010] 3. The rate of increase of astigmatism in the lens near the meridian is proportional to the rate of change of the curvature of the surface in the meridian direction. The technical solution of the present invention can control the rate of change in the meridian direction by adjusting the curvature adjustment factor and the translation factor, thereby controlling the astigmatism distribution of the progressive multifocal lens and controlling the maximum astigmatism within 90% of the added power. Attached Figure Description

[0011] Figure 1 This is a regional distribution map of a progressive multifocal lens based on meridional optimization provided in an embodiment of the present invention.

[0012] Figure 2 This is a flowchart of a progressive multifocal lens front surface design method based on meridional optimization provided by an embodiment of the present invention.

[0013] Figure 3 This is a diagram showing the change in optical power along the meridian of a progressive multifocal lens based on meridian optimization, provided by an embodiment of the present invention.

[0014] Figure 4 This is an optical power distribution diagram of a progressive multifocal lens based on meridional optimization provided in an embodiment of the present invention.

[0015] Figure 5 This is a sagittal diagram of a progressive multifocal lens based on meridional optimization provided in an embodiment of the present invention.

[0016] Figure 6 This is a sphericity distribution diagram of a progressive multifocal lens based on meridional optimization provided in an embodiment of the present invention.

[0017] Figure 7 This is a cylindrical power distribution diagram of a progressive multifocal lens based on meridional optimization provided in an embodiment of the present invention.

[0018] Figure 1 In the middle: 1. Distant vision zone; 2. Near vision zone; 3. Transition zone; 4. Peripheral astigmatism zone. Detailed Implementation

[0019] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] Example 1

[0021] This embodiment provides a progressive multifocal lens based on meridional optimization and its design method.

[0022] See appendix Figure 1This embodiment provides a region distribution map of a progressive multifocal lens based on meridian optimization. The progressive multifocal lens includes a distance vision zone 1, a near vision zone 2, a transition zone 3, and a peripheral astigmatism zone 4. The distance vision zone is located in the upper region of the lens and is used for viewing distant objects. The near vision zone is located in the lower region of the lens and is used for viewing near objects. The transition zone is located between the distance vision zone and the near vision zone and is used for viewing intermediate-distance objects. The astigmatism zone is located on both sides of the transition zone and affects the clarity of vision.

[0023] In this embodiment, the rear surface of the lens is spherical, and the front surface is a progressive surface. The design process is detailed in the appendix. Figure 2 .

[0024] The lens parameters are as follows:

[0025] The specific implementation steps are as follows:

[0026] 1. The optical power D along the meridian of the front surface of the lens. f (u) is set to: D f (u)=Dd+(Dr-Dd) / (1+e (-k(u-x0) )) Where Dd is the focal length of the distance vision zone, Dr is the focal length of the near vision zone; k is the curvature adjustment factor; x0 is the translation factor; u is the distance from any point on the meridian to the center point of the lens; in this embodiment, the curvature adjustment factor k is 0.38, and the translation factor x0 is 8; The optical power distribution along the meridian of the front surface was calculated; the calculation results are shown in the appendix. Figure 3 As shown.

[0027] 2. Divide the lens surface into an 81×81 matrix, with each point 1.0 mm apart. In a coordinate system, construct the correspondence between any point (x, y) on the front surface of the lens and u using a contour expression. Then, assign the optical power D along the meridian. f (u) The distribution diffuses to the front surface of the lens, resulting in the power distribution D at various points on the front surface of the lens. f ; The outline expression is as follows: Where, x d x is the distance from the focal point of the distance vision zone to the center of the lens. nThe distance between the focal point of the near vision zone and the center point of the lens is denoted as . The coordinate system is a Cartesian rectangular coordinate system constructed with the center point of the front surface of the lens as the origin O. The positive x-axis is horizontal to the right along the arc direction of the front surface of the lens, the positive y-axis is vertically upward along the meridian direction of the front surface of the lens, and the z-axis is perpendicular to the xoy plane and satisfies the right-hand rule with the x-axis and y-axis.

[0028] See appendix Figure 4 This is a power distribution diagram of the front surface of the lens.

[0029] 3. Calculate the radius of curvature r(u) at each point on the front surface of the lens: r(u)=(n-1) / D f Where n is the refractive index of the lens material;

[0030] 4. Calculate the coordinates of the centers of curvature at each point on the front surface of the lens. ξ(u)=ur(u)sinθ η(u)=0 Where θ is the angle between the line connecting each point on the lens to its corresponding center of curvature and the z-axis;

[0031] 5. Calculate the sag z1(x,y) corresponding to each point on the front surface of the lens:

[0032] See appendix Figure 5 This is the front surface sagittal diagram of the progressive multifocal lens provided in this embodiment, which shows that the lens surface distribution is smooth and without abrupt changes.

[0033] See appendix Figure 6 This is a spherical power distribution diagram of the progressive multifocal lens provided in this embodiment. From the distance vision zone to the near vision zone, the optical power distribution on the lens shows a gradual trend, and there are no abrupt changes in optical power across the entire lens, meeting the power requirements for clear vision of the patient.

[0034] See appendix Figure 7 This embodiment provides a cylindrical power distribution diagram of the progressive multifocal lens. The peripheral astigmatism area is concentrated on both sides of the progressive channel, the astigmatism within the effective visual area is small, and the maximum astigmatism on the entire lens is controlled within 90% of the added power.

[0035] The results demonstrate that the design method for progressive multifocal lenses based on meridional optimization provided by this invention simplifies the lens design steps, reduces the computational load, and effectively controls the power distribution in the distance vision zone, near vision zone, and progressive channel of the lens, while keeping astigmatism within 90% of the added power.

Claims

1. A design method for a progressive multifocal lens based on meridional optimization, wherein the lens includes a distance vision zone (1), a near vision zone (2), a transition zone (3), and a peripheral astigmatism zone (4); the rear surface of the lens is spherical, characterized in that... The design method for the front surface of a lens includes the following steps: (1) The optical power along the meridian of the front surface of the lens Set to: in, D d For fixed focus in the distance viewing area, D r The focal length of the near field of view; k Curvature adjustment factor; x 0 is the translation factor; u This is the distance from any point on the meridian to the center point of the lens. (2) In the coordinate system, construct the coordinate system of any point (x, y) on the front surface of the lens using the contour line expression. u The correspondence will determine the optical power along the meridian. The distribution diffuses across the front surface of the lens, resulting in the optical power distribution at various points on the front surface of the lens. ; The outline expression is as follows: in, The distance from the center point of the lens to the focal point in the distance vision zone. The distance between the focal point of the near vision zone and the center point of the lens; the coordinate system is a Cartesian rectangular coordinate system constructed with the center point of the front surface of the lens as the origin O, the positive direction of the x-axis is horizontal to the right along the arc direction of the front surface of the lens, the positive direction of the y-axis is vertically upward along the meridian direction of the front surface of the lens, and the z-axis is perpendicular to the xoy plane and satisfies the right-hand rule with the x-axis and y-axis; (3) Calculate the radius of curvature of each point on the front surface of the lens. : Where n is the refractive index of the lens material; (4) Calculate the coordinates of the curvature centers corresponding to each point on the front surface of the lens. : in, Let z be the angle between the line connecting each point on the lens to its corresponding center of curvature and the z-axis. (5) Calculate the sagitta corresponding to each point on the front surface of the lens. : 。 2. A progressive multifocal lens obtained by the design method according to claim 1.

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