Continuous focal depth lens and preparation method thereof
By introducing a spiral diffraction structure and smooth phase transition into ophthalmic lenses, the problems of visual interference and unstable visual quality in existing presbyopia correction techniques have been solved, achieving continuous depth of focus and high-quality vision while reducing halos and glare.
Patent Information
- Application Number
- CN202511355869.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-22
- Publication Date
- 2026-03-06
AI Technical Summary
Existing presbyopia correction techniques, such as traditional diffractive multifocal lenses, refractive multifocal lenses, and extended depth-of-field lenses, cannot avoid visual interference (such as halos and glare) and visual quality dependence on pupil size when providing continuous depth of focus.
A continuous depth-of-focus lens based on helical diffraction is used. By setting a diffraction structure on the substrate layer, a continuous depth of focus is formed by the continuous change of helical phase delay and radial change rate. Combined with a smooth phase transition, light scattering is reduced.
It achieves high-quality vision from far to near, while significantly reducing visual interference, providing excellent visual quality and pupil adaptability, and reducing abnormal visual phenomena such as halos and glare.
Smart Images
Figure CN121613545A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the fields of ophthalmic optics and optical engineering technology, and in particular to a continuous depth-of-focus lens and its fabrication method. Background Technology
[0002] Presbyopia is an age-related loss of the eye's accommodative ability, leading to decreased near and intermediate vision. Current corrective techniques mainly include traditional diffractive multifocal lenses, refractive multifocal lenses, and extended depth of focus (EDoF) lenses, but all of them have significant drawbacks:
[0003] Traditional diffractive multifocal lenses (such as ReSTOR and Tecnis Multifocal) split light through concentric ring-shaped discontinuous steps, resulting in light energy loss, decreased contrast sensitivity, and severe visual interference (abnormal visual phenomena) such as halo and glare caused by light scattering from the sharp edges of the steps.
[0004] Refractive multifocal lenses: performance is highly dependent on pupil size, visual quality is unstable, and the transition zone between different refractive regions may introduce aberrations.
[0005] Extended depth of field (EDoF) lenses (such as Symfony): provide a continuous depth of field by stretching the focal point, but typically sacrifice near-vision peak sharpness and contrast, and may produce alternative visual artifacts such as starbursts.
[0006] In recent years, optical vortex (spiral phase) technology has been known in fields such as optical tweezers and microscopic imaging, but its application in ophthalmic vision correction is mostly limited to the spiral focal length design based on the principle of refraction. Current refraction schemes cannot solve the inherent scattering and visual interference problems of diffractive multifocal lenses.
[0007] Therefore, there is an urgent need in this field for a presbyopia correction solution that can provide continuous high-quality vision from far to near and fundamentally suppress visual interference. Summary of the Invention
[0008] Based on this, this application provides a continuous depth-of-focus lens based on helical diffraction and its fabrication method. The lens is based on a helical diffractive optical element (SDOE) and is an ophthalmic lens, which solves the problems in the prior art that it is impossible to avoid visual interference (such as halos and glare) while providing continuous depth of focus and that visual quality depends on pupil size.
[0009] In a first aspect, embodiments of the present invention provide a continuous depth-of-focus lens based on helical diffraction, comprising a substrate layer and a diffraction structure disposed on the substrate layer; the diffraction structure is composed of one or N consecutive helical arms; wherein, N≥2 and is an integer;
[0010] The diffraction structure is used to apply a helical phase delay to the incident light wavefront, and the radial rate of change of the phase delay changes continuously with the radial coordinate of the diffraction structure. The phase delay stretches the focal point along the optical axis, so that the lens has a continuous depth of focus.
[0011] Optionally, the diffraction surface of the diffraction structure consists of multiple diffraction points. The phase distribution of each diffraction point is constituted by the phase distribution function. Sure;
[0012] Wherein, the phase distribution function Based on spiral phase parameter After normalization, it satisfies:
[0013] ;
[0014] ;
[0015] in, For the spiral phase parameter; The phase is the normalized value; r is the radial coordinate of the diffraction point. These are the angular coordinates of the diffraction point. It is the starting angle of the spiral; B(r) is the radial variation coefficient of the diffraction point as a function of the radial coordinate r.
[0016] Optionally, the radial variation coefficient By diffraction initial radius and the maximum radius of the lens optical zone The linear interpolation between them is determined as follows:
[0017] when hour, ;
[0018] when hour, ;
[0019] in, The initial phase coefficient, To terminate the phase coefficient, The starting radius of the diffraction is 1. It is the maximum radius of the lens's optical region.
[0020] Optionally, the added power of the front and rear focal points corresponding to the radial position r of the continuous depth-of-focus lens satisfies:
[0021] , ;
[0022] in, Let be the luminous intensity at the front focal point at the radial position r. λ is the luminous intensity at the back focal point at the radial position r, and λ is the design wavelength.
[0023] Optionally, the phase distribution function By applying a smoothing function to the spiral phase parameters The result is obtained after normalization.
[0024] The smoothing function is a nonlinear function used to achieve continuous phase transition within a phase period of 0 to 2π.
[0025] Optionally, the smoothing function includes one of the arctangent function, hyperbolic tangent function, or sigmoid function.
[0026] Optionally, a basic optical surface is formed on one side surface of the substrate layer, and the diffraction structure is superimposed on the basic optical surface;
[0027] The basic optical surface is one of a sphere, an aspherical surface, or a complex surface.
[0028] Optionally, the continuous depth-of-focus lens is an intraocular lens, contact lens, scleral lens, corneal implant, or spectacle lens.
[0029] Based on the same inventive concept, this application also provides a method for fabricating a continuous depth-of-focus lens based on helical diffraction, used to fabricate the continuous depth-of-focus lens based on helical diffraction provided in the first aspect, comprising:
[0030] A substrate layer is provided, on one side of which a diffraction structure is designed; the diffraction structure includes one or N consecutive helical arms; N≥2, where N is an integer;
[0031] A spiral phase delay is applied to the incident light wavefront, and the radial rate of change of the phase delay varies continuously with the radial coordinate of the diffraction structure. The phase delay stretches the focal point along the optical axis, giving the lens a continuous depth of focus.
[0032] Optionally, a helical phase delay is applied to the incident light wavefront, and the radial rate of change of the phase delay varies continuously with the radial coordinates of the diffraction structure. The specific steps are as follows:
[0033] Diffraction points are set on the diffraction surface of the diffraction structure. The input parameters include the initial phase coefficient. End phase coefficient Radial position where diffraction begins Maximum radius of the lens optical zone The number of spiral arms N, the starting angle of the spiral ;
[0034] Calculate each diffraction point Radial variation coefficient Wherein, the radial variation coefficient At the radial position where diffraction begins With the maximum radius of the lens optical zone Changes between;
[0035] The spiral phase parameters of each diffraction point are calculated based on a combination of radial and angular components. ;
[0036] ;
[0037] The spiral phase parameter is smoothed using a smoothing function. Perform normalization processing, and then normalize the phase. Applied to each diffraction point on the entire diffraction surface The final phase distribution function of the diffraction surface of the diffraction structure is obtained. ,satisfy:
[0038] ;
[0039] in, The phase is the normalized value; These are the radial coordinates of the diffraction point. These are the angular coordinates of the diffraction points; the smoothing function is a nonlinear function used to generate a smooth phase transition within a phase period of 0 to 2π.
[0040] Output phase distribution function The lens is then processed using manufacturing equipment to fabricate its diffractive surface.
[0041] Optionally, the input parameters may also include a phase coefficient that controls the steepness of the phase curve.
[0042] The normalization process for the spiral phase parameter includes:
[0043] The intermediate phase distribution function is obtained by mathematically processing the spiral phase parameters based on the phase coefficient and smoothing function.
[0044] The intermediate phase distribution function is normalized to the range of [0, 2π] to obtain the final phase distribution function of the diffraction surface of the diffraction structure.
[0045] In summary, the continuous depth-of-field lens based on helical diffraction provided by this invention includes a substrate layer and a diffraction structure disposed on one side surface of the substrate layer. The diffraction structure consists of one or N continuous helical arms. The diffraction structure is configured to apply a helical phase retardation to the incident light wavefront, and the radial rate of change of the phase retardation continuously varies with the radial coordinate of the diffraction structure. The phase retardation stretches the focal point along the optical axis, giving the lens a continuous depth of field. This application utilizes the principle of diffraction to generate helical diffraction carrying orbital angular momentum (OAM) by applying a helical phase retardation that includes an azimuth term. This vortex beam forms a hollow ring distribution in the focal field and naturally stretches the focal point along the optical axis, forming a Bessel-like beam or "light needle," thereby achieving extended depth of field (EDoF). This element generates an extended continuous depth of field through a unique diffraction structure, while greatly reducing light scattering by utilizing a smooth phase transition, thus providing excellent continuous vision while minimizing visual interference. Attached Figure Description
[0046] Figure 1 This is a schematic diagram of a continuous depth-of-focus lens based on helical diffraction provided in this application;
[0047] Figure 2 yes Figure 1 The provided test image is a two-dimensional grayscale of the final phase map of the continuous depth-of-focus lens;
[0048] Figure 3 yes Figure 1 Test diagram of the phase profile of a continuous depth-of-focus lens along the AA' direction;
[0049] Figure 4 This is a test plot of the off-focus spread function (PSF) of a continuous depth-of-focus lens simulation provided in this application;
[0050] Figure 5 This is a diagram of the transfocus modulation transfer function (MTF) curve of a continuous depth-of-focus lens simulation provided in this application at an object distance of 5 meters and a spatial frequency of 30 lp / mm.
[0051] Figure 6 This is a flowchart of the method for fabricating a continuous depth-of-focus lens based on helical diffraction provided in this application;
[0052] Figure 7 This is a meridional view of a rigid gas permeable (RGP) contact lens at the starting angle;
[0053] Figure 8This is a test diagram of the phase profile of a rigid gas permeable (RGP) contact lens;
[0054] Figure 9 This is a two-dimensional grayscale test image of the final phase map of a rigid gas permeable (RGP) contact lens. Detailed Implementation
[0055] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the present application and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the present application are shown in the drawings, not the entire structure. Various modifications and variations can be made to the present application without departing from its spirit or scope, which will be apparent to those skilled in the art. Therefore, the present application is intended to cover modifications and variations falling within the scope of the corresponding claims (the claimed technical solutions) and their equivalents. It should be noted that the implementation methods provided in the embodiments of the present application can be combined with each other without contradiction.
[0056] Figure 1 This is a schematic diagram of a continuous depth-of-focus lens based on spiral diffraction provided in this application. Figure 2 yes Figure 1 The provided test image is a two-dimensional grayscale representation of the final phase map of the continuous depth-of-focus lens. Figure 3 yes Figure 1 Test diagram of the phase profile of a lens with continuous depth of field along the AA' direction. Figure 4 This is a test plot of the off-focus spread function (PSF) simulated by a continuous depth-of-focus lens provided in this application. Figure 5 This is a plot of the transfocus modulation transfer function (MTF) curve of a continuous depth-of-focus lens simulated in this application at an object distance of 5 meters and a spatial frequency of 30 lp / mm. (Reference) Figures 1-3 This application provides a continuous depth-of-focus lens based on helical diffraction, which can be applied to presbyopia correction. The continuous depth-of-focus lens provided in this application includes a substrate layer 01 and a diffraction structure 02 disposed on the substrate layer 01. Figure 1 (As shown in the black diffraction structure in the middle), the diffraction structure 02 consists of one or N consecutive spiral arms 021. The diffraction structure 02 is used to apply a spiral phase delay to the incident light wavefront, and the radial rate of change of the phase delay changes continuously with the radial coordinate of the diffraction structure 02. The phase delay stretches the focal point along the optical axis, so that the lens has a continuous depth of focus.
[0057] Where N ≥ 2 and is an integer. It should be noted that the embodiments of this application... Figure 1 The example given is N=3, where the diffraction structure 02 consists of 3 consecutive spiral arms 021, but is not limited to this.
[0058] The diffraction surface of diffraction structure 02 consists of multiple diffraction points. The phase distribution of each diffraction point is constituted by the phase distribution function. Determine the phase distribution function. Based on spiral phase parameter After normalization, it satisfies:
[0059] , (1.1);
[0060] (1.2)
[0061] in, For the spiral phase parameter; The phase is the normalized value; These are the radial coordinates of the diffraction point. These are the angular coordinates of the diffraction point. It is the starting angle of the spiral; is the radial variation coefficient of the diffraction point as a function of the radial coordinate, and N is the number of spiral arms.
[0062] Specifically, the continuous depth-of-focus lens based on helical diffraction provided in this application is a novel helical diffractive optical element (SDOE) that can be used inside or on the surface of ophthalmic lenses. This continuous depth-of-focus lens consists of a continuous, two-dimensional phase distribution function. The defined phase distribution function Generated through a mathematical algorithm. Unlike conventional diffractive lenses that rely on concentric rings in the prior art, the continuous depth-of-focus lens provided in this application is characterized by one or more continuous spiral arms 201.
[0063] The physical principle used in this application is: a phase term with azimuth angle correlation. The phase element generates an optical vortex. This spiral wavefront structure causes the beam to carry orbital angular momentum (OAM) and form a characteristic lobe-shaped annular intensity distribution on the focal plane.
[0064] Crucially, this vortex structure inherently stretches the focal point along the optical axis, creating what is known as a "Bezier-like beam" or "light needle." Axial stretching is the fundamental mechanism for achieving extended depth of field (EDoF).
[0065] This application utilizes diffraction properties. The design of the diffraction structure 02 diffraction surface profile does not refract light in the manner of classical geometric optics, but rather applies a precisely controlled phase delay to the incident wavefront. Through the interference between light waves in different parts of this phase structure, extended depth of field (EDoF) is ultimately achieved.
[0066] The principle of light wave interference satisfies the Huygens-Fresnel principle and Kirchhoff diffraction theory.
[0067] refer to Figures 3-5 A key innovation of this application lies in the introduction of a smooth, or "softened," phase transition between the 2π phase periods of the diffraction structure O2. This transition is achieved through a continuous nonlinear function (e.g., an arctangent function), rather than the abrupt changes and discontinuous steps characteristic of existing diffraction microstructures. This property can significantly reduce higher-order diffraction and light scattering, thereby fundamentally reducing visual artifacts such as halos and glare.
[0068] Specifically, such as Figure 3 The phase profile shown indicates that the phase profile of the diffraction structure 02 of the continuous depth-of-focus lens provided in this application is smooth.
[0069] like Figure 4 The point spread function (PSF) shown indicates that the imaging quality using the continuous depth-of-focus lens provided in this application is clear.
[0070] The point spread function (PSF) describes the image distribution formed on the imaging plane (such as a camera sensor) after an ideal point light source (infinitesimal) passes through an optical system.
[0071] like Figure 5 As shown in the modulation transfer function (MTF), the continuous depth-of-focus lens simulation meets the requirements of eye observation at an object distance of 5 meters and a spatial frequency of 30 lp / mm.
[0072] The modulation transfer function (MTF), also known as the spatial contrast transfer function or spatial frequency contrast sensitivity function, is a function of spatial frequency that reflects the ability of an optical system to transmit sinusoidal modulation schemes of various frequencies. Typically, in lens design, an MTF > 0.22 is sufficient for human visual perception.
[0073] Another key innovation of this application is the introduction of a radial variation coefficient that varies with radial position into the algorithm for defining the phase. This allows the optical properties of the diffractive structure 02 (such as its local refractive power contribution) to be continuously tunable with radial distance from the optical center. This design provides unprecedented degrees of freedom for ophthalmic applications, enabling the optimization of light energy distribution based on pupil size.
[0074] This application combines a diffraction structure, a softened phase transition, and radial modulation to create a highly efficient continuous depth-of-focus lens based on helical diffraction. This continuous depth-of-focus lens can produce an extended and continuous depth-of-focus range, providing high-quality vision from far to near, while its visual interference level is comparable to or even better than that of a monofocal lens.
[0075] The phase distribution function of the continuous depth-of-focus lens based on helical diffraction provided in the embodiments of this application is described below. The specific parameters and acquisition methods are described in detail.
[0076] Based on the same inventive concept, this application also provides a method for fabricating a continuous depth-of-focus lens based on optical vortexes, which is used to design and fabricate the continuous depth-of-focus lens based on optical vortexes provided in this application. Figure 6 This is a flowchart of a method for fabricating a continuous depth-of-focus lens based on helical diffraction, as provided in this application. (Refer to...) Figure 6 The method for fabricating a continuous depth-of-focus lens based on helical diffraction provided in this application includes:
[0077] S101. Provide a substrate layer, and design a diffraction structure on one side surface of the substrate. The diffraction structure includes one or N consecutive helical arms. N≥2, where N is an integer.
[0078] Specifically, the continuous depth-of-focus lens provided in the embodiments of this application can be an intraocular lens, contact lens, scleral lens, corneal implant, or spectacle lens.
[0079] For example, refer to Figure 1 The substrate layer 01 can be a lens for reading glasses for people with presbyopia. The diffraction structure 02 is disposed on one side surface of the substrate layer 01.
[0080] A helical phase retardation is applied to the incident light wavefront, and the radial rate of change of the phase retardation continuously varies with the radial coordinates of the diffraction structure. This phase retardation stretches the focal point along the optical axis, giving the lens a continuous depth of focus. The specific steps are as follows:
[0081] S102. Set diffraction points on the diffraction surface of the diffraction structure. Input parameters.
[0082] The input parameters include the initial phase coefficient. End phase coefficient Radial position where diffraction begins Maximum radius of the lens optical zone The number of spiral arms N, the starting angle of the spiral etc. Among them, the maximum radius of the optical region... It is also equal to half the diameter (FOD) of the lens base curve area (or optical center area), i.e. (FOD / 2).
[0083] S103, Calculate each diffraction point Radial variation coefficient .
[0084] Among them, the radial variation coefficient At the radial position where diffraction begins With the maximum radius of the lens optical zone The changes between them.
[0085] Specifically, in order to make the characteristics of the diffraction fringes vary with the radial position, this application introduces a radially correlated radial variation coefficient on the diffraction surface of the diffraction structure. .
[0086] Among them, the radial variation coefficient is a nonlinear function of the radial coordinate r of the diffraction point.
[0087] Optional, radial variation coefficient By diffraction starting radius and the maximum radius of the lens optical zone The linear interpolation between them is determined.
[0088] Specifically, when using linear interpolation to determine the radial variation coefficient satisfy:
[0089] When radial position ≤ Diffraction starting radius At that time, the following conditions are met:
[0090] , (2.1).
[0091] When radial position > Diffraction starting radius At that time, the following conditions are met:
[0092] , (2.2).
[0093] in, The initial phase coefficient, To terminate the phase coefficient, The starting radius of the diffraction is 1. It is the maximum radius of the lens's optical region.
[0094] The radial variation coefficient provided in this application This is achieved using continuous linear interpolation, which allows for a smooth, pupil-dependent transition in the lens's optical properties. For example, by appropriately setting the initial phase coefficient... and the end phase coefficient The value can be designed to be in the central region ( Figure 1 The central white area 03 (corresponding to the user's pupil) has stronger multifocal characteristics to meet the needs of close-range reading, and smoothly transitions to hyperopic or extended depth of field (EDoF) characteristics towards the edge area.
[0095] in, It is the diffraction initiation radius at which diffraction begins. The area within ( Figure 1 The central white area (03) is a normal optical zone unaffected by diffraction, providing clear, single vision.
[0096] S104. Calculate the spiral phase parameters of each diffraction point based on a combination of radial and angular components. .
[0097] Among them, the spiral phase parameter satisfy:
[0098] , (1.1).
[0099] Specifically, this application introduces a helical phase parameter on the diffraction surface of the diffraction structure. This parameter defines the phase of the diffraction structure. Helical phase parameter. The calculation is based on the combination of radial and angular components in the above formulas (2.1) to (2.3).
[0100] in, These are the radial coordinates of the diffraction point. Here are the angular coordinates (in radians) of the diffraction point. The radial variation coefficient is calculated for the above formulas (2.1) and (2.2).
[0101] It should be noted that this algorithm does not simply superimpose a vortex phase with a lens phase. Instead, it interweaves both within a single spiral phase parameter. This configuration inherently links the caustic and vortex characteristics, enabling more controllable and efficient generation of the desired extended depth of focus range.
[0102] S105. Applying a smoothing function to the spiral phase parameters Perform normalization processing, and then normalize the phase. Applied to each diffraction point on the entire diffraction surface The final phase distribution function of the diffraction surface of the diffraction structure is obtained. .
[0103] Among them, the final phase distribution function satisfy:
[0104] (1.2).
[0105] in, The phase after normalization. These are the radial coordinates of the diffraction point. These are the angular coordinates of the diffraction point. Smoothing function. It is a nonlinear function used to generate a smooth phase transition within a phase period of 0 to 2π.
[0106] To ensure a smooth phase transition between 0 and 2π and avoid abrupt phase jumps, embodiments of this application employ a smoothing function. Regarding the above spiral phase parameters Normalization is performed to obtain a "softened" sawtooth phase profile. The normalized phase is then... Applied to each diffraction point on the entire diffraction surface The final phase distribution function of the diffraction surface of the diffraction structure is obtained. .
[0107] Among them, the smoothing function It is a nonlinear function used to achieve continuous phase transition within a phase period of 0 to 2π.
[0108] For example, smoothing function This includes one of the following: arctangent function, hyperbolic tangent function, or sigmoid function.
[0109] The normalization process for the spiral phase parameter includes:
[0110] Step S1: Mathematically process the spiral phase parameters based on the phase coefficient and smoothing function to obtain the intermediate phase distribution function.
[0111] Step S2: Normalize the intermediate phase distribution function to the range of [0, 2π] to obtain the final phase distribution function of the diffraction surface of the diffraction structure.
[0112] As an example, with the smoothing function Taking the arctangent function as an example, the input parameters also include a phase coefficient A that controls the steepness of the phase curve. The arctangent function is used to adjust the spiral phase parameters. The normalization process includes:
[0113] Step S11: Process the spiral phase parameters using the arctangent function. Obtain the intermediate phase distribution function .
[0114] Among them, the intermediate phase distribution function satisfy:
[0115] , (3.1).
[0116] Step S12: The intermediate phase distribution function Normalized to the interval [0, 2π], it satisfies:
[0117] , (3.2).
[0118] in, , .
[0119] Step S13: Normalize the phase Applied to each diffraction point on the entire diffraction surface of the diffraction structure. This yields the final two-dimensional phase map. The final phase distribution function of the diffraction surface of the diffraction structure is then obtained. .Right now .
[0120] Wherein, the phase distribution function Define the final phase distribution of the diffraction structure.
[0121] It should be noted that the embodiments of this application use the arctangent function (arctan()) to provide a periodic oscillation, which is transformed into a "softened" jagged or shimmering profile (such as...). Figure 3 (As shown).
[0122] However, conventional diffraction microstructures in existing technologies have sharp phase edges. According to the principles of physics, sharp edges are the main source of wide-angle light scattering, which the human visual system perceives as halos and glare.
[0123] Based on this, this application introduces a smoothing function. Transitions can minimize scattering and direct more light energy into the useful focal length range, thereby reducing unwanted visual artifacts.
[0124] Furthermore, this application can control the steepness of this transition by controlling the phase coefficient A (i.e., phase_A) of the phase curve, so that the "softness" of the profile can be further optimized.
[0125] A larger A value approaches a sharp step, while a smaller A value produces a smoother transition. The larger the A value, the closer the phase curve is to a square wave.
[0126] S106, Output Phase Distribution Function The lens is then processed using manufacturing equipment to fabricate its diffractive surface.
[0127] Specifically, the two-dimensional phase map obtained in this application embodiment is then processed by a smoothing window function (Apodization) and converted into actual surface depression or protrusion depth (Sag), thereby generating diffraction surface data that can be used for optical simulation.
[0128] It is important to emphasize that the basic principle of formula (1.2) is that the additional optical path difference (OPD) generated by the surface depth must be equal to the required phase shift. This relationship can be derived from the basic theory of diffraction optics. The final phase surface (as shown in Figure 1) can be produced using high-precision manufacturing techniques, such as single-point diamond turning, laser ablation, or precision molding.
[0129] Optionally, the added power of the front and rear focal points corresponding to the radial position r of the lens satisfies:
[0130] , ;
[0131] in, Let be the luminous intensity at the front focal point at the radial position r. λ is the luminous intensity at the back focal point at the radial position r, and λ is the design wavelength.
[0132] In this context, "addition" refers to the additional power in a pair of progressive multifocal glasses or reading glasses used for near vision (lower half) compared to the area used for distance vision (upper half).
[0133] Optionally, the estimation of the lens focal depth satisfies:
[0134] .
[0135] Where DOF is the total focal depth of the lens. The luminosity at the radial infinity position far is... This represents the luminous intensity at the radial near position (near).
[0136] Based on the above embodiments, the scope of protection of this application is not limited to the above embodiments. In addition, continuous depth-of-focus lenses with various phase distributions can also be realized by changing the number of spiral arms (N), nonlinear radial modulation, smoothing function, etc., to meet the application requirements of different optical performance.
[0137] Based on the above embodiment, the number of spiral arms N is changed. Specifically, N can be any integer greater than or equal to 1. According to the vortex principle, a higher value of N will generate vortices with a higher topological charge, which will change the energy distribution of the lens and the diameter of the central dark area to suit different vision corrections.
[0138] Based on the above embodiments, the nonlinear radial modulation is changed. Specifically, the radial variation coefficient... Not limited to linear interpolation. Radial variation coefficient. The function can be a polynomial, exponential, or other function to create more complex out-of-focus curve effects. For example, it can achieve a sharper focus in the far middle and a slightly weaker focus in the near, or vice versa.
[0139] Based on the above embodiments, the smoothing function can be changed. Specifically, the arctangent function can satisfy the smoothing optimization, but other sigmoid functions can also be used to achieve a soft phase transition. The embodiments of this application are not limited to this.
[0140] Based on the above embodiments, refer to Figure 1 A basic optical surface can be set on one side surface of the substrate layer 01, and the diffraction structure 02 is superimposed on the basic optical surface. The basic optical surface can be one of a sphere, an aspherical surface, or a complex surface.
[0141] Specifically, the diffraction surface of the diffraction structure provided in this application embodiment is combined with a base surface, and the helical diffraction profile is superimposed on a base optical surface. This base surface can be a sphere, an aspherical surface, or a complex surface, thereby fabricating a single device capable of simultaneously correcting multiple refractive errors.
[0142] For example, aspherical surfaces can be used to correct corneal spherical aberration, while toric surfaces can be used to correct astigmatism.
[0143] In summary, the continuous depth-of-focus lens based on helical diffraction provided in this application has the following advantages compared with the prior art:
[0144] (1) It has continuous depth of focus and excellent visual quality, and the diffraction structure is combined with radial modulation (radial variation coefficient). It can produce an extended and continuous depth of focus range, providing high-quality continuous vision from far to near.
[0145] (2) It has pupil adaptability: the radial variation coefficient B(r) allows the optical properties of the lens (such as local light-adding power) to change continuously with the radial distance (i.e. pupil size), thereby optimizing the light energy distribution under different lighting conditions and making the visual quality more stable.
[0146] (3) It can significantly reduce visual interference: a smooth phase transition based on the arctangent function (or other S-shaped functions) is used to replace the sharp steps of traditional diffraction, which fundamentally reduces higher-order diffraction and light scattering, thereby greatly suppressing abnormal visual phenomena such as halos and glare.
[0147] (4) It has strong design flexibility: by adjusting the function form of the number of spiral arms N, the phase coefficient A, and the radial variation coefficient B(r) (such as linear or nonlinear), the optical performance can be flexibly customized to meet personalized needs.
[0148] Based on the same inventive concept, this application also provides a storage medium storing a computer program. When the computer program is executed by a processor, it implements the method for fabricating a continuous depth-of-focus lens based on helical diffraction provided in the above embodiments. This storage medium also has the effective effects of the method for fabricating a continuous depth-of-focus lens based on helical diffraction provided in the above embodiments, which will not be elaborated here.
[0149] Based on the same inventive concept, this application also provides an apparatus, including a memory, a processor, and a computer program stored in the memory. When the processor executes the computer program, it implements the method for fabricating a continuous depth-of-focus lens based on helical diffraction provided in the above embodiments. This apparatus also has the effective effects of the method for fabricating a continuous depth-of-focus lens based on helical diffraction provided in the above embodiments, which will not be elaborated here.
[0150] Based on the above embodiments, the processor executes a computer program to calculate the diffraction phase distribution of the continuous depth-of-focus lens as follows:
[0151] graph TD;
[0152] subgraph "Step 1: Input and Initialization";
[0153] A [Start] --> B (Enter initial parameters) B_start, B_end, r_start, r_max, N, θ_start, phase_A, λ);
[0154] End
[0155] subgraph "Step 2: Calculate (r, θ) point by point";
[0156] B --> C["Calculate the radial variation coefficient B(r)"];
[0157] C --> D{r <= r_start?};
[0158] D -- is --> E["B(r) = B_start"];
[0159] D -- No --> F["B(r) = B_start + (B_end - B_start) * (r - r_start) / (r_max - r_start)"];
[0160] E --> G["Calculate the spiral phase parameters p(r, θ)" p = 2π * (r² / B(r) - N* (θ - θ_start) / 2π)"];
[0161] F --> G;
[0162] End
[0163] subgraph "Step 3: Phase Shaping and Normalization";
[0164] G --> H["Using the arctan function to create a softening profile"] Φ_raw = arctan(A* cos(p))"];
[0165] H --> I["Normalize phase to [0, 2π]" Φ_norm = 2π - (Φ_raw -Φ_min) / (Φ_max - Φ_min) * 2π Where Φ_max / min = arctan(±A)"];
[0166] End
[0167] subgraph "Step 4: Generate final data";
[0168] I --> J["Generate the final two-dimensional diffraction phase map"] Φ(r, θ) = Φ_norm"];
[0169] J --> K[" Post-processing (optional) 1. Apply the smooth window function (Apodization) 2. Convert the phase to surface depth (Sag);
[0170] End
[0171] Subgraph "Step 5: Output and Performance Analysis";
[0172] K --> L (Final output: Diffraction surface data that can be used for optical simulation;
[0173] B --> M [Calculate optical performance];
[0174] M --> N["Added luminosity Add(r) = 2λ / B(r)"];
[0175] M --> O["Total depth of focus (DOF) ≈ |2λ / B_end - 2λ / B_start|"];
[0176] L --> P [End];
[0177] N --> P;
[0178] O --> P;
[0179] End
[0180] style K fill: #f9f, stroke: #333, stroke-width: 2px.
[0181] The calculation program provided in this application uses a spiral phase mask-based method to generate a diffraction surface. Its core idea is to create a two-dimensional phase map where the phase is modulated in a specific spiral manner according to the radial and angular positions. The final diffraction surface morphology (recesses or protrusions) of the diffraction structure is obtained by scaling this phase map.
[0182] The continuous depth-of-focus lens provided in this application embodiment can be integrated into any ophthalmic lens designed to correct presbyopia.
[0183] For example, in intraocular lens (IOL) applications, the diffraction surface of a continuous depth-of-focus lens can be applied to the anterior or posterior surface of an IOL made of standard materials such as hydrophilic / hydrophobic acrylates or silicone.
[0184] For example, in corneal implant (Inlays / Onlays) applications, the diffraction surface of a continuous depth-of-focus lens can be fabricated onto a biocompatible implant placed within the corneal stroma.
[0185] For example, in contact lens applications, the diffraction surface of a continuous depth-of-focus lens can be molded onto the front or rear surface of a soft or rigid gas permeable contact lens (RGP).
[0186] As an example, taking rigid gas permeable (RGP) contact lenses, the diffractive surface is applied to the front surface of the lens, and the specific parameters meet the following requirements:
[0187] The lens material is XO, with a refractive index of 1.415. The base curve is 8.4 mm. The prescription power is -3D, the front surface radius of curvature is 8.94 mm, the phase coefficient A (controlling the steepness of the phase curve) is 0.6, and the initial phase coefficient... = 1.5, End Phase Coefficient = 2.5, diffraction onset radius =1.5, the maximum radius of the lens's optical zone = 4, number of spiral arms N=3.
[0188] The lathe machining path satisfies the following: at the 0° meridian, the front surface is non-axisymmetric, and varies along each meridian. The base curve refers to the radius of curvature of the central region of the inner surface of the contact lens (the side that contacts the cornea).
[0189] Figure 7 This is a meridional view of a rigid gas permeable (RGP) contact lens at the starting angle. Figure 8 This is a test diagram of the phase profile of a rigid gas permeable (RGP) contact lens. Figure 9 This is a two-dimensional grayscale test image of the final phase map of a rigid gas permeable (RGP) contact lens. Among them, Figure 7 This illustrates the matching relationship between the posterior surface curve of a rigid gas permeable (RGP) contact lens and the anterior surface curve of the cornea in a specific meridional direction.
[0190] Combination Figures 7-9 The rigid gas permeable (RGP) contact lens provided in this application utilizes the principle of diffraction. By constructing a micron-scale spiral phase structure with a smooth phase transition on the lens surface, it stretches the focal point through light interference and diffraction, thus forming a continuous depth of field. By "softening" the transition of the 2π phase period through the arctangent function, it fundamentally solves the problem of light scattering and visual interference caused by sharp steps in traditional diffractive optics.
[0191] Note that the above are merely preferred embodiments and technical principles of this application. Those skilled in the art will understand that this application is not limited to the specific embodiments described herein, and the features of various embodiments of this application can be partially or wholly coupled or combined with each other, and can cooperate and be technically driven in various ways. Various obvious changes, readjustments, combinations, and substitutions can be made by those skilled in the art without departing from the scope of protection of this application. Therefore, although this application has been described in detail through the above embodiments, this application is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of this application, and the scope of this application is determined by the scope of the appended claims.
Claims
1. A continuous focal depth lens based on spiral diffraction, characterized in that, The continuous focal depth lens comprises a substrate layer and a diffraction structure arranged on the substrate layer; the diffraction structure comprises one or N continuous spiral arms; wherein N is an integer greater than or equal to 2. The diffraction structure is used to apply a spiral phase delay to an incident light wave front, and the radial variation rate of the phase delay continuously varies with the radial coordinate of the diffraction structure, and the phase delay stretches the focal point along the optical axis direction, so that the lens has a continuous focal depth.
2. The continuous depth of focus lens of claim 1, wherein, The diffraction surface of the diffraction structure is composed of a plurality of diffraction points The phase distribution of each diffraction point is determined by a phase distribution function Wherein, the phase distribution function Based on the spiral phase parameter Normalized processing, meet: ； ； wherein is a spiral phase parameter; is a normalized phase; r is a radial coordinate of the diffraction point, is an angular coordinate of the diffraction point, is a starting angle of the spiral; is a radial variation coefficient of the diffraction point as a function of the radial coordinate, and the radial variation coefficient B(r) is a non-linear function of the radial coordinate r of the diffraction point.
3. The continuous depth of focus lens of claim 2, wherein, the radial variation coefficient by linear interpolation between the diffraction starting radius and the maximum radius of the lens optical zone is determined, in particular: When Time, ; When Time, ; wherein, is a start phase coefficient, is an end phase coefficient, is a diffraction start radius, is a maximum radius of the lens optical zone.
4. The continuous depth of focus lens of claim 1, wherein, The additivity of the front focal point and the rear focal point of the continuous focal depth lens at a radial position r satisfies: ， ； wherein is the vignetting of the front focus at radial position r, is the vignetting of the back focus at radial position r, and λ is the design wavelength.
5. The continuous depth of focus lens of claim 1, wherein, the phase distribution function by employing a smoothing function on the spiral phase parameter after normalization processing The smooth function is a nonlinear function used to realize continuous phase transition in a phase period of 0 to 2π.
6. The continuous depth of focus lens of claim 5, wherein, The smooth function comprises one of an inverse tangent function, a hyperbolic tangent function or an S-shaped function.
7. The continuous depth of focus lens of claim 1, wherein, One side surface of the substrate layer is provided with a basic optical curved surface, and the diffraction structure is superimposed on the basic optical curved surface. The basic optical curved surface is one of a spherical surface, an aspherical surface or a complex curved surface.
8. The continuous depth of focus lens of claim 1, wherein, The continuous focal depth lens is an intraocular lens, a contact lens, a scleral lens, a corneal implant or an eyeglass lens.
9. A method for producing a continuous focal depth lens based on spiral diffraction, for producing the continuous focal depth lens based on spiral diffraction according to any one of claims 1 to 8, characterized in that The continuous focal depth lens comprises: A substrate layer is provided, and a diffraction structure is designed on one side surface of the substrate layer; the diffraction structure comprises one or N continuous spiral arms; N is an integer greater than or equal to 2. A spiral phase delay is applied to an incident light wave front, and the radial variation rate of the phase delay continuously varies with the radial coordinate of the diffraction structure, and the phase delay stretches the focal point along the optical axis direction, so that the lens has a continuous focal depth.
10. The method of claim 9, wherein, A spiral phase delay is applied to an incident light wave front, and the radial variation rate of the phase delay continuously varies with the radial coordinate of the diffraction structure, and the phase delay stretches the focal point along the optical axis direction, so that the lens has a continuous focal depth. Setting diffraction points on the diffractive structure diffractive surface ; the input parameters include a start phase coefficient , an end phase coefficient , a radial position of the start of diffraction , a maximum radius of the lens optical zone , the number N of spiral arms, the start angle of the spiral ; Calculate each diffraction point Radial variation coefficient Wherein, the radial variation coefficient At the radial position where diffraction begins With the maximum radius of the lens optical zone Changes between; The helical phase parameter of each diffraction point is calculated based on a combination of a radial component and an angular component ; ； The spiral phase parameter is normalized by a smoothing function The normalized phase is applied to each diffraction point on the entire diffraction surface to obtain the final phase distribution function of the diffraction structure diffraction surface , which satisfies: ； wherein is the normalized phase; is the radial coordinate of the diffraction point, is the angular coordinate of the diffraction point; the smoothing function is a non-linear function for producing a smooth phase transition over the phase period of 0 to 2π; Output phase distribution function to a manufacturing facility to machine the diffractive surface of the lens.
11. The method of claim 10, wherein, The input parameters further comprise a phase coefficient for controlling the steepness of the phase curve, The normalization process of the spiral phase parameter comprises: The spiral phase parameter is mathematically processed based on the phase coefficient and the smooth function to obtain an intermediate phase distribution function; The intermediate phase distribution function is normalized to the range of [0, 2π] to obtain the final phase distribution function of the diffraction structure diffraction surface.