Search

KR-102964183-B1 - multifocal lens

KR102964183B1KR 102964183 B1KR102964183 B1KR 102964183B1KR-102964183-B1

Abstract

The present invention relates to a multifocal lens (1) having a plurality of concentric diffraction zones (7, 8, 9, 10) on a lens surface (2), wherein a diffraction phase structure is defined in each diffraction zone, which can be expressed by the following function equation (1) or a smoothed version of the following function equation (1), where ξ represents a position within each diffraction zone in the radial direction, φ(ξ) represents a phase shift that occurs when light passes through the position indicated by ξ, w1 and w2 define the spatial division of each diffraction zone in the radial direction, p1 , p2 and p3 represent slopes, and q2 and q3 are constants. The position ξ depends on the square of the radial distance to the center of the lens surface and is normalized with respect to the radial width of each diffraction zone, and the slopes p1 , p2 and p3 are negative.

Inventors

  • 왕 준
  • 시모노프 알렉세이

Assignees

  • 호야 메디컬 싱가포르 피티이. 리미티드

Dates

Publication Date
20260512
Application Date
20210715
Priority Date
20200715

Claims (15)

  1. In a multifocal lens having several concentric diffraction zones on the lens surface, A diffraction phase structure is defined in each diffraction region (7, 8, 9, 10), which can be expressed as the following piecewise function containing three phase terms or a smoothed version of said piecewise function: Here, ξ represents a position within each of the diffraction zones (7, 8, 9, 10) in the radial direction, φ(ξ) represents a phase shift that occurs when light passes through the position indicated by ξ, w1 and w2 define the spatial partitioning of each of the diffraction zones (7, 8, 9, 10) in the radial direction according to the three phase terms, p1 , p2 , and p3 represent the slopes of the three phase terms, q2 and q3 are constants, where ξ depends on the square of the radiation distance to the center of the surface (2) of the lens (1) and is normalized with respect to the radiation width of each of the diffraction zones (7, 8, 9, 10), the slopes p1 , p2 , and p3 are negative, and the slopes are given by the condition p1 ≠ p2 and p3 A multifocal lens having several concentric diffraction zones on the lens surface, satisfying at least one of ≠p 2 .
  2. A multifocal lens according to claim 1, wherein the lens (1) is a trifocal lens having diffraction orders of 0, +1 and +2.
  3. A multifocal lens according to claim 1 or 2, wherein the constants q2 and q3 are positive.
  4. A multifocal lens according to claim 3, wherein the slope p1 is within the range of -1.1 to -1.0, the slope p2 is within the range of -1.1 to -1.0, the slope p3 is within the range of -1.1 to -1.0, the constant q2 is within the range of 0.3 to 0.4, and the constant q3 is within the range of 1.0 to 1.1.
  5. A multifocal lens according to claim 3, wherein the slope p1 is within the range of -1.2 to -1.0, the slope p2 is within the range of -1.3 to -1.2, the slope p3 is within the range of -1.2 to -1.0, the constant q2 is within the range of 0.7 to 0.8, and the constant q3 is within the range of 1.0 to 1.2.
  6. A multifocal lens according to claim 1 or 2, wherein the slope p1 is within the range of -1.2 to -0.4, the slope p2 is within the range of -1.0 to -0.1, the slope p3 is within the range of -1.2 to -0.4, the constant q2 is within the range of -0.2 to 0.3, and the constant q3 is within the range of 0.4 to 1.2.
  7. A multifocal lens according to claim 1 or 2, wherein the constant w1 is 0.25 and the constant w2 is 0.75, such that the radiation width of the intermediate phase term is twice the radiation width of the inner phase term.
  8. A multifocal lens according to claim 1 or 2, wherein the smoothed version of the function φ(ξ) is obtained by convolutioning the function φ(ξ) with a Gaussian kernel, and the Gaussian kernel has a standard deviation within the range of 0.02 to 0.04.
  9. In paragraph 1 or 2, at least the outer boundary (11) of the innermost diffraction zone (7) is A multifocal lens defined by, wherein k represents each of the diffraction zones, λ is the wavelength of light, and p is a predefined value defining additional refractive power.
  10. In claim 9, the mathematical formula of claim 9 defines the outer boundary of the innermost diffraction zone (7), and the outer boundary of the other diffraction zones (8, 9, 10) is A multifocal lens defined by
  11. A multifocal lens according to claim 1 or 2, wherein the constants w1 and w2 are the same for all diffraction zones (7, 8, 9, 10).
  12. A multifocal lens according to claim 1 or 2, wherein the slopes p1 , p2 , and p3 and the constants q2 and q3 are the same for all diffraction zones (7, 8, 9, 10).
  13. A multifocal lens according to claim 1 or 2, wherein the slopes p1 , p2 , and p3 and the constants q2 and q3 are not the same for all diffraction zones (7, 8, 9, 10).
  14. A multifocal lens according to claim 1 or 2, wherein the slopes p1 , p2 , and p3 and the constants q2 and q3 are different for all diffraction zones (7, 8, 9, 10).
  15. A method for manufacturing a multifocal lens having several concentric diffraction zones on a lens surface, - A step of mathematically providing a diffraction phase structure for each diffraction region (7, 8, 9, 10) by providing a next individual function including three phase terms for each diffraction region (7, 8, 9, 10) or a smoothed version of said next individual function, wherein Here, ξ represents a position within each of the diffraction zones (7, 8, 9, 10) in the radial direction, φ(ξ) represents a phase shift that occurs when light passes through the position indicated by ξ, w1 and w2 define the spatial division of each of the diffraction zones (7, 8, 9, 10) in the radial direction according to the three phase terms, p1 , p2 , and p3 represent the slopes of the three phase terms, q2 and q3 are constants, wherein ξ depends on the square of the radiation distance to the center of the surface (2) of the lens (1) and is normalized with respect to the radiation width of each of the diffraction zones (7, 8, 9, 10), the slopes p1 , p2 , and p3 are negative, and the slopes satisfy at least one of the conditions p1 ≠ p2 and p3 ≠ p2. The step of mathematically providing the above-mentioned diffraction phase structure, and - A step of forming a diffracting multifocal lens (1) such that the above diffraction zones (7, 8, 9, 10) have a mathematically provided diffraction phase structure A method for manufacturing a multifocal lens having several concentric diffraction zones on a lens surface including

Description

multifocal lens The present invention relates to a multifocal lens having a plurality of concentric diffraction zones on the lens surface. The present invention also relates to a method for manufacturing a multifocal lens having a plurality of concentric diffraction zones on the lens surface and a multifocal lens that can be manufactured by this method. European patent EP 2 375 276 B1 (PTL 1) discloses a diffracting multifocal lens having an annular diffraction pattern formed concentrically and repeatedly on the lens surface to exhibit a diffraction effect of light. Although the diffracting multifocal lens disclosed in the European patent already provides good optical properties, further improvement of optical properties is required, for example, with respect to chromatic aberration, visual acuity for a specific viewing distance, etc. [Citation List] [Patent Literature] [PTL 1] EP 2 375 276 B1 FIG. 1 schematically and exemplarily illustrates one embodiment of a multifocal lens. Figure 2 schematically and exemplarily illustrates a cross-section of a sag profile along the lens diameter. Figure 3 schematically and exemplarily illustrates a cross-section of the phase profile along the lens diameter of a lens of the far-distance dominant lens type. Figure 4 schematically and exemplarily illustrates the through-focus contrast response for near-predominant and far-predominant lens types. Figure 5 schematically and exemplarily illustrates a cross-section of the phase profile along the lens diameter of a near-field dominant lens type. FIG. 6 schematically and exemplarily illustrates one embodiment of a multifocal lens. Figure 7 schematically and exemplarily illustrates a cross-section of the phase profile along the lens diameter of a mid-range field of view type lens. Figure 8 schematically and exemplarily illustrates the through-focus contrast response for a mid-range field of view lens type. FIG. 9 illustrates a flowchart exemplarily showing one embodiment of a method for manufacturing a multifocal lens having a plurality of annular diffraction zones on the lens surface. FIG. 1 schematically and exemplarily illustrates one embodiment of a multifocal lens (1) having a plurality of annular diffraction zones (7, 8, 9, 10) on a surface (2). The lens (1) is attached to a fixing element (4) for fixing the lens (1) to the eye to replace the removed natural lens with the lens (1). Thus, the lens (1) functions as a refractive and diffractive medium to replace the natural lens of the eye, serving as an orthotic lens intended to be positioned in the lens capsule of the eye after the removal of an extracapsular cataract. However, the lens may be another type of eyepiece, such as a contact lens. Each diffraction phase structure is defined in each diffraction zone (7, 8, 9, 10), which can be expressed as an individual function φ(ξ) defined by mathematical formula (1) containing three phase terms, or as a smoothed version of the individual function. The surface (2) on which the diffraction zones (7, 8, 9, 10) are provided is the front surface of the lens (1). The diffraction zones (7, 8, 9, 10) extend across the central portion of the front surface (2) of the lens (1), and in this embodiment, four diffraction zones (7, 8, 9, 10) are provided, and the radiation distance to the center (3) of the surface (2) at the outer boundary of the outermost diffraction zone is equal to 3.2 mm. The radiation width of the diffraction zones (7, 8, 9, 10) decreases as the radiation distance to the center (3) of the lens surface (2) of each zone (7, 8, 9, 10) increases. Additionally, since the surface (2) provided with a plurality of annular diffraction zones (7, 8, 9, 10) is the refractive surface (2) of the lens (1), the outermost diffraction zone is surrounded by a refractive zone (5) that does not include a diffraction structure. Thus, the lens surface (2) is a curved surface that provides a basic refractive power together with the refractive surface, i.e., the opposing second rear refractive surface. Accordingly, the front surface (2) has an inner region having diffraction zones (7, 8, 9, 10), where the inner region provides refractive power and diffraction power, and the outer region (5) surrounding the inner region provides only refractive power. In this embodiment, the refractive front surface (2) is an aspherical lens surface. The rear surface may also be an aspherical surface or a spherical surface. If the rear surface is a spherical surface, its radius of curvature may be, for example, -18.84 mm for a refractive power of 20.0 D. The rear surface may also be a toric surface, that is, its shape may be donut-shaped to correct astigmatic refractive errors. The sagittal height of the refractive surface having a donut shape can be expressed by Equations (4) and (5). Here, x is the distance from the center of the lens in the first direction perpendicular to the optical axis of the lens, y is the distance from the center of the lens in the seco