Method for providing a refractive microstructure on the surface of a spectacle lens and spectacle lens design

Abstract

A method for providing refractive microstructures (5) on a surface (4) of an eyeglass 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), wherein, in order to form the refractive microstructures (5), 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 to the locations where the refractive microstructures (5) are to be formed before curing or pinning the at least one first 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 the amount of the at least one second curable material (16) before leveling the protrusions 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) of the at least one curable material (6). In addition, a spectacle lens with refractive microstructures (5) is provided. The spectacle lens comprises a spectacle lens body (3) having a surface (4), the surface being provided with the refractive microstructures (5). These 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, such as lenslets, annular focusing structures, structures with a refractive index profile, etc., on the surface of a spectacle lens, in particular a spectacle lens for slowing or stopping the progression of myopia. Furthermore, the present invention relates to a spectacle lens design with microstructures, in particular a spectacle lens design for slowing or stopping the progression of myopia.

[0002] Myopia has reached epidemic proportions in many 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 stands for spherical equivalent refraction) among adolescents, which significantly 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 or halting myopia progression. One approach uses progressive multifocal lenses to reduce the work required to accommodate the eye and, therefore, reduce the stimulus for eye growth. Another approach relies on spectacle lenses with small lenses or ring-shaped structures outside the area of ​​the spectacle lens used for central vision. The small lenses or ring-shaped structures provide a focal power that produces peripheral myopic defocus outside of central vision. This manipulates peripheral vision, reducing the stimulus for eye growth. For example, spectacle lenses with microstructures, small lenses, or annular structures are disclosed in the following documents: CN 111796364 A, CN 104678572 A, EP 3553594 A1, EP 3561578 A1, US 2016 / 0054588 A1, US 2017 / 0131567 A1, US 2017 / 027691 A1, US 10,571,717 B2, WO 2018 / 026697 A1, WO 2018 / 076057 A1, WO 2019 / 166657 A1, WO 2020 / 113212 A1, and WO 2021 / 059887 A1. In particular, combining progressive multifocal lenses with small lenses offers a promising approach to slowing or halting the progression of myopia.

[0004] The small lenses of eyeglass lenses can be produced, for example, by casting or molding processes, as disclosed, for example, in US Pat. No. 10,571,717 B2, EP 3561578 A1, EP 3640713 A1, EP 3640714 A1, and WO 2019 / 166657 A1. However, while molding is only manageable for thermoplastic materials and therefore imposes restrictions on the materials that can be used for eyeglass lenses with small lenses, casting with curable plastics is very difficult due to the exothermic curing process and the shrinkage that accompanies curing, and casting is also quite expensive. Furthermore, when using prefabricated semi-finished lens blanks to manufacture eyeglass lenses, molding or casting eyeglass lenses with small lenses is difficult because it is difficult to mold or cast the small lenses onto such lens blanks. Molding or casting the small lenses that are already in the semi-finished lens blank is of no use because the position of the area with the small lenses cannot be re-optimized for the finished eyeglass lens.

[0005] US2021 / 0001578 A1 describes a light modifier comprising printed optical elements for vehicle lamps. These optical elements are printed layer by layer on a translucent substrate, with each layer being cured before printing the next. 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 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 be printed layer by layer.

[0006] CN 111796364 A, EP 3553594 A1, WO 2018 / 026697 A1, and WO 2018 / 076057 A1 disclose methods for producing small lenses without using a molding or casting process. Specifically, CN 111796364 A discloses the production of small lenses using foils, while EP 3553594 A1, WO 2018 / 026697 A1, and WO 2018 / 076057 A1 disclose the production of small lenses using additive manufacturing (such as 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, forming uncured protrusions. These protrusions are then cured using ultraviolet light to form the final small lens. However, such printed lenses typically have very high power, around 100 dpt or greater, an order of magnitude higher than the power desired for spectacle lenses used to slow or stop myopia progression. Therefore, printing lenses with the appropriate power is very difficult 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. WO 2021 / 214197 A1 and WO 2021 / 209527 A1 disclose that the lens 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 achieving the appropriate focal power of the refractive microstructure while using standard additive manufacturing equipment (i.e., commercially available printers).

[0009] With respect to WO 2021 / 214197 A1, a second object of the present invention is to disclose a spectacle lens design having a refractive microstructure of appropriate focal power in a layer present on the surface, which spectacle lens design can be manufactured with standard additive manufacturing equipment and which layer allows for improved 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 that serves as a substrate on which the refractive microstructure is formed. The spectacle lens body can be a spectacle lens manufactured to provide prescribed vision correction properties. The spectacle lens body can be a standard spectacle lens produced in batches to provide standardized correction, or it can be a personalized spectacle lens produced for an individual wearer to provide personalized correction according to the wearer's prescription, which may be the case in particular when the spectacle lens is a progressive addition lens (PAL). Alternatively, the spectacle lens body can be a spectacle lens for virtual reality (VR) glasses or augmented reality (AR) glasses, with or without correction. Furthermore, the spectacle lens body can be a semi-finished lens blank, i.e., a lens blank whose one surface has already been polished to its final shape and whose other surface has yet to be machined and polished to achieve the prescribed vision correction properties. 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 the 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, a nozzle arrangement comprises at least one nozzle for ejecting a curable material toward a surface. Typically, the nozzle arrangement is part of a printhead and comprises a one-dimensional nozzle array (i.e., a row of nozzles) or a two-dimensional nozzle array. The two-dimensional nozzle array may comprise at least two rows of nozzles. These multiple rows of nozzles may be aligned with each other, or adjacent rows of nozzles may be shifted relative to each other along the direction in which the rows extend, the shifted distance being a fraction of the distance between adjacent nozzles in a row, thereby achieving a staggered arrangement of multiple rows of nozzles.

[0017] layer

[0018] In the context of the present invention, the term "layer" refers to a quantity 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 dimensions are 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 the refractive microstructure.

[0021] Covering

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

[0023] Curable materials

[0024] In the context of the present invention, the term "curable material" refers to a liquid or viscous monomeric or prepolymeric material or formulation that can solidify or undergo polymerization and cross-linking processes to form a polymeric material. The polymerization and cross-linking 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 reaction. The initiator can be activated by an external stimulus (e.g., electromagnetic radiation, particle beam or heat).

[0027] Pinning

[0028] In the context of the present invention, the term "pinning" shall refer to a process in which a level of polymerization and / or cross-linking is obtained that is lower than the level after full curing, yet the viscosity of the polymer material is still greatly increased to prevent a significant amount of material from flowing on a time scale that is larger (preferably at least twice, more preferably at least five times) than the time scale required to complete the desired structure. Reduced polymerization and / or cross-linking can be achieved, for example, by a reduced stimulus (e.g., reduced electromagnetic radiation intensity or heat intensity) or by a reduced stimulus duration. In addition, the term "pinning" shall also include the case in which 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 that is larger than the time scale required to complete the desired structure, while a layer below the surface layer undergoes cross-linking that is sufficient to prevent significant material from flowing on a time scale that is larger 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 noble gas atmosphere) will allow for 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 spectacle lens body. The focal power can be optical power, so as to provide a point or line focus. The line focus need not extend along a straight line but can also extend along a curved line (e.g., a circular line). However, the refractive microstructure does not necessarily need to provide a point or line focus, as long as it modifies the curvature or direction of the incident wavefront more than the spectacle lens body.

[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 material within a fluid, 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 a process in which surface protrusions of a liquid or viscous material are leveled out 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 (such as, for example, monomers or other species 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 of 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 if they differ from each other by at least 0.5 parts per thousand, preferably by 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 0.5 parts per thousand, preferably by no more than 1 part per thousand.

[0056] focal length

[0057] In the context of the present invention, the term "focal power" refers to the ability of a lens or 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 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 is usually considered in prescriptions with the "cylindrical" value or the abbreviation "cyl"). "Vertex 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 bundle of rays if its diameter does not exceed 0.05 mm, in particular 0.01 mm.

[0058] Myopic 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] Add 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, with the aid of accommodation, will provide a focused image on the fovea and, when added to the optical power of the spectacle lens, provides myopic defocus. This additional power is not to 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 generally 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 optical 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 an annular focusing structure may, for example, comprise structures similar to those described in EP 3553594 A1, EP 3561578 A1, WO 2019 / 166653A1, WO 2019 / 166654A1, WO 2019 / 166655A1, WO 2019166657 A1, WO 2019 / 166659A1 and WO2019 / 206569 A1, or structures similar to those disclosed in US2016 / 054588 A1, US2017 / 227788 A1, US2017 / 276961A1, US2019 / 227342 A1, WO 07 / 041796A1, WO 09 / 129528A1 or WO10 / 129465A1, respectively.

[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 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 apex of the groove of the upper and lower rings of the frame, in a vertical plane containing the principal direction (DIN ISO 13666:2019, section 3.2.37), where the principal direction is the direction of the line of sight to an object at infinity (usually taken as the horizontal direction) measured with the naked eye looking straight ahead in a habitual head and body posture (DIN ISO 13666:2019, section 3.2.25), and the line of sight is the path of a 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 on the retina (usually the fovea) (DIN ISO 13666:2019, section 3.2.24). Typical values ​​of the actual wearing anteversion angle lie in the range of -20 degrees to +30 degrees. The actual wearing bezel face curvature is the horizontal angle, measured in a horizontal plane containing the principal direction, between the principal direction and a perpendicular to a reference line passing through the apex of the grooves of the nasal and temporal bezels of the frame (DIN ISO 13666:2019, Section 3.2.38). Typical values ​​for the actual wearing bezel face curvature lie in the range of -5 degrees to +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 primary position (DIN ISO 13666:2019, Section 3.2.40), where the primary position is the position of the eye when looking in the principal direction (DIN ISO 13666:2019, Section 3.2.26). Typical values ​​for the vertex distance lie in the range of 5 mm to 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] Eyeglass 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 a model of the eye of the spectacle lens wearer, the position / arrangement of a model of objects to be viewed by the spectacle lens wearer under specific conditions of use of the spectacle lens, and a model of the physiological vision properties of the spectacle lens wearer.

[0074] In particular, the spectacle lens optical design may include a power distribution over the active area of ​​the spectacle lens as perceived by a predetermined 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 impairment, 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 spectacle lens wearer with the above-mentioned calculated optical properties of the spectacle lens.

[0076] The term "target optical design of a spectacle lens" refers to a draft optical design of a spectacle lens, the optical properties of which correspond to or are equal to the target optical properties. The term "actual optical design of a spectacle lens" refers to the calculated optical properties of a spectacle lens obtained as a result of an optimization process / calculation, which aims to achieve the target optical design of the spectacle lens as closely as possible. Such optimization processes / calculations, in particular for progressive spectacle lenses or custom-made 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 (e.g. non-transitory and / or electronic and / or optical) data carrier. Furthermore, a spectacle lens manufactured according to the spectacle lens design may be considered a physical representation of the spectacle lens design.

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

[0079] In a first step, the 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 a spectacle wearer can include, for example, the wearer's refractive error and the wearer's accommodative ability, which are determined using refractive measurements and are regularly included in the prescription in the form of prescribed values ​​for spherical power, cylindrical power, (if applicable) axis position, prismatic power, and base curvature, as well as lower addition (if the spectacle lenses are progressive multifocal lenses). Furthermore, pupil distance and pupil size, for example, 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 usage conditions include the actual wearing position of the spectacle lens in front of the eye (usually relative to the eye's center of rotation) 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 anteroposterior and lateral tilt angles. This data is incorporated into an object distance model, to which ray tracing methods can be applied.

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

[0083] Furthermore, the design of the surface geometry of the front and back surfaces and the design of the refractive index distribution over the entire spectacle lens are specified. For example, the front surface can be selected as a spherical surface, and the back surface as a variable focus surface. Both surfaces can also be initially selected as spherical surfaces. The choice of surface geometry for the first draft generally 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 its spherical shape, while the back surface is to be given the shape of a variable focus surface.

[0084] In a further step, the paths of the main rays are determined by a large number of evaluation points. It is possible that in the vicinity of each main ray a local wavefront can be established for the respective main ray. Design and Development of Progressive Lenses, Deutsche OptikerZeitung, DOZ 10 / 95, pp. 42-46, states that the number of evaluation points typically ranges from 1,000 to 1,500. EP 2,115,527 B1 suggests more than 8,000 evaluation points. Although the refractive index is generally wavelength-dependent, dispersion is typically not considered 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] Among them, 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 termination 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 having corresponding design features (a physical representation of a spectacle lens design) or to a numerical data set describing the design features (a numerical representation of a spectacle lens design). For example, such a data set may be stored in a computer memory 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 the Internet or a local area network (LAN). In particular, a data set similar to a representation of a progressive spectacle lens design may include a description of the geometry and medium of the progressive spectacle lens. Such a description may, for example, include a mathematical description of the front surface, the back surface, the arrangement of these surfaces relative to one another (including thicknesses), and the edge definition of the progressive spectacle lens, as well as the refractive index profile of the medium used to produce the spectacle lens. The representation may be in coded or even encrypted form. The term "medium" here refers to the material(s) or substance(s) from which the spectacle lens is produced.

[0092] According to a first aspect of the present invention, a method for providing a refractive microstructure on the surface of an eyeglass lens body is provided, 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 can be embodied as a lenslet, an annular focusing structure, a structure having a refractive index profile, or any other structure that provides a focal power in addition to the focal power provided by the eyeglass lens body. Furthermore, the surface of the eyeglass lens body can be the surface of a progressive multifocal lens.

[0093] According to the present invention, an additive manufacturing process includes 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 includes curing or pinning the layer of the at least one first curable material having the additional amount of the at least one first curable material or the amount of the at least one second curable material before flattening a 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 additional amount of the at least one first curable material or the at least one second curable material of the amount is applied before solidifying or pinning the at least one first curable material, surface protrusions with an approximate spherical curvature in at least one direction and / or concentration gradients are developed at the position where the refractive microstructure should be formed. After the additional amount of the at least one first curable material or the at least one second curable material of the amount is applied, these protrusions and / or these concentration gradients begin to coalesce immediately after the additional amount of the at least one first curable material or the at least one second curable material of the amount has been applied. This coalescence causes the layer surface to be leveled over time at the position where the additional amount of the at least one first curable material or the at least one second curable material of the amount has been applied, and therefore causes the approximate spherical curvature to be flattened, and / or causes the concentration gradient at the position where the additional amount of the at least one first curable material or the at least one second curable material of the amount has been applied to be reduced. Flattening the curvature of the approximate spherical surface (that is, increasing the radius of curvature) and / or reducing the concentration gradient and thus allowing the use of solidification or pinning, so that after solidification or pinning, a desired degree of curvature and / or a 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 this at least one first curable material of this additional amount or this at least one second curable material of this amount reduces curvature and / or 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 solidification or pinning process.

[0096] Furthermore, in the case of use of at least one second curable material, the use of the at least one second curable material allows the coalescence speed to be influenced by means of 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 smaller 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 smaller than the refractive index of the at least one second curable material. By basing the refractive power at least in part on a refractive index gradient, positive refractive power can be achieved with refractive microstructures that protrude less from the surface than if their refractive power were based solely on their geometry, which allows the resulting surface to have a relatively flat topography. 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 with depressions at the locations of the refractive microstructures in the layer surface. For example, the formation of a flat topography or depressions can be promoted by applying an 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 locations to the locations on the surface of the eyeglass lens body where the refractive microstructures should be formed, and preferably applying this amount of the at least one second curable material only to the locations where the refractive microstructures should be formed. In the case of immiscible first and second curable materials, the second material will partially immerse itself in the first curable material, thereby producing a biconvex structure. When the first and second curable materials having suitable properties (including, for example, surface tension and density) are selected, this effect can be used to form biconvex small lenses 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 indices 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 determined at least in part by the extent to which the at least one first curable material and the at least one second curable material diffuse into each other 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, if the refractive power is to be based solely on the surface geometry, either an additional amount of the at least one first curable material can be applied where the refractive microstructure is to 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 0.5 parts per thousand, preferably no more than 0.1 parts per thousand. In this case, the focal power provided by the refractive microstructure is not affected by 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 primarily 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 the case of inkjet printing, in a single pass of the nozzle arrangement. This can be achieved, for example, by varying the number of droplets of curable material applied to different locations on the surface. Alternatively, 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 the additive manufacturing process, such as in a first pass of the nozzle arrangement, a continuous base layer can be applied to the surface of the eyeglass lens body 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 at least one second curable material is applied to the base layer at locations where the refractive microstructure is to be formed, while the at least one first curable material in the base layer has not yet cured or pinned. The base 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 the refractive microstructures to be given 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 pinning 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] -The 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 additive manufacturing process.

[0112] -Atmospheric humidity during the additive manufacturing 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 the initiator for starting polymerization. In addition, there is a curable material formulation with an initiator, which needs to be stimulated to be activated so as to induce solidification or pinning reaction. This activation can be provided by heat, particle beam 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 amount of the at least one second curable material, and / or the diffusion of the amount of the at least one second curable material, and thus affect the final topography and / or material distribution at the location of the refractive microstructure. The topography and / or material distribution, in the case where the at least one first curable material and the at least one second curable material have different refractive indices, will determine the focal power of the refractive microstructure. Thus, 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 further comprise the steps: covering layer is applied to the layer of this at least one first curable material with this additional amount or this at least one first curable material with this at least one second curable material of this amount. Covering layer can for example be applied by inkjet printing or by coating technology (such as spin coating). And, the lamination process of the foil with adhesive in the situation that has or does not have bonding layer helps can be used. In addition, covering layer can be applied after solidifying or pinning the layer of this at least one first curable material with this additional amount or this at least one first curable material with this at least one second curable material of this amount, to avoid undesirably affecting the application process of applying covering layer on this at least one first curable material with this additional amount or this at least one first curable material layer with this at least one second curable material of this amount.

[0121] A sufficiently thick covering 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 or onto the covering layer, which improves the usability of the eyeglass lens. In addition, the focal power of the refractive microstructure can be determined at least in part by the ratio of the refractive index of the covering 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 covering layer material based on 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 covering 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 covering layer material can be at least 0.5 parts per thousand, 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 covering 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, positive power may be provided even if the refractive microstructure has a concave curvature.

[0122] In the method according to the present 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 microstructures are 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 greater than the refractive index of the material of the spectacle lens body by at least 0.5 parts per thousand, preferably at least 1 percent.

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

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

[0125] When the refractive microstructures are covered by a cover layer, a flat surface that follows the surface of the lens body can be achieved. The refractive index of the cover layer can be lower than that of the refractive microstructures. In particular, the refractive index of the cover layer can be at least 0.5 parts per thousand, preferably at least 1 percent lower than that of the refractive microstructures. This helps ensure that refractive microstructures with a convex curvature provide positive focal power. However, in principle, the refractive index of the cover layer can also be higher than that of the refractive microstructures. In particular, the refractive index of the cover layer can be at least 0.5 parts per thousand, preferably at least 1 percent higher than that of the refractive microstructures. In this case, even refractive microstructures with a concave curvature can provide positive focal power. Thus, the cover layer allows for a wider variety of possible geometries of the refractive microstructures. In particular, in a system of refractive microstructures and cover layer, a refractive index of the cover layer that is higher than that of the refractive microstructures reduces the refractive power provided to the geometry of the refractive microstructures and thus allows for refractive microstructures with smaller radii of curvature. Furthermore, selecting an appropriate refractive index for the cover layer allows for fine-tuning of the refractive power provided by the system of refractive microstructures and cover layer.

[0126] According to yet another aspect of the present invention, a data set is provided that includes at least one of the following types of data: (i) a numerical representation of a spectacle lens according to the present invention, for the purpose of using the numerical representation of the spectacle lens to manufacture the spectacle lens according to the present invention, and (ii) data containing computer-readable instructions for controlling one or more manufacturing machines to produce the spectacle lens according to the present invention. The data set allows the data to be sent to a manufacturer of the spectacle lens. The purpose of using the numerical representation of the spectacle lens to manufacture the spectacle lens according to the present invention may include the purpose of generating data containing 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 inventive method 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] Figure 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] Figure 10 A cross-sectional view of an example of a spectacle lens manufactured according to the method of the present invention is shown.

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

[0135] Figure 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 will be 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 present 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 this 3D printing process, a 3D structure is formed by printing the structure onto a substrate using a polymer ink.

[0138] 3D printing is accomplished using 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 exemplary embodiment, the nozzle arrangement 8 is part of a single printhead comprising a one-dimensional nozzle array (i.e., a row of nozzles) extending perpendicular to the direction of relative movement between the nozzle arrangement 8 and the spectacle lens body 4. However, the printhead may also comprise a two-dimensional nozzle array, for example, two or more rows of nozzles. The rows of nozzles in 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. Alternatively, 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 by a distance that is a fraction of the distance between adjacent nozzles in a row, thereby achieving a staggered arrangement of the rows of nozzles. This staggered arrangement can increase the resolution achievable during printing.

[0139] The polymer ink of this exemplary embodiment (i.e., the first curable material 6) cures by polymerization of monomers and / or oligomers and by crosslinking the polymer chains in the ink material. Polymerization and crosslinking are initiated by an initiator that 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 for use as the first curable material 6 in this exemplary embodiment are (meth)acrylate-based polymer inks, preferably solvent-free. However, polymer inks containing a small proportion of solvent can also be used if the substrate layer thickness is sufficiently small to allow the solvent to evaporate prior to the curing process. Typical materials for the spectacle lens body 3 are thermoplastics (e.g., polycarbonate) or thermosetting plastics (e.g., CR-39). Table 1 lists a list of polymers suitable for forming the spectacle lens body 3.

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

[0142]

[0143] The polymer ink used to form the first curable material 6 of the base layer 1 can have a refractive index that is the same as the refractive index of the material of the spectacle 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 0.5 parts per thousand, preferably no more than 0.1 parts per thousand. However, the first curable material 6 and the material of the spectacle lens body 3 do not need to have the same refractive index. In particular, the refractive index of the first curable material 6 can be lower than that of the material of the spectacle lens body, which can be beneficial in designing an additional anti-reflective (AR) coating. Furthermore, the first curable material 6 should also be suitable as a substrate for the hard coating later applied to the base layer 1 and for the refractive microstructures present in the base layer 1. Furthermore, 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 spectacle lens having the refractive microstructures is less than 3, preferably less than 1, and ideally less than 0.5, and the haze is less than 1.0%, preferably less than 0.5%.

[0144] The typical thickness of the substrate layer 1 is in the range of 1 to 100 μm, preferably in the range of 5 to 50 μm. In order to prevent the formation of unwanted structures in thin substrate layers (i.e., substrate layers with a thickness of less than 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 of 15 to 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 direction of movement of the print head 8 is determined by Figure 2). This 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 the short time after the droplets forming the protrusions 15 have been printed onto the base layer 1, the curvature of the protrusions 15 is high, i.e. the radius of curvature is small, and therefore the refractive power provided by the protrusions 15 is high, whereas 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 flattens, i.e. 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 solidifies. Therefore, controlling the time before pinning or curing begins and the time given to pin or cure the first curable material 6 (i.e. 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 rate and the pinning or curing rate. 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 energy 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] -The temperature of the nozzle arrangement during the additive manufacturing process.

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

[0153] -Atmospheric temperature during the additive manufacturing process.

[0154] -Atmospheric humidity during the additive manufacturing 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 reduction 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 protrusions 15 with the base layer 1 before the protrusions 15 are completely fused with the base layer 1 in order to maintain the curvature of the protrusions 15 at a level that provides the desired refractive power, which is no more than 10 dpt and typically between 1.5 and 5.5 dpt. The time it takes for the protrusions 15 to completely fuse 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 this exemplary embodiment, any material transfer is interrupted or significantly slowed by pinning. In this 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 for the surface layer in contact with the oxygen-containing atmosphere, which 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 fully solidified without pinning.

[0162] In this exemplary embodiment, pinning (or complete curing) is initiated with the help of an initiator, which in this exemplary embodiment is a photoinitiator. To activate the photoinitiator to initiate pinning (or curing), the protrusions 15 and the base layer 1 are irradiated with ultraviolet radiation (i.e., radiation having a wavelength in the range of 10 to 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 undergoing crosslinking is used without the need for an initiator.

[0163] Due to pinning (or curing), the fusion of the protrusions 15 into 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 to 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 microstructures 5, should not depend on whether they were 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 would 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 would start to fuse at the same time.

[0165] In this 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 cover 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 cover layer 7 and the base layer 1 with the protrusions 15. In this exemplary embodiment, the cover layer 7 is printed onto the base layer 1 with the protrusions 15. However, the cover layer 7 can also be applied by spin coating or with the help of an adhesive foil. After the cover 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 formed by the protrusions 15 is completely covered by the cover layer 7. To achieve this goal, the thickness of the cover layer 7 is typically in the range of 2 to 15 times the height of the refractive microstructure 5 formed by the protrusions 15 protruding from the base layer 1, in particular in the range of 5 to 10 times the height of the refractive microstructure 5 protruding from the base 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 a layer thickness in the range of 1 to 100 μm, in particular in the range of 1 to 50 μm. Possible materials are epoxides, epoxy-thiol systems, mercapto-vinyl-based systems, urethanes, polysiloxane-based systems, etc.

[0168] Without the cover layer 7, the focal power 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 of 1.50 to 1.74, the refractive index difference will generally be in the range of 0.5 to 0.74. With the cover layer 7, this refractive index difference will be reduced, which will allow for a higher curvature of the refractive microstructures 5. Thus, the refractive index of the cover layer 7 can be used to compensate for excessive curvature of the refractive microstructures 5.

[0169] In this exemplary embodiment, the viscosity of the base layer 1 can be varied to appropriately adjust the fusion speed of the refractive microstructures 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). Furthermore, the viscosity can be varied 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 additive manufacturing occurs during the pinning process, by the UV radiation dose used for pinning, by the initiator content, and the like.

[0170] Although the same first curable material 6 is used to form the base layer 1 and the protrusion 15 in the first exemplary embodiment described so far, 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 direction of movement of the print head 8 is represented by Figure 5 Indicated by the arrow in .

[0172] In the second exemplary embodiment, the print 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, results in the formation of protrusions 25 that protrude 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 for 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 in the case of Figure 3 Already described.

[0174] What has been said about 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 protrusions 25 in a single pass of the print head 8. Figure 6 In a third exemplary embodiment of the method of the invention shown in FIG, the nozzle arrangement is implemented as two print heads 27, 28. Each of the print heads 27, 28 may comprise 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 and 28 are used to print a layer 21 of the first curable material 6 and the protrusions 25' protruding from the layer 21 in a single pass of the print heads 27 and 28. The relative movement direction between the print heads 27 and 28 and the spectacle lens body 3 is indicated by the arrows. 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 in a single pass of the print heads 27 and 28, the remaining steps of the method for providing the 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 quantity 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 with 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 according to the present invention will now be described. 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 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 directions between the print heads 27, 28 and the spectacle lens body 3 are indicated by arrows. 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 the manner in which the refractive properties of the refractive microstructures 5' are achieved. For this purpose, a second curable material 16 is used, which has a refractive index that is different from and higher than that of the first curable material 6.

[0180] In the fourth exemplary embodiment, the amount of first curable material 6 applied to the surface 4 of the spectacle lens body 3 at locations where the refractive microstructures 5' are to be formed using the first print head 27 is less than the amount of first curable material 6 applied to other locations on the surface 4. Consequently, the layer 31 is formed with recesses 32 at those locations where the refractive microstructures 5' are to be formed. Although the recesses 32 do not reach the surface 4 of the spectacle lens body 3 in this exemplary embodiment, there may be embodiments 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 microstructures to be formed. For example, for typical lateral dimensions of the refractive microstructures to be formed, the recesses 32 may expose the surface 4 when the layer 31 of the first curable material 6 has a maximum thickness of up to 10 μm, whereas they are unlikely to expose the surface 4 when the layer 31 of the first curable material 6 has a greater thickness. Typical lateral dimensions of the refractive microstructures 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 liquid, 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 recess 32 and the lowest refractive index in the part 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 lenslet 5'. The gradient refractive index lenslet 5' in Figure 8 The center is indicated by a dotted area, where a higher density of dots indicates a higher refractive index. Figure 10 Shown Figure 9 Figure 2 shows the refractive index profile from left to right in the figure. In practice, the gradient-index lenslet 5' will protrude slightly from the surface because the time given to diffuse the first curable material 6 and the second curable material 16 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 second curable material 16 printed into the recess 32. Furthermore, the slope of the gradient determines the power of the gradient index lenslet 5', such that adjusting the duration of the diffusion process allows adjustment of the 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 this exemplary embodiment is accomplished by pinning or curing the first and second curable materials 6, 16.

[0183] The use of gradient-index lenslets 5' allows the formation of a layer 31 with refractive microstructures 5' that has a flat surface 3, or at least a flatter surface than the surface of a layer in which the refractive microstructures are based solely on the surface geometry of the refractive microstructures. This can be advantageous if additional layers (such as, for example, hard coatings, transmittance-modifying layers, antireflection layers, etc.) are applied on top of the layer 31 with refractive microstructures 5'. In particular, a flat surface can 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 can be further improved.

[0184] Figure 10 A cross-sectional view of a spectacle lens 100 that has been manufactured according to the method of the present invention is shown. The spectacle lens comprises a spectacle lens body 3 and a layer 1 having refractive microstructures 5, which, in this exemplary embodiment, provide a positive focal power in addition to the focal power of the spectacle lens body 3 due to the curvature of their surface protruding from the layer 1. On top of the layer 1 having the protruding refractive microstructures 5, there is a layer 7 that is thick enough to flatten the protruding parts of the refractive microstructures 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 help to increase 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 addition lens (PAL).

[0185] In this exemplary embodiment, the thickness of layer 1 is 45 μm, and the refractive microstructures 5 protrude from layer 1 by approximately 1 μm. To achieve 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 this 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 antireflection layer 103 is provided on top of hard layer 101. Note that other layer systems can also be provided on top of cover layer 7, such as layers with absorptive or reflective properties, as they are used, for example, in sunglasses.

[0186] Note that in other exemplary embodiments, the elevation from the surface of the base layer 1 can be greater or less than 1 μm, and can range from 0 to 10 μm, depending, inter alia, on the desired focal power achieved with the refractive microstructures 5. An elevation approaching 0 μm would mean that the surface of the base layer 1 with the refractive microstructures 5 is nearly flat. Such a flat surface can exist if the refractive properties of the refractive microstructures 5 are due to differences or gradients in their refractive indices rather than to the curvature of their surfaces. If the refractive properties of the refractive microstructures 5 are achieved by virtue of their curvature, their elevation from the surface ranges from 0.2 to 10 μm, and often from 0.4 to 1.5 μm. To achieve a flat surface for the cover layer 7, the cover layer needs to have a thickness ranging from 1 to 50 μm, depending on the extent to which the refractive microstructures 5 protrude from the base layer 1.

[0187] exist Figure 11 In the illustrated spectacle lens 100, the material forming the protruding refractive microstructures 5 is the same as the material of layer 1. This material has the same refractive index as the material of the spectacle lens body 3. This means that the refractive index of the refractive microstructures 5 and layer 1 differs from the refractive index of the spectacle lens body 3 by no more than 0.5 parts per thousand, and preferably by no more than 0.1 parts per thousand. Typical materials that can be used as the materials for the refractive microstructures 5 and layer 1 have a refractive index between 1.30 and 1.75. Typical materials for spectacle lens bodies have a refractive index in the range of 1.50 to 1.74. To provide a positive power in addition to the power of the spectacle lens body 3, the refractive microstructures 5 need to have a higher refractive index than the cover layer 7. Therefore, it is desirable to use materials with a refractive index at the upper end of the range of 1.30 to 1.75 for layer 1 and the refractive microstructures 5, and to use a material with a refractive index at the lower end of this 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 can allow a steeper curvature than the refractive microstructure 5 having an interface with air.

[0188] Despite Figure 10 A specific combination of refractive indices is presented in the exemplary embodiments shown, but other combinations of refractive indices are possible. Figure 10Alternatively to the exemplary embodiment shown, the refractive index of the refractive microstructures 5 can differ from the refractive index of the spectacle lens body 3. In particular, the refractive index of the refractive microstructures 5 can 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 alternatively, the refractive index of the cover layer 7 can correspond to the refractive index of the spectacle lens body 3 or can be greater than the refractive index of the spectacle lens body 3. In the case where layer 1 has the same refractive index as the spectacle lens body 3, a refractive index of the cover layer 7 corresponding to the refractive index of the spectacle lens body 3 will prevent unwanted refraction or Fresnel reflections at the interfaces between the spectacle lens body 3 and layer 1, and between 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 the case where 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 having the refractive microstructures 5, or even an inverted geometry, i.e., a concave curvature (such as depressions or dimples) rather than a convex curvature. However, this alternative is primarily used if an additional power in addition to the power provided by the spectacle lens body 3 is to be achieved. Alternatively, in the absence of the cover layer 7, the refractive index of the layer 1 can be lower than the refractive index of the spectacle lens body 3, which may be beneficial if an antireflection layer is to be applied to the layer 1.

[0189] although Figure 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 layer 1, but they may have refractive properties at least partially or even completely due to a refractive index gradient present in the refractive microstructures 5. The use of a refractive index gradient allows layer 1 to have a flatter surface or even a completely flat surface, compared to refractive microstructures 5 having refractive properties due to the geometry of the protrusions protruding from 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 that of the first curable material.

[0190] In a top view of a spectacle lens, the refractive microstructures can have various shapes. Figure 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 ( Figure 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] Figure 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 provided 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 ( Figure 12 (not shown) protrudes. 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 in refractive index, or by a combination of curvature and a difference or gradient in 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 inward and radially outward from the center of the ring. Other geometric shapes of the refractive microstructures 5 in a plan view of the spectacle lens 100 are conceivable to those skilled in the art. Therefore, the geometry of the refractive microstructures 5 should not be limited to lenslets and ring-shaped microstructures. Although the spectacle lens body 3 of the spectacle lens 120 is the spectacle lens body of a single-vision spectacle lens, it can also be the 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 three refractive microstructures arranged in a 3x3 array was formed on a 9 mm x 9 mm area of ​​a glass substrate (SCHOTTD263T eco). In a first step, a fluid base layer with a thickness of 45 μm was printed onto the glass substrate using a (meth)acrylate-based polymer ink using a standard 3D printer's printhead in a first pass. Then, a pattern of refractive microstructures was printed onto the base layer using the same (meth)acrylate-based polymer ink in a second pass. This pattern consisted of nine microstructures arranged in a 3x3 array. Four of these patterns were printed in successive passes of the printhead, each of which took 12 seconds. Immediately after printing the last of these four patterns, they were pinned using UV radiation with wavelengths of 365 nm and 395 nm to disrupt material flow while the patterned substrate was 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 their refractive microstructure diameters, their protrusion from the base layer, the radius of the sphere that best fits the curvature of the microstructures, and their focal length. The focal length was estimated based on a refractive index of 1.50 for the (meth)acrylate-based polymer ink. The results are summarized in the table below:

[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. Similarly, the slope of the refractive microstructures and the focal power provided by them decrease with increasing time elapsed before pinning. On the other hand, the diameter of the sphere that best fits the microstructure's curvature increases with increasing time elapsed before pinning, as does the diameter of the refractive microstructures. This behavior is due to the coalescence of the printed refractive microstructures with the base layer over time.

[0200] Of the four patterns presented in the table, Patterns 3 and 4 demonstrate that the refractive microstructures have a power suitable for a small lens of a spectacle lens used to slow or stop myopia progression. The power of the refractive microstructure of the second pattern is somewhat lower, but may still be suitable for a small lens of a spectacle lens used to slow or stop myopia progression, whereas the power of the refractive microstructure of the first pattern is too low to be used as a small lens of a spectacle lens used to slow or stop myopia progression.

[0201] Furthermore, it was observed that if the refractive microstructures within the pattern were closer together, the coalescence of the refractive microstructures took longer. This is likely due to the fact that lateral material transport is hindered or affected by adjacent structures. Therefore, in the case of refractive microstructures arranged close together, the time required before pinning is longer than for refractive microstructures positioned further apart.

[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 microstructures 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 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 could be used to slow or halt myopia progression.

[0205] Third specific example

[0206] In a third specific example, both the layer and the refractive microstructures are printed in a single pass of the print head. In doing so, the layer is printed with a pattern having 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 having the depressions has a first refractive index, and the ink used to print the refractive microstructures in the depressions has a second refractive index that is higher than the first refractive index. The inks for the layer and the refractive microstructures diffuse over time, creating a refractive index gradient with the highest refractive index at the center of the refractive microstructures and the lowest refractive index in the region between adjacent refractive microstructures.

[0207] Fourth specific example

[0208] In a fourth specific example, a refractive microstructure was printed onto a curved substrate without a 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 this substrate. The small lens was printed using the same procedure as for pattern 4 in the first specific example, while the annular focusing structure was printed using the same procedure as in the second specific example.

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

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

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

[0212] The present invention has been described with reference to exemplary embodiments and specific examples of the present method and the resulting spectacle lens designs. Given these exemplary embodiments and specific examples, those skilled in the art will be able to conceive of modifications to the present method and spectacle lens designs. Therefore, the scope of the present invention should not be limited by these exemplary embodiments or specific examples, but rather solely 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 certain 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) with the additional amount of the at least one first curable material (6) or the certain amount of the at least one second curable material (16).

2. The method according to claim 1, wherein 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 smaller than the amount of the at least one first curable material (6) applied to other positions, and a certain 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, wherein: The layer 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 certain amount of the at least one second curable material (16) 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 certain amount of the at least one second curable material (16) to the substrate layer (1) at the 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 claim 1 or 2, wherein: In order to form these refractive microstructures (5, 5'), before curing or pinning, a certain amount of the at least one second curable material (16) is applied to the position 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, wherein 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, wherein The focal length of these refractive microstructures (5') is at least partially determined by the extent to which the at least one first curable material (6) and the at least one second curable material (16) diffuse into each other before the layer (1, 21, 31) of the at least one first curable material (6) having the certain amount of the at least one second curable material (16) is cured or pinned.

7. The method according to claim 5, wherein The focal length of these refractive microstructures (5') is at least partially determined by the extent to which the at least one first curable material (6) and the at least one second curable material (16) diffuse into each other before the layer (1, 21, 31) of the at least one first curable material (6) having the certain amount of the at least one second curable material (16) is cured or pinned.

8. The method according to claim 1 or 2, wherein: In order to form these refractive microstructures (5, 5'), before curing or pinning, a certain 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.

9. The method according to claim 1 or 2, wherein: A covering layer (7) of covering 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 the at least one second curable material (16) with the amount of the at least one second curable material (16).

10. The method according to claim 9, wherein 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 the at least one second curable material (16) with the amount of the at least one second curable material (16).

11. The method according to claim 9, wherein The focal power of the refractive microstructures (5, 5') is determined at least in part 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).

12. The method according to claim 10, wherein The focal power of the refractive microstructures (5, 5') is determined at least in part 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).

13. The method according to claim 9, wherein 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).

14. The method according to claim 10, wherein 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).

15. The method according to claim 11, wherein 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).

16. The method according to claim 1 or 2, wherein: The power of these refractive microstructures (5, 5') is set using at least one of the following parameters: - Time until curing or pinning 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; - rheological properties of the at least one first curable material (6) or 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; - 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 (6), 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).

17. The method according to claim 1 or 2, wherein: 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).

18. The method according to claim 1 or 2, wherein: 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).

19. The method according to claim 1 or 2, wherein: 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 spectacle lens body (3).

20. The method according to claim 1 or 2, wherein A 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 the at least one second curable material (16) with the certain amount is formed on the surface of a progressive multifocal lens (110).

21. A spectacle lens (100, 110, 120) with refractive microstructures (5), comprising a spectacle lens body (3) having 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), wherein the spectacle lens (100, 110, 120) is manufactured by a method as claimed in any one of claims 1 to 20.

22. The spectacle lens (100, 110, 120) according to claim 21, characterized in that The refractive microstructures (5) have refractive properties at least in part due to a refractive index gradient present in the refractive microstructures (5).

23. The spectacle lens (100, 110, 120) according to claim 21 or claim 22, characterized in that These microstructures (5) are covered by a cover layer (7).

24. The spectacle lens (100, 110, 120) according to claim 23, characterized in that The refractive index of the cover layer (7) is lower than the refractive index of the refractive microstructures (5).

25. The spectacle lens (100, 110, 120) according to claim 21 or claim 22, characterized in that The refractive index of these refractive microstructures (5) is greater than the refractive index of the spectacle lens body (3).

26. A computer-readable storage medium having stored thereon a data set comprising at least one of the following types of data: (i) a numerical representation of a spectacle lens (100, 110, 120) according to any one of claims 21 to 25, the numerical representation being configured for the purpose of manufacturing a spectacle lens according to any one of claims 21 to 25 using the numerical representation of the spectacle lens, and (ii) data comprising computer-readable instructions for controlling one or more manufacturing machines to produce a spectacle lens (100, 110, 120) according to any one of claims 21 to 24.

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