Computer-based methods for calculating digital twins of eyeglass lenses

Abstract

The present invention relates to a computer-implemented method configured for calculating a digital twin of an eyeglass lens for use in the manufacture of the lens, the digital twin having a predefined power distribution and comprising a stack of layers having a plurality of individual layers, each individual layer having a uniform refractive index and a non-uniform layer thickness that varies spatially, the method being characterized by the step of: determining the spatial variation of the layer thickness of the individual layers to achieve the predefined power distribution through spatial control of the optical path length.

Description

[0001] The present invention relates to a computer-implemented method for calculating a digital twin of an eyeglass lens as described in the preamble of claim 1, and an eyeglass lens as described in the preambles of claims 13 and 15. Background Technology

[0002] WO 2020 / 165439 A1 discloses a refractive optical component, particularly for the production of spectacle lenses. This refractive optical component includes a body having a refractive index profile modulated at least along a principal axis, the refractive index profile having multiple maximum and minimum values, wherein the thickness of each layer varies within a range perpendicular to the principal axis, and wherein the maximum value of the refractive index profile within a given layer in the direction perpendicular to the principal axis is less than 20. On the other hand, these layers have a constant refractive index within themselves. Variation occurs only in the region of the interface between two adjacent layers. According to WO 2020 / 165439 A1, specific optical and / or geometric data of the body to be manufactured can be used as construction data. Alternatively or additionally, construction data should be determined from the prescription data of the spectacle lens to be manufactured.

[0003] The problem to be solved

[0004] Based on WO 2020 / 165439 A1, particularly on page 37, lines 24 to 27, which discloses the calculation of structural data of a body based on prescription data of a spectacle lens, particularly the refractive index profile of the body and control parameters for controlling material application by means of an additive manufacturing apparatus for the body, the object of the present invention is to provide a specific algorithm for calculating layer structure based on a predefined target power distribution of a spectacle lens. Summary of the Invention

[0005] This problem has been solved by the computer-implemented method according to claim 1 and the spectacle lens according to claims 13 and 15.

[0006] The dependent claims list preferred embodiments that can be implemented in isolation or in any arbitrary combination.

[0007] The computer-implemented method is configured to calculate a digital twin of an eyeglass lens for use in the manufacture of the lens. The digital twin has a predefined power distribution and comprises multiple individual layers, each having a uniform refractive index and a spatially varying non-uniform layer thickness. The stack of layers comprises individual layers with different uniform refractive indices. The computer-implemented method according to the invention is characterized by the following steps:

[0008] - Determine the spatial variation of the layer thickness of the individual layers to achieve the predefined focal length distribution through spatial control of the optical path length.

[0009] Alternatively, the computer-implemented method is configured to calculate a stack of layers representing a digital twin of the spectacle lens, so as to apply the calculation to the manufacture of the lens. The digital twin has a predefined power distribution, and the stack of layers has multiple individual layers, each with a uniform refractive index and a spatially varying non-uniform layer thickness. The method is characterized by the following steps:

[0010] - Determine the spatial variation of the layer thickness of the individual layers to achieve the predefined focal length distribution through spatial control of the optical path length.

[0011] Alternatively, the computer-implemented method is configured to calculate a stack of layers representing a digital twin of an eyeglass lens, so as to apply the calculation to the manufacture of the lens. The digital twin has a predefined power distribution, and the stack has multiple individual layers, each with a uniform refractive index and a spatially varying non-uniform layer thickness. The stack includes individual layers with different uniform refractive indices. The method is characterized by the following steps:

[0012] - Determine the spatial variation of the layer thickness of the individual layers to achieve the predefined focal length distribution through spatial control of the optical path length.

[0013] A "digital twin" of an eyeglass lens is a mathematical description of the lens surface of its front surface and a mathematical description of the lens surface of its rear surface, wherein the mathematical description includes the relative orientation of the lens surface of the front surface relative to the lens surface of the rear surface and the refractive index distribution n(x,y,z) of the eyeglass lens. Correspondingly, a digital twin of a gradient refractive index eyeglass lens is a mathematical description of the lens surface of its front surface and a mathematical description of the lens surface of its rear surface, wherein the mathematical description includes the relative orientation of the lens surface of the front surface relative to the lens surface of the rear surface and the refractive index distribution n(x,y,z) of the gradient refractive index eyeglass lens. In the digital twin of an eyeglass lens, the refractive index distribution n(x,y,z) is preferably uniform within a single layer. In the digital twin of a gradient refractive index eyeglass lens, the refractive index distribution n(x,y,z) is non-uniform within the gradient refractive index eyeglass lens. The refractive distribution n(x,y,z) is either in the same coordinate system as the mathematical description, or the transformation in the coordinate system of the mathematical description is known. The digital twins of spectacle lenses and the digital twins of gradient-index spectacle lenses are each used in the manufacture of spectacle lenses. When a digital twin of a gradient-index spectacle lens is converted into a physical entity, it is preferably not a gradient-index spectacle lens itself, but rather a spectacle lens that exhibits the characteristics of a digital twin of a gradient-index spectacle lens in terms of the optical path length of the same incident beam passing through the lens. Converting a digital twin of a gradient-index spectacle lens into a physical entity is preferably the same as converting a stack of layers of a gradient-index spectacle lens's digital twin into a physical entity. In other words, the optical path length of the same incident beam passing through the lens is equal to the optical path length passing through the digital twin of the gradient-index spectacle lens at the same position or at the same discrete position.

[0014] Therefore, it is preferable to compare the optical path lengths of identical vertically incident beams or identical nearly vertically incident beams. A vertically incident beam preferably refers to an incident beam that is perpendicular to a plane passing through the optical or geometric center of the spectacle lens and, for comparison purposes, also passing through the optical or geometric center of the digital twin of the gradient-index spectacle lens, said plane being perpendicular to the optical axis or z-direction of both the spectacle lens and the digital twin of the gradient-index spectacle lens.

[0015] The digital twin lens surfaces of both spectacle lenses and gradient index spectacle lenses are as defined in Section 3.4 of ISO 13666:2019(E), or similarly as defined in Section 3.4 of ISO 13666:2019(E). The digital twin lens surfaces of both spectacle lenses and gradient index spectacle lenses can be shaped as one of the following:

[0016] - Spherical surfaces, as defined in Section 3.4.1 of ISO 13666:2019(E),

[0017] - Cylindrical surfaces, as defined in Section 3.4.2 of ISO 13666:2019(E),

[0018] - Aspherical surfaces, as defined in Section 3.4.3 of ISO 13666:2019(E),

[0019] - A toroidal surface, as defined in section 3.4.6 of ISO 13666:2019(E),

[0020] - Non-atoroidal surfaces, as defined in Section 3.4.7 of ISO 13666:2019(E),

[0021] - Zoom surfaces, as similarly defined in Section 3.4.10 of ISO 13666:2019(E),

[0022] - Meridionally-compensated aspherical surfaces, as similarly defined in section 3.4.11 of ISO 13666:2019(E).

[0023] In other words, the front surface of the digital twin of each of the spectacle lens and the gradient refractive index spectacle lens can be shaped according to one of the aforementioned lens surfaces, and the rear surface of the digital twin of each of the spectacle lens and the gradient refractive index spectacle lens can be shaped according to one of the aforementioned lens surfaces.

[0024] Similar to Section 3.2.13 of ISO 13666:2019(E), the front surface of the digital twin of both the spectacle lens and the gradient-index spectacle lens is defined as the surface intended to be away from the eye assembly when the digital twin is transferred into the spectacle lens. Similar to Section 3.2.14 of ISO 13666:2019(E), the rear surface of the digital twin of both the spectacle lens and the gradient-index spectacle lens is defined as the surface intended to be closer to the eye assembly when the digital twin is transferred into the spectacle lens. The digital twin is transferred into the spectacle lens, for example, preferably by an additive manufacturing method, and more preferably by inkjet printing; that is, the digital twin is transformed into a physical entity. Examples of such additive manufacturing methods are stereolithography (SLA) 3D printing or selective laser melting (SLM) 3D printing.

[0025] The average refractive index distribution n(x,y) of the spectacle lens in the z-direction is the refractive index distribution that the spectacle lens should have after being preferably manufactured by additive manufacturing, and more preferably after inkjet printing. The refractive index distribution n(x,y,z) preferably specifies the refractive index at either a) each x,y,z position or b) each discrete x,y,z position of the digital twin of both the spectacle lens and the gradient refractive index spectacle lens.

[0026] A digital twin of an eyeglass lens is a mathematical description or representation of the lens surface, including a refractive index distribution n(x,y,z), which is computer-readable data or in the form of computer-readable data. A digital twin of a gradient refractive index eyeglass lens is a mathematical description or representation of the lens surface, including a refractive index distribution n(x,y,z), which is computer-readable data or in the form of computer-readable data. The computer-readable data may (i) be stored on a computer-readable storage medium or (ii) transmitted via a data signal. The computer-readable storage medium may be a non-transitory tangible computer-readable storage medium. The computer-readable data may additionally include manufacturing instructions for converting the digital twins of both the eyeglass lens and the gradient refractive index eyeglass lens into physical entities (i.e., for manufacturing the eyeglass lens), preferably manufacturing instructions for additive manufacturing methods, and more preferably printing instructions for inkjet printing the eyeglass lens. Alternatively, the computer-readable data may include printing instructions that, when executed by an inkjet printer, cause the inkjet printer to inkjet print the eyeglass lens.

[0027] Alternatively or concurrently, the digital twin of a spectacle lens or a digital twin of a gradient index spectacle lens can be one of the following:

[0028] - An analytical description or analytical model describing or representing the spectacle lens or the gradient refractive index spectacle lens. The analytical description or analytical model preferably includes or includes: (i) a mathematical formula describing the lens surface of the front surface of the digital twin of the spectacle lens or the digital twin of the gradient refractive index spectacle lens; (ii) a mathematical formula describing the lens surface of the rear surface of the digital twin of the spectacle lens or the digital twin of the gradient refractive index spectacle lens; and (iii) a mathematical formula describing the refractive index distribution n(x,y,z), which preferably specifies the refractive index in: a) each x,y position of the front surface or each discrete x,y position of the front surface; b) each x,y position of the rear surface or each discrete x,y position of the rear surface; and c) each x,y,z position between the front surface and the rear surface or each discrete x,y,z position between the front surface and the rear surface.

[0029] - An analytical description or analytical model that describes or represents the spectacle lens or the gradient refractive index spectacle lens, the analytical description or analytical model further including manufacturing instructions, preferably manufacturing instructions for an additive manufacturing method for 3D printing the spectacle lens, more preferably (i) for inkjet printing the spectacle lens or (ii) printing instructions that cause an inkjet printer to inkjet print the spectacle lens when executed by an inkjet printer.

[0030] - Presented in the form of an analytical description or analytical model representing the spectacle lens or the gradient refractive index spectacle lens;

[0031] - Presented in the form of an analytical description or analytical model representing the eyeglass lens or the gradient refractive index eyeglass lens, the analytical description or analytical model further comprising manufacturing instructions, preferably manufacturing instructions for an additive manufacturing method for 3D printing the eyeglass lens, more preferably (i) for inkjet printing the eyeglass lens or (ii) printing instructions for causing an inkjet printer to inkjet print the eyeglass lens when executed by an inkjet printer;

[0032] - The analysis description or the analysis model is (i) computer-readable data or (ii) in the form of computer-readable data;

[0033] - The analysis description or the analysis model is (i) computer-readable data or (ii) in the form of computer-readable data, which further includes manufacturing instructions, preferably manufacturing instructions for an additive manufacturing method for 3D printing the eyeglass lens, and more preferably (i) for inkjet printing the eyeglass lens or (ii) printing instructions for causing an inkjet printer to inkjet print the eyeglass lens when executed by an inkjet printer.

[0034] - The analysis description or the analysis model (i) is stored on a computer-readable storage medium or (ii) is transmitted via a data signal. The computer-readable storage medium may be a non-transitory tangible computer-readable storage medium;

[0035] - Numerical data describing or representing the spectacle lens or the gradient refractive index spectacle lens. The numerical data preferably includes or represents a transformation of the analytical description or the analytical model. The numerical data preferably includes a pattern comprising discrete x,y positions on or on the front surface of the digital twin of the spectacle lens or the digital twin of the gradient refractive index spectacle lens, and discrete x,y positions on or on the rear surface of the digital twin of the spectacle lens or the digital twin of the gradient refractive index spectacle lens. The pattern including discrete x,y positions can be arbitrarily adapted or selected. Preferably, the pattern including discrete x,y positions is adapted or selected to take into account the printing resolution of the corresponding SLA or SLM 3D printing method. More preferably, the pattern including discrete x,y positions is adapted or selected to take into account the printing resolution of an inkjet printer, i.e., the discrete x,y positions preferably take into account the printing resolution of the inkjet printer, preferably the printing resolution of the inkjet printhead of the inkjet printer. Therefore, the numerical data includes function values ​​of an analytical description or analytical model for each of the discrete x, y positions of the lens surface. The x, y, z values ​​of the front and rear surfaces are described in the same coordinate system, or the relative orientation of the coordinate systems of the front and rear surfaces is included in the numerical data. A refractive index distribution is included in the numerical data, comprising a pattern including function values ​​of an analytical description or analytical model for: (i) the discrete x, y positions (n(x, y)) on or on the front surface of the digital twin of the lens; (ii) the discrete x, y positions (n(x, y)) on or on the rear surface of the digital twin of the lens; and (iii) the discrete x, y, z positions (n(x, y, z)) between the front and rear surfaces. Preferably, the numerical data is used as the basis for calculating the stacked structure of the digital twin of the lens or the stacked structure of the digital twin of the gradient refractive index lens. Compared to using the previously defined analytical description or model as the basis for calculating the stacked layers, less computational power is required when using the numerical data as the basis for calculation. In other words, calculating the stacked layers using the numerical data is computationally less expensive.

[0036] - Numerical data describing or representing the eyeglass lens or the gradient refractive index eyeglass lens, the numerical data further including manufacturing instructions, preferably manufacturing instructions for an additive manufacturing method for 3D printing the eyeglass lens, more preferably (i) for inkjet printing the eyeglass lens or (ii) printing instructions for causing an inkjet printer to inkjet print the eyeglass lens when executed by an inkjet printer.

[0037] - Presented in the form of numerical data describing or representing the eyeglass lens or the gradient refractive index eyeglass lens;

[0038] - Presented in the form of numerical data describing or representing the eyeglass lens or the gradient refractive index eyeglass lens, the numerical data further including manufacturing instructions, preferably manufacturing instructions for an additive manufacturing method for 3D printing the eyeglass lens, more preferably (i) for inkjet printing the eyeglass lens or (ii) printing instructions for causing an inkjet printer to inkjet print the eyeglass lens when executed by an inkjet printer.

[0039] - The numerical data is (i) computer-readable data or (ii) in the form of computer-readable data;

[0040] - The numerical data is (i) computer-readable data or (ii) in the form of computer-readable data, the computer-readable data further comprising manufacturing instructions, preferably manufacturing instructions for an additive manufacturing method for 3D printing the eyeglass lens, and more preferably (i) for inkjet printing the eyeglass lens or (ii) printing instructions for causing an inkjet printer to inkjet print the eyeglass lens when executed by an inkjet printer.

[0041] The numerical data is (i) stored on a computer-readable storage medium or (ii) transmitted via a data signal. The computer-readable storage medium may be a non-transitory tangible computer-readable storage medium;

[0042] - Computer-readable data describing or representing the eyeglass lens or the gradient refractive index eyeglass lens;

[0043] - Computer-readable data describing or representing the eyeglass lens or the gradient refractive index eyeglass lens, the computer-readable data further comprising manufacturing instructions, preferably manufacturing instructions for an additive manufacturing method for 3D printing the eyeglass lens, and more preferably (i) inkjet printing instructions for inkjet printing the eyeglass lens or (ii) printing instructions for causing an inkjet printer to inkjet print the eyeglass lens when performed by an inkjet printer.

[0044] - Presented in the form of computer-readable data describing or representing the spectacle lens or the gradient refractive index spectacle lens;

[0045] - Presented in the form of computer-readable data describing or representing the eyeglass lens or the gradient refractive index eyeglass lens, the computer-readable data further comprising manufacturing instructions, preferably manufacturing instructions for an additive manufacturing method preferably used for 3D printing the eyeglass lens, and more preferably (i) for inkjet printing the eyeglass lens or (ii) printing instructions for causing an inkjet printer to inkjet print the eyeglass lens when performed by an inkjet printer.

[0046] The computer-readable data (i) is stored on a computer-readable storage medium or (ii) is transmitted via a data signal. The computer-readable storage medium may be a non-transitory tangible computer-readable storage medium;

[0047] - A virtual representation of spectacle lenses or gradient index spectacle lenses;

[0048] - A virtual representation of a lens or gradient index lens in the form of computer-readable data;

[0049] - A virtual representation of a spectacle lens or a gradient refractive index spectacle lens in the form of computer-readable data, the computer-readable data further comprising manufacturing instructions, preferably manufacturing instructions for an additive manufacturing method for 3D printing the spectacle lens, and more preferably (i) for inkjet printing the spectacle lens or (ii) printing instructions for causing an inkjet printer to inkjet print the spectacle lens when executed by an inkjet printer.

[0050] The virtual representation of the spectacle lens or gradient index spectacle lens is respectively (i) stored on a computer-readable storage medium or (ii) transmitted via a data signal. The computer-readable storage medium may be a non-transitory tangible computer-readable storage medium;

[0051] The virtual representation of the spectacle lens or gradient index spectacle lens is each in the form of computer-readable data, which (i) is stored on a computer-readable storage medium or (ii) is transmitted via a data signal. The computer-readable storage medium may be a non-transitory tangible computer-readable storage medium.

[0052] The terms "x,y,z position", "x,y position", "discrete x,y,z position", and "discrete x,y position" are each defined in an x,y,z coordinate system. This coordinate system is defined as follows: the origin of the x,y,z coordinate system is defined by the predefined point of the digital twin of the spectacle lens, or the predefined point of the digital twin of the gradient refractive index spectacle lens, or the predefined point of the gradient refractive index spectacle lens. The "z-direction" is defined by i) the surface normal or ii) the principal direction of the predefined point. The "x,y direction" lies in a plane perpendicular to the surface normal or the principal direction. In the plane perpendicular to the surface normal or the principal direction, the x-direction and y-direction are perpendicular to each other. The predefined point is preferably the digital twin of the spectacle lens or the geometric center of the spectacle lens, or the digital twin of the gradient refractive index spectacle lens or the geometric center of the gradient refractive index spectacle lens. Similar to section 3.2.25 of ISO 13666:2019(E), the principal direction of the digital twin of the spectacle lens is defined as the direction of the virtual representation of the line of sight (3.2.24) when looking straight ahead with uncorrected visual acuity towards an object at infinity (generally considered horizontal). As in section 3.2.25 of ISO 13666:2019(E), the principal direction of the spectacle lens is defined as the direction of the line of sight (3.2.24) when looking straight ahead with uncorrected visual acuity towards an object at infinity, measured with a habitual head and body posture (generally considered horizontal).

[0053] Similar to Section 3.2.6 of ISO 13666:2019(E), the geometric center of the digital twin of the spectacle lens is defined as the intersection of the horizontal centerline (3.2.3) and the vertical centerline (3.2.4) of the rectangular frame that virtually circumscribes the shape of the digital twin. As defined in Section 3.2.6 of ISO 13666:2019(E), the geometric center of the spectacle lens is the intersection of the horizontal centerline (3.2.3) and the vertical centerline (3.2.4) of the rectangular frame that circumscribes the shape of the uncut spectacle lens (3.8.8).

[0054] The previous definition of the geometric center should be applied accordingly to digital twins and gradient index lenses.

[0055] As defined in section 3.5.2 of ISO 13666:2019(E), a “spectacle lens” or lens is an ophthalmic lens that is worn in front of the eyeball but does not come into contact with the eyeball (3.5.1).

[0056] As defined in section 3.2.13 of ISO 13666:2019(E), the front surface is the surface of the lens (3.5.2) intended to be away from the eye during assembly. As defined in section 3.2.14 of ISO 13666:2019(E), the rear surface is the surface of the lens (3.5.2) intended to be closer to the eye during assembly.

[0057] In the context of this invention, the eyeglass lens is further defined as a physical representation of the corresponding digital twin of the eyeglass lens. Alternatively, the digital twin, transformed into a physical entity, is the eyeglass lens. Preferably, the eyeglass lens is 3D printed, and more preferably, it is an inkjet-printed physical representation of the corresponding digital twin.

[0058] Gradient-index spectacle lenses are defined as spectacle lenses having a predefined refractive index at each x, y, z position or at each discrete x, y, z position, wherein the predefined refractive index preferably varies between different x, y, z positions or between different discrete x, y, z positions. In other words, the refractive index of a gradient-index spectacle lens is non-uniform. The variation in refractive index between different x, y, z positions or between different discrete x, y, z positions is preferably continuous.

[0059] The "layer stack" comprises multiple layers, each having a uniform refractive index and a spatially varying non-uniform layer thickness. In addition to the multiple layers, the layer stack preferably includes a base layer. The base layer preferably has a uniform layer thickness and a uniform refractive index. The base layer is a layer preferably applied to, and preferably inkjet-printed in or on, an optionally removable substrate.

[0060] Preferably, the layer stack comprises up to 400 stacked individual layers, more preferably up to 360 stacked individual layers. More preferably, the layer stack comprises 50 to 340 stacked individual layers, more preferably 60 to 320 stacked individual layers, more preferably 70 to 300 stacked individual layers, and most preferably 80 to 280 stacked individual layers.

[0061] "Power distribution" includes (i) the power distribution of the lens or (ii) the power distribution of the digital twin of the lens. As defined in Section 3.1.10 of ISO 13666:2019(E), the power of a lens is the ability of a lens (3.5.2) or optical surface to alter the curvature or direction of an incident wavefront through refraction. Similar to the definition given in Section 3.1.10 of ISO 13666:2019(E), the power of the digital twin of a lens should mean the ability of the digital twin or the interface of the stack of layers of the digital twin to alter the curvature or direction of a virtual incident wavefront through refraction. The interface separates two adjacent individual layers in the stack of layers of the digital twin. The power distribution specifies (i) the power of the lens at any location or at any discrete location of the lens, or (ii) the power of the digital twin of the lens at any location or at any discrete location of the digital twin of the lens. The power distribution also includes (i) the power distribution of a gradient-index lens or (ii) the power distribution of a digital twin of a gradient-index lens. As similarly defined in Section 3.1.10 of ISO 13666:2019(E), the power of a gradient-index lens is the ability of the lens to change the curvature or direction of an incident wavefront by refraction. Similar to the definition given in Section 3.1.10 of ISO 13666:2019(E), the power of a digital twin of a gradient-index lens should mean the ability of the digital twin to change the curvature or direction of a virtual incident wavefront by refraction. The power distribution specifies (i) the power of a gradient-index lens at any location or at any discrete location, or (ii) the power of a digital twin of a gradient-index lens at any location or at any discrete location.

[0062] "Predefined focal power distribution" includes (i) a predefined focal power distribution of the lens or (ii) a predefined focal power distribution of the digital twin of the lens. The predefined focal power distribution of the digital twin of the lens is preferably preset or specified in an analytical description or model describing or representing the lens. The predefined focal power distribution of the lens corresponds to the predefined focal power distribution of the digital twin of the lens. When manufacturing the lens with consideration for the predefined focal power distribution of the digital twin, the predefined focal power distribution of the digital twin is physically present in or physically realized in the lens. The lens is preferably manufactured by an additive manufacturing method, more preferably by inkjet printing.

[0063] Preferably, a) at each location of the 3D-printed eyeglass lens, preferably the inkjet-printed eyeglass lens, or b) at each discrete location of the 3D-printed eyeglass lens, preferably the inkjet-printed eyeglass lens, the deviation between the predefined focal power distribution of the digital twin and the focal power distribution of the eyeglass lens is less than or equal to 1 / 1000D. The predefined focal power distribution further includes (i) a predefined focal power distribution of a gradient refractive index eyeglass lens or (ii) a predefined focal power distribution of the digital twin of a gradient refractive index eyeglass lens. The predefined focal power distribution of the digital twin of a gradient refractive index eyeglass lens is preferably preset or specified in an analytical description or analytical model describing or representing the gradient refractive index eyeglass lens. The predefined focal power distribution of the gradient refractive index eyeglass lens corresponds to the predefined focal power distribution of the digital twin of the gradient refractive index eyeglass lens. When manufacturing the eyeglass lens considering the predefined focal power distribution of the digital twin of the gradient refractive index eyeglass lens, the predefined focal power distribution of the digital twin is physically present in or physically realized in the eyeglass lens. The eyeglass lenses are preferably manufactured by additive manufacturing, and more preferably by inkjet printing.

[0064] Preferably, a) at each position of the 3D-printed eyeglass lens, preferably the inkjet-printed eyeglass lens, or b) at each discrete position of the 3D-printed eyeglass lens, preferably the inkjet-printed eyeglass lens, the deviation between the predefined power distribution of the digital twin and the power distribution of the eyeglass lens is less than or equal to 1 / 1000D.

[0065] Preferably, the "spatially varying non-uniform layer thickness" of each layer in the digital twin stack of a spectacle lens (i) or (ii) a spectacle lens means that the layer thickness of the same individual layer is different at different locations or at different discrete locations. Preferably, the spatially varying non-uniform layer thickness of each layer in the digital twin stack of a gradient refractive index spectacle lens (i) or (ii) a gradient refractive index spectacle lens means that the layer thickness of the same individual layer is different at different locations or at different discrete locations. Preferably, the spatially varying non-uniform layer thickness of an individual layer in the stack projected onto a plane defined by the x and y directions is, in a side view, the shortest distance between the following points in the z direction.

[0066] A point on the outermost surface of a single layer in a stacked body, perpendicular to that point in the z-direction at the nearest interface of that single layer, has a shortest distance that differs from the shortest distance between another point on the outermost surface and a point on the nearest interface of that single layer perpendicular to that other point in the z-direction.

[0067] A point on the interface of a single layer in a stacked body, and a point on the nearest interface of that single layer that is perpendicular to that point in the z-direction, has a shorter distance that is different from the shortest distance between another point on that interface and a point on the nearest interface of that single layer that is perpendicular to that other point in the z-direction.

[0068] The "uniform refractive index" of a single layer is a constant refractive index or the same refractive index of that single layer. A single layer with a uniform refractive index should mean that the single layer has no refractive index distribution. In a lens or a digital twin of a lens, each x, y, z position or each discrete x, y, z position of a single layer in the layer stack has the same refractive index. Preferably, in a digital twin of a gradient refractive index lens, each x, y, z position or each discrete x, y, z position of a single layer in the layer stack of the digital twin of the gradient refractive index lens has the same refractive index. In the lens or the digital twin, adjacent single layers of the layer stack may have a) a uniform refractive index in each single layer, or b) a uniform refractive index that is different from the uniform refractive index of adjacent or different single layers. In a lens, the single layers corresponding to the single layers with a uniform refractive index in the layer stack of the digital twin of the lens are preferably made of the same material, preferably 3D printed with the same material, and more preferably printed with the same fluid inkjet. Regarding the digital twin of an eyeglass lens, the uniform refractive index of a single layer is either a constant refractive index or the same refractive index for that single layer. For the calculation of the layer stack of the digital twin, the constant refractive index of each single layer is used as the basis, i.e., an exact value of the refractive index is used as the basis for each single layer. In the eyeglass lens, the single layers with uniform refractive index corresponding to the layer stack of the digital twin of the gradient refractive index eyeglass lens are preferably made of the same material, preferably 3D printed using the same material, and more preferably printed using the same fluid jet printing. Regarding the digital twin of a gradient refractive index eyeglass lens, the uniform refractive index of a single layer is preferably either a constant refractive index or the same refractive index for that single layer. For the calculation of the layer stack of the digital twin of the gradient refractive index eyeglass lens, the constant refractive index of each single layer is used as the basis, i.e., an exact value of the refractive index is used as the basis for each single layer. Regarding eyeglass lenses, especially 3D printed eyeglass lenses, preferably layered inkjet printed eyeglass lenses, it is preferable not to consider the refractive index gradient within the printed single layers, because the single layers have a uniform refractive index. Regarding spectacle lenses, when based on the same material, a single layer is preferably referred to as having a uniform refractive index.

[0069] Spatial control of optical path length enables the calculation of a digital twin of a spectacle lens, such that the optical path length of a stack of layers through the digital twin of the lens is equal to the optical path length through the digital twin at the same or discrete positions. Specifically, spatial control of optical path length enables the calculation of a digital twin of a gradient refractive index spectacle lens, such that the optical path length of a stack of layers through the digital twin of the gradient refractive index spectacle lens is equal to the optical path length through the digital twin at the same or discrete positions, the stack comprising individual layers with different uniform refractive indices in distinct individual layers.

[0070] Spatial control of the optical path length enables the calculation of a stacked digital twin of the lens such that the optical path length through the stacked digital twin is equal to the optical path length through the digital twin at the same or discrete positions. The stacked digital twin is calculated such that the optical path length through the stacked digital twin is equal to the optical path length through the digital twin at the same or discrete positions.

[0071] Specifically, spatial control of the optical path length enables the calculation of a stacked digital twin of a gradient-index spectacle, such that the optical path length through the stacked digital twin of the gradient-index spectacle is equal to the optical path length through the digital twin of the gradient-index spectacle at the same or discrete positions, wherein the stacked digital twin comprises individual layers with different uniform refractive indices. The calculation of the stacked digital twin of the gradient-index spectacle ensures that the optical path length through the stacked digital twin is equal to the optical path length through the digital twin of the gradient-index spectacle at the same or discrete positions.

[0072] Spatial control is selected such that the optical path length in the z-direction, the sum of the individual layers (i.e., through multiple individual layers, each with a spatially varying non-uniform layer thickness), is equal to the optical path length through the digital twin of (i) or (ii) the lens, with each compared optical path length being compared at the corresponding position or at the corresponding discrete position.

[0073] Specifically, spatial control is selected such that the optical path length in the z-direction through the sum of individual layers (i.e., through multiple individual layers, each having a spatially varying non-uniform layer thickness, including distinct individual layers with different refractive indices) is equal to the optical path length through (i) a gradient-index lens or (ii) a digital twin of a gradient-index lens, with each compared optical path length being compared at the corresponding position or at the corresponding discrete position.

[0074] The term “equal to” preferably includes one of the following optical path length conditions:

[0075] The optical path length through the stacked layers of the lens is the same as the optical path length through the lens itself.

[0076] The optical path length through the stacked layers of the digital twin of the spectacle lens is the same as the optical path length through the digital twin itself.

[0077] The optical path length through the layered stack of the gradient-index spectacle (which comprises individual layers with different uniform refractive indices) is the same as the optical path length through the gradient-index spectacle.

[0078] The optical path length through the digital twin stack of the gradient-index lens (the stack comprises individual layers with different uniform refractive indices in distinct layers) is the same as the optical path length through the digital twin of the gradient-index lens.

[0079] - The deviation between the optical path length of the stacked body passing through the lens and the optical path length passing through the lens is less than the wavelength of visible light.

[0080] - The optical path length of the stacked digital twin passing through the lens deviates from the optical path length passing through the digital twin less than the visible light wavelength.

[0081] - The optical path length deviation through the gradient refractive index lens of the stacked body (which comprises individual layers with different uniform refractive indices in distinct layers) is less than that of the visible light wavelength.

[0082] - The optical path length deviation between the digital twin of the gradient refractive index lens and the digital twin passing through the gradient refractive index lens (the stack comprising individual layers with different uniform refractive indices in distinct layers) is less than that of the visible light wavelength.

[0083] Each optical path length being compared belongs to the same incident beam at the corresponding position or at the corresponding discrete position.

[0084] The deviation of the compared optical path length below the visible light wavelength (380nm-780nm) can be, for example, less than 300nm, less than 200nm, or less than 100nm. Preferably, the deviation is the same or at least similar for the compared optical path lengths at different corresponding positions or different corresponding discrete positions. If the deviations are not the same or at least not similar, undesirable effects (such as blurring) may occur in the spectacle lens or gradient index spectacle lens.

[0085] Preferably, for spatial control of optical path length, the optical path lengths of identical incident beams are compared. Preferably, the optical path lengths of identical perpendicularly incident beams or identical nearly perpendicularly incident beams are compared. A “perpendicular” incident beam preferably refers to an incident beam perpendicular to, for example, a plane passing through the optical center or geometric center of the digital twin of i) the lens or ii) the lens, said plane being perpendicular to the optical axis or z-direction of the digital twin of i) the lens or ii) the lens. As defined in Section 3.2.15 of ISO 13666:2019(E), the optical center of the lens is the intersection of the optical axis (3.1.8) and the front surface (3.2.13) of the lens (3.5.2). Similar to Section 3.2.15 of ISO 13666:2019(E), the optical center of the digital twin of the lens should be defined as the intersection of the optical axis and the front surface of the digital twin of the lens. As defined in Section 3.1.8 of ISO 13666:2019(E), the optical axis of a spectacle lens is a straight line connecting the centers of curvature of the two surfaces of the lens (3.5.2). Similar to Section 3.1.8 of ISO 13666:2019(E), the optical axis of the digital twin of the spectacle lens should be defined as a straight line connecting the centers of curvature of the two surfaces of the digital twin of the spectacle lens. The permissible range for a “nearly” perpendicular incident beam is preferably 0° to 20°, more preferably 1° to 15°, more preferably 2° to 12°, and most preferably from 3° to 10°, each permissible range for a perpendicular incident beam perpendicular to a plane passing through the optical center or geometric center of the digital twin of i) the spectacle lens or ii) the spectacle lens, said plane being perpendicular to the optical axis or z-direction of the digital twin of i) the spectacle lens or ii) the spectacle lens. Accordingly, a perpendicularly incident beam preferably refers to an incident beam perpendicular to, for example, a plane passing through the optical center or geometric center of the digital twin of i) the gradient refractive index lens or ii) the gradient refractive index lens, said plane being perpendicular to the optical axis or z-direction of the digital twin of i) the gradient refractive index lens or ii) the gradient refractive index lens. The previous definitions of optical center, geometric center, and optical axis should be applied by analogy to the digital twin of the gradient refractive index lens or the gradient refractive index lens itself.

[0086] The aforementioned problems are completely solved by the computer-implemented method described above. In order to calculate the digital twin of the spectacle lens without changing the optical path length passing through it at the same or the same discrete positions, a predefined power distribution of the digital twin of the spectacle lens is considered, without needing to consider conditions such as the refractive index profile characterized by the three-dimensional Fourier transform as described in WO 2020 / 165439 A1, page 7, line 13 to page 10, line 18.

[0087] The computer-implemented method is further configured to generate manufacturing instructions for manufacturing spectacle lenses, preferably for generating additive manufacturing instructions for manufacturing spectacle lenses, and more preferably for generating printing instructions for inkjet-printed spectacle lenses. The manufacturing instructions, preferably additive manufacturing instructions, and more preferably printing instructions are each based on a digital twin of the spectacle lens. The purpose of the manufacturing instructions and preferably additive manufacturing instructions is to manufacture spectacle lenses in layers. The purpose of the printing instructions is to inkjet-print spectacle lenses in layers.

[0088] In a preferred embodiment of the invention, in a computer-implemented method configured to generate printing instructions for inkjet-printed spectacle lenses, in order to generate the printing instructions, a digital twin of the spectacle lens having a predefined power distribution is sliced ​​into a stack of multiple individual layers, each individual layer having a uniform refractive index and a spatially varying non-uniform layer thickness. The method is characterized by the following steps:

[0089] - The digital twin is sliced ​​so that the spatial variation of the layer thickness of the individual layers is achieved by spatial control of the optical path length to realize the predefined focal length distribution.

[0090] Generating print instructions includes the following steps, preferably in a given order:

[0091] a) The digital twin of the eyeglass lens is sliced ​​into a stacked body, preferably the digital twin of the eyeglass lens is sliced ​​into a stacked body and a base layer;

[0092] b) Convert each individual layer of the stacked layer, preferably each individual layer of the stacked layer and the base layer, into a spatial volume element pattern. In the spatial volume element pattern, each volume element is positioned at a discrete x, y, z position. In the spatial volume element pattern, each volume element represents an ink droplet. In the spatial volume element pattern, the volume element serves as a virtual placeholder for the ink droplet. In the spatial volume element pattern, when printing eyeglasses using layered inkjet printing, each volume element positioned at a discrete x, y, z position serves as a virtual placeholder for each ink droplet to be positioned at the corresponding discrete x, y, z position on the eyeglasses. Each volume element is a computer-readable representation of the digital positioning of the ink droplet at the discrete x, y, z position in the spatial volume element pattern of the digital twin of the eyeglasses. Preferably, in order to convert the digital twin into the spatial volume element pattern, the printing resolution of the inkjet printer, preferably the printing resolution of the inkjet printhead of the inkjet printer, is considered.

[0093] c) The spatial volume element pattern is converted into printing instructions. When executed by an inkjet printer, the printing instructions cause the inkjet printer to print the eyeglass lens layer by layer using inkjet printing. Preferably, the spatial volume element pattern is converted into printing instructions. When executed by an inkjet printer, the printing instructions cause the inkjet printhead of the inkjet printer to release jets at corresponding discrete x, y, z positions in the layer to form ink droplets. Preferably, the printing instructions are computer-readable data, including an image stack (one image for each layer to be inkjet printed, such as a TIFF image) and a text file in, for example, .xml format. The text file preferably includes instructions for the inkjet printing order of the image stack corresponding to the layer stack. The text file preferably further includes process parameters required for layer-by-layer inkjet printing of the eyeglass lens, such as the power of LED-cured ink droplets (the ink droplets preferably include a UV-curable fluid) and the elevation of the inkjet printhead at the z position after inkjet printing of a layer to avoid collision between the inkjet printhead and the inkjet-printed layer.

[0094] A "print instruction" is computer-readable data that, when executed by an inkjet printer, causes the inkjet printer to print eyeglass lenses.

[0095] The print instruction is computer-readable data based on a sliced ​​digital twin of the spectacle lens. The print instruction is in the form of computer-readable data and is based on a sliced ​​digital twin of the spectacle lens; when executed by an inkjet printer, the print instruction causes the inkjet printer to inkjet print the spectacle lens.

[0096] The print instructions, as computer-readable data or in the form of computer-readable data, are preferably (i) stored on a computer-readable storage medium or (ii) transmitted via a data signal. The computer-readable storage medium may be a non-transitory tangible computer-readable storage medium.

[0097] The printing instructions are configured, when executed by the inkjet printer, to cause the inkjet printer to inkjet print eyeglass lenses. The printing instructions are computer-readable data configured, when executed by the inkjet printer, to cause the inkjet printer to inkjet print eyeglass lenses in layers, wherein, starting from a base layer directly adjacent to an optionally removable substrate, ink droplets are positioned at discrete x, y, z positions in each individual layer. The discrete x, y, z positions of the ink droplets positioned in the layers to inkjet print the eyeglass lenses correspond to the discrete x, y, z positions of volume elements in a spatial volume element pattern of a digital twin of the eyeglass lenses to be inkjet printed.

[0098] The printing instructions are intended for inkjet printing of eyeglass lenses. The printing instructions are applicable to the use of inkjet printing of eyeglass lenses. The printing instructions are computer-readable data, (i) used or (ii) configured for layered inkjet printing of eyeglass lenses using the data. Inkjet printing of the eyeglass lens begins by directly inkjet printing a base layer in or on an optionally removable substrate, continuing layered inkjet printing until the final inkjet-printed eyeglass lens is completed. The positioning of each ink droplet at a discrete x, y, z position in each layer is specified by the corresponding discrete x, y, z position of a volume element in a spatial volume element pattern of a digital twin of the eyeglass lens to be inkjet printed.

[0099] Preferably, when the printing instruction is executed by the inkjet printer, the printing instruction causes the printhead of the inkjet printer to release jets at corresponding discrete x, y, z positions in the layer to form ink droplets.

[0100] The base layer is inkjet printed on or therein, or the base layer and its directly adjacent substrate may be removable from or remain on the inkjet-printed spectacle lens. Preferably, the spectacle lens and the substrate are removable from each other.

[0101] Preferably, the printing instructions are in a computer-readable data format, which includes an image stack (one image for each individual layer to be inkjet printed, such as a TIFF image) and a text file in a format such as .xml, as previously described.

[0102] When printing eyeglass lenses using layered inkjet printing, when an ink droplet is positioned at a discrete x, y, z position in the spatial volume element pattern of the sliced ​​digital twin of the eyeglass lens according to a volume element, the discrete x, y, z position of the volume element in the spatial volume element pattern of the sliced ​​digital twin of the eyeglass lens "corresponds" to the discrete x, y, z position of the ink droplet. The ink droplet is positioned at that discrete position in the spatial volume element pattern intended to achieve its discrete positioning. Similarly, when printing eyeglass lenses using layered inkjet printing, when an ink droplet is positioned at the discrete x, y, z position in the spatial volume element pattern of the digital twin where the volume element has been used as a virtual representation or virtual placeholder, the discrete x, y, z position of the ink droplet "corresponds" to the discrete x, y, z position of the volume element in the spatial volume element pattern of the sliced ​​digital twin of the eyeglass lens.

[0103] "Discrete" should mean an integer multiple of the minimum nozzle distance of an inkjet printhead or an arrangement of two or more inkjet printheads.

[0104] "Slicing" is the process of converting the digital twin of an eyeglass lens into a stack of layers. Slicing is the calculation of the stack of layers of the digital twin of the eyeglass lens, preferably including the stack of layers and an additional base layer. Preferably, slicing is the conversion of the digital twin, digitally represented by numerical data (as defined above), into a stack of layers. Less computational power is required when using numerical data as the basis for slicing compared to using the previously defined analytical description or model. In other words, slicing the numerical data is computationally less expensive. Slicing converts the digital twin into a stack of layers to predefine the layer thickness at each discrete x, y, z position for each layer. Slicing converts the digital twin into a stack of layers comprising multiple individual layers, each individual layer (preferably separate from the base layer) having a uniform refractive index and a spatially varying non-uniform layer thickness. The non-uniform layer thickness is digitally predetermined at the center of each individual layer, at the edges of each individual layer, and between each discrete x, y, z position of each individual layer. Preferably, when projected onto a plane defined by the x and y directions, preferably in a plan view, each individual layer in the stack has the same spatial extension.

[0105] The digital twin can be sliced ​​such that the total number of individual layers in the stack is divisible by the minimum number of individual layers having different uniform refractive indices. In the case where the stack comprises multiple individual layers each having a first uniform refractive index and multiple individual layers each having a second uniform refractive index, the minimum number of individual layers having different uniform refractive indices is two, and the total number of individual layers in the stack is divisible by two. The multiple individual layers each having a first uniform refractive index and the multiple individual layers each having a second uniform refractive index can be arranged in the stack in the following manner.

[0106] - Alternatingly, that is, a single layer with a first uniform refractive index is followed by a single layer with a second uniform refractive index, or

[0107] - Arrange in any order.

[0108] In the case where the stacked body comprises a plurality of individual layers each having a first uniform refractive index, a plurality of individual layers each having a second uniform refractive index, and a plurality of individual layers each having a third uniform refractive index, the minimum number of individual layers having different uniform refractive indices is three, and the total number of individual layers in the stacked body is divisible by three. The plurality of individual layers each having a first uniform refractive index, the plurality of individual layers each having a second uniform refractive index, and the plurality of individual layers each having a third uniform refractive index can be arranged in the stacked body as follows:

[0109] - Including repeating stacks, these repeating stacks comprising a single layer having a first uniform refractive index, a single layer having a second uniform refractive index, and a single layer having a third uniform refractive index, or

[0110] -Including repeating stacks, these repeating stacks comprising a single layer having a first uniform refractive index, a single layer having a third uniform refractive index, and a single layer having a second uniform refractive index, or

[0111] - Including repeating stacks, these repeating stacks comprising a single layer having a second uniform refractive index, a single layer having a first uniform refractive index, and a single layer having a third uniform refractive index, or

[0112] - Including repeating stacks, these repeating stacks comprising a single layer having a second uniform refractive index, a single layer having a third uniform refractive index, and a single layer having a first uniform refractive index, or

[0113] -Including repeating stacks, these repeating stacks comprising a single layer having a third uniform refractive index, a single layer having a first uniform refractive index, and a single layer having a second uniform refractive index, or

[0114] -Including repeating stacks, which include a single layer having a third uniform refractive index, a single layer having a second uniform refractive index, and a single layer having a first uniform refractive index, or

[0115] - Arrange in any order.

[0116] When the stacked layer comprises multiple individual layers each having a first uniform refractive index, multiple individual layers each having a second uniform refractive index, multiple individual layers each having a third uniform refractive index, and multiple individual layers each having a fourth uniform refractive index, the total number of individual layers in the stacked layer is divisible by four. When the stacked layer comprises multiple individual layers each having a uniform refractive index, wherein the minimum number of individual layers with different refractive indices is greater than four, the total number of individual layers in the stacked layer is divisible by the corresponding minimum number of different refractive indices as described above. The foregoing preferably applies to arrangements where the minimum number of individual layers with different refractive indices is four or more. Preferably, for the digital twin (… Figure 1 The 100 in the middle is sliced ​​so that every interface of the stacked layers ( Figure 1 The form of 02 in the digital twin is derived from the front surface ( Figure 1 The lens surface of the 01 in the image is related to the rear surface of the digital twin. Figure 1 The linear combination of the lens surfaces (08) is determined. Each other interface of the stacked layers ( Figure 1The form of 03 in the middle is taken into account two separate layers that have the other interfaces in common. Figure 1 In the case of a uniform refractive index of 10, 11), the lens surface of the front surface of the digital twin is a linear combination of the lens surface of the rear surface of the digital twin. The two separate layers having the common other interface are each defined by the other interface and two different closest second interfaces. Considering the uniformly different refractive indices of the two separate layers having the common other interface means that through the closest second interface ( Figure 1 The optical path length of a single layer, as defined in (09) at each discrete x, y, z position, is equal to the optical path length through the corresponding gradient refractive index layer at the corresponding discrete x, y, z position. The gradient refractive index layer is formed by the closest second interface ( Figure 1 The gradient refractive index layer (09) is defined as a single layer having a predefined refractive index at each x, y, z position or at each discrete x, y, z position, which preferably varies between different x, y, z positions or between different discrete x, y, z positions. In other words, the refractive index of the gradient refractive index layer is non-uniform. The variation of the refractive index between different x, y, z positions or between different discrete x, y, z positions in the gradient refractive index layer is preferably continuous. The gradient refractive index layer can be considered as a gradient refractive index lens having a portion of the same predefined power distribution as a gradient refractive index lens. The stacking of gradient refractive index layers, each having a portion of the same predefined power distribution as a gradient refractive index lens, in the z-direction results in a gradient refractive index lens having a predefined power distribution.

[0117] Preferably, the digital twin is sliced ​​into three to seven, preferably four to six, individual layers defined by two closest second interfaces. Preferably, the three to seven individual layers defined by two closest second interfaces include a single layer defined by the front surface of the digital twin and the closest second interface, and a single layer defined by the rear surface of the digital twin and the closest second interface. In the respective gradient refractive index layers, a gradient refractive index is given between the uniformly different refractive indices of the two individual layers having the other common interface. Preferably, the gradient refractive index is determined between the uniform refractive indices of the two individual layers having the other common interface, thereby disregarding the uniform refractive index itself. Preferably, the gradient refractive index in the respective gradient refractive index layer is limited by a minimum effective refractive index and a maximum effective refractive index, i.e., the gradient refractive index lies between the minimum effective refractive index and the maximum effective refractive index. This limitation preferably ensures that the two individual layers are continuous individual layers over their entire spatial extension. The minimum effective refractive index of the respective gradient refractive index layer is preferably defined as:

[0118]

[0119] And the maximum effective refractive index of the corresponding gradient refractive index layer is preferably defined as:

[0120]

[0121] Wherein, n0 is one of the two individual layers ( Figure 1 The refractive index of 10 in the middle, n0+Δn is the refractive index of the other single layer of the two single layers ( Figure 1 The refractive index of 11) in the equation is α, and α>1.

[0122] More preferably, the digital twin is sliced ​​so that the base layer ( Figure 1 The form of the first interface (not shown) is determined by a linear combination of the lens surfaces of the front and rear surfaces of the digital twin. This first interface is then the first interface in every other interface. Preferably, the stacked layers are sliced ​​such that, taking into account the uniform refractive index of the two individual layers sharing a common last interface, the form of the last interface opposite the first interface is determined by a linear combination of the lens surfaces of the front and rear surfaces of the digital twin. This last interface is then the last interface in each of the other interfaces. The front surface of an eyeglass lens is defined in Section 3.2.13 of ISO 13666:2019(E), and the rear surface of an eyeglass lens is defined in Section 3.2.14 of ISO 13666:2019(E). Similar to Section 3.2.13 of ISO 13666:2019(E), the front surface of the digital twin of an eyeglass lens should be defined as the surface intended to be away from the eye assembly when the digital twin is inkjet printed as an eyeglass lens. Similar to Section 3.2.14 of ISO 13666:2019(E), the rear surface of a digital twin of an eyeglass lens should be defined as the surface intended to be closer to the eye when the digital twin is inkjet printed as an eyeglass lens. The lens surface of an eyeglass lens is defined in Section 3.4 of ISO 13666:2019(E). The lens surface of a digital twin of an eyeglass lens should be defined as in or similarly according to Section 3.4 of ISO 13666:2019(E). The form of the interface is the morphology of the interface. As previously stated, the form of the interface is determined by: (i) a linear combination of the lens surface of the front surface of the digital twin and the rear surface of the digital twin, or (ii) a linear combination of the lens surface of the front surface of the digital twin and the lens surface of the rear surface of the digital twin, taking into account the uniform refractive index of the individual layers separated by the interface.

[0123] Optionally,

[0124] - A separate layer defined by the second interface and the nearest other interface, or

[0125] - Multiple separate layers defined by each of the second interface and the nearest other interface, or

[0126] -Each individual layer is defined by the second interface and the nearest other interfaces.

[0127] Sliced, making its internal interface ( Figure 1 Each internal form of (04, 05) is a linear combination of the form of the second interface and the form of the other interfaces. The internal interface is an interface within a separate layer defined by the second interface and the other interfaces. Preferably, each separate layer defined by the second interface and the nearest other interface is sliced ​​such that each internal form of its internal interface is a linear combination of the form of the second interface and the form of the other interfaces.

[0128] Preferably, each individual layer defined by the second interface and the nearest other interface is sliced ​​such that the total number of individual layers defined by a) the nearest internal interface, b) the second interface and the nearest internal interface, and c) the other interface and the nearest internal interface is generated by dividing the maximum layer thickness of the individual layer defined by the second interface and the nearest other interface by the maximum layer thickness of the individual layer defined by a), b), or c) (i.e., by the maximum layer thickness of the inkjet printable individual layer).

[0129] In addition, preferably,

[0130] -A separate layer defined by the back surface of the digital twin and the nearest other interfaces, and

[0131] - A separate layer defined by the front surface of the digital twin and the nearest other interfaces.

[0132] Sliced ​​so that, relative to the rear surface, its internal interface ( Figure 1 The internal form of 04, 05) is a linear combination of the lens surface of the rear surface and the form of the corresponding nearest other interface, and relative to the front surface, its internal interface ( Figure 1The internal form of 04, 05) is a linear combination of the lens surface of the front surface and the form of the corresponding nearest other interface. Preferably, the individual layer defined by the rear surface and the corresponding nearest other interface is sliced ​​such that the total number of individual layers defined by d) the nearest internal interface, e) the rear surface and the nearest internal interface, and f) the other interface and the nearest internal interface is obtained by dividing the maximum layer thickness of the individual layer defined by the rear surface and the corresponding nearest other interface by the maximum layer thickness of the individual layer defined by d), e), or f). Similarly, preferably, the individual layer defined by the front surface and the corresponding nearest other interface is sliced ​​such that the total number of individual layers defined by g) the front surface and the nearest internal interface, h) the nearest internal interface, and i) the other interface and the nearest internal interface is obtained by dividing the maximum layer thickness of the individual layer defined by the front surface and the other interface by the maximum layer thickness of the individual layer defined by g), h), or i).

[0133] Particularly preferred is to slice the digital twin of the eyeglasses lens so that in the first step, each interface ( Figure 1 The form of 02 in the digital twin is derived from the front surface ( Figure 1 The lens surface of the 01 in the image is related to the rear surface of the digital twin. Figure 1 The linear combination of the lens surface (08) in the middle is determined. In the second step, each individual layer (by a) of the resulting first stacked body has two closest interfaces (individual layer = Figure 1 The separate layer defined by the front surface and the nearest interface in (b) or (c) the rear surface and the nearest interface in (09) is sliced ​​to include the first internal interface. Figure 1 03 in the middle). Taking into account the first part layer (e.g., Figure 1 The uniform refractive index of 10) and the second partial layer (e.g., Figure 1In the case of a uniform refractive index (11) of the digital twin, the form of the first internal interface is determined by a linear combination of the lens surface of the front surface of the digital twin and the lens surface of the rear surface of the digital twin, wherein the first partial layer and the second partial layer share the first internal interface. Preferably, each individual layer defined by a) two closest interfaces, b) the front surface and the closest interface, or c) the rear surface and the closest interface is sliced ​​into the first internal interface comprising dividing each individual layer into the first partial layer and the second partial layer, such that the optical path length at each discrete x, y, z position of the individual layer defined by a), b), or c) is equal to the optical path length through the corresponding gradient refractive index layer. In the gradient refractive index layer, the gradient refractive index lies between the uniform refractive index of the first partial layer and the uniform refractive index of the second partial layer. Preferably, the gradient refractive index is determined between the uniform refractive indices of the two partial layers, which share the first internal interface but do not have the corresponding uniform refractive index itself. Preferably, the gradient refractive index in the corresponding gradient refractive index layer is limited by a minimum effective refractive index and a maximum effective refractive index, that is, the gradient refractive index lies between the minimum effective refractive index and the maximum effective refractive index, as explained previously. Each individual layer in the first layer stack is sliced ​​into a second layer stack, each including a first internal interface, to generate the digital twin. In a third optional step,

[0134] - A separate layer defined by the interface and the nearest first internal interface, or

[0135] - Multiple separate layers defined by each free interface and the nearest first internal interface, or

[0136] -Each individual layer is defined by the interface and the nearest first inner interface.

[0137] The digital twin is sliced ​​into one or more second internal interfaces, thus creating a third layer of stacked structure. The form of the second internal interface is determined by a linear combination of the form of the first internal interface and the form of the second internal interface.

[0138] In addition, preferably,

[0139] -A separate layer defined by the front surface of the digital twin and the nearest first internal interface, and

[0140] - A separate layer defined by the rear surface of the digital twin and the nearest first internal interface.

[0141] The surface is sliced ​​to include one or more second internal interfaces. Regarding the front surface, the form of the second internal interface is determined by a linear combination of the forms of the lens surface of the front surface and the corresponding nearest first internal interface. Regarding the rear surface, the form of the second internal interface is determined by a linear combination of the forms of the lens surface of the rear surface and the corresponding nearest first internal interface.

[0142] Preferably, each individual layer defined by a) the interface and the nearest first internal interface, b) the front surface and the nearest first internal interface, or c) the rear surface and the nearest first internal interface is sliced, such that the total number of individual layers defined by d) the nearest second internal interface, e) the interface and the nearest second internal interface, f) the first internal interface and the nearest second internal interface, g) the front surface and the nearest second internal interface, or h) the rear surface and the nearest second internal interface is generated in the following manner:

[0143] - For each individual layer defined by a), the maximum layer thickness of said individual layer as defined by a) is divided by the maximum layer thickness of the individual layers as defined by d), e), and f). The individual layers defined by d), e), and f) each refer to the corresponding individual layer within each individual layer defined by a).

[0144] - For a single layer defined by b), the maximum layer thickness of said single layer defined by b) is divided by the maximum layer thickness of the single layers defined by d), g), and e). Each of the single layers defined by d), g), and e) refers to the corresponding single layer within the single layer defined by b).

[0145] - For a single layer defined by c), the maximum layer thickness of the single layer defined by c) is divided by the maximum layer thickness of the single layers defined by h), d), and e). The single layers defined by h), d), and e) each refer to the corresponding single layer within the single layer defined by c).

[0146] Preferably, the total number of individual layers in the third stack depends on the maximum layer thickness that can be inkjet printed.

[0147] As previously mentioned, in the third optional step, prior to slicing the second layer of the stack...

[0148] - A separate layer defined by the interface and the nearest first internal interface, or

[0149] - Multiple separate layers defined by each free interface and the nearest first internal interface, or

[0150] -Each individual layer is defined by the interface and the nearest first inner interface.

[0151] Instead of the aforementioned third optional step, each of the second layer stacks can be sliced ​​to include only one second internal interface. Preferably, in this case, the form of the second internal interface is determined by a linear combination of the form of the interface and the form of the nearest first internal interface, which define a corresponding separate layer, thereby taking into account the refractive index of the first portion layer and the refractive index of the second portion layer, which share the second internal interface. Taking into account the refractive indices of the first and second portion layers with the common second internal interface, preferably, the optical path length through the separate layer defined by the interface and the nearest first internal interface is equal to the optical path length through the corresponding gradient refractive index layer at each discrete x, y, z position. In the corresponding gradient refractive index layer, the gradient refractive index is determined between the refractive index of the first portion layer and the refractive index of the second portion layer, thereby disregarding the refractive index itself. Preferably, in the gradient refractive index layer, the gradient refractive index is determined between the minimum effective refractive index and the maximum effective refractive index.

[0152] Alternatively,

[0153] -A separate layer defined by the front surface of the digital twin and the closest first internal interface, and

[0154] - The individual layers defined by the back surface of the digital twin and the nearest first internal interface are each sliced ​​into only one second internal interface, similar to what was previously described.

[0155] Preferably, only one single layer defined by the interface and the nearest first internal interface, or by the front surface and the nearest first internal interface, or by the rear surface and the nearest first internal interface, is sliced ​​to include only one second internal interface as described above.

[0156] The single layer and the other single layers in the second layer stack are each sliced ​​as previously described in optional step three, preferably converted into inkjet printable single layers.

[0157] Optionally,

[0158] - Multiple separate layers defined by the interface and the nearest first inner interface, or

[0159] - A separate layer defined by the interface and the nearest first internal interface, and a separate layer defined by the front surface and the nearest first internal interface, or

[0160] - A separate layer defined by the interface and the nearest first internal interface, and a separate layer defined by the rear surface and the nearest first internal interface, or

[0161] - A separate layer defined by the interface and the nearest first internal interface, and a separate layer defined by the front surface and the nearest first internal interface, and a separate layer defined by the rear surface and the nearest first internal interface.

[0162] Each is sliced ​​into a specific second internal interface, as described above.

[0163] The individual layers described above and the other individual layers in the second layer stack are each sliced ​​as previously described in optional step three.

[0164] In order to generate printing instructions, step b) is preferably performed after slicing (i.e., when step a) is completed, that is, converting each individual layer of the stacked body into a spatial volume element pattern.

[0165] Preferably, to slice the digital twin of the eyeglass lens into a stack of layers, a maximum layer thickness for each individual layer of the stack is preset. The maximum layer thickness is preferably determined by the maximum inkjet printable layer thickness of one or more ink droplets, taking into account the print resolution of the inkjet printer. For example, a 30 pL ink droplet volume after curing and a droplet distance of 25 μm produce a layer thickness of 48 μm. More preferably, the determination of the maximum layer thickness takes into account the positioning of adjacent ink droplets within the same individual layer, within a minimum distance from the individual ink droplet. This positioning of adjacent ink droplets within the minimum distance preferably prevents the individual ink droplet from spreading completely. Preferably, the minimum distance is preset by the print resolution of the inkjet printer, preferably by the print resolution of the inkjet printhead of the inkjet printer. Preferably, for slicing, a minimum layer thickness for each individual layer in the stack is preset, the minimum layer thickness being preferably determined by the minimum layer thickness that still produces consecutive individual layers. More preferably, the determination of the minimum layer thickness takes into account the maximum distance between two individual ink droplets inkjet-printed in the same layer. The maximum distance between the two individual ink droplets is the maximum distance at which the two individual ink droplets are allowed to coalesce. Due to this coalescence, continuous individual layers can be printed by inkjet printing.

[0166] Preferably, slicing ensures knowledge of the layer thickness at each discrete x, y, z position of each individual layer in the stacked layers. In other words, slicing determines the spatial variation of the layer thickness of each individual layer with non-uniform layer thickness. The positioning of ink droplets within a minimum distance or within a maximum distance, preferably according to the print resolution of the inkjet printer, and more preferably according to the print resolution of the inkjet printhead of the inkjet printer, is a supporting tool for slicing the digital twin of the eyeglass lens into a stacked layer. Preferably, the eyeglass lens is printed using the inkjet printer. Alternatively or additionally, knowledge of the thickness of the digital twin (i.e., the center thickness, the edge thickness, and the thickness at each discrete x, y position in between) supports slicing the digital twin of the eyeglass lens into a stacked layer. Similar to the definition given in Section 3.2.47 of ISO 13666:2019(E), the center thickness of the digital twin should mean the thickness of the digital twin of the eyeglass lens at its reference point, defined normal to the front surface of the digital twin. Similar to the definition given in Section 3.2.19 of ISO 13666:2019(E), the reference point of the digital twin should correspond to a point on the front surface of the finished inkjet-printed spectacle lens where a specific portion verifies the applicable power. Similar to the definition given in Section 3.2.48 of ISO 13666:2019(E), the edge thickness should refer to the thickness at a point on the edge of the digital twin of the spectacle lens. The layer thickness at each corresponding x, y, z position of a single inkjet-printed layer depends on the density of ink droplets in the single layer: the more ink droplets positioned within the area element, the higher the layer thickness in the area element. The area element is preferably preset to include more than ten discrete positions for ink droplets within a single layer, i.e., more than ten (i) positions for positioning ink droplets or (ii) positions where ink droplets can be positioned but are not. Preferably, when projected onto a plane defined by the x and y directions, the area element can have, for example, 100 areas for discrete locations of ink droplets, ten in the x direction and ten in the y direction. In other words, in a single layer of inkjet printing, the layer thickness within the area element is defined as the number of ink droplets multiplied by the droplet volume divided by the area element.

[0167]

[0168] Preferably, in accordance with the foregoing limitations regarding minimum and maximum layer thicknesses, the digital twin is sliced ​​into a stack comprising a minimum number of individual layers. This minimum number may depend on the minimum number of individual layers having different refractive indices. This applies when the digital twin should be sliced ​​into a stack comprising the following:

[0169] (i) A stack of one or more alternating individual layers with different refractive indices, wherein one of the alternating individual layers has a first uniform refractive index and another of the alternating individual layers has a second uniform refractive index, or

[0170] (ii) A stack of one or more non-alternating individual layers with different refractive indices, wherein one has a first uniform refractive index and one has a second uniform refractive index.

[0171] The minimum number of individual layers in the stacked body can be an integer multiple of two.

[0172] In the case where the digital twin should be sliced ​​into a stack of layers comprising the following items

[0173] (i) A stack of one or more individual layers with different refractive indices, wherein the three individual layers are repeated in the same order, wherein the first individual layer has a first uniform refractive index, the second individual layer has a second uniform refractive index, and the third individual layer has a third uniform refractive index, or

[0174] (ii) A stack of one or more individual layers having different refractive indices, wherein the three individual layers are not repeated in any order, one of which has a first uniform refractive index, one of which has a second uniform refractive index, and one of which has a third uniform refractive index.

[0175] The minimum number of individual layers in the stacked body can be an integer multiple of three.

[0176] In the case where the digital twin should be sliced ​​into a stack of layers comprising the following items

[0177] (i) A stack of one or more individual layers with different refractive indices, the four individual layers repeating one another in the same order, wherein the first individual layer has a first uniform refractive index, the second individual layer has a second uniform refractive index, the third individual layer has a third uniform refractive index, and the fourth individual layer has a fourth uniform refractive index, or

[0178] (ii) A stack of one or more individual layers having different refractive indices, wherein the four individual layers are not repeated in the same order, one of which has a first uniform refractive index, one of which has a second uniform refractive index, one of which has a third uniform refractive index, and one of which has a fourth uniform refractive index.

[0179] The minimum number of individual layers in the stacked body can be an integer multiple of four.

[0180] In cases where the digital twin is to be sliced ​​into layers comprising stacks of more than four separate layers with different refractive indices, the previously described terms are preferably similarly applicable.

[0181] "Inkjet printhead" should refer to a single inkjet printhead or an arrangement of two or more inkjet printheads.

[0182] A “spatial volume element pattern” is a digital representation or virtual description of the volume elements of each layer of a sliced ​​digital twin of an eyeglass lens. Each layer preferably includes each individual layer of a stacked body and a base layer. The digital representation or virtual description is computer-readable data or is in the form of computer-readable data. The computer-readable data may (i) be stored on a computer-readable storage medium or (ii) transmitted via a data signal. The computer-readable storage medium may be a non-transitory tangible computer-readable storage medium. In the spatial volume element pattern, each volume element is spatially located at a discrete x, y, z position. In the spatial volume element pattern, each volume element at a discrete x, y, z position represents an ink droplet to be positioned at the corresponding discrete x, y, z position when the eyeglass lens is inkjet printed, preferably when the eyeglass lens is layered inkjet printed.

[0183] The aforementioned problems are completely solved by the computer-implemented method described above. In order to slice the digital twin of the spectacle lens without changing the optical path length passing through it at the same position, the predefined power distribution of the digital twin is taken into account, without needing to consider conditions such as the refractive index profile characterized by the three-dimensional Fourier transform as described on page 7, line 13 to page 10, line 18 of WO 2020 / 165439A1.

[0184] In a preferred embodiment of the invention, the computer-implemented method is characterized in that the stacked body includes

[0185] - A first plurality of individual layers, each having a spatially varying non-uniform layer thickness and a first uniform refractive index.

[0186] - A second plurality of individual layers, each having a spatially varying non-uniform layer thickness and a second uniform refractive index, the second uniform refractive index being different from the first uniform refractive index.

[0187] The computer-implemented method is configured to calculate a digital twin of an eyeglass lens for use in the manufacture of the lens. The method includes the following steps:

[0188] - In the stacked structure of the digital twin, a first plurality of individual layers and a second plurality of individual layers are provided or arranged, each of the first plurality of individual layers having a spatially varying non-uniform layer thickness and a first uniform refractive index, and each of the second plurality of individual layers having a spatially varying non-uniform layer thickness and a second uniform refractive index, wherein the second uniform refractive index is different from the first uniform refractive index.

[0189] The arrangement or configuration of the first plurality of individual layers and the second plurality of individual layers in the layer stack such that, at each location or at each discrete x, y, z position, the optical path length through the layer stack is equal to the optical path length through the lens or through the digital twin of the lens at the corresponding location or at the corresponding discrete x, y, z position. The arrangement or configuration of the first plurality of individual layers and the second plurality of individual layers in the layer stack such that, at each location or at each discrete x, y, z position, the optical path length through the layer stack is equal to the optical path length through the gradient refractive index lens or through the digital twin of the gradient refractive index lens. In the gradient refractive index lens or in the digital twin of the gradient refractive index lens, the refractive index gradient is between two...

[0190] - A first refractive index that is the same as the first uniform refractive index of each of the first plurality of individual layers, and

[0191] - A second refractive index that is the same as the second uniform refractive index of each of the second plurality of individual layers.

[0192] Preferably, as previously explained, the refractive index gradient lies between the first refractive index and the second refractive index, but does not have the first and second refractive indices themselves.

[0193] Preferably, the digital twin of the gradient refractive index spectacle lens is used as the basis for slicing, and preferably, numerical data describing or representing the gradient refractive index spectacle lens is used to slice the digital twin.

[0194] Arranging the first plurality of individual layers and the second plurality of individual layers in the layer stack to achieve an equivalent optical path length at each corresponding position or each corresponding discrete x,y,z position in the layer stack and a) in the gradient refractive index lens or b) in the digital twin of the gradient refractive index lens allows for layered manufacturing of the lens. As previously described, by manufacturing the gradient refractive index lens according to the arrangement of the first plurality of individual layers and the second plurality of individual layers, the refractive index distribution n(x,y,z) of the digital twin of the gradient refractive index lens is transformed into a physical entity. Preferably, the digital twin is transformed into a physical entity by manufacturing the gradient refractive index lens using an additive manufacturing method. More preferably, the digital twin is transformed into a physical entity by layered inkjet printing the gradient refractive index lens according to the predetermined arrangement of individual layers with different uniform refractive indices. A decisive advantage of the arrangement of the first plurality of individual layers and the second plurality of individual layers is that the refractive index distribution n(x,y,z) of the digital twin of the gradient refractive index lens is manufacturable without applying material according to the refractive index distribution n(x,y,z) at each location or at each discrete x,y,z location. A particularly decisive advantage of this arrangement is that the refractive index distribution n(x,y,z) of the digital twin of the gradient refractive index lens is inkjet printable without inkjet printing according to the refractive index distribution n(x,y,z) at each discrete x,y,z location.

[0195] Optionally or additionally, the modulation transfer function of the stacked body is substantially the same as the modulation transfer function of the corresponding digital twin of the gradient-index spectacle. The modulation transfer function of the stacked body is substantially the same as the modulation transfer function of the corresponding digital twin of the gradient-index spectacle when a) the two modulation transfer functions are the same or b) the deviation between the two modulation transfer functions is preferably less than 7%, preferably in the range of 0.5% to 5%, more preferably in the range of 1% to 4%, and most preferably in the range of 1.2% to 3%.

[0196] Preferably, the first plurality of individual layers and the second plurality of individual layers are arranged in the layer stack such that the modulation transfer function of the layer stack is substantially the same as the modulation transfer function of the corresponding digital twin of the gradient refractive index spectacle. Preferably, the first plurality of individual layers and the second plurality of individual layers are arranged in the layer stack such that the modulation transfer function as the modulation transfer function of the corresponding digital twin of the gradient refractive index spectacle is only diffraction-limited. In other words, the first plurality of individual layers and the second plurality of individual layers are arranged in the layer stack to reproduce the diffraction-limited modulation transfer function of the corresponding digital twin of the gradient refractive index spectacle.

[0197] Arranging the first plurality of individual layers and the second plurality of individual layers in the stack such that the modulation transfer function of the stack is substantially the same as the modulation transfer function of the corresponding digital twin of the gradient refractive index eyeglasses preferably solves the challenges associated with inkjet printing gradient refractive index eyeglasses.

[0198] Preferably, the difference between the first uniform refractive index and the second uniform refractive index is selected from at least one of the following:

[0199] - A refractive index difference of at least 0.05;

[0200] - A refractive index difference of at least 0.1;

[0201] - A refractive index difference of at least 0.15;

[0202] - A refractive index difference of at least 0.2;

[0203] - A refractive index difference of at least 0.21.

[0204] WO 2020 / 165439 A1 discloses, on page 2, line 30 to page 3, line 6, that the maximum refractive index difference in the direction parallel to the principal axis is at most 0.2, at most 0.1, at most 0.05, and has further intervals up to a maximum refractive index difference of at most 0.0001. WO 2020 / 165439 A1 further discloses, on page 2, line 30 to page 3, line 6, the pursuit of a minimum refractive index difference. In contrast, the present invention does not aim to minimize the refractive index difference at the interface between a first individual layer having a first uniform refractive index and a second individual layer having a second refractive index, but rather uses available materials for manufacturing said individual layers, particularly available fluids for inkjet printing said individual layers, to ensure proper adhesion at the interface between two individual layers with different refractive indices.

[0205] In this invention, preferably, the refractive index distribution n(x,y,z) of the digital twin of a pre-defined gradient refractive index spectacle lens is used. As previously described, the digital twin is sliced ​​such that the optical path length through its stacked layers is equal at each position or at each discrete position to the optical path length at the corresponding position or at the corresponding discrete position of the digital twin. In the digital twin, a first plurality of individual layers (each having a spatially varying non-uniform layer thickness and a first uniform refractive index) and a second plurality of individual layers (each having a spatially varying non-uniform layer thickness and a second uniform refractive index) are arranged such that the effective refractive index at each position or at each discrete x,y,z position satisfies the pre-defined refractive index distribution n(x,y,z) of the digital twin. The effective refractive index depends on the ratio of the first uniform refractive index, the second uniform refractive index, and the non-uniform layer thickness, as illustrated below with respect to a two-layer stack. The optical path length of a vertically incident beam passing through a two-layer stack (the two-layer stack consists of: a) a first single layer having a spatially varying non-uniform layer thickness d1 and a first uniform refractive index n1, and b) a second single layer having a spatially varying non-uniform layer thickness d2 and a second uniform refractive index n2, wherein the vertically incident beam enters the two-layer stack at a point on the surface of the first single layer and exits the two-layer stack at a vertical point on the surface of the second single layer) is defined as:

[0206] Optical path length = d1n1 + d2n2 = (d1 + d2)n eff , where n eff = Effective refractive index.

[0207] In d1=α1d min , α1≥1, d min =Minimum layer thickness; d2 = α2d min α2≥1; n1=n0, n0=minimum

[0208] Refractive index; when n2 = n0 + Δn, Δn = refractive index difference, the effective refractive index is determined as:

[0209]

[0210] This indicates that the effective refractive index depends on the ratio of the first uniform refractive index, the second uniform refractive index, and the thickness of the non-uniform layer.

[0211] The maximum layer thickness is defined as αd. min In this case, the minimum effective refractive index is determined as:

[0212]

[0213] And the maximum effective refractive index was determined to be:

[0214]

[0215] This indicates that the effective refractive index range is smaller than the range including the first uniform refractive index and the second uniform refractive index.

[0216] In a preferred embodiment of the invention, the computer-implemented method is characterized in that the stacked body includes

[0217] - A first plurality of individual layers, each having a spatially varying non-uniform layer thickness and a first uniform refractive index.

[0218] - A second plurality of individual layers, each having a spatially varying non-uniform layer thickness and a second uniform refractive index, the second uniform refractive index being different from the first uniform refractive index.

[0219] - A third plurality of individual layers, each having a spatially varying non-uniform layer thickness and a third uniform refractive index, the third uniform refractive index being different from the first uniform refractive index and different from the second uniform refractive index.

[0220] The computer-implemented method is configured to calculate a digital twin of an eyeglass lens for use in the manufacture of the lens. The method includes the following steps:

[0221] - In the stacked structure of the digital twin, a first plurality of individual layers, a second plurality of individual layers, and a third plurality of individual layers are provided or arranged, each of the first plurality of individual layers having a spatially varying non-uniform layer thickness and a first uniform refractive index, each of the second plurality of individual layers having a spatially varying non-uniform layer thickness and a second uniform refractive index, the second uniform refractive index being different from the first uniform refractive index, and each of the third plurality of individual layers having a spatially varying non-uniform layer thickness and a third uniform refractive index, the third uniform refractive index being different from both the first and second uniform refractive indices.

[0222] The arrangement or configuration of the first, second, and third individual layers in the layer stack is such that at each position or discrete x,y,z position in the layer stack, the optical path length through the layer stack is equal to the optical path length through the lens or through the digital twin of the lens at the corresponding position or discrete x,y,z position. The arrangement or configuration of the first, second, and third individual layers in the layer stack is such that at each position or discrete x,y,z position, the optical path length through the layer stack is equal to the optical path length through the gradient refractive index lens or through the digital twin of the gradient refractive index lens. In the gradient refractive index lens or in the digital twin of the gradient refractive index lens, the refractive index gradient is between two...

[0223] - A first refractive index that is the same as the first uniform refractive index of each of the first plurality of individual layers.

[0224] - A second refractive index that is the same as the second uniform refractive index of each of the second plurality of individual layers, and

[0225] - A third refractive index that is the same as the third uniform refractive index of each of the third plurality of individual layers.

[0226] Preferably, the refractive index gradient is between the first refractive index, the second refractive index and the third refractive index, but does not have the first refractive index, the second refractive index and the third refractive index themselves, as previously explained regarding two different refractive indices.

[0227] Preferably, the digital twin of the gradient refractive index spectacle lens is used as the basis for slicing, and preferably, numerical data describing or representing the gradient refractive index spectacle lens is used to slice the digital twin.

[0228] Arranging the first, second, and third individual layers in the layer stack allows for the layered fabrication of the gradient refractive index spectacle by achieving an equivalent optical path length at each corresponding position or at each corresponding discrete x, y, z position in the layer stack, and a) in the corresponding gradient refractive index spectacle or b) in the corresponding digital twin of the gradient refractive index spectacle. As previously described, by fabricating the gradient refractive index spectacle according to the arrangement of the first, second, and third individual layers, the refractive index distribution n(x, y, z) of the digital twin of the gradient refractive index spectacle is transformed into a physical entity. Preferably, the digital twin is transformed into a physical entity by manufacturing the gradient refractive index spectacle using an additive manufacturing method. More preferably, the digital twin is transformed into a physical entity by layering and inkjet printing the gradient refractive index spectacle according to the predetermined arrangement of individual layers with different refractive indices. A decisive advantage of the arrangement of the first plurality of individual layers, the second plurality of individual layers, and the third plurality of individual layers is that the refractive index distribution n(x,y,z) of the digital twin of the gradient refractive index lens is manufacturable without applying material according to the refractive index distribution n(x,y,z) at each location or at each discrete x,y,z location. A particularly decisive advantage of this arrangement is that the refractive index distribution n(x,y,z) of the digital twin of the gradient refractive index lens is inkjet-printable without inkjet printing according to the refractive index distribution n(x,y,z) at each discrete x,y,z location.

[0229] Optionally or additionally, the first plurality of individual layers, the second plurality of individual layers, and the third plurality of individual layers are arranged in the layer stack such that the modulation transfer function of the layer stack is substantially the same as the modulation transfer function of the corresponding digital twin of the gradient refractive index spectacle. The modulation transfer function of the layer stack is substantially the same as the modulation transfer function of the corresponding digital twin of the gradient refractive index spectacle when (i) the two modulation transfer functions are the same or (ii) the deviation between the two is preferably less than 7%, preferably in the range of 0.5% to 5%, more preferably in the range of 1% to 4%, and most preferably in the range of 1.2% to 3%.

[0230] Preferably, the first plurality of individual layers, the second plurality of individual layers, and the third plurality of individual layers are arranged in the layer stack such that the modulation transfer function, as the modulation transfer function of the corresponding digital twin of the gradient refractive index spectacle, is only diffraction-limited. Preferably, the first plurality of individual layers, the second plurality of individual layers, and the third plurality of individual layers are arranged in the layer stack to reproduce the diffraction-limited modulation transfer function of the corresponding digital twin of the gradient refractive index spectacle.

[0231] Preferably, a) the difference between the first uniform refractive index and the second uniform refractive index, or b) the difference between the first uniform refractive index and the third uniform refractive index, or c) the difference between the second uniform refractive index and the third uniform refractive index, is each selected from at least one of the following:

[0232] - A refractive index difference of at least 0.05;

[0233] - A refractive index difference of at least 0.1;

[0234] - A refractive index difference of at least 0.15;

[0235] - A refractive index difference of at least 0.2;

[0236] - A refractive index difference of at least 0.21.

[0237] In the digital twin of the gradient refractive index spectacle lens, the refractive index distribution n(x,y,z) is constrained by the first uniform refractive index, the second uniform refractive index, and the third uniform refractive index. A preset refractive index distribution n(x,y,z) is defined in the digital twin of the gradient refractive index spectacle lens. As previously described, the digital twin of the gradient refractive index spectacle lens is sliced ​​such that the optical path length through its stacked layers is equal at each position or at each discrete position to the optical path length at the corresponding position or at the corresponding discrete position of the digital twin. In the digital twin of the gradient refractive index spectacle lens, a first plurality of individual layers (each having a spatially varying non-uniform layer thickness and a first uniform refractive index), a second plurality of individual layers (each having a spatially varying non-uniform layer thickness and a second uniform refractive index), and a third plurality of individual layers (each having a spatially varying non-uniform layer thickness and a third uniform refractive index) are arranged such that the effective refractive index at each position or at each discrete x,y,z position satisfies the preset refractive index distribution n(x,y,z) of the digital twin. The effective refractive index depends on the ratio of the first uniform refractive index, the second uniform refractive index, the third uniform refractive index, and the thickness of the non-uniform layer, as illustrated below with respect to a three-layer stack. The optical path length of a vertically incident beam passing through the three-layer stack (which consists of: a) a first single layer having a spatially varying non-uniform layer thickness d1 and a first uniform refractive index n1; b) a second single layer having a spatially varying non-uniform layer thickness d2 and a second uniform refractive index n2; and c) a third single layer having a spatially varying non-uniform layer thickness d3 and a second uniform refractive index n3, wherein the vertically incident beam enters the three-layer stack at a point on the surface of the first single layer and exits the three-layer stack at a vertical point on the surface of the third single layer) is defined as:

[0238] Optical path length = d1n1 + d2n2 + d3n3 = (d1 + d2 + d3)n eff , where n eff = Effective refractive index.

[0239] In d1=α1d min , α1≥1, d min =Minimum layer thickness; d2 = α2d min α2≥1; d3=α3d min ; n1 = n0, n0 = minimum refractive index; n2 = n0 + βΔn, 0 < β < 1, Δn = refractive index difference; in the case of n3 = n0 + Δn, the effective refractive index is determined as:

[0240]

[0241] This indicates that the effective refractive index depends on the ratio of the first uniform refractive index, the second uniform refractive index, the third uniform refractive index, and the thickness of the non-uniform layer.

[0242] In a preferred embodiment of the present invention, the computer-implemented method includes at least one of the following steps:

[0243] - Calculate the transition region between a first single layer having a first uniform refractive index and a second single layer having a second uniform refractive index, the transition region having a refractive index gradient.

[0244] - Calculate the transition region between a second single layer having a second uniform refractive index and a first single layer having a first uniform refractive index, the transition region having a refractive index gradient.

[0245] The computer-implemented method is configured to calculate a digital twin of an eyeglass lens for use in the manufacture of the lens, preferably after a first plurality of individual layers and a second plurality of individual layers have been arranged in a layer stack. The method includes the following steps:

[0246] - Calculate the transition zone between individual layers with different refractive indices.

[0247] Preferably, the digital twin of the gradient refractive index spectacle lens is sliced ​​into a stack of layers such that the optical path length of a preferably perpendicular or nearly perpendicular incident beam passing through the stack is equal at each position or at each discrete position to the corresponding optical path length passing through the digital twin at the corresponding position or at the corresponding discrete position, as previously explained. The stack is preferably sliced ​​into: a) a first plurality of individual layers, each having a non-uniform layer thickness and a first uniform refractive index; and b) a second plurality of individual layers, each having a non-uniform layer thickness and a second uniform refractive index, as previously described. Depending on the arrangement of the first plurality of individual layers and the second plurality of individual layers in the stack, the arrangement enables the optical path length of the digital twin to be achieved, as previously described, through one or more interfaces between a) the first individual layer having a spatially varying non-uniform layer thickness and a first uniform refractive index and b) the second individual layer having a spatially varying non-uniform layer thickness and a second uniform refractive index.

[0248] Preferably, after the digital twin of the gradient refractive index spectacle lens is sliced ​​into a stack, and after the first plurality of individual layers and the second plurality of individual layers are arranged in the stack, a transition region is calculated between a) a first individual layer having a spatially varying non-uniform thickness and a first uniform refractive index and b) a second individual layer having a spatially varying non-uniform layer thickness and a second uniform refractive index. The transition region preferably includes the interface between the first individual layer and the second individual layer. The transition region preferably has a refractive index gradient.

[0249] Preferably, the transition region is calculated as

[0250] The transition region begins with a first single layer having a spatially varying non-uniform layer thickness and a first uniform refractive index, and ends with a second single layer having a spatially varying non-uniform layer thickness and a second uniform refractive index. The transition preferably includes an interface between the first and second single layers, and the transition preferably has a refractive index gradient from the first uniform refractive index to the second uniform refractive index.

[0251] -The transition region begins with a second single layer having a spatially varying non-uniform layer thickness and a second uniform refractive index and ends with a first single layer having a spatially varying non-uniform layer thickness and a first uniform refractive index, wherein the transition region preferably includes an interface between the second single layer and the first single layer, and the transition preferably has a refractive index gradient from the second uniform refractive index to the first uniform refractive index.

[0252] The transition zone can be calculated as either a) starting at the first individual layer and ending at the second individual layer, or b) starting at the second individual layer and ending at the first individual layer. Preferably, a) the transition zone is calculated as starting at the first individual layer and ending at the second individual layer, and b) the transition zone is calculated as starting at the second individual layer and ending at an adjacent first individual layer, which is adjacent to the second individual layer but is not the first individual layer.

[0253] Preferably, a transition region is calculated for each interface between a) a first individual layer having a spatially varying non-uniform layer thickness and a first uniform refractive index and b) a second individual layer having a spatially varying non-uniform layer thickness and a second uniform refractive index.

[0254] If the digital twin of a gradient refractive index lens is sliced ​​into at least one layer in a stacked body...

[0255] -A stack A, wherein the stack A comprises multiple individual layers, each individual layer having a spatially varying non-uniform layer thickness and a first uniform refractive index.

[0256] -A stack B adjacent to stack A, wherein stack B comprises multiple individual layers, each individual layer having a spatially varying non-uniform layer thickness and a second uniform refractive index.

[0257] -A stack C adjacent to the stack B, wherein the stack C comprises a plurality of individual layers, each having a spatially varying non-uniform layer thickness and the first uniform refractive index.

[0258] In this case, the transition region can be calculated as a) starting at stack A and ending at stack B, or b) starting at stack B and ending at stack C. Preferably, a) the transition region is calculated as starting at stack A and ending at stack B, or b) the transition region is calculated as starting at stack B and ending at stack C.

[0259] Preferably, a transition region is calculated at the interface between adjacent individual layers with different refractive indices, each of the adjacent individual layers having a uniform refractive index and a non-uniform layer thickness distributed spatially, such that in wave optics simulations of light propagating through a sliced ​​digital twin stack of layers of a gradient refractive index spectacle lens, no light is reflected at the interface. Figure 2 Preferably, in the wave optics simulation, visible light (380 nm to 780 nm) propagates through the stacked layers.

[0260] Preferably, a transition region is calculated for each interface between adjacent individual layers with different refractive indices in a sliced ​​digital twin stack of a gradient refractive index spectacle lens, each of the adjacent individual layers having a uniform refractive index and a non-uniform layer thickness distributed spatially. Preferably, each transition region is calculated to obtain a wave optics simulation of the stack with no light reflection at each interface.

[0261] Preferably, a transition region is calculated for each interface between adjacent individual layers having different refractive indices, each of which has a uniform refractive index and a spatially distributed non-uniform layer thickness, independent of the interfaces in the sliced ​​digital twin stack of the gradient refractive index spectacle lens.

[0262] -a) The interface between a single layer L included in the stack and b) a single layer 1 not included in the stack, the stack comprising a plurality of single layers, each having a spatially distributed non-uniform layer thickness and the same uniform refractive index, the single layer 1 being adjacent to the single layer L in the sliced ​​digital twin of the stack.

[0263] -a) The interface between individual layer 2 and b) individual layer 3, wherein the individual layer 3 has a uniform refractive index that is different from that of the individual layer 2;

[0264] -a) the interface between a single layer M included in a stack N and b) an adjacent single layer O included in a stack P, wherein the stack N comprises a plurality of single layers, each having a spatially distributed non-uniform layer thickness and the same uniform refractive index, and the stack P comprises a plurality of single layers, each having a spatially distributed non-uniform layer thickness and the same uniform refractive index, and the adjacent single layer O has a uniform refractive index different from that of the single layer M.

[0265] In a sliced ​​digital twin of a gradient refractive index spectacle lens, a) a plurality of first individual layers, each having a spatially distributed non-uniform layer thickness and a first uniform refractive index, and b) a plurality of second individual layers, each having a spatially distributed non-uniform layer thickness and a second uniform refractive index, can be arranged in the layer stack of the digital twin as a stack comprising individual layers having spatially distributed non-uniform layer thicknesses and the same uniform refractive index. In the layer stack of the digital twin, adjacent individual layers having the same uniform refractive index are preferably understood as distinct individual layers.

[0266] Preferably, the transition region has the same thickness over its entire spatial extension. Preferably, the transition has a constant thickness over its entire spatial extension in the range of 800 nm to 1200 nm, more preferably 850 nm to 1150 nm, more preferably 900 nm to 1100 nm, and most preferably 950 nm to 1050 nm.

[0267] When gradient refractive index spectacle lenses are preferably manufactured using additive manufacturing methods, a calculated transition region is taken into account, the effect of which reduces Fresnel reflection loss at the interface in the gradient refractive index spectacle lens. When the gradient refractive index spectacle lens is preferably inkjet printed according to a printing instruction that takes into account the calculated transition region, the effect of the transition region is that Fresnel reflection loss at the interface is reduced in the inkjet-printed gradient refractive index spectacle lens.

[0268] When the digital twin of a gradient-index spectacle is calculated to include one or more transition zones, the refractive index difference between a single layer with a first uniform refractive index and a single layer with a second refractive index is negligible. However, a limiting factor regarding the refractive index is that the material used to manufacture such a single layer, and in particular the fluid used for inkjet printing a single layer with the corresponding refractive index, must be available.

[0269] In a preferred embodiment of the present invention, the computer-implemented method includes at least one of the following steps:

[0270] - Calculate the transition region between a first single layer having a first uniform refractive index and a second single layer having a second uniform refractive index, the transition region having a refractive index gradient.

[0271] - Calculate the transition region between a second single layer having a second uniform refractive index and a first single layer having a first uniform refractive index, the transition region having a refractive index gradient.

[0272] - Calculate the transition region between a first single layer having a first uniform refractive index and a third single layer having a third uniform refractive index, the transition region having a refractive index gradient.

[0273] - Calculate the transition region between a third single layer having a third uniform refractive index and a first single layer having a first uniform refractive index, the transition region having a refractive index gradient.

[0274] - Calculate the transition region between a second single layer having a second uniform refractive index and a third single layer having a third uniform refractive index, the transition region having a refractive index gradient.

[0275] - Calculate the transition region between a third single layer having a third uniform refractive index and a second single layer having a second uniform refractive index, the transition region having a refractive index gradient.

[0276] The computer-implemented method is configured to calculate a digital twin of an eyeglass lens for use in the manufacture of the lens. Preferably, after arranging in a stack of layers a first plurality of individual layers, each having a spatially varying non-uniform layer thickness and a first uniform refractive index, a second plurality of individual layers, each having a spatially varying non-uniform layer thickness and a second uniform refractive index, and a third plurality of individual layers, each having a spatially varying non-uniform layer thickness and a third uniform refractive index, the method includes the following steps in order to reproduce the corresponding optical path length at corresponding positions or corresponding discrete positions passing through the eyeglass lens or the digital twin passing through the eyeglass lens.

[0277] - Calculate the transition zone between individual layers with different refractive indices.

[0278] Preferably, the digital twin of the gradient refractive index spectacle lens is sliced ​​into a stack comprising the first plurality of individual layers, the second plurality of individual layers, and the third plurality of individual layers, arranged to reproduce corresponding optical path lengths at corresponding locations or corresponding discrete locations across the digital twin. Arranging the first plurality of individual layers, the second plurality of individual layers, and the third plurality of individual layers in the stack creates more interfaces between individual layers with different refractive indices. Preferably, to avoid Fresnel reflection losses at the interfaces between individual layers with different refractive indices, a transition region of one or more interfaces is calculated, similar to that previously described.

[0279] - Beginning in a first individual layer and ending in a second individual layer, the transition region preferably includes the interface between the first and second individual layers, and preferably has a refractive index gradient from a first uniform refractive index to a second uniform refractive index.

[0280] - Beginning in the second individual layer and ending in the first individual layer, the transition region preferably includes the interface between the second individual layer and the first individual layer, and the transition region preferably has a refractive index gradient from the second uniform refractive index to the first uniform refractive index.

[0281] - Beginning in a first individual layer and ending in a third individual layer, the transition region preferably includes an interface between the first and third individual layers, and preferably has a refractive index gradient from a first uniform refractive index to a third uniform refractive index.

[0282] - Beginning in a third individual layer and ending in a first individual layer, the transition region preferably includes the interface between the third individual layer and the first individual layer, and the transition region preferably has a refractive index gradient from a third uniform refractive index to a first uniform refractive index.

[0283] - Beginning in a second individual layer and ending in a third individual layer, the transition region preferably includes an interface between the second and third individual layers, and preferably has a refractive index gradient from a second uniform refractive index to a third uniform refractive index.

[0284] - Beginning at the third individual layer and ending at the second individual layer, the transition region preferably includes the interface between the third individual layer and the second individual layer, and the transition region preferably has a refractive index gradient from the third uniform refractive index to the second uniform refractive index.

[0285] Preferably, the transition is calculated for each interface between individual layers with different refractive indices. In the case of, for example, a four-layer stack consisting of a first individual layer having a first uniform refractive index and adjacent to a second individual layer having a second uniform refractive index, the second individual layer is further adjacent to a third individual layer having a third uniform refractive index, which in turn is further adjacent to another first individual layer having a first uniform refractive index. In the exemplary four-layer stack,

[0286] - A first transition region is calculated to begin at the first individual layer and end at the second individual layer, the first transition region including the interface between the first individual layer and the second individual layer, and the transition region having a refractive index gradient from the first uniform refractive index to the second uniform refractive index.

[0287] - The second transition region is calculated to begin at the second individual layer and end at the third individual layer, the second transition region including the interface between the second individual layer and the third individual layer, and the transition region having a refractive index gradient from the second uniform refractive index to the third uniform refractive index.

[0288] - The third transition region is calculated to begin at the third individual layer and end at the other first individual layer, the third transition region including the interface between the third individual layer and the other first individual layer, and the transition region having a refractive index gradient from the third uniform refractive index to the first uniform refractive index.

[0289] Regardless of whether a single layer is part of a stack of multiple single layers having the same uniform refractive index, or regardless of whether a single layer is a single layer, preferably, a transition region is calculated for one or more interfaces between adjacent single layers with different refractive indices (each of the adjacent single layers has a uniform refractive index and a non-uniform layer thickness distributed spatially). Preferably, a transition region is calculated for each interface between adjacent single layers with different refractive indices (each of the adjacent single layers has a uniform refractive index and a non-uniform layer thickness distributed spatially).

[0290] Preferably, the interfaces between adjacent individual layers with different refractive indices, preferably the transition region of each interface, are calculated, each of the adjacent individual layers having a uniform refractive index and a non-uniform layer thickness distributed spatially, such that in wave optics simulations of light propagating through a sliced ​​digital twin stack of layered structures of gradient refractive index spectacle lenses, no light is reflected at the interfaces, preferably at each of the interfaces.

[0291] Preferably, in the wave optics simulation, visible light (380 nm to 780 nm) propagates through the stacked layers.

[0292] Preferably, the transition region has the same thickness over its entire spatial extension. Preferably, the transition has a constant thickness over its entire spatial extension in the range of 800 nm to 1200 nm, more preferably 850 nm to 1150 nm, more preferably 900 nm to 1100 nm, and most preferably 950 nm to 1050 nm.

[0293] In a preferred embodiment of the invention, the computer-implemented method is characterized in that the spatial variation of the layer thickness of a single layer includes a minimum layer thickness and a maximum layer thickness, the ratio of the minimum layer thickness to the maximum layer thickness being selected from at least one of the following:

[0294] a) The ratio of minimum layer thickness to maximum layer thickness is at least 1:5;

[0295] b) The ratio of minimum layer thickness to maximum layer thickness is at least 1:8;

[0296] c) The ratio of minimum layer thickness to maximum layer thickness is at least 1:10;

[0297] d) The ratio of minimum layer thickness to maximum layer thickness is at least 1:12;

[0298] e) The ratio of minimum layer thickness to maximum layer thickness is at least 1:15.

[0299] The computer-implemented method is configured to calculate a digital twin of an eyeglass lens for use in the manufacture of the lens. The method includes the following steps:

[0300] - Set the spatial variation of the layer thickness of a single layer to include one of the ratios between the aforementioned minimum layer thickness and maximum layer thickness.

[0301] Setting the spatial variation of the individual layer thickness to include one of the aforementioned ratios between the minimum and maximum layer thicknesses advantageously allows for greater flexibility in calculating the digital twin of the spectacle lens, particularly regarding the realization of the refractive index distribution. Preferably, in the layer stack of the digital twin of the spectacle lens, more than 90%, more preferably more than 92%, and more preferably more than 95% of all individual layers are set to include one of the aforementioned ratios. In the layer stack of the digital twin of the spectacle lens, individual layers can be set to include the same aforementioned ratio, or different individual layers can be set to include different aforementioned ratios.

[0302] Preferably, the ratio between the minimum layer thickness and the maximum layer thickness begins at one of the aforementioned ratios and ends at a ratio of 1:20, preferably 1:25.

[0303] For example, the higher the ratio between the minimum and maximum layer thickness of a single layer, the higher the refractive index gradient that can be achieved in the stack of layers of the digital twin of the eyeglass lens, the stack comprising a) a first plurality of individual layers, each having a spatially varying non-uniform layer thickness and a first uniform refractive index, and b) a second plurality of individual layers, each having a spatially varying non-uniform layer thickness and a second uniform refractive index, the second uniform refractive index being different from the first uniform refractive index.

[0304] Preferably, in the layer stack, more than 90%, more than 92%, and more preferably more than 95% of the individual layers (i.e., the first plurality of individual layers and the second plurality of individual layers) have one of the aforementioned ratios.

[0305] The ratios between the maximum and minimum layer thicknesses of at least 1.05, at least 1.1, at least 1.2, at least 1.3, and at least 1.5 disclosed in lines 1 to 4 of page 21 of WO 2020 / 165439 A1 cannot achieve the same high flexibility in calculating digital twins of eyeglass lenses as the aforementioned ratios.

[0306] In a digital twin of a gradient refractive index spectacle lens, a predefined refractive index distribution n(x,y,z) is established. In the layer stack of the digital twin, the layer stack includes i) a first plurality of individual layers, each having a spatially distributed non-uniform layer thickness and a first uniform refractive index; and ii) a second plurality of individual layers, each having a spatially distributed non-uniform layer thickness and a second uniform refractive index, for example, along the line of sight (…). Figure 112) The cut through the stacked body illustrates the refractive index distribution n(x,y). In section 3.2.4 of ISO 13666:2019(E), the line of sight is defined as the ray path from the point of interest (i.e., the fixation point) in object space to the center of the entrance pupil of the eye and its continuation in image space from the center of the exit pupil to the fixation point of the retina (typically the fovea). Similar to section 3.2.4 of ISO 13666:2019(E), the line of sight in a digital twin of eyeglasses should describe the ray path from the point of interest (i.e., the fixation point) in object space to the center of the virtually represented entrance pupil of the virtually represented eye and its continuation in image space from the center of the virtually represented exit pupil to the virtually represented fixation point of the retina (typically the fovea). When the digital twin is preferably manufactured by an additive manufacturing method, and more preferably inkjet printed as a gradient refractive index lens, the refractive index distribution n(x,y) is responsible for the gradient refractive index orthogonal to the viewing direction.

[0307] Consider, for example, a two-layer stack consisting of: a) a first single layer having a spatially distributed non-uniform layer thickness and a first uniform refractive index, and b) a second single layer having a spatially distributed non-uniform layer thickness and a second uniform refractive index. A predetermined maximum layer thickness a is considered for each single layer in the two-layer stack. max d min and the preset minimum layer thickness d min ,and

[0308] -For any selected point x on the surface of the first single layer a Preset refractive index n: in,

[0309] -The two stacked layers are relative to point x a The refractive index gradient γ is:

[0310] - The total thickness d(x) of the two stacked layers a ) is: d(x a )=(α 1,a +α 2,a )d min , where α 1,a d min The first individual layer is relative to the point x. a The layer thickness, α 2a d min It is the second separate layer relative to the point x a The thickness of the layer,

[0311] And for another point x on the surfaceb The layer thickness d(x) of the two stacked layers b ) is further preset as d(x b )=(α b,1 +α b,2 )d min , where α b,1 d min The first individual layer is relative to the point x. b The layer thickness, α b,2 d min The second separate layer is relative to the point x. b The layer thickness, then

[0312]

[0313]

[0314] Relative to point x a Or relative to the point x b This means perpendicular to, for example, passing through the point x. a Or through the point x b In the plane of the line of sight.

[0315] By referring to the aforementioned arbitrary selection of point x on the surface of the first individual layer a The refractive index of the two stacked layers relative to the point x a The refractive index gradient and the predefined spatial thickness distribution of the two stacked layers are used for each additional point x on the first individual layer. b x c The layer thicknesses of the first and second individual layers are uniquely determined.

[0316] Turning to a sliced ​​digital twin stack of a gradient refractive index spectacle lens, the stack comprises i) a first plurality of individual layers, each having a spatially distributed non-uniform layer thickness and a first uniform refractive index, and ii) a second plurality of individual layers, each having a spatially distributed non-uniform layer thickness and a second uniform refractive index. This means that, in designing the digital twin of the gradient refractive index spectacle lens, the achievable refractive index distribution n(x,y,z) and spatial distribution of layer thickness for the individual layers have preferably been considered. It should also be considered that the digital twin can be translated into a physical entity; preferably, the digital twin can be manufactured by additive manufacturing methods; more preferably, the digital twin can be inkjet printed.

[0317] In a layered stack of a digital twin of a gradient refractive index spectacle lens, the digital twin has a preset refractive index distribution n(x,y,z). The layered stack includes i) a first plurality of individual layers, each having a spatially distributed non-uniform layer thickness and a first uniform refractive index; ii) a second plurality of individual layers, each having a spatially distributed non-uniform layer thickness and a second uniform refractive index; and iii) a third plurality of individual layers, each having a spatially distributed non-uniform layer thickness and a third uniform refractive index. For example, a cut along the line of sight through the layered stack shows the refractive index distribution n(x,y).

[0318] Consider, for example, a three-layer stack consisting of: a) a first single layer having a spatially distributed non-uniform layer thickness and a first uniform refractive index; b) a second single layer having a spatially distributed non-uniform layer thickness and a second uniform refractive index; and c) a third single layer having a spatially distributed non-uniform layer thickness and a third uniform refractive index. For any chosen point x on the surface of the first single layer... a Consider the following:

[0319] -The three-layer stacked body is at point x a The preset total thickness d(x) a ):

[0320] d(x a )=d a d min d a =α a,1 +α a,2 +α a,3 , where α a,1 d min The first individual layer is relative to the point x. a The layer thickness, α a,2 d min The second separate layer is relative to the point x. a The layer thickness, α a,3 d min The third separate layer is relative to the point x. a The thickness of the layer,

[0321] -The point x a The preset refractive index n(x) a ): in,

[0322] lead to and Where, α i ≥1 and α i ≤αmax , i = 1, 2, 3.

[0323] For different arbitrarily chosen points x on the surface b Consider the following:

[0324] -The three-layer stacked body is at point x b The preset total thickness d(x) a ):

[0325] d(x b )=d b d min ,d b =α b,1 +α b,2 +α b,3 , where α b,1 d min The first individual layer is relative to the point x. b The layer thickness, α b,2 d min The second separate layer is relative to the point x. b The layer thickness, α b,3 d min The third separate layer is relative to the point x. b The thickness of the layer,

[0326] -The point x b The preset refractive index n(x) b ): in,

[0327] lead to and Where, α i ≥1 and α i ≤α max Let i = 1, 2, 3, and the refractive index gradient be:

[0328] Compared to the two-layer stack as explained above, the three-layer stack is presupposed at point x. a The total thickness d(x) in a Furthermore, it is presupposed that the three-layer stacked body is located at point x. b The total thickness d(x) in b Point x as described in (a) and (b) b The refractive index in the first individual layer is not uniquely determined for every additional point x on the first individual layer. c x d …the layer thickness of the first individual layer, the second individual layer, and the third individual layer.

[0329] In a layered stack of a gradient refractive index eyeglass lens, the digital twin has a preset refractive index distribution n(x,y,z). The layered stack comprises more than three individual layers, each with a non-uniform layer thickness and a uniform refractive index. The digital twin can be sliced ​​using additional degrees of freedom.

[0330] In a preferred embodiment of the present invention, the computer-implemented method includes the following steps:

[0331] - Determine the spatial variation such that the optical path length through a pair of adjacent individual layers at each location is equal to the optical path length through the corresponding gradient refractive index layer, each of the adjacent individual layers having a different uniform refractive index from one another.

[0332] Calculate the digital twin of the eyeglass lens such that the optical path length through two adjacent individual layers with different refractive indices at each position is equivalent to the optical path length through the corresponding gradient refractive index layer at the corresponding position.

[0333] The digital twin of the spectacle lens is sliced ​​into a stack of layers comprising multiple individual layers, each having a uniform refractive index and a spatially distributed, non-uniform layer thickness, as previously explained. The digital twin of the spectacle lens is sliced ​​into a stack such that the optical path length through each pair of individual layers with different refractive indices, preferably perpendicular or nearly perpendicular, is equivalent at each location or at each discrete x,y,z location to the optical path length through the corresponding gradient refractive index layer to reach the corresponding location or discrete x,y,z location of each of the pairs of individual layers, preferably perpendicular or nearly perpendicular, such that the optical path length is equal to the optical path length through the corresponding gradient refractive index layer to reach the corresponding location or discrete x,y,z location of each individual layer.

[0334] In a preferred embodiment of the present invention, the computer-implemented method includes the following steps:

[0335] - Determine the spatial variation such that the form of the interface is a linear combination of the lens surface of the front surface of the lens and the lens surface of the rear surface of the lens.

[0336] In a preferred embodiment of the present invention, the computer-implemented method includes the following steps:

[0337] - Slice the digital twin of the eyeglass lens so that the interface is a linear combination of the lens surface of the front surface and the lens surface of the rear surface of the digital twin.

[0338] In a preferred embodiment of the present invention, the computer-implemented method includes the following steps:

[0339] - Determine the spatial variation such that the form of the interface is a linear combination of the lens surface of the front surface of the lens and the lens surface of the rear surface of the lens, thereby taking into account the uniform refractive index of individual layers and the different uniform refractive indices of adjacent individual layers with a common interface.

[0340] In a preferred embodiment of the present invention, the computer-implemented method includes the following steps:

[0341] - Slice the digital twin of the eyeglass lens such that the interface is a linear combination of the lens surface of the front surface and the lens surface of the rear surface of the digital twin, thereby taking into account the uniform refractive index of individual layers and the different uniform refractive indices of adjacent individual layers with a common interface.

[0342] The following explanation of the four preferred embodiments of the present invention relates to sliced ​​digital twins of eyeglass lenses:

[0343] The digital twin of the spectacle lens is sliced ​​into a stack of layers comprising i) a first plurality of individual layers, each having a spatially varying non-uniform layer thickness and a first uniform refractive index, and ii) a second plurality of individual layers, each having a spatially varying non-uniform layer thickness and a second uniform refractive index, as previously explained. In the stack, the form of every other interface is determined by a linear combination of the lens surfaces of the front and rear surfaces of the digital twin, as previously explained. In the stack, the form of each other interface is determined by a linear combination of the lens surfaces of the front and rear surfaces of the digital twin, thereby taking into account the uniform refractive index of the two individual layers having a common every other interface.

[0344] The digital twin of the eyeglass lens is preferably sliced ​​into a stacked body in three steps. In the first step, the digital twin is sliced ​​into a first stacked body, such that each interface ( Figure 1 The form of 02 in the digital twin is generated by a linear combination of the lens surfaces of the front and rear surfaces of the digital twin. In the first layer stack, a single layer ( Figure 1 The 09 in the first layer stack is formed by the front surface and the nearest interface of the digital twin, or by two nearest interfaces, or by the rear surface and the nearest interface of the digital twin. In the second step, each individual layer in the first layer stack is sliced ​​to produce a second layer stack of the digital twin. In the second step, each individual layer in the first layer stack is sliced ​​to include a first internal interface ( Figure 1 (03 in the middle). The first internal interface is formed by dividing each individual layer in the first layer stack into a first partial layer having a first uniform refractive index ( Figure 1 10) and a second partial layer with a second uniform refractive index ( Figure 1 11) is used to determine this. Each individual layer is divided into a first partial layer and a second partial layer such that the optical path length of a preferably perpendicular or nearly perpendicular incident beam through the first partial layer and the second partial layer is equivalent at each position or each discrete x,y position of each individual layer in the first layer stack to the optical path length through the corresponding gradient refractive index layer at the corresponding position or the corresponding discrete x,y position. In the corresponding gradient refractive index layer, the gradient refractive index is between the first uniform refractive index and the second uniform refractive index, as explained previously. The division of each individual layer into the first partial layer and the second partial layer is such that the partial layer thickness t of the first partial layer is... (x,y)第一部分层 Through at each location or at each discrete x,y location To determine, where n(x,y) = the refractive index of the digital twin at the position or the discrete x,y position, n1 = the first uniform refractive index of the first partial layer, n2 = the second uniform refractive index of the second partial layer, and n1 ≠ n2.

[0345] The process of dividing each individual layer into a first partial layer and a second partial layer results in the second partial layer having a partial layer thickness of t. (x,y)第二部分层 Through at each location or at each discrete x,y location To determine, where n(x,y) = the refractive index of the digital twin at the position or at the discrete x,y position, n1 = the first uniform refractive index of the first partial layer, n2 = the second uniform refractive index of the second partial layer, and n1 ≠ n2.

[0346] The first uniform refractive index is preferably a high uniform refractive index, preferably a constant uniform refractive index >1.50 at 550 nm. The second uniform refractive index is preferably a low uniform refractive index, preferably a constant uniform refractive index ≤1.50 at 550 nm.

[0347] In the third step, for each individual layer in the second layer stack ( Figure 1 In step 10, 11) are sliced ​​to produce a third layer stack. In the third step, each individual layer included in the second layer stack is sliced ​​to include a second internal interface ( Figure 1(04, 05) or multiple second internal interfaces. In the second layer stack, a single layer is formed by: i) the front surface of the digital twin and the nearest first internal interface or the front surface of the digital twin and the nearest interface, or ii) the first internal interface and the nearest interface, or iii) the rear surface of the digital twin and the nearest first internal interface or the rear surface of the digital twin and the nearest interface. In the third step, whichever applies,

[0348] - The layer formed by the front surface of the digital twin and the nearest first internal interface is sliced ​​to include one or more second internal interfaces, each form of which is determined by a linear combination of the lens surface of the front surface and the form of the nearest first internal interface.

[0349] - The layer formed by the front surface and the nearest interface of the digital twin is sliced ​​into one or more second internal interfaces, each form of which is determined by a linear combination of the forms of the lens surface of the front surface and the nearest interface.

[0350] - The layer formed by the first internal interface and the nearest interface is sliced ​​into layers including one or more second internal interfaces, each form of which is determined by a linear combination of the forms of the first internal interface and the forms of the nearest interface.

[0351] - The layer formed by the back surface of the digital twin and the nearest first internal interface is sliced ​​into sections including one or more second internal interfaces, each form of which is determined by a linear combination of the surface form of the back surface and the form of the nearest first internal interface.

[0352] - The layer formed by the back surface of the digital twin and the nearest interface is sliced ​​into one or more second internal interfaces, each form of which is determined by a linear combination of the surface form of the back surface and the form of the nearest interface.

[0353] As described in the four preferred embodiments above, determining the spatial distribution or slicing the digital twin ensures that the digital twin can be converted into a physical entity, preferably manufactured by additive manufacturing methods, and more preferably by inkjet printing.

[0354] In a preferred embodiment of the invention, the computer-implemented method is characterized by the following steps, preferably in a given order:

[0355] - Determine the discrete x of a single layer m ,y m ,z m...x n ,y n ,z n The actual value of the layer thickness at the location is the same discrete x as that of the individual layer. m ,y m ,z m ...x n ,y n ,z n The deviation of the default nominal value of the layer thickness at the location, and

[0356] - Determine the sum of the deviation of the layer thickness and the actual value.

[0357] As explained previously regarding the generation of print instructions, in step b), each individual layer of the sliced ​​digital twin stack of the eyeglass lens is converted into a spatial volume element pattern. In this spatial volume element pattern, each volume element is positioned or not positioned at a discrete x-axis, depending on the spatial variation in the non-uniform layer thickness of each individual layer of the stack. m ,y m ,z m ...x n ,y n ,z n Location.

[0358] Position the volume element at the discrete x-axis. m ,y m ,z m ...x n ,y n ,z n Location means digitally placing, virtually arranging, or digitally distributing volume elements across discrete x. m ,y m ,z m ...x n ,y n ,z n Position. Locate the volume element at the discrete x-axis. m ,y m ,z m ...x n ,y n ,z n The location preferably includes (i) digitally placing the volume element within a separate layer and / or (ii) digitally placing the volume element in an adjacent separate layer, in a separate layer every other layer, in a separate layer adjacent to a separate layer every other layer, etc. Positioning a volume element should include positioning a volume element at a discrete x-axis. m ,y m ,z m ...x n ,y n ,zn At the location, more volume elements may be positioned at the discrete x-axis. m ,y m ,z m ...x n ,y n ,z n At location. A "non-positional" volume element should mean at discrete x. m ,y m ,z m ...x n ,y n ,z n No volume element is positioned at this location.

[0359] Volume elements can be represented digitally, described virtually, or displayed digitally as, for example, a cuboid with a preset edge length. Preferably, a volume element is digitally represented as a cube with a preset edge length.

[0360] As explained previously, slicing a digital twin of an eyeglass lens into a stacked volume includes determining the spatial distribution of the non-uniform layer thickness for each individual layer. For each discrete x of each individual layer... m ,y m ,z m ...x n ,y n ,z n Location determines layer thickness. The layer thickness is defined at each discrete x-axis position within a single layer. m ,y m ,z m ...x n ,y n ,z n The location has a default nominal value.

[0361] Preferably, when the stacked layers are projected into a plane defined by the x and y directions, and when the spatial volume element pattern of each individual layer of the stacked layers is viewed, for example, in a side view, then in each discrete x-axis of the individual layer... m ,y m ,z m ...x n ,y n ,z n The actual value of the layer thickness is determined at the location. When viewing the individual layer in a side view, one or more volume elements are positioned at the discrete x-axis of the individual layer. m ,y m ,z m ...x n ,y n ,z n The location causes the discrete x m ,ym ,z m ...x n ,y n ,z n Actual value of layer thickness at the location

[0362] - The same discrete x greater than the individual layer m ,y m ,z m ...x n ,y n ,z n The default nominal value of the layer thickness at the location, or

[0363] - smaller than the same discrete x of the individual layer m ,y m ,z m ...x n ,y n ,z n The default nominal value of the layer thickness at the location, or

[0364] - equal to the same discrete x of the individual layer m ,y m ,z m ...x n ,y n ,z n The default nominal value for the layer thickness at the location.

[0365] The deviation between the actual value and the default nominal value is the difference between the two values.

[0366] The determination of the sum of the deviation of the layer thickness and the actual value is used as i) to locate the volume element in the discrete x of the individual layer. m+1 ,y m+1 ,z m+1 ...x n+1 ,y n+1 ,z n+1 Location or ii) not positioning volume elements on a discrete layer m+1 ,y m+1 ,z m+1 ...x n+1 ,y n+1 ,z n+1 The valid basis for determining the location. Therefore, the determination is used to decide whether a volume element should be positioned or not in a discrete x-layer where one or more volume elements are already positioned. m ,y m ,z m ...x n ,y n ,z nThe volume elements at the location are adjacent and in a separate layer on top of it.

[0367] When the stacked layers are projected onto a plane defined by the x and y directions, each individual layer has a discrete x-axis. m+1 ,y m+1 ,z m+1 ...x n+1 ,y n+1 ,z n+1 The location of a volume element and its discrete x-coordinate in an adjacent single layer in which one or more volume elements are already located. m ,y m ,z m ...x n ,y n ,z n Volume elements at a position are directly adjacent and on top of each other if the two volume elements differ only at their z-positions.

[0368] The steps of the computer-implemented method are performed for each individual layer of the stack except the last individual layer, namely, determining the deviation of the actual value of the layer thickness from the default nominal value of the layer and determining the sum of the deviation of the layer thickness and the actual value.

[0369] In a preferred embodiment of the invention, the computer-implemented method is characterized by at least one of the following conditions:

[0370] - When the sum is greater than half of the default nominal value of the layer thickness, the volume element is not positioned on the discrete x-axis of the individual layer. m+1 ,y m+1 ,z m+1 ...x n+1 ,y n+1 ,z n+1 Location;

[0371] - When the sum is less than or equal to half of the default nominal value of the layer thickness, the volume element is positioned at a discrete x-axis on a separate layer. m+1 ,y m+1 ,z m+1 ...x n+1 ,y n+1 ,z n+1 Location.

[0372] Based on the aforementioned conditions, the volume element is positioned at the discrete x-axis. m+1 ,y m+1 ,z m+1 ...x n+1 ,y n+1 ,z n+1 Position or not positioning the volume element at the discrete xm+1 ,y m+1 ,z m+1 ...x n+1 ,y n+1 ,z n+1 Position correction of discrete x in adjacent individual layers m ,y m ,z m ...x n ,y n ,z n The actual value of the layer thickness at the location is the same discrete x as that of the adjacent individual layer. m ,y m ,z m ...x n ,y n ,z n The deviation from the default nominal value of the layer thickness at the location. Preferably, in the adjacent individual layers, one or more volume elements are ultimately located. Preferably, as mentioned above, the volume element is numerically represented as a cuboid with a preset edge length, more preferably as a cube with a preset edge length. The correction for the deviation can be:

[0373] - Correct the actual value to correspond to the default nominal value, or

[0374] - Undercorrect the actual value so that it does not correspond to the default nominal value, or

[0375] - The actual value is overcorrected so that it does not correspond to the default nominal value.

[0376] Preferably, the correction of the deviation adjusts the actual value to correspond to the default nominal value.

[0377] If the correction to the deviation would cause undercorrection or overcorrection of the actual value, then the undercorrection or overcorrection is distributed equally. Preferably, this equal distribution occurs during the layered manufacturing of the spectacle lens, for example, the total volume of material positioned in a single layer is preferably equal to the volume of that single layer. Preferably, according to the aforementioned printing instructions, this equal distribution is further preferably performed during the layered inkjet printing of the spectacle lens, for example, the total volume of ink droplets to be positioned in a single layer is preferably equal to the volume of that single layer.

[0378] When a volume element is positioned according to condition (i) or (ii) not positioned, the maximum distance between two adjacent volume elements in a single layer is considered. This maximum distance is preferably a distance corresponding to the distance that allows adjacent ink droplets to coalesce and form a continuous layer.

[0379] Furthermore, when the volume element is positioned or not positioned according to the conditions (i) and (ii) respectively, the variation in the distance between two adjacent volume elements in a single layer is preferably minimized. When preferably printing eyeglass lenses in layers using inkjet printing, this minimization of the variation in the distance between two adjacent ink droplets in a single layer preferably enables the surface of the single layer to be as smooth as possible.

[0380] The conditions of the computer-implemented method are applied to each individual layer of the stack except the last individual layer, the conditions determining whether to position or not position volume elements based on the conditions.

[0381] In a preferred embodiment of the invention, the computer-implemented method is further characterized by at least one step selected from the following:

[0382] - Determine the discrete x of the individual layer after the positioning of the volume element. m+1 ,y m+1 ,z m+1 ...x n+1 ,y n+1 ,z n+1 The deviation of the default nominal value of the layer thickness at the location, and the distribution of the deviation to adjacent discrete x values ​​within the same individual layer. o+1 ,y o+1 ,z o+1 ...x p+1 ,y p+1 ,z p+1 Location;

[0383] - Determine the discrete x of the individual layer after the positioning of the volume element. m+1 ,y m+1 ,z m+1 ...x n+1 ,y n+1 ,z n+1 The deviation of the default nominal value of the layer thickness at the location, and the transfer of the deviation to a discrete x-value separated by a single layer. m+2 ,y m+2 ,z m+2 ...x n+2 ,y n+2 ,z n+2 Location;

[0384] - Determine the discrete x of the individual layer after the non-positioning of the volume element. m+1 ,y m+1 ,z m+1 ...x n+1 ,y n+1 ,z n+1The deviation of the default nominal value of the layer thickness at the location, and the distribution of the deviation to adjacent discrete x values ​​within the same individual layer. o+1 ,y o+1 ,z o+1 ...x p+1 ,y p+1 ,z p+1 Location;

[0385] - Determine the discrete x of the individual layer after the non-positioning of the volume element. m+1 ,y m+1 ,z m+1 ...x n+1 ,y n+1 ,z n+1 The deviation of the default nominal value of the layer thickness at the location, and the transfer of the deviation to a discrete x-value separated by a single layer. m+2 ,y m+2 ,z m+2 ...x n+2 ,y n+2 ,z n+2 Location.

[0386] If the individual layer is the last individual layer in the stack, the deviation can only be distributed within that last individual layer. If the layer every other individual layer is the last individual layer in the stack, the deviation can only be transferred when the last individual layer is that layer every other individual layer.

[0387] In (i) the discrete x-axis of the volume element is positioned in the separate layer m+1 ,y m+1 ,z m+1 ...x n+1 ,y n+1 ,z n+1 Position or (ii) not positioning the volume element in the discrete x of the separate layer m+1 ,y m+1 ,z m+1 ...x n+1 ,y n+1 ,z n+1 After determining the location, the discrete x of the individual layer is determined. m+1 ,y m+1 ,z m+1 ...x n+1 ,y n+1 ,z n+1 The actual value of the layer thickness at the location, and compare this actual value with the discrete x of the individual layer. m+1 ,y m+1 ,z m+1 ...x n+1 ,yn+1 ,z n+1 The layer thickness at the specified location is compared to the default nominal value. Preferably, as previously stated, the volume element is numerically represented as a cube with a preset edge length, more preferably as a cube with a preset edge length. The deviation from the default nominal value will be:

[0388] - Distributed to adjacent discrete x within the same individual layer o+1 ,y o+1 ,z o+1 ...x p+1 ,y p+1 ,z p+1 Location, and

[0389] -Transfer to discrete x separated by a single layer m+2 ,y m+2 ,z m+2 ...x n+2 ,y n+2 ,z n+2 Location.

[0390] Distribute the deviation to adjacent discrete x within the same individual layer. o+1 ,y o+1 ,z o+1 ...x p+1 ,y p+1 ,z p+1 The location should include distributing the deviation to a neighboring discrete x. o+1 ,y o+1 ,z o+1 ...x p+1 ,y p+1 ,z p+1 Position or multiple adjacent x o1+1 ,y o1+1 ,z o1+1 ...x p1+1 ,y p1+1 ,z p1+1 Location. The distribution of the deviation will mean that when determining the discrete x o+1 ,y o+1 ,z o+1 ...x p+1 ,y p+1 ,z p+1 Position or the discrete x o1+1 ,y o1+1 ,z o1+1 ...x p1+1 ,y p1+1 ,z p1+1 When considering the actual layer thickness at a location, the deviation should be taken into account. If the discrete x of the individual layer... m+1 ,y m+1,z m+1 ...x n+1 ,y n+1 ,z n+1 The actual value of the layer thickness at the location is less than the discrete x. m+1 ,y m+1 ,z m+1 ...x n+1 ,y n+1 ,z n+1 The default nominal value of the layer thickness at the location is then considered in light of the deviation, for example, in adjacent discrete x-coordinates. o+1 ,y o+1 ,z o+1 ...x p+1 ,y p+1 ,z p+1 Position, adding the difference in layer thickness to the adjacent discrete x o+1 ,y o+1 ,z o+1 ...x p+1 ,y p+1 ,z p+1 In the actual layer thickness at the location. If the discrete x of the layer... m+1 ,y m+1 ,z m+1 ...x n+1 ,y n+1 ,z n+1 The actual value of the layer thickness at the location is greater than the discrete x. m+1 ,y m+1 ,z m+1 ...x n+1 ,y n+1 ,z n+1 The default nominal value of the layer thickness at the location is then considered in light of the deviation, for example, in adjacent discrete x-coordinates. o+1 ,y o+1 ,z o+1 ...x p+1 ,y p+1 ,z p+1 Position, the difference in layer thickness from the adjacent discrete x o+1 ,y o+1 ,z o+1 ...x p+1 ,y p+1 ,z p+1 Subtract from the actual layer thickness at the location. If the discrete x of the layer m+1 ,y m+1 ,z m+1 ...x n+1 ,y n+1 ,z n+1The actual value of the layer thickness at the location is equal to the discrete x. m+1 ,y m+1 ,z m+1 ...x n+1 ,y n+1 ,z n+1 The default nominal value of the layer thickness at the location does not need to be transferred.

[0391] Following the aforementioned distribution of the deviation, the computer-implemented method uses the adjacent discrete x... o+1 ,y o+1 ,z o+1 ...x p+1 ,y p+1 ,z p+1 The position continues and the steps described therein are applied, namely, determining the discrete x of the layer. o+1 ,y o+1 ,z o+1 ...x p+1 ,y p+1 ,z p+1 The actual value of the layer thickness at the location, and this actual value is compared with the discrete x of the individual layer. o+1 ,y o+1 ,z o+1 ...x p+1 ,y p+1 ,z p+1 The layer thickness at that location is compared to the default nominal value. The deviation from the default nominal value is calculated as follows:

[0392] - Distributed into adjacent discrete x within the same individual layer q+1 ,y q+1 ,z q+1 ...x r+1 ,y r+1 ,z r+1 Location, and

[0393] -Transfer to discrete x separated by a single layer m+2 ,y m+2 ,z m+2 ...x n+2 ,y n+2 ,z n+2 Location.

[0394] Continue with the determination until for each discrete x of the individual layer m+1 ,y m+1 ,z m+1 ...x n+1 ,y n+1 ,z n+1 The location determines the deviation between the actual value of the layer thickness and the default nominal value of the layer thickness.

[0395] The sum of the deviations and the considered deviations distributed in the individual layers is preferably zero to ensure that the total ink droplet volume in the inkjet-printed eyeglass lens is equal to the volume of the individual layer to be inkjet-printed.

[0396] The deviation is transferred to discrete x separated by a single layer. m+2 ,y m+2 ,z m+2 ...x n+2 ,y n+2 ,z n+2 Position should mean taking into account the deviation in the separate layer, so that the volume element is preferably positioned at a discrete x in the separate layer. m+2b ,y m+2b ,z m+2b ...x n+2b ,y n+2b ,z n+2b Position, thus not located in the discrete x of the individual layer m+1 ,y m+1 ,z m+1 ...x n+1 ,y n+1 ,z n+1 The position is at the top of the volume element. Therefore, when preferably layered inkjet printing of eyeglass lenses and according to the volume element in discrete x... m+2b ,y m+2b ,z m+2b ...x n+2b ,y n+2b ,z n+2b When the positioning is used to locate the ink droplet, the transfer facilitates (i) achieving an interface within the lens or (ii) making the surface of the lens as smooth as possible.

[0397] In a preferred embodiment of the invention, the aforementioned computer-implemented method is further configured for manufacturing eyeglass lenses.

[0398] In a preferred embodiment of the invention, the aforementioned computer-implemented method is further configured to manufacture spectacle lenses using an additive manufacturing method.

[0399] In a preferred embodiment of the invention, the aforementioned computer-implemented method is further configured for inkjet printing eyeglass lenses.

[0400] In a preferred embodiment of the invention, a method for layered inkjet printing of eyeglass lenses according to printing instructions, wherein when the printing instructions are executed by an inkjet printer, the printing instructions cause the inkjet printer to layer-by-layer inkjet printing of the eyeglass lenses, the printing instructions having been generated by a computer-implemented method as described above.

[0401] Referring to the previous four embodiments, refer to the explanations given above regarding the computer-implemented methods. These explanations and preferred embodiments should apply.

[0402] The computer according to the present invention includes a processor configured to perform the following steps:

[0403] - Determine the spatial variation of the layer thickness of each individual layer in the stacked structure to achieve either a digital twin of the lens or a predefined power distribution of the lens through spatial control of the optical path length.

[0404] And inkjet printers.

[0405] Refer to the above explanation of the computer-implemented method. These explanations and preferred embodiments should apply.

[0406] An apparatus including a computer and an inkjet printer, the computer including a processor configured to perform the following steps:

[0407] - Determine the spatial variation of the layer thickness of each individual layer in the stack to achieve a predefined power distribution of the digital twin of the spectacle lens through spatial control of the optical path length.

[0408] Refer to the above explanation of the computer-implemented method. These explanations and preferred embodiments should apply.

[0409] In a preferred embodiment of the present invention, the data processing system includes a processor and a storage medium coupled to the processor, wherein the processor is adapted to perform the following steps:

[0410] - Determine the spatial variation of the layer thickness of each individual layer in the stacked structure to achieve either a digital twin of the lens or a predefined power distribution of the lens through spatial control of the optical path length.

[0411] This is based on a computer program stored on that storage medium.

[0412] The computer program may be stored on a non-transitory tangible computer-readable storage medium. The computer program includes instructions that, when executed by a computer, cause the computer to perform the aforementioned computer-implemented method. Refer to the above explanation regarding the computer-implemented method. These explanations and preferred embodiments should apply.

[0413] The computer program according to the invention includes instructions that, when executed by a computer, cause the computer to perform the computer-implemented method described above.

[0414] The computer program may be stored on a non-transitory tangible computer-readable storage medium, and the computer program includes instructions that, when executed by a computer, cause the computer to perform the computer-implemented method described above.

[0415] In a preferred embodiment of the present invention, a computer-readable storage medium thereon stores the computer program. The computer-readable storage medium may be a non-transitory tangible computer-readable storage medium.

[0416] In a preferred embodiment of the invention, a computer-readable storage medium is provided thereon storing the digital twin of the eyeglass lens, the digital twin being configured to be fed to one or more manufacturing machines to manufacture the eyeglass lens.

[0417] In a preferred embodiment of the invention, a computer-readable storage medium stores the digital twin of the eyeglass lens, the digital twin being configured to be fed to one or more inkjet printers for inkjet printing of the eyeglass lens.

[0418] In a preferred embodiment of the invention, the data signal carries the computer program.

[0419] In a preferred embodiment of the invention, a data signal carries the digital twin of the eyeglass lens, the digital twin being configured to be fed to one or more manufacturing machines to manufacture the eyeglass lens.

[0420] In a preferred embodiment of the invention, a data signal carries the digital twin of the eyeglass lens, the digital twin being configured as one or more inkjet printers to inkjet print the eyeglass lens.

[0421] The spectacle lens according to the present invention has

[0422] -Predefined focal length distribution, and

[0423] A layered stack having multiple individual layers, each having a uniform refractive index and a spatially varying non-uniform layer thickness, the layered stack comprising at least...

[0424] ○ A first plurality of individual layers, each having a spatially varying non-uniform layer thickness and a first uniform refractive index.

[0425] ○ A second plurality of individual layers, each having a spatially varying non-uniform layer thickness and a second uniform refractive index, wherein the second uniform refractive index differs from the first uniform refractive index.

[0426] The contribution of all interfaces between the first plurality of individual layers and the individual layers of the second plurality of individual layers to the predefined focal length distribution is within at least one range selected from:

[0427] -5% to 25%

[0428] -10% to 20%

[0429] -12% to 18%.

[0430] All interfaces are interfaces within the stacked layers of the lens, without considering the front and back surfaces of the lens.

[0431] Each interface separates two separate layers, each with a uniform refractive index and a spatially varying non-uniform layer thickness, whereby the uniform refractive indices of the two separate layers differ from each other, contributing to the predefined power distribution of the lens. Therefore, the interfacial power distribution is caused by each interface that separates two separate layers with different uniform refractive indices and each with a spatially varying non-uniform layer thickness.

[0432] Interface between the following items

[0433] - A first separate layer, the first separate layer having a first non-uniform layer thickness and a first uniform refractive index varying with a first space, the first separate layer being separated from the following via the interface.

[0434] - A second separate layer having a second non-uniform layer thickness and a second uniform refractive index that vary with a second space, wherein the second spatial variation differs from the first spatial variation, and the second uniform refractive index differs from the first uniform refractive index.

[0435] This causes the focal length distribution at the interface.

[0436] Interface between the following items

[0437] - A first separate layer, the first separate layer having a first non-uniform layer thickness and a first uniform refractive index varying with a first space, the first separate layer being separated from the following by a first interface.

[0438] - A second separate layer having a second non-uniform layer thickness and a second uniform refractive index that vary with a second space, the second uniform refractive index being different from the first uniform refractive index, and the second spatial variation being different from the first spatial variation and the third spatial variation of the third non-uniform layer thickness of the third separate layer. The second separate layer is separated from the following by a second interface.

[0439] - A third separate layer having a third non-uniform layer thickness and a uniform refractive index that varies with a third space, the uniform refractive index being different from the second uniform refractive index but the same as the first uniform refractive index, the third spatial variation being the same as the first spatial variation.

[0440] This causes the focal length distribution at the interface.

[0441] The previously exemplified descriptions for two or three separate layers should be applied by analogy to each interface of a layered stack of eyeglass lenses that separates separate layers with spatially varying non-uniform layer thicknesses and different uniform refractive indices.

[0442] The front and rear surfaces of the lens cause the surface power distribution and thus contribute to the predefined power distribution.

[0443] The predefined power distribution is the sum of the surface power distribution caused by the front and rear surfaces of the lens and the interface power distribution caused by each interface of the two separate individual layers of the lens stack, each individual layer having a spatially varying non-uniform layer thickness, and the two individual layers having different uniform refractive indices from each other.

[0444] For example, the refractive index difference between a first single layer having a first refractive index and a second single layer having a second refractive index of 0.1 (the first and second single layers have spatially varying non-uniform layer thicknesses) causes an interfacial power distribution at each interface of the layer stack of the lens, which contributes to 20% of the total interfacial power distribution of the lens's predefined power distribution.

[0445] Preferably, the non-uniform layer thickness includes spatial variations selected from one of the following:

[0446] - At least 500%;

[0447] -At least 800%;

[0448] - At least 1000%;

[0449] -At least 1200%;

[0450] - At least 1500%.

[0451] The spatial variation should include a preferred spatial variation in the non-uniform layer thickness of individual layers, preferably including a minimum layer thickness and a maximum layer thickness. At least one of the aforementioned spatial variations is preferably achieved in at least 90%, more preferably at least 92%, and more preferably at least 95% of all individual layers in the layer stack of the spectacle lens. Preferably, the spatial variation in the non-uniform layer thickness of individual layers begins with one of the aforementioned spatial variations and reaches a maximum of 2000%, preferably a maximum of 2500%. The spatial variations of different individual layers can be the same or different.

[0452] As described on page 22, lines 20-24 of WO 2020 / 16539 A1, the maximum variation in distance between adjacent interfaces of adjacent layers is 30%, 20%, 10%, 5%, 3%, 2%, and 1%. Spatial variation in inhomogeneous layer thickness is insufficient to achieve a predefined power distribution. Furthermore, as described on page 2, lines 30 to page 3, lines 6 of WO 2020 / 16539 A1, the combination of a maximum 30% spatial variation in inhomogeneous layer thickness with a refractive index difference of at most 0.2 between individual layers is insufficient to achieve a predefined power distribution.

[0453] In a preferred embodiment of the present invention, the spectacle lens has

[0454] -Predefined focal length distribution, and

[0455] A layered stack having multiple individual layers, each having a uniform refractive index and a spatially varying non-uniform layer thickness, the layered stack comprising at least...

[0456] ○ A first plurality of individual layers, each having a spatially varying non-uniform layer thickness and a first uniform refractive index.

[0457] ○ A second plurality of individual layers, each having a spatially varying non-uniform layer thickness and a second uniform refractive index, wherein the second uniform refractive index differs from the first uniform refractive index.

[0458] ○ A third plurality of individual layers, each having a spatially varying non-uniform layer thickness and a third uniform refractive index, wherein the third uniform refractive index differs from the first and second uniform refractive indices.

[0459] The contribution of all interfaces between the first plurality of individual layers and the individual layers of the second plurality of individual layers to the predefined focal length distribution is within at least one range selected from:

[0460] -5% to 25%

[0461] -10% to 20%

[0462] -12% to 18%.

[0463] As previously described, each interface separates two separate layers, each of which has a uniform refractive index and a spatially varying non-uniform layer thickness. The uniform refractive index of one separate layer differs from that of the other, which contributes to the predefined power distribution of the lens.

[0464] Interface between the following items

[0465] - A first separate layer, the first separate layer having a first non-uniform layer thickness and a first uniform refractive index varying with a first space, the first separate layer being separated from the following by a first interface.

[0466] - A second separate layer having a second non-uniform layer thickness and a second uniform refractive index that vary with a second spatial variation, which differs from the first spatial variation, and also differs from the third spatial variation of a third separate layer having a third spatial variation and a third uniform refractive index. This second separate layer is separated from the following by a second interface.

[0467] - A third separate layer, having a third non-uniform layer thickness and a third refractive index, wherein the third spatial variation may be the same as the first spatial variation.

[0468] This causes a first and second interface focal length distribution at the first and second interfaces, i.e., an interface focal length distribution.

[0469] Interface between the following items

[0470] - A first separate layer, the first separate layer having a first non-uniform layer thickness and a first refractive index that vary with a first space, the first separate layer being separated from the following by a first interface.

[0471] - A second separate layer having a second non-uniform layer thickness and a second refractive index that vary with a second space, the second refractive index being different from the first uniform refractive index, the second spatial variation being different from the first spatial variation, and the second spatial variation being different from the third spatial variation of a third separate layer having a third spatial variation and a third refractive index, the second separate layer being separated from the following by a second interface.

[0472] - A third separate layer having a third non-uniform layer thickness and a third uniform refractive index that vary with a third space, the third refractive index being different from the first and second refractive indices, and the third spatial variation being different from the fourth spatial variation of a fourth separate layer having a fourth non-uniform layer thickness and a fourth refractive index that vary with a fourth space, the third separate layer being separated from the following by a third interface.

[0473] - A fourth separate layer having a fourth non-uniform layer thickness and a fourth uniform refractive index that vary with a fourth space, wherein the fourth uniform refractive index a) is different from the third uniform refractive index and b) is the same as the first refractive index or the second refractive index, and the fourth spatial variation A) is different from the third spatial variation and B) is the same as the first spatial variation or the second spatial variation.

[0474] At the first interface, at the second interface, and at the third interface, a first interface focal length distribution, a second interface focal length distribution, and a third interface focal length distribution are caused, i.e., interface focal length distribution.

[0475] The previously exemplified descriptions for three or four individual layers should be applied by analogy to each interface of a layered stack of eyeglass lenses that separates individual layers with spatially varying non-uniform layer thicknesses and different uniform refractive indices.

[0476] As previously stated, the front and rear surfaces of the lens cause a surface power distribution and thus also contribute to a predefined power distribution, which is the sum of the surface power distribution caused by the front and rear surfaces of the lens and the interface power distribution caused by each interface of the two separate individual layers of the lens's stack, each individual layer having a spatially varying non-uniform layer thickness, and the two individual layers having a uniform refractive index that is different from each other.

[0477] A lens, the lens having

[0478] -Predefined focal length distribution, and

[0479] A layer stack comprising multiple individual layers, each having a uniform refractive index and a spatially varying non-uniform layer thickness, the layer stack including individual layers with different uniform refractive indices.

[0480] The characteristic is that the ratio of the minimum layer thickness to the maximum layer thickness of each individual layer is selected from at least one of the following:

[0481] a) The ratio of minimum layer thickness to maximum layer thickness is at least 1:5;

[0482] b) The ratio of minimum layer thickness to maximum layer thickness is at least 1:8;

[0483] c) The ratio of minimum layer thickness to maximum layer thickness is at least 1:10;

[0484] d) The ratio of minimum layer thickness to maximum layer thickness is at least 1:12;

[0485] e) The ratio of minimum layer thickness to maximum layer thickness is at least 1:15.

[0486] The stacked body may include at least:

[0487] - A first plurality of individual layers, each having a spatially varying non-uniform layer thickness and a first uniform refractive index.

[0488] - A second plurality of individual layers, each having a spatially varying non-uniform layer thickness and a second uniform refractive index, the second uniform refractive index being different from the first uniform refractive index.

[0489] - A third plurality of individual layers, each having a spatially varying non-uniform layer thickness and a third uniform refractive index, the third uniform refractive index being different from the first uniform refractive index and the second uniform refractive index.

[0490] Referring to the above explanations regarding the computer-implemented method and the spectacle lens, these explanations and preferred embodiments should apply.

[0491] In a preferred embodiment of the present invention, the spectacle lens has

[0492] -Predefined focal length distribution, and

[0493] A layered stack having multiple individual layers, each with a uniform refractive index and a spatially varying non-uniform layer thickness.

[0494] The predefined focal length distribution is achieved by the ratio of the minimum layer thickness to the maximum layer thickness of each individual layer, and this ratio is selected from at least one of the following:

[0495] a) The ratio of minimum layer thickness to maximum layer thickness is at least 1:5;

[0496] b) The ratio of minimum layer thickness to maximum layer thickness is at least 1:8;

[0497] c) The ratio of minimum layer thickness to maximum layer thickness is at least 1:10;

[0498] d) The ratio of minimum layer thickness to maximum layer thickness is at least 1:12;

[0499] e) The ratio of minimum layer thickness to maximum layer thickness is at least 1:15.

[0500] An eyeglass lens includes a stack of layers having a plurality of individual layers, each having a uniform refractive index and a spatially varying layer thickness. The spatial variation in the layer thickness of the individual layers, comprising one of the aforementioned ratios between a minimum and a maximum layer thickness, advantageously enables the conversion of a digital twin of the eyeglass lens, preferably calculated according to the aforementioned computer-implemented method, into a physical entity. The digital twin is preferably converted into a physical entity by an additive manufacturing method, more preferably by inkjet printing. Regarding the aforementioned ratio, the advantages described with respect to the computer-implemented method should apply.

[0501] In a preferred embodiment of the invention, the spectacle lens is a coated spectacle lens, as defined in section 3.18.1 of ISO 13666:2019(E), wherein the coated spectacle lens is a lens to which one or more surface layers are added to modify one or more properties of the lens (3.5.2). The one or more surface layers may be selected from at least one of the following: a hard coating as defined in Section 3.18.2 of ISO 13666:2019(E), an anti-reflective coating as defined in Section 3.18.3 of ISO 13666:2019(E), a transparent coating as defined in Section 3.18.4 of ISO 13666:2019(E), a hydrophobic coating as defined in Section 3.18.5 of ISO 13666:2019(E), a hydrophilic coating as defined in Section 3.19.6 of ISO 13666:2019(E), an anti-fog coating as defined in Section 3.19.7 of ISO 13666:2019(E), and an antistatic coating as defined in Section 3.18.8 of ISO 13666:2019(E).

[0502] In a preferred embodiment of the invention, the dataset includes at least one of the following types of data: (i) a digital twin of the eyeglass lens configured to be fed to one or more manufacturing machines to manufacture the eyeglass lens; or (ii) data containing computer-readable instructions for controlling one or more manufacturing machines to manufacture the eyeglass lens; or (iii) a digital twin of the eyeglass lens for use in the manufacture of the eyeglass lens.

[0503] Preferably, the dataset includes at least one of the aforementioned types of computer-readable data. The digital twin of the eyeglass lens is configured for use in the manufacture of the eyeglass lens.

[0504] In a preferred embodiment of the invention, the dataset (i) is in the form of a computer-readable data signal, or (ii) is stored on a computer-readable medium, or (iii) includes computer-readable data, the dataset including at least one of the following types of data: (i) a digital twin of the eyeglass lens configured to be fed to one or more manufacturing machines to manufacture the eyeglass lens, or (ii) data containing computer-readable instructions for controlling one or more manufacturing machines to manufacture the eyeglass lens, or (iii) a digital twin of the eyeglass lens for use in the manufacture of the eyeglass lens.

[0505] The digital twin of the eyeglass lens is configured for use in the manufacture of the eyeglass lens.

[0506] In a preferred embodiment of the invention, the dataset includes at least one of the following types of data: (i) a digital twin of the eyeglass lens configured to be fed to one or more inkjet printers for inkjet printing of the eyeglass lens; or (ii) data containing computer-readable instructions for controlling one or more inkjet printers to inkjet print the eyeglass lens; or (iii) a digital twin of the eyeglass lens for use in inkjet printing of the eyeglass lens.

[0507] The digital twin of the eyeglass lens is configured to be used for inkjet printing of the eyeglass lens.

[0508] In a preferred embodiment of the invention, the dataset (i) is in the form of a computer-readable data signal, or (ii) is stored on a computer-readable medium, or (iii) includes computer-readable data, the dataset including at least one of the following types of data: (i) a digital twin of the eyeglass lens configured to be fed to one or more inkjet printers for inkjet printing of the eyeglass lens, or (ii) data containing computer-readable instructions for controlling one or more inkjet printers to inkjet print the eyeglass lens, or (iii) a digital twin of the eyeglass lens for using the digital twin for inkjet printing of the eyeglass lens.

[0509] The digital twin of the eyeglass lens is configured to be used for inkjet printing of the eyeglass lens.

[0510] Non-transitory tangible computer-readable storage media may include or carry datasets according to the four preferred embodiments above.

[0511] In a preferred embodiment of the invention, a dataset of computer-readable printing instructions is configured for inkjet printing of eyeglass lenses, the dataset being (i) stored on a computer-readable storage medium or (ii) transmitted via a data signal. The computer-readable storage medium may be a non-transitory tangible computer-readable storage medium. The non-transitory tangible computer-readable storage medium may include or carry the dataset. The dataset is intended for inkjet printing of eyeglass lenses.

[0512] The dataset includes printing instructions that have been generated as previously described. The dataset includes printing instructions that have been generated by: a) slicing the digital twin of the eyeglasses into a stack of layers, b) converting each layer in the stack into a spatial volume element pattern, and c) converting the spatial volume element pattern into printing instructions that, when executed by an inkjet printer, cause the inkjet printer to print the eyeglasses layer by layer using inkjet printing.

[0513] Every definition given in this application, especially every definition set in quotation marks, shall apply to the entire application.

[0514] Figure 1 A stacked structure of a digital twin of an eyeglass lens or an eyeglass lens is shown.

[0515] Figure 2 Wave optics simulation of light propagating through a sliced ​​digital twin stack of layers of a gradient-index spectacle lens is shown.

[0516] Figure 3 A flowchart is shown that visualizes a process with layer thickness deviations.

Claims

1. A computer-implemented method configured to calculate a digital twin (100) of an eyeglass lens for use in the manufacture of the lens, the digital twin having a predefined power distribution and comprising a stack of layers having a plurality of individual layers, each individual layer having a uniform refractive index and a spatially varying non-uniform layer thickness, the stack comprising individual layers having different uniform refractive indices. The method is characterized by the following steps - Determine the spatial variation of the layer thickness of the individual layers to achieve the predefined focal length distribution through spatial control of the optical path length. The spatial control of the optical path length enables the calculation of the digital twin of the lens, such that the optical path length of the stacked layers of the digital twin passing through the lens is equal to the optical path length passing through the digital twin at the same position or at the same discrete position.

2. The method according to claim 1, characterized in that, The stacked body includes - A first plurality of individual layers, each having a spatially varying non-uniform layer thickness and a first uniform refractive index. - A second plurality of individual layers, each having a spatially varying non-uniform layer thickness and a second uniform refractive index, the second uniform refractive index being different from the first uniform refractive index.

3. The method according to claim 2, characterized in that, The method includes at least one of the following steps: - Calculate the transition region between a first single layer having a first uniform refractive index and a second single layer having a second uniform refractive index, the transition region having a refractive index gradient. - Calculate the transition region between a second single layer having a second uniform refractive index and a first single layer having a first uniform refractive index, the transition region having a refractive index gradient.

4. The method according to any one of the preceding claims, characterized in that, The spatial variation of the layer thickness of a single layer includes a minimum layer thickness and a maximum layer thickness, the ratio of which is selected from at least one of the following: a) The ratio of minimum layer thickness to maximum layer thickness is at least 1:5; b) The ratio of minimum layer thickness to maximum layer thickness is at least 1:8; c) The ratio of minimum layer thickness to maximum layer thickness is at least 1:10; d) The ratio of minimum layer thickness to maximum layer thickness is at least 1:12; e) The ratio of minimum layer thickness to maximum layer thickness is at least 1:

15.

5. The method according to any one of claims 1 to 3, characterized by the following steps: - Determine the spatial variation such that the optical path length through a pair of (09) adjacent individual layers (10, 11) at each position is equal to the optical path length through the corresponding gradient refractive index layer, each of the adjacent individual layers (10, 11) having a different uniform refractive index from each other, and in the corresponding gradient refractive index layer, a gradient refractive index is given between the uniform refractive indices of the adjacent individual layers (10, 11).

6. The method according to any one of claims 1 to 3, characterized by the following steps: - Determine the spatial variation such that the form of the interface (02) is a linear combination of the shape of the front surface (01) of the lens and the shape of the rear surface (08) of the lens.

7. The method according to claim 6, characterized in that, - Consider the uniform refractive index of a single layer (10) and the different uniform refractive indices of adjacent single layers (11) with a common interface (03).

8. The method according to any one of claims 1 to 3, characterized in that... The following additional steps: - Determine the discrete x of a single layer m ,y m ,z m ... x n ,y n ,z n The actual value of the layer thickness at the location is the same discrete x as that of the individual layer. m ,y m ,z m ... x n ,y n ,z n The deviation of the default nominal value of the layer thickness at the location, and The sum of the deviation of the layer thickness and the actual value is determined (302), and it is characterized in that one of the following conditions applies: - When the sum is greater than half of the default nominal value of the layer thickness, the volume element is not positioned on the discrete x-axis of the individual layer. m+1 ,y m+1 ,z m+1 ... x n+1 ,y n+1 ,z n+1 Location (305); - When the sum is less than or equal to half of the default nominal value of the layer thickness, the volume element is positioned at a discrete x-axis on a separate layer. m+1 ,y m+1 ,z m+1 ... x n+1 ,y n+1 ,z n+1 Location (306).

9. The method according to claim 8, characterized in that... Select from at least one of the following steps: - Determine the discrete x of the individual layer after the positioning of the volume element. m+1 ,y m+1 ,z m+1 ... x n+1 ,y n+1 ,z n+1 The deviation of the default nominal value of the layer thickness at the location, and the distribution of the deviation to adjacent discrete x values ​​within the same individual layer. o+1 ,y o+1 ,z o+1 ... x p+1 ,y p+1 ,z p+1 Location (308); - Determine the discrete x of the individual layer after the positioning of the volume element. m+1 ,y m+1 ,z m+1 ... x n+1 ,y n+1 ,z n+1 The deviation of the default nominal value of the layer thickness at the location, and the transfer of the deviation to a discrete x-value separated by a single layer. m+2 ,y m+2 ,z m+2 ... x n+2 ,y n+2 ,z n+2 Location (309); - Determine the discrete x of the individual layer after the non-positioning of the volume element. m+1 ,y m+1 ,z m+1 ... x n+1 ,y n+1 ,z n+1 The deviation of the default nominal value of the layer thickness at the location, and the distribution of the deviation to adjacent discrete x values ​​within the same individual layer. o+1 ,y o+1 ,z o+1 ... x p+1 ,y p+1 ,z p+1 Location (308); - Determine the discrete x of the individual layer after the non-positioning of the volume element. m+1 ,y m+1 ,z m+1 ... x n+1 ,y n+1 ,z n+1 The deviation of the default nominal value of the layer thickness at the location, and the transfer of the deviation to a discrete x-value separated by a single layer. m+2 ,y m+2 ,z m+2 ... x n+2 ,y n+2 ,z n+2 Location (309).

10. The method according to any one of claims 1 to 3, further configured for manufacturing spectacle lenses.

11. An apparatus comprising a computer and an inkjet printer, said computer including a processor configured to perform the following steps: - Determine the spatial variation of the layer thickness of each individual layer in the stack to achieve a predefined power distribution of the digital twin of the spectacle lens through spatial control of the optical path length. Each individual layer has a uniform refractive index and a spatially varying non-uniform layer thickness; the stacked body comprises individual layers with different uniform refractive indices, and The spatial control of the optical path length enables the calculation of the digital twin of the lens, such that the optical path length of the stacked layers of the digital twin passing through the lens is equal to the optical path length passing through the digital twin at the same position or at the same discrete position.

12. A computer program product comprising a computer program including instructions that, when executed by a computer, cause the computer to perform the method according to any one of claims 1 to 9.

13. An eyeglass lens, manufactured according to a computer-implemented method according to any one of claims 1 to 10 and / or using the apparatus according to claim 11, the eyeglass lens having - Predefined focal length distribution, and - A stacked body having multiple individual layers, each having a uniform refractive index and a spatially varying non-uniform layer thickness, the stacked body comprising at least... The first plurality of individual layers, each having a spatially varying non-uniform layer thickness and a first uniform refractive index, The second plurality of individual layers each have a spatially varying non-uniform layer thickness and a second uniform refractive index, the second uniform refractive index being different from the first uniform refractive index. Its features are, The contribution of all interfaces between the first plurality of individual layers and the individual layers of the second plurality of individual layers to the predefined focal length distribution is within at least one range selected from: 5% to 25%, 10% to 20%, 12% to 18%.

14. The spectacle lens according to claim 13, characterized in that, The spatial variation is selected from one of the following spatial variations, including the minimum layer thickness and the maximum layer thickness: - At least 500% spatial variation; - At least 800% spatial variation; - At least 1000% spatial variation; - At least 1200% spatial variation; - At least 1500% spatial variation.

15. An eyeglass lens, manufactured according to a computer-implemented method according to any one of claims 1 to 10 and / or using the apparatus according to claim 11, the eyeglass lens having - Predefined focal length distribution, and - A layer stack having multiple individual layers, each having a uniform refractive index and a spatially varying non-uniform layer thickness, the layer stack comprising individual layers with different uniform refractive indices. Its features are, The ratio of the minimum layer thickness to the maximum layer thickness for each individual layer is selected from at least one of the following: a) The ratio of minimum layer thickness to maximum layer thickness is at least 1:5; b) The ratio of minimum layer thickness to maximum layer thickness is at least 1:8; c) The ratio of minimum layer thickness to maximum layer thickness is at least 1:10; d) The ratio of minimum layer thickness to maximum layer thickness is at least 1:12; e) The ratio of minimum layer thickness to maximum layer thickness is at least 1:

15.

16. A computer-readable storage medium having a dataset stored thereon, the dataset comprising at least one of the following types of data: (i) data containing computer-readable instructions for controlling one or more manufacturing machines to manufacture eyeglass lenses according to claim 13 or 15, or (ii) a digital twin of an eyeglass lens according to claim 13 or 15, the digital twin being configured to be used for manufacturing the digital twin of an eyeglass lens according to claim 13 or 15.

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