Method of providing refractive microstructures on surface of ophthalmic lens and ophthalmic lens design

Abstract

A method for providing refractive microstructures (5) on a surface (4) of a spectacle lens body (3) is provided. The refractive microstructures (5 ') are formed on the surface (4) by an additive manufacturing process, wherein the refractive microstructures (5) are formed by applying at least one curable material (6) and curing the at least one curable material (6). The additive manufacturing process comprises-forming a layer (1) of at least one first liquid or viscous curable material (6), in which in order to form the refractive microstructures (5), the at least one first liquid or viscous curable material (6) is cured or pinned before curing or pinning the at least one first curable material (6). Applying an additional amount of the at least one first curable material (6) or an amount of the at least one second liquid or viscous curable material (16) at the location where the refractive microstructures (5) are to be formed; and-before leveling the projections formed by the additional amount of the at least one first curable material (6) or the amount of the at least one second curable material (16) by a material transport process within a liquid or viscous material in the layer (1) of the at least one curable material (6), and curing or pinning the layer (1) of the at least one first curable material (6) with the additional amount of the at least one first curable material (6) or with the amount of the at least one second curable material (16). Furthermore, an ophthalmic lens with refractive microstructures (5) is provided. The spectacle lens comprises a spectacle lens body (3) having a surface (4) provided with the refractive microstructures (5). The refractive microstructures (5) are at least partially fused with the layer (1) present on the surface (4) and have refractive properties at least partially due to a refractive index gradient.

Description

[0001] The present invention relates to a method for providing refractive microstructures on the surface of a spectacle lens, in particular a spectacle lens for slowing down or stopping the progression of myopia, such as, for example, small lenses, annular focusing structures, structures with a refractive index profile, etc. In addition, the present invention relates to a spectacle lens design with microstructures, in particular a spectacle lens design for slowing down or stopping the progression of myopia.

[0002] Myopia has reached epidemic proportions in many East Asian countries, with some large urban centers reporting myopia prevalence approaching 100% among 18-19 year olds (Jung SK, Lee JH, Kakizaki H, et al., Prevalence of myopia and its association with body stature and educational level in 19-year-old male conscripts in Seoul, South Korea. Invest. Ophthalmol. Vis. Sci. 2012;53:5579-5583). It was estimated that there were approximately 2 billion myopic people worldwide in 2010, and some recent epidemiological models suggest that this number will increase to 5 billion by 2050 (Holden BA, Fricke TR, Wilson DA, et al., Global Prevalence of Myopia and High Myopia and Temporal Trends from 2000 through 2050. Ophthalmol. 2016, 123: 1036–1042). In addition, there is a growing trend of high myopia (defined as SER ≤ -5.00 D, where SER represents spherical equivalent refraction) among adolescents, which greatly increases the risk of eye diseases such as cataracts, glaucoma, retinal detachment, and myopic maculopathy, all of which can lead to irreversible vision loss (Wong TY, Ferreira A, Hughes R, et al. Epidemiology and disease burden of pathologic myopia and myopic choroidal neovascularization: an evidence-based systematic review. Am. J. Ophthalmol. 2014;157:9–25).Epidemiological models predict that the number of people with high myopia worldwide will increase from approximately 300 million in 2010 to 1 billion in 2050 (Holden et al., 2016). This will inevitably lead to very high costs to society in terms of treating visual impairment and lost productivity.

[0003] There are different approaches to slowing down or stopping the progression of myopia. In one approach, progressive multifocal lenses are used to reduce the work required to accommodate the eye and therefore reduce the stimulus for eye growth. Another approach is based on spectacle lenses where there are small lenses or ring structures outside the area of ​​the spectacle lens used for central vision. The small lenses or ring structures provide a focal power that results in peripheral myopic defocus outside of central vision. This will manipulate peripheral vision so that the stimulus for eye growth is reduced. For example, spectacle lenses with microstructures or small lenses or annular structures are disclosed in the following documents: CN 111796364 A, CN 104678572 A, EP 3 553 594 A1, EP 3 561 578A1, US2016 / 0054588 A1, US2017 / 0131567 A1, US 2017 / 027691A1, US10,571,717B2, WO 2018 / 026697 A1, WO 2018 / 076057A1, WO 2019 / 166657 A1, WO 2020 / 113212 A1, and WO 2021 / 059887A1. In particular, combining progressive multifocal lenses with small lenses yields a promising method for slowing down or stopping the progression of myopia.

[0004] The small lens of the spectacle lens can be produced, for example, by a casting or molding process, as disclosed, for example, in US10,571,717B2, EP 3 561 578 A1, EP 3 640 713 A1, EP 3 640 714A1, and WO 2019 / 166657 A1. However, while molding is manageable only for thermoplastic materials and therefore imposes restrictions on the materials that can be used for spectacle lenses with small lenses, casting with curable plastics is very difficult due to the exothermic curing process and the shrinkage accompanying curing, and in addition, casting is quite expensive. In addition, when a prefabricated semi-finished lens blank is used to manufacture the spectacle lens, it is difficult to mold or cast the spectacle lens with a small lens because it is difficult to mold or cast the small lens onto such a lens blank. Molding or casting a small lens already in a semi-finished lens blank does not help because the position of the zone with the small lens cannot be re-optimized for the finished spectacle lens.

[0005] US2021 / 0001578 A1 describes a light modifier comprising printed optical elements for vehicle lights. These optical elements are printed layer by layer on a translucent substrate, wherein each layer is cured before printing the next layer. However, the printing method described in US2021 / 0001578 A1 is not suitable for printing small lenses, etc., on the surface of eyeglass lenses intended to slow down or stop the progression of myopia, because the small lenses, etc. that need to be printed on the surface of such eyeglass lenses are too small to print them layer by layer.

[0006] Methods for providing small lenses without using a molding or casting process are disclosed in CN 111796364 A, EP 3 553 594 A1, WO 2018 / 026697 A1 and 2018 / 076057 A1. Specifically, CN 111796364 A discloses the production of small lenses by using foils, while EP 3553 594 A1, WO 2018 / 026697 A1 and WO 2018 / 076057 A1 disclose the manufacture of small lenses by additive manufacturing (like inkjet printing). Specifically, WO 2018 / 026697 A1 discloses a printing method in which droplets of uncured printing material are sprayed onto the surface of an eyeglass lens using a commercially available inkjet printer. Upon contact with the lens surface, the droplets wet the surface, thereby forming uncured protrusions. The final small lenses are formed by curing these protrusions using ultraviolet light. However, such printed lenses usually have very high power, about 100 dpt or more, an order of magnitude higher than the power desired for eyeglass lenses used to slow or stop myopia progression. Therefore, it is very difficult to print lenses with appropriate power using standard additive manufacturing equipment.

[0007] WO 2021 / 214197 A1, WO 2021 / 209527 A1, and US 2021 / 0354409 A1 disclose spectacle lenses comprising refractive microstructures in the form of small lenses that are at least partially fused to a layer present on the surface. In WO 2021 / 214197 A1 and WO 2021 / 209527 A1 it is disclosed that the line is a progressive spectacle lens.

[0008] With respect to WO 2018 / 026697 A1, a first object of the present invention is to disclose a method for providing a refractive microstructure on the surface of an eyeglass lens, which method allows to achieve the appropriate focal power of the refractive microstructure while using standard additive manufacturing equipment (i.e., commercially available printers).

[0009] Relative to WO 2021 / 214197 A1, a second object of the present invention is to disclose an eyeglass lens design having a refractive microstructure of appropriate focal power in a layer present on the surface, which eyeglass lens design can be manufactured with standard additive manufacturing equipment and which layer allows improving the adhesion and / or long-term stability of subsequent layers.

[0010] The first object is achieved by a method for providing a refractive microstructure on the surface of a spectacle lens as claimed in claim 1. The second object is achieved by a spectacle lens design as claimed in claim 16. The dependent claims define further developments of the invention.

[0011] Eyeglass lens body

[0012] In the context of the present invention, the term "spectacle lens body" refers to a spectacle lens used as a substrate on which a refractive microstructure is formed. The spectacle lens body may be a spectacle lens manufactured to provide vision correction properties according to a prescription. The spectacle lens body may be a standard spectacle lens produced in batches and providing standardized correction, or it may be a personalized spectacle lens produced for an individual wearer to provide personalized correction according to the wearer's prescription, which may occur in particular when the spectacle lens is a progressive multifocal lens (PAL). As an alternative, the spectacle lens body may be a spectacle lens for virtual reality (VR) glasses or augmented reality (AR) glasses that provide or do not provide correction. In addition, the spectacle lens body may be a semi-finished lens blank, that is, a lens blank: one surface of which has been polished to its final shape, while the other surface is to be machined and polished to achieve the vision correction properties according to the prescription. In the case where the spectacle lens body is a semi-finished lens blank, the refractive microstructure will be applied to the finished finished surface.

[0013] Additive Manufacturing Process

[0014] In the context of the present invention, the term "additive manufacturing process" refers to a process of forming a three-dimensional object by depositing material onto a substrate according to a digital 3D model. A three-dimensional object is typically formed by depositing material layer by layer until the three-dimensional object is complete. In the context of the present invention, an additive manufacturing process is a 3D printing process that uses a curable ink material (i.e., the ink material is cured or cross-linked).

[0015] Nozzle arrangement

[0016] As used throughout this specification, the nozzle arrangement includes at least one nozzle for ejecting a curable material toward a surface. Typically, the nozzle arrangement is a part of a printhead and includes a one-dimensional nozzle array (i.e., a row of nozzles) or a two-dimensional nozzle array. The two-dimensional nozzle array may include at least two rows of nozzles. These multiple rows of nozzles may be aligned with each other, or adjacent rows of nozzles may be displaced relative to each other along the direction in which each row extends, the distance of the displacement being a fraction of the distance between adjacent nozzles in a row, thereby realizing a staggered arrangement of multiple rows of nozzles.

[0017] layer

[0018] In the context of the present invention, the term "layer" refers to a certain amount of material covering a surface or extending between two surfaces. A layer can be structured, for example by including openings in the layer, as long as it covers a lateral area on the surface whose size is at least one order of magnitude greater and typically at least two orders of magnitude greater than the thickness of the material covering the surface.

[0019] Basal layer

[0020] In the context of the present invention, the term "base layer" refers to a layer that is applied to the surface of the eyeglass lens in a first pass of additive manufacturing (e.g., in a first pass of nozzle arrangement), to which additional material is added at specific locations in a second pass of the additive manufacturing process (e.g., in a second pass of nozzle arrangement) to form a refractive microstructure.

[0021] Covering

[0022] In the context of the present invention, the term "covering layer" refers to a layer which covers the refractive microstructure and, if applicable, the substrate layer.

[0023] Curable Materials

[0024] In the context of the present invention, the term "curable material" refers to a liquid or viscous monomer or prepolymer material or formulation that can solidify or undergo polymerization and crosslinking processes to form a polymer material. The polymerization and crosslinking reactions can be induced, for example, by ultraviolet radiation, heat, catalysts, etc.

[0025] Curing

[0026] In the context of the present invention, the term "curing" shall refer to solidifying, polymerizing or crosslinking a curable material, such as a monomer or prepolymer formulation. The polymerization or crosslinking reaction may or may not require an initiator or catalyst to initiate the polymerization and crosslinking reactions. The initiator can be activated by an external stimulus, such as electromagnetic radiation, a particle beam or heat.

[0027] Pinning

[0028] In the context of the present invention, the term "pinning" shall refer to a process that results in a polymerization and / or cross-linking level lower than that after full curing, yet still greatly increases the viscosity of the polymer material so as to prevent a significant amount of material from flowing on a time scale greater than (preferably at least twice, more preferably at least five times) the time scale required to complete the desired structure. Reduced polymerization and / or cross-linking can be achieved, for example, by reduced stimulation (e.g., reduced electromagnetic radiation intensity or heat intensity) or by reduced stimulation duration. In addition, the term "pinning" shall also include the following situation: a thin surface layer having a thickness of less than 3 μm, preferably less than 1 μm, and even more preferably less than 0.5 μm does not undergo cross-linking or undergoes cross-linking that is insufficient to prevent significant material from flowing on a time scale greater than the time scale required to complete the desired structure, while the layer below the surface layer undergoes cross-linking that is sufficient to prevent significant material from flowing on a time scale greater than the time scale required to complete the desired structure. For example, some curable materials do not undergo cross-linking in the presence of oxygen. Due to oxygen inhibition, the surface layer of such a material (also referred to as the oxygen inhibition layer) will not undergo polymerization or will not fully undergo polymerization, while the bulk undergoes more polymerization until the maximum achievable cure level is reached. With such a curable material, complete or partial removal of oxygen from the surrounding atmosphere or the use of a protective atmosphere (such as an inert gas atmosphere, like a nitrogen atmosphere, a carbon dioxide atmosphere, or a rare gas atmosphere) will allow complete crosslinking rather than pinning.

[0029] Droplets

[0030] In the context of the present invention, the term "droplet" refers to a volume of liquid below 200 pl dispensed by inkjet printing or similar techniques. For printing complex refractive microstructures, smaller volumes would be advantageous, for example, 50 pl or less.

[0031] Refractive microstructure

[0032] In the context of the present invention, the term "refractive microstructure" refers to a structure that provides a focal power in addition to that provided by the main body of the spectacle lens. The focal power may be an optical power so as to provide a point or line focus. The line focus need not extend along a straight line but may also extend along a curved line, such as a circular line. However, the refractive microstructure does not necessarily need to provide a point or line focus, as long as it changes the curvature or direction of the incident wavefront more than the main body of the spectacle lens.

[0033] Rheological properties

[0034] In the context of the present invention, the term "rheological properties" refers to the flow characteristics of a liquid.

[0035] Surface energy

[0036] In the context of the present invention, the term "surface energy" refers to the amount by which intermolecular bonds are broken when a surface is created.

[0037] Surface tension

[0038] In the context of the present invention, the term "surface tension" refers to the tendency of a stationary liquid surface to contract in order to achieve the smallest possible surface area.

[0039] Convection / convection speed

[0040] In the context of the present invention, the term "convection" refers to the directional bulk flow of a material within a fluid that occurs, for example, due to temperature differences or a driving force. The driving force may be, for example, the tendency of the surface of a liquid or viscous material to reduce surface tension by flattening surface structures protruding from the surface. "Convection velocity" is the velocity of the flowing material.

[0041] Coalescence

[0042] In the context of the present invention, the term "coalescence" refers to the process by which surface protrusions of a liquid or viscous material are flattened by a material transport process within the liquid or viscous material.

[0043] diffusion

[0044] In the context of the present invention, the term "diffusion" refers to the gradient-driven movement of molecules or particles in a fluid, which movement flattens the gradient (e.g., concentration gradient) over time. A typical example is the random movement of molecules or particles (like, for example, monomers or other kinds of molecules) in a two-phase system of miscible fluids, which movement flattens over time the gradient in concentration of the two phases initially present in the fluid.

[0045] Atmospheric humidity

[0046] In the context of the present invention, the term "atmospheric humidity" refers to the water content of the atmosphere.

[0047] Atmospheric composition

[0048] In the context of the present invention, the term "atmospheric composition" refers to the relative amounts of gases that form the atmosphere.

[0049] Surfactants

[0050] In the context of the present invention, the term "surfactant" refers to a substance that controls the surface tension of a liquid.

[0051] protrude

[0052] In the context of the present invention, the term "protrusion" refers to a structure that emerges from a surface.

[0053] Refractive Index

[0054] In the context of the present invention, the term "refractive index" of a material refers to the ratio of the propagation speed of monochromatic radiation with a given wavelength in a vacuum to the propagation speed of said monochromatic radiation in the material (cf. DIN ISO 13666:2019, Section 3.1.5). The given wavelength may be, for example, 587.6 nm (helium d-line).

[0055] In the context of the present invention, two refractive indices are considered to be different refractive indices if they differ from each other by at least 5 parts per thousand, preferably at least 1 part per thousand. On the other hand, two refractive indices are considered to be the same if they differ from each other by no more than 5 parts per thousand, preferably no more than 1 part per thousand.

[0056] Focal Power

[0057] In the context of the present invention, the term "focal power" refers to the ability of a lens or an optical surface to change the curvature or direction of an incident wavefront by refraction (DIN ISO 13666:2019, section 3.1.10). The term "optical power" is a collective term for the spherical vertex power of a spectacle lens, which brings a paraxial parallel beam to a single focus and which is usually considered in prescriptions with the "spherical" value or the abbreviation "sph", and the cylindrical vertex power, which brings a paraxial parallel beam to two separate focal lines at right angles to each other (DIN ISO 13666:2019, section 3.10.2) and which is usually considered in prescriptions with the "cylindrical" value or the abbreviation "cyl". The "vertical power" is the reciprocal of the paraxial vertex focal length (DIN ISO 13666:2019, section 3.10.7). Within the scope of the present description, a beam is considered to be a paraxial beam of rays if its diameter does not exceed 0.05 mm, in particular 0.01 mm.

[0058] Myopia Defocus

[0059] In the context of the present invention, the term "myopic defocus" refers to a situation where light is focused at such a distance in front of the fovea that a focused image cannot be achieved on the fovea even with the help of accommodation. Peripheral myopic defocus is myopic defocus that occurs outside the visual field beyond the fovea.

[0060] Additional power

[0061] In the context of the present invention, the term "additional power" applies to the power added to the optical power of a spectacle lens, wherein the optical power of the spectacle lens will provide a focused image on the fovea with the help of accommodation, and when added to the optical power of the spectacle lens, the additional power provides myopic through focus. This additional power must not be confused with the lower addition of a progressive multifocal lens.

[0062] Progressive multifocal lenses

[0063] In the context of the present invention, the term "progressive multifocal lens" applies to a power-changing lens with two power reference points that are typically designed to provide correction for presbyopia and clear vision at distance and near (DIN ISO 13666:2019, section 3.7.8), wherein a power-changing lens is a spectacle lens with a smooth power change without discontinuities over part or all of its area, which is designed to provide more than one power (DIN ISO 13666:2019, section 3.7.7).

[0064] Ring

[0065] In the context of the present invention, a structure shall be considered to be "annular" if there is a continuous path within the structure which surrounds an unstructured area, or if the structure consists of substructures distributed along a path which surrounds an unstructured area.

[0066] Ring focusing structure

[0067] In the context of this specification, the term "annular focusing structure" applies to structures providing an annular focal line as well as structures providing a plurality of (eg equidistantly arranged, preferably mainly linear or point-shaped) focal points along the annular line. Such annular focusing structures may, for example, comprise structures similar to those described in EP 3 553 594 A1, EP 3 561 578 A1, WO 2019 / 166653 A1, WO 2019 / 166654 A1, WO 2019 / 166655 A1, WO 2019166657 A1, WO 2019 / 166659 A1 and WO 2019 / 206569 A1, or structures similar to those described in US 2016 / 054588 A1, US 2017 / 227788 A1, US 2017 / 276961 A1, US 2019 / 227342 A1, WO 07 / 041796 A1, WO 09 / 129528 A1 or WO Structures similar to those disclosed in 10 / 129465A1.

[0068] Glasses lenses

[0069] In the context of this specification, a spectacle lens is an ophthalmic lens that is worn in front of the eye but not in contact with the eye (DIN ISO 13666:2019, section 3.5.2), where an ophthalmic lens is a lens intended for measuring, correcting and / or protecting the eye, or for changing its appearance (DIN ISO 13666:2019, section 3.5.1).

[0070] Actual wearing position

[0071] In the context of this specification, the "actual wearing position" is the position (including orientation) of the spectacle lens relative to the eye and face during wearing (DIN ISO 13666:2019, Section 3.2.36). The actual wearing position is determined by the actual wearing anteversion angle, the actual wearing bezel facial curvature, and the vertex distance. The actual wearing anteversion angle is the vertical angle between the horizontal direction and the perpendicular direction of a reference line passing through the vertices of the grooves of the upper and lower rings of the frame in a vertical plane containing the principal direction, wherein the principal direction is the direction of the line of sight to an object at infinity measured with the naked eye looking straight ahead in a habitual head and body posture (generally taken as the horizontal direction) (DIN ISO 13666:2019, section 3.2.25), and the line of sight is the path of the ray from the point of interest (i.e. the point of fixation) 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 point of fixation (generally the fovea) on the retina (DIN ISO 13666:2019, section 3.2.24). Typical values ​​of the actual wearing anteversion angle lie in the range between -20 degrees and +30 degrees. The actual wearing bezel face curvature is the horizontal angle between the main direction and the perpendicular direction of a reference line passing through the apex of the grooves of the nasal bezel and the temporal bezel of the frame in a horizontal plane containing the main direction (DIN ISO 13666:2019, Section 3.2.38). Typical values ​​of the actual wearing bezel face curvature are in the range between -5 degrees and +30 degrees. The vertex distance is the horizontal distance between the back surface of the spectacle lens and the vertex of the cornea measured when the eye is in the first eye position (DIN ISO 13666:2019, Section 3.2.40), wherein the first eye position is the position of the eye when looking in the main direction (DIN ISO 13666:2019, Section 3.2.26). Typical values ​​of the vertex distance are in the range between 5 mm and 30 mm. The actual wearing position can be an individual actual wearing position determined for a specific individual, or a general actual wearing position determined for a defined group of wearers.

[0072] Glasses lens design

[0073] In the context of this specification, the term "spectacle lens optical design" is used to denote the calculated / predetermined or defined optical properties of a spectacle lens, typically for a predetermined specific wearer, taking into account the position / arrangement of the spectacle lens relative to the eye model of the spectacle lens wearer, the position / arrangement of the model of objects to be viewed by the spectacle lens wearer under specific conditions of use of the spectacle lens, and the physiological visual property model of the spectacle lens wearer.

[0074] In particular, the spectacle lens optical design may comprise a power distribution over an active area of ​​the spectacle lens, which power distribution is perceived by an intended wearer of the spectacle lens in a predetermined actual wearing position relative to the wearer's (model) eye and a predetermined object distance model. The power distribution is calculated based on the distance and orientation of the spectacle lens relative to the model eye, the distance and orientation of the spectacle lens relative to the model object, and physiological parameters of the spectacle wearer, such as the wearer's visual defects, i.e., for example, the wearer's refractive error, the wearer's accommodation ability and the wearer's pupil distance.

[0075] The term "spectacle lens geometry" refers to the geometric shape of a spectacle lens which provides the above-mentioned calculated spectacle lens optical properties for the spectacle wearer.

[0076] The term "spectacle lens target optical design" refers to a draft spectacle lens optical design, the optical properties of which correspond to or are equal to the target optical properties. The term "spectacle lens actual optical design" refers to the calculated spectacle lens optical properties obtained as a result of an optimization process / calculation, which aims to achieve the spectacle lens target optical design as closely as possible. Such optimization processes / calculations, in particular for progressive spectacle lenses or customized single-vision lenses, are disclosed, for example, in: Werner Konzeption und Entwicklung von Deutsche OptikerZeitung, DOZ 10 / 95, pp. 42-46.

[0077] Such a spectacle lens optical or geometrical design may be stored on a computer-readable (eg non-transitory and / or electronic and / or optical) data carrier. Furthermore, a spectacle lens manufactured according to the spectacle lens design may be considered as a physical representation of the spectacle lens design.

[0078] The following outlines the basic steps of an example of a method for designing eyeglass lenses:

[0079] In a first step, individual user data or application data of the glasses wearer are recorded. This includes obtaining (physiological) data that can be assigned to the glasses wearer and obtaining the usage conditions when the glasses wearer will wear the glasses to be designed.

[0080] Physiological data of the spectacle wearer may include, for example, the refractive error of the wearer and the accommodative ability of the wearer, which are determined by means of refraction measurement and are regularly included in the prescription in the form of prescription values ​​for spherical power, cylindrical power, (if applicable) axis position, prism power, and base curvature and lower addition (if the spectacle lenses are progressive multifocal lenses). In addition, for example, pupil distance and pupil size are determined under different lighting conditions. The convergence behavior of the eye is derived from the pupil distance for different viewing directions and object distances.

[0081] These conditions of use include the actual wearing position of the spectacle lens in front of the eye (usually relative to the rotation center of the eye) and the object distance at which the spectacle wearer should see clearly for different viewing directions. For example, the placement of the spectacle lens in front of the eye can be determined by recording the corneal vertex distance as well as the anteversion and lateral tilt angles. These data are included in the object distance model, to which the ray tracing method can be applied.

[0082] In a subsequent step, a spectacle lens design draft with a large number of evaluation points is determined based on these recorded data. The design draft includes the target optical properties of the spectacle lens at the corresponding evaluation points. The target properties include, for example, the permissible deviations of the prescription spherical power and astigmatism distributed over the entire spectacle lens taking into account the lower addition, as specified by arranging the lens in front of the eye and by the basic distance model.

[0083] Furthermore, the design of the surface geometry of the front and rear surfaces and the design of the refractive index distribution over the entire spectacle lens is specified. For example, the front surface can be selected as a spherical surface and the rear surface as a varifocal surface. Both surfaces can also be initially selected as spherical surfaces. The choice of the surface geometry of the first draft usually only determines the convergence (speed and success) of the optimization method used. It should be assumed, for example, that the front surface is to retain a spherical shape, while the rear surface is to be given the shape of a varifocal surface.

[0084] In a further step, the paths of the chief rays are determined by a large number of evaluation points. It is possible that in the vicinity of each chief ray a local wavefront can be established for the respective chief ray. Design and Development of Progressive Lenses, Deutsche OptikerZeitung, DOZ 10 / 95, pp. 42-46, the number of evaluation points is usually in the range of 1000 to 1500. EP 2 115 527 B1 recommends more than 8000 evaluation points. Although the refractive index is usually dependent on the wavelength, the dispersion is usually not taken into account and the calculation is performed for the so-called design wavelength. However, it cannot be ruled out that the optimization process takes different design wavelengths into account, as described, for example, in EP 2 383 603 B1.

[0085] In a subsequent step, the above-mentioned optical properties of the spectacle lens at the respective evaluation point are determined by evaluating the influence of the spectacle lens on the beam path of the chief ray and, if necessary, evaluating the local wavefront in the vicinity of the evaluation point.

[0086] In a further step, the design of the spectacle lens is evaluated depending on the determined optical properties and the individual user data. The back surface geometry and, where appropriate, the refractive index profile of the spectacle lens design can be modified by minimizing an objective function, e.g.

[0087]

[0088] Where P m Represents the weight at the evaluation point m, W n represents the weight of the optical property n, T n represents the target value of the optical characteristic n at the corresponding evaluation point m, and A n represents the actual value of the optical characteristic n at the evaluation point m.

[0089] In other words, the local surface geometry of the back surface and, as the case may be, the local refractive index of the spectacle lens in the corresponding visual beam path is modified by the evaluation point until the stop criteria are met.

[0090] Indication of eyeglass lens design

[0091] In the context of the present invention, the expression "representation of a spectacle lens design" refers to an implementation of a spectacle lens with corresponding design features (physical representation of a spectacle lens design) or to a numerical data set describing the design features (numerical representation of a spectacle lens design). For example, such a data set may be stored in a memory of a computer or on a computer-readable (in particular non-transitory) storage medium. In addition, the data set may be retrieved from a data network, such as from the Internet or a local area network (LAN). In particular, a data set similar to the representation of a progressive spectacle lens design may comprise a description of the geometry and medium of the progressive spectacle lens. Such a description may, for example, comprise a mathematical description of the front surface, the back surface, the arrangement of these surfaces relative to each other (including thickness) and the edge definition of the progressive spectacle lens, as well as the refractive index profile of the medium used to make the spectacle lens. The representation may be in coded form or even in encrypted form. The term "medium" here refers to the material(s) or substance(s) from which the spectacle lens is made.

[0092] According to a first aspect of the invention, there is provided a method for providing a refractive microstructure on a surface of a spectacle lens body, wherein the refractive microstructure is formed on the surface by an additive manufacturing process, wherein the refractive microstructure is formed by applying at least one curable material and curing the at least one curable material. The refractive microstructure may be implemented as a small lens, an annular focusing structure, a structure with a refractive index profile, or any other structure that provides a focal power in addition to the focal power provided by the spectacle lens body. Furthermore, the surface of the spectacle lens body may be the surface of a progressive multifocal lens.

[0093] According to the present invention, the additive manufacturing process comprises: forming a layer of at least one first liquid or viscous curable material, wherein in order to form a refractive microstructure, an additional amount of the at least one first curable material or an amount of at least one second liquid or viscous curable material is applied to the location where the refractive microstructure is to be formed before curing or pinning the at least one first curable material. In addition, the additive manufacturing process comprises: curing or pinning the layer of the at least one first curable material with the additional amount of the at least one first curable material or with the amount of the at least one second curable material before flattening the protrusion formed by the additional amount of the at least one first curable material or the amount of the at least one second curable material by a material transfer process within the liquid or viscous material in the layer of the at least one curable material.

[0094] Where the additive manufacturing process is a printing process, the amount of the at least one first curable material or the amount of the at least one second curable material applied to a location on the surface may be set by the number of droplets of curable material applied to said location.

[0095] Due to the fact that the at least one first curable material of the additional amount or the at least one second curable material of the amount is applied before curing or pinning the at least one first curable material, a surface protrusion with an approximate spherical curvature in at least one direction and / or a concentration gradient is developed at the position where the refractive microstructure should be formed. After applying the at least one first curable material of the additional amount or the at least one second curable material of the amount, these protrusions and / or these concentration gradients immediately begin to coalesce after the at least one first curable material of the additional amount or the at least one second curable material of the amount has been applied. This coalescence makes the layer surface leveled over time at the position where the at least one first curable material of the additional amount or the at least one second curable material of the amount has been applied, and therefore makes the approximate spherical curvature flattened, and / or makes the concentration gradient at the position where the at least one first curable material of the additional amount or the at least one second curable material of the amount has been applied reduce. Flattening the curvature of the approximate spherical surface (i.e., increasing the radius of curvature) and / or reducing the concentration gradient allows the use of curvature or pinning, so that after curing or pinning, the desired degree of curvature and / or the desired concentration gradient can be achieved. Then, the resulting curvature and / or concentration gradient form a microstructure with a desired refractive power. The aggregation of the at least one first curable material of the additional amount or the at least one second curable material of the amount reduces the curvature and / or the concentration gradient, and therefore reduces the refractive power provided at the position where the refractive microstructure should be formed. Therefore, the desired refractive power can be achieved by stopping the aggregation at the right time point by means of the curing or pinning process.

[0096] In addition, in the case of using at least one second curable material, the use of the at least one second curable material allows the coalescence speed to be influenced by selecting a suitable material combination for the at least one first curable material and the at least one second curable material. In addition, the refractive index of the at least one first curable material may be different from the refractive index of the at least one second curable material. In this context, different refractive indices should be refractive indices that differ from each other by at least 5 thousandths, preferably at least 1 percent. In the case of miscible first and second curable materials, this allows the refractive power of the refractive microstructure to be based on a refractive index gradient, instead of or in addition to the surface geometry of the layer applied to the surface of the eyeglass lens body. In order for the refractive power of the refractive microstructure to be based on a refractive index gradient, it is preferred that the refractive index of the at least one first curable material is less than the refractive index of the at least one second curable material. In particular, the refractive index of the at least one first curable material may be at least 5 thousandths, preferably at least 1 percent less than the refractive index of the at least one second curable material. By making the refractive power at least partially based on the refractive index gradient, positive refractive power can be achieved with refractive microstructures, which protrude less from the surface than when their refractive power is based only on their geometry, which allows the resulting surface morphology to be relatively flat. If the refractive index of the at least one second curable material is significantly higher than the refractive index of the at least one first curable material, it is even possible to have positive refractive power in the case of depressions at the positions of the refractive microstructures in the layer surface. For example, the formation of a flat morphology or depression can be promoted by applying a certain amount of the at least one first curable material that is smaller than the amount of the at least one first curable material applied to other positions to the position where the refractive microstructure should be formed on the surface of the eyeglass lens body, and the at least one second curable material of this amount is preferably applied only to the position where the refractive microstructure should be formed. In the case of immiscible first and second curable materials, the second material will be partially immersed in the first curable material, thereby producing a biconvex structure. When the first and second curable materials with suitable properties (including, for example, surface tension and density) are selected, this effect can be used to form a biconvex small lens with a desired surface shape.

[0097] When the refractive power of the refractive microstructure is based at least in part on the difference in refractive index between the at least one first curable material and the at least one second curable material, the refractive power of the refractive microstructure can be at least in part determined by the extent of mutual diffusion of the at least one first curable material and the at least one second curable material before the layer of the at least one first curable material having the amount of the at least one second curable material is cured or pinned.

[0098] On the other hand, in the case where the refractive power should be based only on the surface geometry, either an additional amount of the at least one first curable material can be applied at the location where the refractive microstructure should be formed, or the at least one first curable material and the at least one second curable material can have the same refractive index. In this context, two refractive indices are considered to be the same if they differ from each other by no more than 5 parts per thousand, preferably no more than 1 part per thousand. In this case, the focal power provided by the refractive microstructure is not affected by the diffusion of the at least one second curable material into the at least one first curable material, so that the focal power of the refractive microstructure is mainly determined by its surface geometry.

[0099] In the method of the present invention for providing a refractive microstructure on the surface of an eyeglass lens body, the layer of the at least one first curable material with the additional amount or the at least one second curable material with the additional amount can be formed in a single step, for example in a single pass of the nozzle arrangement in the case of inkjet printing. This can be achieved, for example, by varying the number of droplets of curable material applied to different locations of the surface. As an alternative, the layer of the at least one first curable material with the additional amount or the at least one second curable material with the additional amount can be formed in a multi-step process. For example, in a first step of an additive manufacturing process, such as in a first pass of the nozzle arrangement, a continuous substrate layer can be applied to the surface of the eyeglass lens body by using the at least one first curable material. Then, in a second step of the additive manufacturing process, such as in a second pass of the nozzle arrangement, the additional amount of the at least one first curable material or the amount of the at least one second curable material is applied to the location of the substrate layer where the refractive microstructure should be formed when the at least one first curable material of the substrate layer has not yet been cured or pinned. The substrate layer applied in the first step does not necessarily need to have a uniform thickness. In particular, the base layer can be thinner at locations where the refractive microstructures are to be formed than at other locations. In both variants, the geometry of the refractive microstructures can be determined by varying the number of droplets applied to different locations. This allows giving the refractive microstructures any desired shape. For example, the distribution of the applied droplets of curable material can be selected so that the droplets merge into spherical or annular refractive microstructures.

[0100] In order to appropriately set the focal power provided by the refractive microstructure, at least one of the following parameters may be used:

[0101] - The time before curing or nailing begins.

[0102] - giving time to the at least one first curable material to cure or be pinned, or giving time to the at least one first curable material and the at least one second curable material to cure or be pinned, after curing or pinning has started.

[0103] - an additional amount of the at least one first curable material or an amount of the at least one second curable material applied at locations where refractive microstructures are to be formed.

[0104] - the rheological properties of the at least one first curable material, or the rheological properties of the at least one first curable material and the at least one second curable material.

[0105] - a combination of the surface energies of the at least one first curable material and the material of the spectacle lens body, or a combination of the surface energies of the at least one first curable material and the at least one second curable material and the material of the spectacle lens body.

[0106] - A combination of the surface tensions of the at least one first curable material and the at least one second curable material.

[0107] - the convection velocity of the at least one first curable material, or the convection velocity of the at least one first curable material and the second curable material.

[0108] -Temperature differences during the additive manufacturing process.

[0109] -Temperature of the nozzle arrangement during the additive manufacturing process.

[0110] -The temperature of the spectacle lens body during the additive manufacturing process.

[0111] -Atmospheric temperature during the AM process.

[0112] -Atmospheric humidity during the AM process.

[0113] -Atmospheric composition during the additive manufacturing process.

[0114] -The strength of the external electric or magnetic field present during the additive manufacturing process.

[0115] - the density of the at least one first curable material, or the density of the at least one first curable material and the at least one second curable material.

[0116] - the chemical composition of the at least one first curable material, or the chemical composition of the at least one first curable material and the at least one second curable material.

[0117] Some formulations of curable materials relate to initiators for starting polymerization reactions. In addition, there are curable material formulations with initiators, which require stimulation to be activated in order to induce curing or pinning reactions. This activation can be provided by heat, particle beams or electromagnetic radiation (such as ultraviolet radiation). Therefore, whether there is an initiator in the chemical composition of the curable material formulation and how many initiators there are will affect the speed of, for example, polymerization and / or crosslinking and how fast polymerization and / or crosslinking start after stimulating the initiator (for example, by irradiating the initiator with ultraviolet radiation).

[0118] A surfactant may be added to at least one of the at least one first curable material and the at least one second curable material in order to control the surface tension and flow behavior of at least one of these materials.

[0119] All of the above parameters affect the coalescence of the additional amount of the at least one first curable material, and / or the coalescence and formation of the at least one second curable material of the amount, and / or the diffusion of the at least one second curable material of the amount, and thus affect the final morphology and / or material distribution at the location of the refractive microstructure. The morphology and / or material distribution will determine the focal power of the refractive microstructure in the case where the at least one first curable material and the at least one second curable material have different refractive indices. Therefore, the method of the present invention provides a large number of parameters for setting the focal power of the refractive microstructure.

[0120] In the inventive method, the additive manufacturing process may comprise the following steps: a covering layer is applied to the layer of the at least one first curable material with the at least one first curable material of the at least one second curable material of the amount. The covering layer can be applied, for example, by inkjet printing or by coating technology (such as spin coating). And, the lamination process of the foil with adhesive in the case of with or without the help of bonding layer can be used. In addition, a covering layer can be applied after curing or pinning the layer of the at least one first curable material with the at least one first curable material of the at least one second curable material of the amount, to avoid undesirably affecting the application process of applying a covering layer on the at least one first curable material layer with the at least one first curable material of the at least one second curable material of the amount.

[0121] A sufficiently thick cover layer allows the surface to follow the surface of the eyeglass lens body without the microstructure protruding from the surface of the finished eyeglass lens. In addition, a protective layer or other functional layer can be applied as a cover layer or applied to the cover layer, which improves the usability of the eyeglass lens. In addition, the focal power of the refractive microstructure can be at least partially determined by the ratio of the refractive index of the cover layer material to the refractive index of the at least one first curable material or the at least one second curable material. Therefore, selecting the refractive index of the cover layer material in view of the refractive index of the at least one first curable material or the at least one second curable material provides an additional parameter for determining the focal power of the refractive microstructure. The refractive index of the cover layer material is preferably less than the refractive index of the at least one first curable material or the at least one second curable material, so that a positive focal power can be provided by the refractive microstructure. In particular, the refractive index of the cover layer material can be at least 5 thousandths, preferably at least 1 percent less than the refractive index of the at least one first curable material or the at least one second curable material. However, in principle, the cover layer material can also have a refractive index greater than the refractive index of the at least one first curable material or the at least one second curable material. In particular, the refractive index of the cover layer material may be at least 5 thousandths, preferably at least 1 percent greater than the refractive index of the at least one first curable material or the at least one second curable material. In this case, even if the refractive microstructure has a concave curvature, a positive power may be provided.

[0122] In the method according to the invention, the at least one first curable material may have the same refractive index as the material of the spectacle lens body, which prevents the formation of a refractive interface between the spectacle lens body and the layer in which the refractive microstructure is embedded. However, the refractive index of at least one of the first curable material and the at least one second curable material may also be greater than the refractive index of the material of the spectacle lens body. In particular, the refractive index of at least one of the first curable material and the at least one second curable material may be at least 5 thousandths, preferably at least 1 percent greater than the refractive index of the material of the spectacle lens body.

[0123] According to a second aspect of the invention, a spectacle lens with a refractive microstructure is provided. The spectacle lens comprises a spectacle lens body having a surface, the surface being provided with a refractive microstructure. The refractive microstructure is at least partially fused with a layer present on the surface and has refractive properties at least partially or even completely due to a refractive index gradient present in the refractive microstructure.

[0124] In the spectacle lens of the present invention, the spectacle lens body can be the spectacle lens body of a progressive multifocal lens. Combining a refractive microstructure with a progressive multifocal lens is particularly effective in slowing down or stopping the progression of myopia. Fusion of the refractive microstructure at least partially with a layer present on the surface of the spectacle lens body allows the spectacle lens to be manufactured with the method of the present invention. Thus, the spectacle lens of the present invention allows the use of standard additive manufacturing processes (such as, for example, inkjet printing) to produce a progressive multifocal lens with a microstructure.

[0125] In the case where the refractive microstructure is covered by a covering layer, a flat surface following the surface of the lens body can be achieved. The refractive index of the covering layer can be smaller than the refractive index of the refractive microstructure. In particular, the refractive index of the covering layer can be at least 5 thousandths, preferably at least 1 percent smaller than the refractive index of the refractive microstructure. This helps to ensure that the refractive microstructure with a convex curvature provides a positive focal power. However, in principle, the refractive index of the covering layer can also be greater than the refractive index of the refractive microstructure. In particular, the refractive index of the covering layer can be at least 5 thousandths, preferably at least 1 percent greater than the refractive index of the refractive microstructure. In this case, even if the refractive microstructure has a concave curvature, a positive focal power can be provided. Therefore, the covering layer allows a wider variation in the possible geometries of the refractive microstructure. In particular, in a system of a refractive microstructure and a covering layer, a refractive index of the covering layer that is greater than the refractive index of the refractive microstructure reduces the refractive power provided to the geometry of the refractive microstructure and thus allows a refractive microstructure with a smaller radius of curvature. In addition, selecting a suitable refractive index of the covering layer allows fine-tuning of the refractive power provided by the system of the refractive microstructure and the covering layer.

[0126] According to yet another aspect of the invention, there is provided a data set comprising at least one of the following types of data: (i) a numerical representation of an inventive spectacle lens for the purpose of manufacturing an inventive spectacle lens using the numerical representation of the spectacle lens, and (ii) data comprising computer readable instructions for controlling one or more manufacturing machines to produce the inventive spectacle lens. The data set allows the data to be sent to a manufacturer of the spectacle lens. The purpose of manufacturing an inventive spectacle lens using the numerical representation of the spectacle lens may include the purpose of generating data comprising computer readable instructions for controlling one or more manufacturing machines to produce the spectacle lens.

[0127] Further features, characteristics and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings.

[0128] Figures 1 to 4 The steps of a first exemplary embodiment of the method of the invention for providing a refractive microstructure are schematically shown.

[0129] Figure 5A second exemplary embodiment of the inventive method of providing a refractive microstructure is schematically shown.

[0130] Figure 6 A third exemplary embodiment of the inventive method of providing a refractive microstructure is schematically shown.

[0131] Figure 7 and Figure 8 A fourth exemplary embodiment of the inventive method of providing a refractive microstructure is schematically shown.

[0132] Fig. 9 The refractive index distribution in the layers of the first curable material and the second curable material after curing or pinning the first curable material and the second curable material, the refractive index of the second curable material being different from the refractive index of the first curable material, is shown.

[0133] Fig.10 A cross-sectional view of an example of a spectacle lens manufactured according to the method of the present invention is shown.

[0134] Fig.11 A plan view of an exemplary embodiment of a spectacle lens manufactured according to the method of the present invention is shown.

[0135] Fig.12 A plan view of another example of a spectacle lens manufactured according to the method of the present invention is shown.

[0136] Now about Figures 1 to 4 A first exemplary embodiment of the method of the invention for providing a refractive microstructure on the surface of a spectacle lens body 3 is described. In this exemplary embodiment, the focal power of the refractive microstructure is determined by the curvature of its surface.

[0137] like Figure 1 As shown, according to a first exemplary embodiment of the method according to the invention, a base layer 1 of a first curable material is applied to a surface 4 of an eyeglass lens body 3 by an additive manufacturing process, which will be referred to as 3D printing in the following. In such a 3D printing process, a 3D structure is formed by printing the structure onto a substrate using a polymer ink.

[0138] 3D printing is accomplished by means of a nozzle arrangement 8, the nozzles of which eject curable material toward the surface 4 of the spectacle lens body 3, while the nozzle arrangement 8 and the spectacle lens body 4 move relative to each other. In the present exemplary embodiment, the nozzle arrangement 8 is part of a single print head, which includes a one-dimensional nozzle array (i.e., a row of nozzles) extending perpendicularly to the direction of relative movement between the nozzle arrangement 8 and the spectacle lens body 4. However, the print head may also include a two-dimensional nozzle array, for example, two or more rows of nozzles. The rows of nozzles of the two-dimensional array may be aligned with each other in the direction of relative movement between the nozzle arrangement 8 and the spectacle lens body 4. As an alternative, adjacent rows of nozzles may be shifted relative to each other in a direction perpendicular to the direction of relative movement between the nozzle arrangement 8 and the spectacle lens body 4, the shifted distance being a fraction of the distance between adjacent nozzles in a row of nozzles, thereby achieving a staggered arrangement of the rows of nozzles. By means of such a staggered arrangement, the resolution achievable during printing may be increased.

[0139] The polymer ink (i.e., first curable material 6) of this exemplary embodiment is cured by polymerization of monomers and / or oligomers and by crosslinking the polymer chains in the ink material. The polymerization and crosslinking are initiated by an initiator, which is activated by an external stimulus, which in this exemplary embodiment is ultraviolet (UV) radiation. In other embodiments, the initiator may be activated by other means (such as, for example, heat or a particle beam), or no initiator may be used at all.

[0140] Suitable 3D polymer inks used as the first curable material 6 in the present exemplary embodiment are (meth)acrylate-based polymer inks, preferably free of solvent. However, polymer inks with a small proportion of solvent can also be used in case the substrate layer thickness is small enough so that the solvent can evaporate before the curing process. Typical materials for the spectacle lens body 3 are thermoplastics (such as polycarbonate) or thermosetting plastics (such as CR-39). A collection of polymers suitable for forming the spectacle lens body 3 is given in Table 1.

[0141] Table 1: Collection of polymers suitable for forming spectacle lens bodies 3

[0142]

[0143] The polymer ink used as the first curable material 6 forming the substrate layer 1 may have a refractive index that is the same as the refractive index of the material of the eyeglass lens body 3. In the context of the present invention, the refractive indices are considered to be the same if they differ from each other by no more than 5 parts per thousand, preferably no more than 1 part per thousand. However, the first curable material 6 and the material of the eyeglass lens body 3 do not need to have the same refractive index. In particular, the refractive index of the first curable material 6 may be lower than the refractive index of the material of the eyeglass lens body, which may be beneficial in designing an additional anti-reflective (AR) coating. In addition, the first curable material 6 should also be suitable as a substrate for a hard coating applied later to the substrate layer 1 and for the refractive microstructures present in the substrate layer 1. In addition, the first curable material 6 must provide sufficient optical quality once cured. In the context of the present invention, sufficient optical quality is achieved if the yellowness index (YI) of the eyeglass lens with the refractive microstructure is lower than 3, preferably lower than 1 and ideally lower than 0.5, and the haze is lower than 1.0% and preferably lower than 0.5%.

[0144] The typical thickness of the substrate layer 1 is in the range between 1 and 100 μm, preferably in the range between 5 and 50 μm. In order to prevent the formation of unwanted structures in thin substrate layers (i.e. substrate layers with a thickness below 20 μm), random noise can be added to the pattern according to which the nozzles in the nozzle arrangement 8 eject droplets, so that the droplets that should form the substrate layer 1 are not printed in a regular pattern. This method is called dithering. In the present exemplary embodiment, the thickness of the substrate layer 1 is in the range between 15 and 50 μm, and in particular can be 45 μm.

[0145] After the substrate layer 1 has been printed onto the surface 4 of the spectacle lens body 3 in a first pass of the print head 8, an additional amount of the first curable material 6 is applied in a second pass of the print head 8 to the stationary liquid substrate layer 1 at the locations where the refractive microstructures 5 are to be formed (the movement direction of the print head 8 is determined by Figure 2). The additional amount of the first curable material 6 forms surface protrusions 15 of the base layer 1, which immediately begin to fuse with the base layer 1 due to coalescence after deposition. In a short period of time after the droplets forming the protrusions 15 have been printed onto the base layer 1, the curvature of the protrusions 15 is high, that is, the radius of curvature is small, and therefore, the refractive power provided by the protrusions 15 is high, while after a long time, the surface energy of the first curable material 6 causes the protrusions 15 to fuse with the base layer 1. Therefore, after a long time, the curvature of the protrusions 15 becomes flat, that is, the radius of curvature increases, which reduces the focal length of the protrusions 15. During the pinning process or the curing process, the fusion rate decreases as the viscosity increases, and eventually stops when the material is cured. Therefore, controlling the time before pinning or curing begins and the time given to pin or cure the first curable material 6 (that is, the material of the base layer 1 and the protrusions 15) allows the final curvature of the protrusions 15 to be determined, and therefore its refractive power. Furthermore, in this exemplary embodiment, additional parameters may be used to control at least one of the fusion speed and the pinning or curing speed. Those parameters include:

[0146] - an additional amount of the at least one first curable material 6 applied at locations where the refractive microstructures are to be formed.

[0147] - The rheological properties of the at least one first curable material 6 .

[0148] - A combination of the surface energies of the at least one first curable material 6 and the material of the spectacle lens body.

[0149] - The convection speed of the at least one first curable material 6 .

[0150] -Temperature differences during the additive manufacturing process.

[0151] -Temperature of the nozzle arrangement during the additive manufacturing process.

[0152] -Temperature of the eyeglass lens body during the additive manufacturing process.

[0153] -Atmospheric temperature during the AM process.

[0154] -Atmospheric humidity during the AM process.

[0155] -Atmospheric composition during the additive manufacturing process.

[0156] -The strength of the external electric or magnetic field present during the additive manufacturing process.

[0157] - The density of the at least one first curable material 6 .

[0158] - The chemical composition of the at least one first curable material 6 .

[0159] In other words, controlled fusion provides a process that allows the curvature of the protrusion 15 to be controlled to decrease (i.e., increase its radius of curvature). The decrease in curvature in turn reduces the focal power provided by the curvature of the protrusion 15. The state in which the refractive microstructure 5 is partially fused with the base layer 1 is as shown in FIG. Figure 3 shown.

[0160] In this exemplary embodiment, it is necessary to stop the fusion of the protrusion 15 with the base layer 1 before the protrusion 15 is completely fused with the base layer 1, so as to keep the curvature of the protrusion 15 at a level that provides the desired refractive power, which is no more than 10 dpt and is generally between 1.5 and 5.5 dpt. The time it takes for the protrusion 15 to be completely fused with the base layer 1 depends on many parameters, including, for example, the temperature and thickness of the base layer 1 and the surface tension involved.

[0161] In order to stop the fusion process, in the present exemplary embodiment, any material transport is interrupted or significantly slowed down by pinning. In the present exemplary embodiment, this means that the first curable material 6 (i.e., the material of the protrusion 15 and the base layer 1) becomes solidified except that the surface layer in contact with the oxygen-containing atmosphere remains unsolidified. In other embodiments, a protective atmosphere without oxygen can be used so that the surface layer also undergoes polymerization, and the protrusion 15 and the base layer 1 will be completely solidified instead of pinning.

[0162] In the present exemplary embodiment, pinning (or full curing) is initiated with the help of an initiator, which in the present exemplary embodiment is a photoinitiator. In order to activate the photoinitiator to start pinning (or curing), the protrusions 15 and the base layer 1 are irradiated with ultraviolet radiation (i.e., radiation with a wavelength in the range between 10 and 400 nm). In other exemplary embodiments, the initiator can be activated by stimuli other than ultraviolet radiation, for example by light in the visible light spectrum, by infrared radiation, by heat or by a particle beam. In addition, exemplary embodiments are conceivable in which a polymer that undergoes crosslinking is used without the need for an initiator.

[0163] Due to pinning (or curing), the fusion of the protrusions 15 in the base layer 1 is stopped. The time between printing the protrusions 15 onto the base layer 1 and stopping the fusion by pinning (or curing) determines the final morphology of the refractive microstructure 5 formed by the protrusions 15. The longer the refractive protrusions 15 are finally fused with the base layer 1, that is, the wider the protrusions 15 extend, the lower their optical power.

[0164] After pinning (or curing), the curvature of the protrusions 15 and therefore the curvature of the refractive microstructure 5 should not depend on whether they are printed at the beginning or at the end of printing the protrusions 15. If the time elapsed between printing the first protrusion 15 and the last protrusion 15 is shorter than the time required for the protrusions 15 to completely fuse with the base layer 1, all the protrusions 15 can be considered as if they will start to fuse at the same time. Since the number of droplets of the first curable material 6 required to print the protrusions 15 is relatively small, a single pass of the print head 8 is sufficient to print all the protrusions 15. This means that the time elapsed between printing the first protrusion 15 and the last protrusion 15 can be kept short, which allows the protrusions 15 to be considered as if they will start to fuse at the same time.

[0165] In the present exemplary embodiment, the complete curing of the pinned substrate layer 1 with the protrusions 15, i.e. the complete crosslinking of the pinned substrate layer 1 with the protrusions, is done at a later point in time, i.e. after the cover layer 7 has been applied to the substrate layer 1 with the protrusions 15, e.g. Figure 4 As shown. However, the pinned base layer 1 with the protrusions 15 can also be completely cured before the covering layer 7 is applied. The fact that the surface film of the base layer 1 with the protrusions 15 is not completely crosslinked after pinning helps to improve the bond between the covering layer 7 and the base layer 1 with the protrusions 15. In the present exemplary embodiment, the covering layer 7 is printed onto the base layer 1 with the protrusions 15. However, the covering layer 7 can also be applied by spin coating or with the aid of an adhesive foil. After the covering layer 7 has been applied, it will protect the base layer 1 with the protrusions 15.

[0166] The thickness of the cover layer 7 is selected so that after curing, the refractive microstructure 5 realized by the protrusions 15 is completely covered by the cover layer 7. In order to achieve this goal, the thickness of the cover layer 7 is generally in the range between 2 and 15 times the height of the refractive microstructure 5 formed by the protrusions 15 protruding from the substrate layer 1, in particular in the range between 5 and 10 times the height of the refractive microstructure 5 protruding on the substrate layer 1.

[0167] Suitable materials for the cover layer 7 are (meth)acrylate-based materials. However, instead of (meth)acrylate-based materials, other curable or solidifying materials can be used for the cover layer 7 if they allow layer thicknesses in the range between 1 and 100 μm, in particular in the range between 1 and 50 μm. Possible materials are epoxides, epoxy-thiol systems, mercapto-vinyl-based systems, urethanes, silicone-based systems, etc.

[0168] Without the cover layer 7, the focal length provided by the refractive microstructures 5 will depend not only on their curvature, but also on the difference in refractive index between the first curable material 6 and air. Thus, for a first curable material with a refractive index in the range between 1.50 and 1.74, the difference in refractive index will be roughly in the range between 0.5 and 0.74. With the cover layer 7, this difference in refractive index will be reduced, which will allow a higher curvature of the refractive microstructures 5. Thus, the refractive index of the cover layer 7 can be used to compensate for an excessive curvature of the refractive microstructures 5.

[0169] In the present exemplary embodiment, the viscosity of the base layer 1 can be changed in order to appropriately set the fusion speed of the refractive microstructure 5 in the base layer 1. The viscosity can be adjusted, for example, by adjusting the temperature of the printing environment and / or the temperature of the printing material (i.e., the first curable material 6). In addition, the viscosity can be changed by pinning the first curable material 6. The degree of pinning can be adjusted, for example, by the oxygen concentration of the atmosphere in which the additive manufacturing occurs during the pinning process, by the UV radiation dose used for pinning, by the initiator content, etc.

[0170] Although in the first exemplary embodiment described so far, the base layer 1 and the protrusion 15 are formed using the same first curable material 6, the base layer 1 may be printed using at least one first curable material, and the protrusion 15 may be printed using at least one second curable material 16 different from the at least one first curable material 6. The at least one first curable material and the at least one second curable material may have the same refractive index or different refractive indices.

[0171] In the following, reference will be made to Figure 5 A second exemplary embodiment of the method of the present invention is described below. The method of the second exemplary embodiment differs from the method of the first exemplary embodiment in that the layer 21 of the first curable material 6 and the protrusions 25 are formed in a single pass of the nozzle arrangement represented by the print head 8. The movement direction of the print head 8 is represented by Figure 5 Indicated by the arrow in the .

[0172] In the second exemplary embodiment, the printing nozzles of the print head 8 print different amounts of the first curable material 6 at different locations on the surface 4 of the spectacle lens body 3. At those locations on the surface 4 where the refractive microstructures 5 should not be formed, the nozzles of the print head 8 eject a certain amount of the first curable material 6 to form a layer 21 of the first curable material 6, while at locations where the refractive microstructures 5 should be formed, the nozzles of the print head 8 eject a larger amount of the first curable material 6. The additional amount of the first curable material 6 applied to the locations on the surface 4 where the refractive microstructures should be formed compared to other locations on the surface 4 causes the formation of protrusions 25 protruding from the layer 21 of the first curable material 6. After the layer 21 having the protrusions 25 has been printed onto the surface 4 of the spectacle lens body 3 by a single pass of the print head 8, the remaining steps of the method of providing the surface 4 of the spectacle lens body 3 with the refractive microstructures 5 are the same as in the first exemplary embodiment.

[0173] As in the first exemplary embodiment, coalescence is stopped by pinning or at least partial curing using ultraviolet radiation, as described with respect to Figure 3 Already described.

[0174] What has been described regarding the nozzle arrangement and materials used in the first exemplary embodiment also applies to the nozzle arrangement and materials of the second exemplary embodiment.

[0175] In the second exemplary embodiment, a single print head 8 is used to print the layer 21 and the protrusion 25 in a single pass of the print head 8. Figure 6 In the third exemplary embodiment of the method of the invention shown in FIG. 1 , the nozzle arrangement is implemented as two print heads 27, 28. Each of the print heads 27, 28 may include a one-dimensional or two-dimensional nozzle array and may have its own separate feed line 29, 30 for feeding the curable material to its nozzle array, such as Figure 6 However, instead of using two print heads 27, 28, a single print head having two or more nozzle arrays may also be used.

[0176] In the third exemplary embodiment, Figure 6The two print heads 27, 28 are used to print a layer 21 of a first curable material 6 and protrusions 25' protruding from the layer 21 in a single pass of the print heads 27, 28. The relative movement direction between the print heads 27, 28 and the spectacle lens body 3 is indicated by an arrow. During the passage over the surface 4 of the spectacle lens body 3, the first print head 27 ejects the first curable material 6 forming the layer 21, while the second print head 28 ejects an additional amount of the first curable material 6 forming the protrusions 25'. After the layer 21 of the first curable material 6 and the protrusions 25' have been printed onto the surface 4 of the spectacle lens body 3 by a single pass of the print heads 27, 28, the remaining steps of the method for providing a refractive microstructure 5 on the surface 4 of the spectacle lens body 3 are the same as in the first exemplary embodiment.

[0177] If the two print heads 27, 28 of the third exemplary embodiment have different feed lines 29, 30 for feeding the curable material, as in Figure 6 As shown, it is also possible to print the layer 21 by ejecting the first curable material 6 with the first print head 27 and to print the protrusion 25' by ejecting a certain amount of the second curable material onto the first curable material 6 with the second print head 28. In the case of using more than two print heads (e.g., three, four, five or even more print heads), more complex combinations of curable materials can be achieved if each print head has its own feed line for feeding the curable material. This can be achieved by a single print head comprising two or more nozzle arrays and separate feed lines for the nozzle arrays.

[0178] In the following, reference will be made to Figure 7 and Figure 8 A fourth exemplary embodiment of the method of the invention is described below. As in the second and third exemplary embodiments, the layer 31 and the protrusion 35 are printed onto the surface 4 of the spectacle lens body 3 in a single printing pass using a nozzle arrangement which is embodied as two print heads 27, 28 with separate feed lines 29, 30. However, instead of being embodied as two print heads 27, 28, the nozzle arrangement can also be embodied as a single print head comprising two or more nozzle arrays and separate feed lines for the nozzle arrays.

[0179] As in the third exemplary embodiment, the relative movement direction between the print heads 27, 28 and the spectacle lens body 3 is indicated by an arrow. The fourth exemplary embodiment differs from the second and third exemplary embodiments in the structure of the layer 31 of the first curable material 6 and in the manner in which the refractive properties of the refractive microstructure 5' are achieved. For this purpose, a second curable material 16 is used, which has a refractive index different from that of the first curable material 6 and higher than that of the first curable material 6.

[0180] In the fourth exemplary embodiment, the amount of the first curable material 6 applied to the surface 4 of the spectacle lens body 3 at the position where the refractive microstructure 5' should be formed by using the first print head 27 is less than the amount of the first curable material 6 applied to the other positions of the surface 4. Therefore, the layer 31 is formed with recesses 32 at those positions where the refractive microstructure 5' should be formed. Although the recesses 32 do not reach the surface 4 of the spectacle lens body 3 in the present exemplary embodiment, there may be an embodiment in which the surface 4 of the spectacle lens body 3 is exposed at the center of the recesses 32. Whether the recesses 32 expose the surface 4 of the spectacle lens body 3 depends on the thickness of the layer 31 and the lateral dimensions of the recesses 32, which in turn depend on the lateral dimensions of the refractive microstructure to be formed. For example, for the typical lateral dimensions of the refractive microstructure to be formed, the recesses 32 may expose the surface 4 in the case where the layer 31 of the first curable material 6 has a maximum thickness of up to 10 μm, while they are likely not to expose the surface 4 in the case where the layer 31 of the first curable material 6 has a greater thickness. The typical lateral dimensions of the refractive microstructure to be formed are 0.1 to 2 mm.

[0181] By using the second print head 28, the second curable material 16 is printed into the recesses 32. Therefore, at least the lower part of the amount of second curable material 16 applied into the recesses 32 is laterally surrounded by the layer 31 of the first curable material 6. Since both the first curable material 6 and the second curable material 16 are still in liquid state, the first curable material 6 and the second curable material 16 (which have a higher refractive index than the first curable material 6) start to diffuse into each other after the protrusions 35 have been formed in the recesses 32. Due to this diffusion process and the different refractive indices, a refractive index gradient is formed, with the highest refractive index at the center of the recesses 32 and the lowest refractive index in the portion of the layer 31 of the first curable material 6 located between the recesses 32. In this way, the refractive microstructure 5' can be implemented as a gradient refractive index lens 5'. The gradient refractive index lens 5' in Figure 8 The center is indicated by a dotted area, where a higher density of dots indicates a higher refractive index. Fig.10 Shows Fig. 9 In practice, the gradient index lenslet 5' will protrude slightly from the surface because the time given to the first curable material 6 and the second curable material 16 to diffuse into each other is limited. Therefore, in addition to being determined by the refractive index gradient, the refractive properties of the refractive microstructure 5' are also determined to a lesser extent by its surface geometry.

[0182] The slope of the refractive index gradient can be adjusted by the duration of the diffusion process, by the lateral dimensions of the recess 32, and by the amount of the second curable material 16 printed into the recess 32. Furthermore, the slope of the gradient determines the focal power of the gradient index lenslet 5', such that adjusting the duration of the diffusion process allows adjusting the focal power of the gradient index lenslet 5'. Similar to stopping the coalescence process in the first to third exemplary embodiments, stopping the diffusion process in the present exemplary embodiment is accomplished by pinning or curing the first and second curable materials 6, 16.

[0183] The use of gradient refractive index lenses 5' allows forming a layer 31 with refractive microstructures 5' which has a flat surface 3 or at least a flatter surface than the surface of a layer in which the refractive microstructures are based only on the surface geometry of the refractive microstructures. This may be advantageous if further layers (like for example hard coatings, transmittance-changing layers, anti-reflection layers, etc.) are applied on top of the layer 31 with refractive microstructures 5'. In particular, a flat surface may help to increase the adhesion and long-term stability of subsequent layers. If the layer 31 with refractive microstructures 5' is not fully cured but only pinned, the adhesion of subsequent layers may be further improved.

[0184] Fig.10 A cross-sectional view of a spectacle lens 100 which has been manufactured according to the method of the invention is shown. The spectacle lens comprises a spectacle lens body 3 and a layer 1 with a refractive microstructure 5 which, in this exemplary embodiment, provides a positive focal power in addition to the focal power of the spectacle lens body 3 by the curvature of its surface protruding from the layer 1. On top of the layer 1 with the protruding refractive microstructure 5, there is a layer 7 which is thick enough to flatten the protrusions of the refractive microstructure 5. By this measure, a flat surface of the cover layer 7 can be achieved, which is advantageous for applying further layers on top of the cover layer. In particular, the flat surface of the cover layer 7 can contribute to increasing the adhesion and long-term stability of subsequent layers. The spectacle lens (100) can be a single vision, bifocal or multifocal spectacle lens or a progressive multifocal lens (PAL).

[0185] In the present exemplary embodiment, the thickness of layer 1 is 45 μm, and the refractive microstructures 5 protrude from layer 1 by an amount of approximately 1 μm. In order to obtain a flat surface, the thickness of cover layer 7 should be approximately 5 to 10 times the height of the refractive microstructures 5 protruding from layer 11. In the present exemplary embodiment, the thickness of cover layer 7 is 10 μm, which corresponds to approximately 5 to 10 times the height of the refractive microstructures 5 protruding from layer 1. A protective hard layer 101 is applied to the flat surface of cover layer 7, and an anti-reflection layer 103 is provided on top of the hard layer 101. Note that other layer systems can also be provided on top of cover layer 7, such as layers with absorption or reflection properties, as they are used for example in sunglasses.

[0186] Please note that in other exemplary embodiments, the amount of elevation from the surface of the substrate layer 1 may be greater or less than 1 μm, and may be in the range between 0 and 10 μm, in particular depending on the focal power achieved with the refractive microstructures 5. An elevation close to 0 μm would mean that the surface of the substrate layer 1 with the refractive microstructures 5 is almost flat. Such a flat surface may exist if the refractive properties of the refractive microstructures 5 are due to differences or gradients in their refractive index rather than to the curvature of their surface. If the refractive properties of the refractive microstructures 5 are to be achieved with the aid of their curvature, their protrusion from the surface is in the range between 0.2 and 10 μm, and often in the range between 0.4 and 1.5 μm. In order to achieve a flat surface of the cover layer 7, the cover layer needs to have a thickness in the range between 1 and 50 μm, depending on the amount by which the refractive microstructures 5 protrude from the substrate layer 1.

[0187] exist Fig.11 In the illustrated spectacle lens 100, the material of which the protruding refractive microstructure 5 is made is the same as the material of the layer 1. This material has the same refractive index as the refractive index of the material of the spectacle lens body 3. This means that the refractive index of the refractive microstructure 5 and the layer 1 differs from the refractive index of the spectacle lens body 3 by no more than 5 parts per thousand, and preferably by no more than 1 part per thousand. Typical materials that can be used as the material of the refractive microstructure 5 and the layer 1 have a refractive index between 1.30 and 1.75. Typical materials for the spectacle lens body have a refractive index in the range from 1.50 to 1.74. In order to provide a positive power in addition to the power of the spectacle lens body 3, the refractive microstructure 5 needs to have a higher refractive index than the refractive index of the cover layer 7. Therefore, it is desirable to use a material having a refractive index at the upper end of the range of 1.30 to 1.75 for the layer 1 and the refractive microstructure 5, and to use a material having a refractive index at the lower end of the range for the cover layer 7. Since the refractive index of the cover layer 7 is higher than that of air, the refractive microstructure having an interface with the cover layer 7 may allow a steeper curvature than the refractive microstructure 5 having an interface with air.

[0188] Despite Fig.10 A specific combination of refractive indices is presented in the exemplary embodiments shown, but other combinations of refractive indices are possible. Fig.10Alternatively to the exemplary embodiment shown, the refractive index of the refractive microstructures 5 may be different from the refractive index of the spectacle lens body 3. In particular, the refractive index of the refractive microstructures 5 may be greater than the refractive index of the spectacle lens body 3, which will reduce the steepness of the curvature required for the refractive microstructures 5 to provide a positive focal power in addition to the focal power provided by the spectacle lens body 3. Additionally or as a further alternative, the refractive index of the cover layer 7 may correspond to the refractive index of the spectacle lens body 3 or may be greater than the refractive index of the spectacle lens body 3. In case the layer 1 has the same refractive index as the spectacle lens body 3, the refractive index of the cover layer 7 corresponding to the refractive index of the spectacle lens body 3 will prevent unwanted refractions or Fresnel reflections at the interface between the spectacle lens body 3 and the layer 1 and between the layer 1 and the cover layer 7. However, in this case, the refractive microstructures 5 need to have a higher refractive index than the refractive index of the cover layer 7 in order to provide a positive focal power in addition to the focal power of the spectacle lens body 3. In case the cover layer 7 has a higher refractive index than the refractive index of the spectacle lens body 3, providing an additional power in addition to the power of the spectacle lens body 3 would require a complementary geometry of the base layer 1 with the refractive microstructures 5, or even an inverted geometry, i.e. a concave curvature (such as depressions or dimples) instead of a convex curvature. However, this alternative is mainly used if an additional power in addition to the optical power provided by the spectacle lens body 3 is to be achieved. In addition, in the absence of the cover layer 7, the refractive index of the layer 1 can be less than the refractive index of the spectacle lens body 3, which may be beneficial if an anti-reflection layer is to be applied to the layer 1.

[0189] although Fig.10 The refractive microstructures 5 of the illustrated spectacle lens 100 have refractive properties due to the geometry of the surface of the protrusions on the layer 1, but they may have refractive properties at least partially or even completely due to the refractive index gradient present in the refractive microstructures 5. The use of a refractive index gradient allows the layer 1 to have a flatter surface or the layer 1 to even have a completely flat surface, compared to a refractive microstructure 5 having refractive properties due to the geometry of the protrusions protruding from the layer 1. However, in the method of providing the refractive microstructures 5, the use of a refractive index gradient to provide the refractive properties of the refractive microstructures 5 requires the use of a second curable material having a refractive index different from the refractive index of the first curable material.

[0190] In the top view of the spectacle lens, the refractive microstructures can have various shapes. Fig.11 1 shows a spectacle lens 110 manufactured according to the method of the present invention, which represents a spectacle lens having refractive microstructures 5, which are formed from a layer 1 ( Fig.11 The spectacle lens body 3 is a spectacle lens body of a progressive multifocal lens 110. However, it can also be a spectacle lens body 3 of a single vision, bifocal or multifocal spectacle lens.

[0191] Fig.12 Another example of a spectacle lens 120 having a refractive microstructure 5 manufactured according to the method of the present invention is shown. In this exemplary embodiment, the refractive microstructure 5 is disposed on the spectacle lens body 3 of the single vision spectacle lens 120 and is similar to a ring having an approximately spherical curvature in the radial direction and extending from layer 1 ( Fig.12 ). However, the refractive properties of the lenslet or ring do not need to be provided by the curvature of its surface, but can also be provided by a difference or gradient of the refractive index, or by a combination of a difference or gradient of the curvature and the refractive index. Depending on the material and geometry of the lenslet, the refractive index within the lenslet can decrease or increase from the center of the lenslet toward its outer edge, and in the ring, the refractive index can decrease or increase radially inwardly and radially outwardly from the center of the ring. Other geometries of the refractive microstructure 5 in a plan view of the spectacle lens 100 are conceivable to a person skilled in the art. Therefore, the geometry of the refractive microstructure 5 should not be limited to lenslets and annular microstructures. Although the spectacle lens body 3 of the spectacle lens 120 is a spectacle lens body of a single-vision spectacle lens, it can also be a spectacle lens body 3 of a bifocal or multifocal lens or a progressive multifocal lens.

[0192] In the following, specific examples of the method of the present invention and their results will be discussed.

[0193] First specific example

[0194] In a first specific example, a pattern consisting of 3 refractive microstructures is formed, which are arranged in a 3x 3 array on a 9mm x 9mm area of ​​a glass substrate (SCHOTT D263T eco). In a first step, a fluid base layer with a thickness of 45 μm is printed onto the glass substrate using a (meth)acrylate-based polymer ink with a print head of a standard 3D printer in the first pass of the print head. The pattern of the refractive microstructures is then printed onto the base layer in the second pass of the print head using the same (meth)acrylate-based polymer ink. The pattern consists of 9 microstructures arranged in a 3x 3 array. Four of these patterns are printed in a continuous plurality of passes of the print head, wherein each of these passes takes 12 seconds. Immediately after printing the last of these four patterns, the four patterns are pinned by using ultraviolet radiation with wavelengths of 365nm and 395nm so that the material flow is interrupted while the substrate with the pattern is still in the printer. Thereafter, the substrate having the pattern was taken out from the printer and cured using ultraviolet radiation having a wavelength of 365 nm under a nitrogen atmosphere.

[0195] Since pinning is done immediately after the last pass of the print head, that is, immediately after the last of the four patterns has been printed, the last pattern (the fourth pattern) is pinned immediately after it is printed, while the third pattern has a waiting time of 12 seconds before pinning, the second pattern has a waiting time of 24 seconds before pinning, and the first pattern has a waiting time of 36 seconds before pinning.

[0196] After curing, the four patterns were evaluated for the diameter of the refractive microstructures, the amount by which they protrude from the base layer, the radius of the sphere that best fits the curvature of the microstructures, and the focal power they provide. The focal power evaluation was based on a refractive index of 1.50 for the (meth)acrylate-based polymer ink. The results are compiled in the following table:

[0197]

[0198]

[0199] As can be seen from the table, the refractive microstructures protrude less from the base layer, the longer the time elapsed before pinning. Likewise, the slope of the refractive microstructure and the focal length provided by the refractive microstructure decrease with increasing time elapsed before pinning. On the other hand, the diameter of the sphere representing the best fit to the curvature of the microstructure increases with increasing time elapsed before pinning, as does the diameter of the refractive microstructure. This behavior is due to the coalescence of the printed refractive microstructure with the base layer over time.

[0200] Among the four patterns presented in the table, patterns three and four show that the refractive microstructure has a power suitable for a small lens of a spectacle lens for slowing down or stopping the progression of myopia. The power of the refractive microstructure of the second pattern is a little low, but may still be suitable for a small lens of a spectacle lens for slowing down or stopping the progression of myopia, while the power of the refractive microstructure of the first pattern is too low to be used as a small lens of a spectacle lens that should slow down or stop the progression of myopia.

[0201] Furthermore, it can be observed that the coalescence of the refractive microstructures takes more time if the refractive microstructures within the pattern are closer to each other. This may be due to the fact that lateral material transport is hindered or affected by adjacent structures. Thus, in the case of refractive microstructures that are arranged close to each other, the time that elapses before pinning needs to be longer than for refractive microstructures that are positioned further away from each other.

[0202] Second specific example

[0203] In the second specific example, instead of small lenses, two concentric annular focusing structures are printed onto the base layer, where pinning begins immediately after the structures are printed. The ink and substrate used to print the base layer and the refractive microstructure are the same as in the first specific example. After pinning and curing, the radii of the resulting concentric inner and outer annular focusing structures are 1.5 mm and 4.5 mm, respectively, and the distance between the two annular focusing structures is 3 mm. For these two annular focusing structures, their width at their base (i.e., where they merge with the base layer) is 1 mm, and they both protrude from the base layer with a height of 0.7 to 0.8 μm. It has been noted that if the thickness of the base layer is the same as in the first specific example, additional unwanted rings may be produced. However, if the thickness of the base layer is reduced, the unwanted rings appear to disappear.

[0204] The cross section of the ring has been spherically fitted in order to calculate an approximation of the power provided by the ring focusing structure. Evaluation of the best fit yielded a power of 4.5 dpt for a refractive index of 1.50, which is well within the range that can be used to slow or stop myopia progression.

[0205] Third specific example

[0206] In a third specific example, both the layer and the refractive microstructure are printed in a single pass of the print head. In doing so, the layer is printed in a pattern with depressions and the refractive microstructures are printed in the depressions. Different (meth)acrylate-based polymer inks are used to print the layer and the refractive microstructures. The substrate is the same as in the first two exemplary embodiments. In this specific example, the ink used to print the layer with depressions has a first refractive index and the ink used to print the refractive microstructures into the depressions has a second refractive index that is higher than the first refractive index. The ink of the layer and the ink of the refractive microstructure diffuse over time, thereby generating a refractive index gradient with the highest refractive index at the center of the refractive microstructure and the lowest refractive index in the area between adjacent refractive microstructures.

[0207] Fourth specific example

[0208] In the fourth specific example, a refractive microstructure was printed onto a curved substrate having no hard coating and having a diameter of 65 mm, a center thickness of 2.0 mm, a radius of curvature of 143.5 mm, a refractive index of 1.50, and a focal power of 0.00 dpt. Both a small lens and an annular focusing structure were printed onto the surface of such a substrate. To print the small lens, the same procedure as pattern four in the first specific example was used, and to print the annular focusing structure, the same procedure as in the second specific example was used.

[0209] In the case of the annular focusing structures, two concentric annular focusing structures were printed. These annular focusing structures protrude from the base layer at a height of 2 to 2.5 μm, with the outer of the two annular focusing structures protruding slightly less than the inner annular focusing structure and having a slightly smaller width. Based on a spherical fit to the cross-section of the annular focusing structures, the focal power of the annulus has been determined to be between 3.4 dpt and 6.5 dpt.

[0210] In the case of printed lenslets, the resulting lenslets had a diameter of 2.54 mm and a rise of 7.24 μm. From a spherical fit to the curvature of the lenslet, the radius of curvature was determined to be 111.8 mm, which yields a power of 4.5 dpt.

[0211] The fourth specific example shows that, through the method of the present invention, small lenses and annular focusing structures can be printed on a curved substrate, wherein the small lenses and the annular focusing structures have suitable focal powers for slowing down or stopping the progression of myopia.

[0212] The present invention has been described with respect to exemplary embodiments and specific examples of the inventive method and the resulting spectacle lens design. With the guidance of the exemplary embodiments and specific examples, a person skilled in the art will be able to conceive modifications to the inventive method and the inventive spectacle lens design. Therefore, the scope of the present invention should not be limited by the exemplary embodiments or specific examples, but only by the appended claims.

Claims

1. A method for providing refractive microstructures (5, 5') on a surface (4) of an eyeglass lens body (3), wherein the refractive microstructures (5, 5') are formed on the surface (4) by an additive manufacturing process, wherein the refractive microstructures (5) are formed by applying at least one curable material (6, 16) and curing the at least one curable material (6, 16), characterized in that The additive manufacturing process includes: - forming a layer (1, 21, 31) of at least one first liquid or viscous curable material (6), wherein, in order to form the refractive microstructures (5, 5'), before curing or pinning the at least one first curable material (6), an additional amount of the at least one first curable material (6) or an amount of at least one second liquid or viscous curable material (16) is applied at the locations where the refractive microstructures (5, 5') are to be formed; as well as - before leveling the protrusion formed by the additional amount of the at least one first curable material (6) or the amount of the at least one second curable material (16) by a material transfer process within the liquid or viscous material in the layer (1, 21, 31) of the at least one curable material (6), curing or pinning the layer (1, 21, 31) of the at least one first curable material (6) having the additional amount of the at least one first curable material (6) or the amount of the at least one second curable material (16).

2. The method according to claim 1, characterized in that The amount of the at least one first curable material (6) applied to the surface (4) of the eyeglass lens body (3) at the positions where the refractive microstructures (5, 5') are to be formed is less than the amount of the at least one first curable material (6) applied to other positions, and the amount of the at least one second curable material (16) is applied to the positions where the refractive microstructures (5, 5') are to be formed.

3. The method according to claim 1 or claim 2, characterized in that: The layer of the at least one first curable material (6) having the additional amount of the at least one first curable material (6) or the at least one second curable material (16) having the additional amount is formed by applying a continuous substrate layer (1) to the surface (4) of the eyeglass lens body (3) using the at least one first curable material (6) in a first step of the additive manufacturing process, and then, in a second step of the additive manufacturing process, applying the additional amount of the at least one first curable material (6) or the amount of the at least one second curable material (16) to the substrate layer (1) at locations where the refractive microstructures (5, 5') are to be formed, while the at least one first curable material (6) of the substrate layer (1) has not yet been cured or pinned.

4. The method according to any one of claims 1 to 3, characterized in that In order to form these refractive microstructures (5, 5'), before curing or pinning, the amount of the at least one second curable material (16) is applied to the positions where these refractive microstructures (5, 5') are to be formed, and the at least one first curable material (6) and the at least one second curable material (16) have different refractive indices.

5. The method according to claim 4, characterized in that The at least one first curable material (6) has a refractive index that is less than the refractive index of the at least one second curable material (16).

6. The method according to claim 4 or claim 5, characterized in that: The focal length of these refractive microstructures (5') is at least partially determined by the extent of mutual diffusion between the at least one first curable material (6) and the at least one second curable material (16) before the layer (1, 21, 31) of the at least one first curable material (6) having the amount of the at least one second curable material (16) is cured or pinned.

7. The method according to any one of claims 1 to 3, characterized in that In order to form these refractive microstructures (5, 5'), before curing or pinning, the amount of the at least one second curable material (16) is applied to the positions where these refractive microstructures are to be formed, and the at least one first curable material (6) and the at least one second curable material (16) have the same refractive index.

8. The method according to any one of claims 1 to 7, characterized in that A covering layer (7) of covering layer material is applied to the layer (1, 21, 31) of the at least one first curable material (6) with the additional amount of the at least one first curable material (6) or with the amount of the at least one second curable material (16).

9. The method according to claim 8, characterized in that The covering layer (7) is applied after curing or pinning the layer (1, 21, 31) of the at least one first curable material (6) with the additional amount of the at least one first curable material (6) or with the amount of the at least one second curable material (16).

10. The method according to claim 8 or claim 9, characterized in that The focal power of the refractive microstructures (5, 5') is at least partially determined by the ratio of the refractive index of the cover layer material to the refractive index of the at least one first curable material (6) or the at least one second curable material (16).

11. The method according to any one of claims 8 to 10, characterized in that The cover layer material has a refractive index that is less than the refractive index of the at least one first curable material (6) or the at least one second curable material (16).

12. The method according to any one of claims 1 to 11, characterized in that The focal power of these refractive microstructures (5, 5') is set using at least one of the following parameters: - time until curing or nailing begins; - giving time for the at least one first curable material (6) to cure or be pinned after the start of curing or pinning, or giving time for the at least one first curable material (6) and the at least one second curable material (16) to cure or be pinned after the start of curing or pinning; - an additional amount of the at least one first curable material (6) or an amount of the at least one second curable material (16) applied at the locations where the refractive microstructures (5, 5') are to be formed; - the rheological properties of the at least one first curable material (6), or the rheological properties of the at least one first curable material (6) and the at least one second curable material (16); - a combination of the surface energies of the at least one first curable material (6) and the material of the spectacle lens body (3), or a combination of the surface energies of the at least one first curable material (6) and the at least one second curable material (16) and the material of the spectacle lens body (3); - a combination of the surface tensions of the at least one first curable material (6) and the at least one second curable material (16); - a convection velocity of the at least one first curable material (6), or a convection velocity of the at least one first curable material (6) and the at least one second curable material (16); - Temperature differences during the additive manufacturing process; - the temperature of the nozzle arrangement (8, 27, 28) during the additive manufacturing process; - the temperature of the spectacle lens body (3) during the additive manufacturing process; - the atmospheric temperature during the additive manufacturing process; - atmospheric humidity during the additive manufacturing process; - the composition of the atmosphere during the additive manufacturing process; -The strength of the external electric or magnetic field present during the additive manufacturing process: - the density of the at least one first curable material (3), or the density of the at least one first curable material (6) and the at least one second curable material (16); as well as - the chemical composition of the at least one first curable material (6), or the chemical composition of the at least one first curable material (6) and the at least one second curable material (16).

13. The method according to any one of claims 1 to 12, characterized in that A surfactant is added to at least one of the at least one first curable material (6) and the at least one second curable material (16).

14. The method according to any one of claims 1 to 13, characterized in that At least one of the at least one first curable material (6) and the at least one second curable material (16) has the same refractive index as the material of the spectacle lens body (3).

15. The method according to any one of claims 1 to 14, characterized in that At least one of the refractive index of the at least one first curable material (6) and the refractive index of the at least one second curable material (16) is greater than the refractive index of the material of the eyeglass lens body (3).

16. The method according to any one of claims 1 to 15, characterized in that A layer (1, 21, 31) of the at least one first curable material (6) having the additional amount of the at least one first curable material (6) or having the amount of the at least one second curable material (16) is formed on the surface of the progressive multifocal lens (110).

17. A spectacle lens (100, 110, 120) with refractive microstructures (5), comprising a spectacle lens body (3) with a surface (4) provided with the refractive microstructures (5), wherein the refractive microstructures (5) are at least partially fused to a layer (1, 21, 31) present on the surface (4), characterised in that The refractive microstructures (5) have refractive properties at least partly due to the refractive index gradient present in the refractive microstructures (5).

18. The spectacle lens (100, 110, 120) according to claim 17, characterized in that These microstructures (5) are covered by a cover layer (7).

19. The spectacle lens (100, 110, 120) according to claim 18, characterized in that The refractive index of the cover layer (7) is lower than the refractive index of the refractive microstructures (5).

20. The spectacle lens (100, 110, 120) according to any one of claims 17 to 19, characterized in that The refractive index of these refractive microstructures (5) is greater than the refractive index of the spectacle lens body (3).

21. A data set comprising at least one of the following types of data: (i) a numerical representation of a spectacle lens (100, 110, 120) as claimed in any of claims 17 to 20 for the purpose of using the numerical representation of the spectacle lens to manufacture a spectacle lens as claimed in any of claims 17 to 20, and (ii) data comprising computer-readable instructions for controlling one or more manufacturing machines to produce a spectacle lens (100, 110, 120) as claimed in any of claims 17 to 20.

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