A method for manufacturing an optical component having at least one optical function

Abstract

METHOD FOR MANUFACTURING AN OPTICAL COMPONENT WITH IMPROVED SURFACE QUALITY USING ADDITIVE MANUFACTURING.A method for manufacturing an optical component having at least one optical function comprising: - manufacturing, using an additive manufacturing process, at least part of an optical element (40) by depositing a plurality of predetermined volume elements (14) of polymerizable material, one part of the optical element (40) being configured to provide at least one part of the optical function of an optical component, said additive manufacturing being carried out in such a way that the optical element (40) comprises an unfinished peripheral surface (42), said unfinished peripheral surface (42) having a relief pattern (44) formed by traces of the additive manufacturing process and having at least one depression (18) relative to another part of the peripheral surface (42), - coating said unfinished peripheral surface (42) with a layer (50) of coating liquid (46) configured to fill at least partially the at least one depression (18).

Description

1 / 27 “METHOD FOR MANUFACTURING AN OPTICAL COMPONENT HAVING AT LEAST ONE OPTICAL FUNCTION”

[0001] The invention relates to the manufacture of optical components, for example, ophthalmic lenses.

[0002] More particularly, the invention relates to a method of manufacturing an ophthalmic component by additive manufacturing.

[0003] The methods for manufacturing ophthalmic components by additive manufacturing are well known. An optical element is formed by the deposition of a plurality of predetermined volumes of material which can be layers of material or a plurality of voxels, that is, elementary volumes of material, formed within the same layer or formed by the deposition of droplets, each droplet being a voxel.

[0004] The deposition of the aforementioned predetermined volumes of material induces a discretized or stepped pattern along the three dimensions, especially in inclined or curved areas of the optical element. This pattern does not allow obtaining a desired optical function when the optical element is an ophthalmic lens or part thereof, due to very high roughness, making this surface unacceptable for optical application.

[0005] A solution to this stepped pattern is, for example, disclosed in WO 2017 / 062857 A1, where a film or membrane is used to spread a resin over an optical element obtained by additive manufacturing to smooth the peripheral surface of an optical component. However, the film or membrane may deform the optical element, or spread the resin unevenly, if the film is too rigid or if the optical element is not yet fully solid. On the other hand, if the film stretches too easily, it may not allow the stepped pattern to be reduced to a fully satisfactory level while still retaining traces of the stepped pattern.

[0006] One problem that the invention aims to solve is, therefore, to provide an improved method that allows manufacturing an ophthalmic component with a smooth peripheral surface providing precise optical function.

[0007] To solve this problem, the invention provides a manufacturing method Petition 870260002718, dated 12 / 01 / 2026, page 11 / 74 2 / 27 of an optical component having at least one optical function, comprising: - to manufacture, using an additive manufacturing process, at least part of an optical element by successively aggregating a plurality of elements of predetermined volume of polymerizable material, the part of the optical element being configured to provide at least part of the optical function of an optical component, said additive manufacturing being carried out in such a way that the optical element comprises an unfinished surface, said unfinished surface having a relief pattern formed by traces of the additive manufacturing process and having at least one depression relative to a mean curved surface of the surface, - Apply and spread, on the aforementioned unfinished surface, a layer of hardenable coating liquid configured to at least partially fill at least one depression; - to harden the hardenable coating liquid layer.

[0008] The invention further provides a method for manufacturing an optical element, comprising providing an optical element with a surface having a stepped pattern such that the optical element is not completely smooth, the method comprising: - Apply and spread a hardenable coating liquid over the surface of the optical element so as to cover the stepped pattern of the optical element. - harden the hardenable coating liquid present on the surface;

[0009] Wherein, before the application of the hardenable coating liquid, the surface with the stepped pattern is an unfinished surface.

[0010] The inventors noted that providing said surface in an unfinished state prior to coating improves the process along two axes. Firstly, the spreading of the hardenable material over the unfinished surface is improved compared to spreading over a finished or hardened surface due to the improved wettability properties. Furthermore Petition 870260002718, dated 12 / 01 / 2026, page 12 / 74 3 / 27 of this, this unfinished state allows the coating liquid to adhere to the surface while the coating hardens.

[0011] This enhanced wettability allows the use of a coating liquid capable of filling the depressions formed by the embossing pattern without forming air inclusions; furthermore, the improved wettability enables the use of a coating liquid with self-leveling properties that can smooth out said depressions in the embossing pattern. Both aspects enable the provision of a continuous outer surface. The outer surface of the optical element is thus smoothed, allowing the optical element's ability to perform its desired optical function to be improved.

[0012] In addition, the coating liquid hardens with the unfinished part of the unfinished surface, thus improving adhesion.

[0013] According to one embodiment of the manufacturing method, the unfinished surface is at least partially uncured before the coating step. Thus, while hardening, the hardenable coating liquid can partially merge with the unfinished surface material, thereby reducing the interface appearance between the two layers. This improves the ability of the optical element to provide the desired optical function.

[0014] In this way, the unfinished surface is partially, but not fully, cured before the coating stage. This partial curing allows the surface to promote adhesion of the coating liquid.

[0015] According to one embodiment of the manufacturing method, the unfinished surface being formed by the outer volume elements that form the optical element and said outer volume elements having a non-zero polymerization rate less than or equal to having received 2 times a light with a surface healing energy representative of Jacobs energy.

[0016] According to one embodiment of the manufacturing method, the unfinished surface is an inhibited layer formed by the extreme portion of the bulk elements that form a surface part of the optical element and in which polymerization was inhibited during the additive manufacturing process. Petition 870260002718, dated 12 / 01 / 2026, p. 13 / 74 4 / 27

[0017] When the optical element is additively manufactured, an inhibited layer is formed on the outer surface of the optical element. This inhibited layer is characterized by a decreasing conversion gradient from the optical element below the inhibited layer to air. The formation of this layer results from the inhibition of polymerization by at least one inhibitory species which is capable of suppressing the initiation of the polymerization reaction or terminating the polymerization reaction. In the case of a radical chain growth polymerization, dioxygen can play the role of inhibitor during additive manufacturing. Reactive radicals created under irradiation are suppressed by oxygen on the surface of the printed layer.

[0018] This inhibited state of an outer layer which is generally undesirable according to standard processes, avoided or removed by cleaning or fully cured in a final curing step, is used according to this disclosure embodiment as a benefit to promote wettability and adhesion and therefore enables smoothing of the stepped pattern generated by additive manufacturing.

[0019] According to one embodiment of the manufacturing method, the coating step comprises the curing of the coating liquid layer deposited on said unfinished surface.

[0020] This curing step allows you to fully cure the coating liquid layer to finish the optical element or only partially cure the coating liquid layer to promote adhesion of another layer of curing liquid. This curing can also be configured to fully cure or finish the unfinished surface beneath the coating liquid.

[0021] According to one embodiment of the manufacturing method, predetermined surface inhibition is achieved by curing under an atmosphere comprising oxygen, in particular during the additive manufacturing of the unfinished surface.

[0022] According to one embodiment of the manufacturing method, a final layer of liquid coating present on the optical component is cured under an oxygen-free atmosphere. Petition 870260002718, dated 12 / 01 / 2026, page 14 / 74 5 / 27

[0023] According to one embodiment of the manufacturing method, the hardenable coating liquid is a polymerizable coating liquid.

[0024] According to one embodiment of the manufacturing method, the hardenable coating liquid comprises at least one type of initiator adapted to initiate a polymerization of the polymerizable material used to manufacture the optical element.

[0025] According to one embodiment of the manufacturing method, the polymerizable material of the external predetermined volume elements that form the optical element and the hardenable coating liquid comprise the same monomer.

[0026] This facilitates the blending between the unfinished outer layer and the coating liquid. Furthermore, providing the unfinished outer layer and the coating liquid with the same material allows for the same refractive index, avoiding undesirable optical limiting effects.

[0027] In a particular embodiment, the hardenable coating material comprises, in addition to the polymerizable material of the external predetermined volume elements that form the optical element, additives adapted to improve the rheological properties of the hardenable coating material, such as spreading or leveling properties.

[0028] According to one embodiment of the manufacturing method, the absolute difference in refractive index between the polymerizable material of the external predetermined volume elements that form the optical element, in a hardened state, and the hardenable coating liquid, in a hardened state, is less than 0.02, preferably less than or equal to 0.01.

[0029] According to one embodiment of the manufacturing method, this further comprises applying and spreading at least one additional layer of hardenable coating liquid over the hardenable coating liquid layer or over another additional hardenable coating liquid layer, and in such a way that before applying and spreading the hardenable coating liquid layer, the hardenable coating liquid layer or said other additional layer Petition 870260002718, dated 12 / 01 / 2026, p. 15 / 74 6 / 27 of the hardenable coating liquid is only partially cured.

[0030] In doing so, the method provides a plurality of coating layers to reduce the stepped pattern. The outer surface of the optical element is therefore further smoothed or with better precision, with a similar total thickness of hardenable coating material applied compared to smoothing using a single layer of coating material. Conversely, it allows a similar level of smoothness to be achieved using a single, thicker coating layer, using less total thickness of hardenable coating material. It also allows the process to be more flexible by choosing the level of smoothness of the outer surface or other parameters.

[0031] According to a variant of said embodiment, before applying and spreading the additional coating liquid layer, the coating liquid layer or said other additional coating liquid layer is at least partially uncured or has an extreme portion inhibited so as to promote the adhesion of the additional coating liquid layers to it.

[0032] According to one embodiment of the manufacturing method, a different coating liquid may be used in a previous coating layer. The said coating liquid used has adjusted rheological or mechanical behavior (higher or lower viscosity, higher or lower self-leveling capacity).

[0033] According to one embodiment of the manufacturing method, the coating layer and the potential additional coating layer are such that the optical element is coated with a smoothing layer with a total thickness greater than a depth dimension of the depression and / or greater than a mean thickness dimension of the predetermined volume element, preferably greater than or equal to at least one and a half times such depth dimension.

[0034] This definition of the smoothing layer thickness ensures that the depression is filled with coating liquid and that the outer surface of the optical element is smoothed. Furthermore, monitoring the smoothing layer thickness allows for a layer with sufficient thickness to... Petition 870260002718, dated 12 / 01 / 2026, p. 16 / 74 7 / 27 Smooth the outer surface, but not too much, in order to optimize the amount of material used and ensure the maintenance of the desired optical element geometry. Therefore, if the optical element is intended to be an ophthalmic lens designed to be fitted into eyeglasses, the optical surface may be a complex surface, potentially with two or more zones with different optical powers. Thus, there is a tension between ensuring that the complexity of the lens's optical surface is maintained and smoothing local reliefs and steps.

[0035] According to one embodiment of the manufacturing method, the aforementioned predetermined inhibition of the end portion is obtained by curing successive layers of hardenable coating under an atmosphere comprising an inhibitor, such as dioxygen.

[0036] According to one embodiment of the manufacturing method, it comprises the complete curing of a final layer of hardenable coating liquid present on the optical component.

[0037] This final curing step allows obtaining a non-sticky or non-adhesive surface for the optical element.

[0038] According to one embodiment of the manufacturing method, the unfinished surface of the optical element is not fully cleaned before the application and spreading steps, so that the surface comprises a layer or sublayer of curable liquid material before applying and spreading, on said unfinished surface, a layer of hardenable coating liquid.

[0039] According to one embodiment of the manufacturing method, the application and spreading steps are carried out by at least one of the following processes: immersion, spraying, rotary coating, inkjet, and polymer blasting.

[0040] All these processes allow the hardenable coating liquid to be distributed across the entire unfinished surface to help smooth the outer surface of the optical element.

[0041] According to one embodiment of the manufacturing method, the optical element comprises a plurality of layers formed by said plurality Petition 870260002718, dated 12 / 01 / 2026, page 17 / 74 8 / 27 of volume elements forming a curved profile, with the relief pattern of said surface being a stepped pattern formed by the edges of said layers.

[0042] The invention is described in more detail below by means of figures which show various preferred embodiments of the invention.

[0043] Figure 1 schematically shows an optical element obtained by depositing predetermined volumes using additive manufacturing.

[0044] Figure 2 shows schematically the optical element with an unfinished surface at the top of the optical element.

[0045] Figure 3 schematically shows the optical element with a hardenable coating liquid coated on the unfinished surface of the optical element.

[0046] Figure 4 schematically shows a plurality of coating layers applied to the unfinished surface of the optical element.

[0047] Figure 5 schematically shows the fully cured optical element with a smoothed outer surface.

[0048] Figure 6 shows the conversion rate of a curable material as a function of the energy supplied to it.

[0049] Figure 7 shows the expected thickness of the layer as a function of the natural logarithm of the energy supplied to it.

[0050] Figure 8 shows schematically a detailed view of the surface of the optical element.

[0051] Figure 9 shows a flowchart of one embodiment of the manufacturing method for controlling acceptance requirements.

[0052] As shown in Figure 1, an optical element 40 is obtained by additive manufacturing, i.e., by depositing a plurality of elements of predetermined volume 14 that are juxtaposed and superimposed to form a plurality of overlapping layers of a material. The optical element 40 is a part of an optical component which may be an ophthalmic lens. The optical element 40 is, for example, formed on a support structure 30. Alternatively, the optical element 40 may be manufactured without any support structure 30. Petition 870260002718, dated 12 / 01 / 2026, page 18 / 74 9 / 27

[0053] The aforementioned optical element 40 is manufactured in relation to a three-dimensional axis system comprising a first and a second surface axis X and Y defining a plane over which the layers of volume elements 14 extend. The three-dimensional axis system also comprises a height axis Z in relation to the thickness of the layers of volume elements 14.

[0054] The aforementioned predetermined volume elements 14 may be layers of material or a plurality of voxels, i.e., elementary volumes of material as defined by additive manufacturing technology: droplets of material for inkjet printing, insolation resolution in stereolithography, multiple voxels being irradiated together with the same layer of material, different layers of such groups of voxels being formed one on top of the other, raw material size in fused deposition. Thus, the aforementioned optical element 40 may comprise at least one of a plurality of layers and a plurality of voxels.

[0055] Note that additive manufacturing in this document corresponds to a three-dimensional printing or stereolithography method, or even a fused filament manufacturing method. Preferably, additive manufacturing is one of stereolithography (SLA), digital light processing stereolithography (DLP-SLA), or (photo)polymer blasting. An advantage of polymer blasting technology is that the additive manufacturing machine can have multiple print heads with various materials. Additive manufacturing technologies comprise processes that create objects by juxtaposing volume elements according to a predetermined arrangement that can be defined in a CAD (Computer Aided Design) file.

[0056] Stereolithography (SLA) and digital light-processing stereolithography (DLP-SLA) work by focusing light, primarily ultraviolet light, onto a container of photocurable liquid resin to form solid layers that stack to create a solid object. In stereolithography (SLA), the liquid resin receives selective light exposure from a laser beam scanning the printing area. Digital light-processing stereolithography (DLP-SLA) uses a digital projector screen to project an image of each layer across the entire surface. Petition 870260002718, dated 12 / 01 / 2026, page 19 / 74 10 / 27 of the resin. Since the projector is a digital screen, the image on each layer is composed roughly of square pixels, resulting in a layer formed from small rectangular blocks called voxels (volume defined by the square pixel and the thickness of the layer).

[0057] Alternatively, pixels can have other shapes, such as hexagonal, diamond-shaped, or elongated depending on the technology used to form the images, for example, LCD or LED pixels or DMD (micro-mirrors).

[0058] A polymer blasting technology uses an inkjet print head to blast droplets of curable liquid resin onto a build platform. The liquid resin is immediately cured by a curing unit, such as a heat source or a light source, and solidified to form layers, or the final optical element, droplet set by droplet set (and form the solid object).

[0059] In this case, in practice, the additive manufacturing technology used is based on projecting a light pattern onto a curable material. The pattern light is, for example, from an infrared light source or a microwave source or an ultraviolet light source. The curable material is, for example, a photopolymer / photocurable resin based on (meth)acrylate monomers / oligomers with a sulfur atom in its backbone, and the optical element is manufactured when all the volume elements have been deposited and this monomer polymerization is fully completed.

[0060] In practice, the photopolymerization process can be characterized by a monomer conversion rate Cv (or, more accurately, polymerization rate) of the curable material. The conversion rate Cv is linked to the physical state of matter of the curable material. Before being irradiated by curable energy, essentially light irradiation, the curable material is liquid. The conversion rate Cv is considered close to 0, notwithstanding slight polymerization due to aging of the curable material. Under irradiation of the curable material by curable surface energy, the curable material is polymerized and progressively changes from a liquid to a solid state. The curable material is undergoing several Petition 870260002718, dated 12 / 01 / 2026, page 20 / 74 11 / 27 states, especially an intermediate state called the gel state, whose corresponding conversion rate Cv depends on the composition of the curable material. The intermediate state corresponds to a state of matter that is neither liquid nor solid, but between the two; in particular, not solid enough to be manipulated without damage or deformation of the part, but with monomers having begun to polymerize with each other, beginning to form parts of a polymer network. The conversion rate Cv of the intermediate state can, for example, be between 10% and 80% for some acrylate monomers, or greater than 5% and / or less than 67% for some others. The curable material is considered to be in a solid state for a conversion rate Cv generally greater than 70%. For some acrylate monomers, the curable material is considered to be in a solid state for a conversion rate Cv greater than 40%.Depending on the material, the curable material is considered to be in a solid state for conversion rates above a critical conversion rate that can be empirically determined to be between approximately 40% and approximately 100%.

[0061] A part of optical element 40 is configured to provide at least a part of an optical function of the optical component.

[0062] It will be recalled that the optical function of a lens, system or optical element means the optical response of this lens or system or element, namely, a function that defines any modification in the propagation and transmission of an optical beam through the lens, system or optical element in question, whatever the angle of incidence of the incident optical beam and whatever the geometric extent of an input diopter illuminated by the incident optical beam. The aforementioned at least one optical function may be simple or complex.

[0063] More specifically, in the ophthalmic field, optical function is defined as the distribution of the user's power and astigmatism characteristics and higher-order aberrations associated with the lens, system, or optical element in all directions of gaze of a user of this lens, system, or element. This assumes, of course, that the geometric positioning of the lens, of Petition 870260002718, dated 12 / 01 / 2026, page 21 / 74 12 / 27 system or optical element in relation to the user's eye was predetermined.

[0064] It is also observed that user power is a way of calculating and adjusting the power of the ophthalmic lens, which differs from the focus power. The calculation of user power ensures that the power perceived by the user (i.e., the power of the light beam entering the eye) when the lens is positioned in the frame and worn by the user, corresponds to the prescribed power. In general, at any point on the lens, especially at the points where distance and near vision are checked, for a varifocal lens, the power measured with a lensometer differs from the user power. However, the user power at the optical center of a single-focus lens is generally close to the power observed with a lensometer positioned at this point.

[0065] Depending on the desired optical function of the optical component, the front and rear sides of the optical element 40 can be flat or curved. The predetermined shape or profile of the optical element 40 is determined depending on the desired optical function of the optical component. A curved surface means that this surface defines a profile that has a non-zero curvature.

[0066] In figures 1 and 2, optical element 40 is partially manufactured. In other words, the manufacturing of optical element 40 is not completed so that optical element 40 does not have its final shape or profile.

[0067] The optical element 40 comprises a surface 42. This surface 42 forms a relief pattern 44 on the optical element 40. The relief pattern 44 is formed by traces from the additive manufacturing process. This relief pattern 44 is in the form of a stepped pattern where each step is formed by an edge of a volume element 14. The depressions 18 are formed by the relief pattern 44 in relation to another part of the surface 42. In particular, the depressions 18 are formed between two end portions or two edges of successive volume elements 14.

[0068] As shown in Figure 2, said surface 42 is a layer of material formed by the extreme portion or skin of the optical element 40. Thus, said surface 42 has a non-zero thickness. Surface 42 forms between 5% and Petition 870260002718, dated 12 / 01 / 2026, page 22 / 74 13 / 27 100% of the thickness of an additively manufactured layer. In other words, surface 42 extends from the top surface of a layer made up of volume elements 14 and has a thickness between 5% and 100% of the thickness of this layer. An additively manufactured layer typically has a thickness of 200 μm.

[0069] The additive manufacturing process is carried out in such a way that surface 42 is unfinished.

[0070] By unfinished, we mean that the layer with the unfinished surface 42 has, at least in part of its thickness, and at least on the unfinished surface, a conversion rate or polymerization rate lower than that desired for the finished optical element: for example, it is at least partially uncured before the application and spreading steps, and that in at least part of its thickness a conversion rate or polymerization rate is non-zero. This part of its thickness can be treated as a sublayer, as it is generally thinner than the usual layers used in the corresponding additive manufacturing process or the additional layers of hardenable material applied according to the present disclosure. In other words, an unfinished layer, or a layer with an unfinished surface, is at least partially, but not totally, polymerized.An unfinished layer, or a layer with an unfinished surface, is a layer that is not entirely solid in the Jacobs sense. As extreme examples, the layer with an unfinished surface may be entirely of a non-solid gel material or, conversely, in a completely opposite way, be solid in the Jacobs sense for most of its thickness, with an unclean surface providing the surface with only a thin coating (between 5 and 50% of the layer thickness) of completely uncured curable liquid material. Most applications of the invention may fall between these two cases.

[0071] By uncured or partially uncured we mean that surface 42 has at least one outer layer or sublayer of curable material that is in a liquid state or in an intermediate state between liquid and solid, although it has a non-zero conversion rate. Petition 870260002718, dated 12 / 01 / 2026, page 23 / 74 14 / 27

[0072] Partially uncured therefore includes having an outer liquid layer or sublayer on the surface, an outer layer or sublayer that is in an intermediate state, or an outer layer or sublayer that is solid enough to be manipulated while having a conversion rate or polymerization rate, which can be substantially increased by a subsequent curing step, for example: said material still contains unpolymerized monomer within it.

[0073] In a partially uncured surface embodiment, the surface 42 of the optical element 40 is not fully cleaned before depositing the hardenable coating liquid 46. The incomplete cleaning aims at and constitutes the preservation / protection of the partially uncured layer or the inhibited layer.

[0074] By not completely clean, we mean that during the application and spreading of the hardenable coating liquid layer, the manufactured device already comprises a thin layer or sublayer of curable liquid material on its surface, already present before the application of the hardenable coating liquid layer. In other words, immediately before the application or spreading of the hardenable coating liquid 46, the surface of the optical element 40 is covered by said thin layer of curable liquid material.

[0075] In one embodiment, incomplete curing retains a liquid layer of the polymerizable material used for the additive manufacturing of the predetermined volume elements that form the optical element on top of said polymerized or partially polymerized outer volume elements of the optical element. This can improve adhesion and blend the hardenable coating liquid with the inhibiting layer. Incomplete cleaning may include washing with shorter solvent exposure duration or just the use of drainage which still leaves a thin layer of liquid on the manufactured device.

[0076] The unfinished surface 42 is then coated with a layer of hardenable coating liquid 46 configured to at least partially fill at least one depression 18. It was observed that keeping the surface 42 unfinished promotes the wettability of the hardenable coating liquid 46 on the Petition 870260002718, dated 12 / 01 / 2026, page 24 / 74 15 / 27 surface 42. The improved wettability afforded by the unfinished surface 42 allows the hardenable coating liquid to stretch and level to fill the depressions 18 formed by the relief pattern 44. Furthermore, keeping the surface 42 unfinished promotes the adhesion of the hardenable coating liquid 46 to the surface 42. The hardenable coating liquid 46 blends with the unfinished surface material 42, thus reducing the interface appearance between the two layers. This significantly improves the ability of the optical element 40 to provide the desired optical function.

[0077] The hardenable coating liquid 46 deposited on said unfinished surface 42 is then cured to harden the hardenable coating liquid layer 46. The hardenable coating liquid 46 is partially cured or fully cured, depending on the number of hardenable coating liquids 46 which are intended to be deposited. In fact, a plurality of hardenable coating liquid layers 46 can be deposited, as shown in figure 4.

[0078] When hardenable coating liquid 46 is deposited using a plurality of layers, the previously deposited hardenable coating liquid 46 corresponds to a first layer 50 of hardenable coating liquid 46. In this case, the first layer 50 is only partially cured to promote the adhesion of another layer of hardenable coating liquid 46. In other words, the first layer 50 is kept unfinished. An additional layer 52 of hardenable coating liquid 46 is deposited on the first layer 50 of hardenable coating liquid 46. A plurality of additional layers 52 of hardenable coating liquid 46 can be deposited to obtain the final shape of the optical element 40. Each additional layer 52 is only partially cured, i.e., kept in an unfinished state, to promote adhesion and wettability of another layer of hardenable coating liquid 46.The optical element 40 is then fully cured to harden the entire optical element 40 into a solid state, as shown in Figure 5.

[0079] When a single layer of hardenable coating liquid 46 is Petition 870260002718, dated 12 / 01 / 2026, page 25 / 74 16 / 27 deposited on the unfinished surface 42, the hardenable coating liquid 46 is then fully cured to harden the entire optical element 40 into a solid state, as shown in figure 5.

[0080] A continuous and smoothed outer surface 48 can thus be obtained, thereby improving the ability of the optical element 40 to perform the desired optical function. By continuous and smoothed surface we mean a surface with no or reduced relief pattern; for example, with a relief pattern at least smaller than ^m, or even smaller than 500nm. In particular, the relief pattern is such that H < KT2, with H being the amplitude of the height change of the target surface, and T the period of the wave formed by the relief pattern and K a constant depending on the refractive index and manufacturing tolerances. In particular, this means that H and T must respect the equation below: ΔΡ * T2H < -----, (n — 1) * 2^2 Where H = amplitude of the change in height of the target surface in μm Delta P = industrial tolerance, is less than 0.12 diopters, or 0.06 diopters, or even 0.02 diopters, depending on the target quality of the optical lens. T = period of the relief pattern, or "wavelength", in millimeters. n = refractive index of the material

[0081] As an example, for a hardened coating material with an index of 1.5, one of the lowest indices used for eyeglass lenses, and the highest industrial tolerance, the maximum height of the embossed patterns depending on the wavelength of said embossed pattern for the surface to be considered continuous and smooth can be found in Table 1 below. T (mm) H (pm) 1 0.012 2 0.049 3 0.109 Petition 870260002718, dated 12 / 01 / 2026, page 26 / 74 17 / 27 4 0.195 5 0.304 6 0.438 7 0.596 8 0.778 9 0.985 10 1.216 Table 1

[0082] It should be noted that the term “roughness” is generally defined for relief patterns with wavelengths smaller than 1 mm. An optical surface for eyeglasses is considered smooth if the Ra (arithmetic mean of amplitude) is less than or equal to 10 nm.

[0083] This multilayer hardenable coating liquid 46 can be configured to create a gradient of thermomechanical or optical properties. For example, the material can be chosen so that scratch resistance is improved or post-coating polishing is facilitated. This can be achieved by altering the curable material of the hardenable coating liquid itself by one or more layers, or an increased percentage of hardener or colloids can be added to the curable material. Furthermore, softening of the material can be chosen for improved impact resistance of the optical element 40. The plurality of layers can form band filtering to cut off predetermined wavelengths, such as harmful blue light.

[0084] Surface 42 can be kept unfinished using a first or second embodiment. The same embodiments can be used to make hardenable coating liquid layers 46 unfinished.

[0085] According to the first embodiment, the unfinished surface 42 is an inhibited layer or sublayer of the outer layers of hardened material. In other words, the polymerization of surface 42 was inhibited during the additive manufacturing process to keep it unfinished. Petition 870260002718, dated 12 / 01 / 2026, page 27 / 74 18 / 27

[0086] After printing an object using additive manufacturing, an inhibited layer is formed on the periphery of the object and is characterized by a decreasing conversion gradient from the part to the air. This inhibited layer or sublayer is formed by the inhibition of polymerization by dioxygen during printing. Thus, the layer is printed or cured under dioxygen or normal atmosphere to maintain the polymerization inhibition phenomenon. Reactive radicals created under irradiation are suppressed by dioxygen on the surface of the printed layer. In the coating field, intense efforts are employed to avoid the formation of this inhibited layer during / after curing. In this first embodiment, the surface 42 is voluntarily formed as an inhibited layer or sublayer to promote the adhesion and spreading of another layer of material and reduce the appearance of interfaces between the layers.

[0087] When applying and spreading surface 42, the inhibited layer is replenished with initiator by diffusion. These initiators are protected from dioxygen. When the hardenable coating liquid 46 is polymerized or cured, the previous inhibited layer or sublayer (surface 42 or a layer of hardenable coating liquid 46) also polymerizes and a new inhibited layer is formed on top of the hardenable coating liquid 46. This configuration in which a new coating layer is deposited over an inhibited layer or sublayer and then partially cured allows the new coating layer to blend with the previous inhibited layer and thus with the already manufactured volume elements 14.

[0088] In this first embodiment, the last layer of hardenable coating liquid 46 of the optical element 40 is deposited under an oxygen-free atmosphere in order to finish this last layer. Once the last layer is applied, the ladder is smoothed, the optical element 40 is placed inside the furnace under an inert atmosphere (nitrogen, for example) to prevent oxygen inhibition and definitively cure the optical element 40. This last layer of hardenable coating liquid 46 is the first layer 50 when a single layer is deposited and an additional layer 52 when a plurality of coating layers are deposited on the optical element 40. Petition 870260002718, dated 12 / 01 / 2026, p. 28 / 74 19 / 27

[0089] According to the second embodiment, surface 42 is unfinished by adjusting the total curing energy (or light dose) supplied to the predetermined volume elements that form surface 42 during the additive manufacturing process. By final curing energy we mean the last irradiation supplied by a light source before the deposition of the hardenable coating liquid layer 46.

[0090] Consequently, during the additive manufacturing process, the curing energy received by the curable material from surface 42 is defined as not being sufficient to completely harden the curable material, keeping it uncured. Thus, surface 42 is supplied only with a predetermined dose of light allowing the curing process to begin, but without reaching a light dose value that would allow surface 42 to completely cure.

[0091] Adjusting the light dose supplied to the curable material allows control of the polymerization rate (or conversion rate) of the curable material. The conversion rates characterizing the intermediate state and the solid state depend on a curing surface energy E (or light dose) derived from the light source, the absorption properties of the curable material, and the efficiency of the initiator to polymerize the curable material.

[0092] Figure 6 shows a graph of the conversion rate Cv (in %) as a function of the curing surface energy E which radiates the curable material.

[0093] The light dose delivered to surface 42 in the current embodiment is adjusted to be less than or equal to the Jacobs energy Ej. This allows the volume elements forming the surface to be partially uncured, i.e., at least part of each of the volume elements forming the surface is uncured. In a variant, the light dose delivered to surface 42 in the current embodiment is adjusted to be less than or equal to the critical Jacobs energy Ec, for example, greater than 0.3*Ec. This allows the volume elements forming the surface to be uncured: i.e., in an intermediate state, although they have not yet initiated polymerization. For example, if the volume elements are voxels, for example, formed by the deposition of a droplet of material by inkjet printing or voxels Petition 870260002718, dated 12 / 01 / 2026, p. 29 / 74 20 / 27 formed by irradiating pixels onto a layer of liquid material, the voxels that form the surface are in an intermediate state.

[0094] It should be noted that if the curable material forming surface 42 received a light dose greater than the Jacobs energy, but less than 3 times, a light dose corresponding to a representative Jacobs energy healing surface energy (Ej), while still being less than the energy required to achieve complete conversion, the predetermined volume elements of the surface may be in an unfinished state within the meaning of the disclosure, although not partially unhealed within the meaning of the disclosure. It is expected that if the energy supplied is less than 2 times Ej, the surface will be in an unfinished state. Figure 8 shows surface 42 forming the unfinished layer for which the light dose was set less than or equal to the Jacobs energy Ej.

[0095] The Jacobs energy Ej corresponds to the minimum surface energy required to provide, for a given curable material of a given thickness, the hardening of the entire given thickness in a solid state sufficient to be measured according to the Jacobs methodology. The Jacobs energy Ej is obtained from the Jacobs equation as follows: Ej = Ec * exp ( th / Dp )

[0096] where th is the thickness of the optical element 40, Dp is the light depth penetration value of the curing surface energy within the curable material and Ec is the critical Jacobs energy defined for the curable material.

[0097] In the case of acrylate monomers cured by the radical chain growth polymerization process, the corresponding conversion rate Cv for a material considered solid, i.e., having received at least the Jacobs energy, is generally around 60% to 80%. According to this conversion rate Cv, the monomer conversion is sufficient for the polymerized material to be in the solid state, even if a higher conversion is necessary for the manufactured device to have adequate mechanical properties. Consequently, it can be considered for acrylate monomers that the advantages of some disclosure modalities may apply to conversion rates lower than 80%. Petition 870260002718, dated 12 / 01 / 2026, page 30 / 74 21 / 27 or 60%.

[0098] The light depth penetration value Dp and the Jacobs critical energy Ec are obtained from a working curve 60 derived from Jacobs' experiments, as shown in Figure 7. The experiment consists of irradiating a curable material (in this document a resin) with a set of known curing surface energies, forming multiple samples irradiated with different curing surface energies, or potentially a sample comprising different irradiated regions with different curing surface energies, and measuring the corresponding polymerized thicknesses of measurable solid material for each sample or sample region. The working curve 60 is a semi-logarithmic representation of the measured thickness of measurably solid polymerized material as a function of the natural logarithm (ln) of the curing surface energy E.

[0099] The application and spreading on the surface 42 can be carried out by technologies commonly used in the ophthalmic field, such as, in particular, an immersion process, a spraying process, a spin coating process, an inkjet process or a polymer blasting process. To avoid risks of damage during transport and dust inclusion, the coating devices can be implemented in an additive manufacturing machine (printing machine or DLP-SLA machine) or in a dedicated unit connected to the printing machine.

[0100] A control process can be implemented in the method according to the invention. A surface measuring device can be used to define the appropriate coating conditions. This is particularly useful when using inkjet / polymer blasting technology, where the amount of resin dispensed can be calculated depending on the position (X,Y).This surface measuring device is preferably a non-contact measuring device.

[0101] The surface measuring device is, for example, an optical measuring device using phase deflectometry technology. In this case, it is preferable to use a wavelength of light that does not activate resin polymerization, particularly if it is ultraviolet light. Alternatively, the surface measuring device uses, for example, an interferometry process. It is preferable to use a Petition 870260002718, dated 12 / 01 / 2026, page 31 / 74 22 / 27 sewing device in combination with this interferometry process. These processes can work in reflection measurement or in transmission and deflection measurement of light. In reflection, it is possible, for example, to work using a non-transmitted wavelength to avoid secondary reflections from the other surface of the optical component, or from an interface between the coating and the unfinished surface. Preferably, the wavelength is chosen so as not to react with the photoinitiators present in the unfinished surface material.

[0102] The manufacturing method can be carried out using a closed-loop process to better monitor the characteristics of the final optical element 40. An example of a closed-loop control process is shown in figure 9.

[0103] The unfinished surface 42 is printed 100 and then measured 110 by a surface measuring device. The characteristics of a first coating layer are determined 120 depending on the measurement performed on the surface 42. These characteristics preferably comprise at least the thickness of the first coating layer. In addition, the frequency or amplitude of waviness or roughness and an average roughness amplitude can be taken into account to determine a necessary rheological property of the first coating layer: thickness, viscosity, surface tension... etc. The first coating layer is then deposited 130 on the surface 42 and measured 140 by the surface measuring device.

[0104] These measurements taken on the first coating layer are compared 150 with the acceptance requirements, for example, a surface quality of the optical element 40 or the thickness of the first coating layer. If the optical element 40 is acceptable, the control process is completed and the first coating surface is fully cured 160 under an inert (oxygen-free) atmosphere. If the optical element 40 is not acceptable, the first coating layer is cured 170 under an oxygen atmosphere. An additional coating layer is calculated 180 and then deposited 190 on the first coating layer. The additional coating layer is also measured 140. Another Petition 870260002718, dated 12 / 01 / 2026, page 32 / 74 23 / 27 comparison 150 is performed to determine if optical element 40 is acceptable with this additional coating layer. A closed loop is thus formed to determine the characteristics and number of additional coating layers to make optical element 40 acceptable.

[0105] In the example above, the surface measurement is performed before curing. Alternatively, the surface measurement can be performed after curing under an oxygenated atmosphere.

[0106] The hardenable coating liquid 46 is a curable material. In one embodiment, the curable material of the hardenable coating liquid 46 is substantially the same as the curable material of the volume elements 14. In fact, using the same material for the hardenable coating liquid 46 and the volume elements 14 promotes the spreading, adhesion, and blending of the hardenable coating liquid 46 onto the unfinished surface material of the optical element. Furthermore, using the same material allows for layers with the same refractive index.In this document, it substantially means that the hardenable coating material would comprise the monomer(s) of the material used to form the predetermined volume elements of the optical element in roughly the same proportions, although possibly having different additives or concentrations of additives or solvents adapted to modify the rheological properties of the hardenable coating material, such as spreading or leveling properties. Exceptionally, it should be noted that some additives may be in the form of monomers, with less than 15% by mass of the monomers.

[0107] In an embodiment where multiple layers of hardenable coating liquid are successively spread on the surface of the optical element, the curable material of the hardenable coating liquid 46 is substantially the same as the curable material of the volume elements 14 for all layers. Alternatively, it may be different for some of the layers, while generally the first layer applied, which is in direct contact with the unfinished surface, would be substantially the same material as the curable material of the volume elements. Petition 870260002718, dated 12 / 01 / 2026, page 33 / 74 24 / 27

[0108] The hardenable coating liquid material 46 preferably comprises at least one type of initiator adapted to initiate a polymerization of the polymerizable or curable material of the bulk element 14.

[0109] Coating parameters must be adapted in relation to factors such as coating technology, rheological behavior of the resin, height of volume elements 14, concavity and curvature of the surface, area to be covered, etc.

[0110] It should be noted that, to have a self-leveling coating, it is preferable to have the highest possible surface tension. To obtain good wettability between a solid surface and a coating liquid, it is preferable to have the smallest contact angle A, below 90°. The contact angle A is related to the surface energy of the solid Ess, the surface energy between the solid and the liquid Esl, and the surface tension of the liquid T by the following equation: Ess = T cos(A) + Esl

[0111] Thus, A = arcs( [Ess-Esl] / T)

[0112] Thus, increasing the surface tension T increases the contact angle and decreases the wettability.

[0113] On the other hand, increasing Ess or decreasing Esl decreases the contact angle and increases wettability.

[0114] Thus, a low surface tension is desired to have good wettability of the coating on the surface and a high surface tension to have good self-leveling properties.

[0115] The inventors identified that having an unfinished material forming the surface decreases the surface energy between the hardenable coating liquid and the surface Esl and increases the surface energy of the surface Ess. Consequently, the use of an unfinished surface allows for improved wettability properties of the surface relative to the hardenable coating liquid. This then improves the spreading of the hardenable coating liquid on the surface and facilitates the filling of any depressions or holes within the surface. Petition 870260002718, dated 12 / 01 / 2026, page 34 / 74 25 / 27

[0116] Furthermore, decreasing the surface energy between the hardenable coating liquid and the surface Ess and increasing Esl allows for a higher surface tension of the hardenable coating liquid while still maintaining a low contact angle. Thus, it is possible to use a material with improved self-leveling properties while enabling good spreading of the hardenable coating material on the surface.

[0117] Furthermore, it should be noted that when using an unfinished surface that is partially liquid or uncured within the meaning of disclosure, the wettability mechanism transitions from a liquid-solid wettability to a liquid-liquid miscibility. The miscibility mechanism is not primarily driven by the surface tension of the coating liquid, but by the solubility parameters of both liquids, such as polarities, dispersion, molecular weight, hydrogen bonds, van der Waals forces, etc. Consequently, the disclosure method, in the case of an unfinished, uncured, or partially liquid surface, allows for high wettability properties with a low influence of the surface tension of the hardenable coating liquid. It is thus possible to use a hardenable coating liquid with a higher surface tension than in a liquid-solid wettability.This phenomenon is amplified if the coating liquid material is chemically similar to the unfinished surface material.

[0118] The rheological behavior of the hardenable coating liquid 46 can be altered by rheological additives for better filling and / or leveling / stretching. The following additives can be used: surface additives, air-releasing additives (when solvents are used), adhesion promoters, coupling agents, wettability additives and dispersants (in the case of filled coatings), viscosity modifiers which can sometimes be monomers and, more generally, rheological agent modifiers.

[0119] These rheological additives can be mixed into the curable material or added during deposition.

[0120] The rheological behavior and coating parameters can be Petition 870260002718, dated 12 / 01 / 2026, page 35 / 74 26 / 27 adapted for each hardenable coating layer. For example, the filling and leveling capacity can only be increased for the additional coating layers 52. This capacity can be progressively adapted for each additional layer to improve leveling behavior.

[0121] The thickness of the coating layers may be different for each layer. The total coating thickness is preferably at least about the height of the 18 depressions (stair steps), for example, between 1 and 200 μm, depending on the additive manufacturing technology employed.

[0122] The hardenable coating liquid 46, as a single layer or a plurality of layers, is such that the surface 42 is coated with a smoothing layer with a coating thickness 54 greater than the depth dimension 56 of the depression 18. The layer thickness and a depth dimension 56 of the depression 18 are defined along the thickness axis Z, as shown in Figure 4. The depth dimension of a depression 18 refers to the length along the thickness axis Z between the upper surfaces of two successive layers of volume elements 18. The coating thickness 54 is preferably considered along the thickness axis Z at a point located in a void between two layers or volume elements 14 on the surface.Alternatively, the coating thickness 54 can be defined by the shortest distance between a void between two layers or volume elements of the surface 42 of the optical element 40 and the outer surface of the hardenable coating layer and / or the outer surface 48 of the optical element. This outer surface 48 corresponds to the outer surface 48 of the optical element 40 when fully cured, including the curing of at least one hardenable coating layer.

[0123] Alternatively or in combination, the coating thickness 54 is greater than a predetermined average thickness dimension of the volume element 14. The average thickness can be calculated by averaging the thickness along the Z-axis for each of the layers and / or voxels used for Petition 870260002718, dated 12 / 01 / 2026, p. 36 / 74 27 / 27 manufacture the optical element. Preferably, the coating thickness 54 is greater than or equal to at least one and a half times such depth dimension 56 or average thickness dimension. Petition 870260002718, dated 12 / 01 / 2026, p. 37 / 74

Claims

1 / 4 CLAIMS 1. Method of manufacturing an optical component having at least one optical function, comprising: - manufacturing, using an additive manufacturing process, at least part of an optical element (40) by successively adding a plurality of predetermined volume elements (14) of polymerizable material, a part of the optical element (40) being configured to provide at least part of the optical function of an optical component, said additive manufacturing being carried out in such a way that the optical element (40) comprises an unfinished surface (42), said unfinished surface (42) having a relief pattern (44) formed by traces of the additive manufacturing process and having at least one depression (18) relative to a mean curved surface of the surface (42),- applying and spreading on said unfinished surface (42) a layer (50) of hardenable coating liquid (46) configured to at least partially fill at least one depression (18), - hardening the hardenable coating liquid layer; characterized in that it further comprises: applying and spreading at least one additional layer (52) of hardenable coating liquid over a layer (50) of hardenable coating liquid (46) or over another additional layer (52) of hardenable coating liquid (46), and in such a way that before applying and spreading or coating the additional layer (52) of hardenable coating liquid (46), the layer (50) of hardenable coating liquid (46) or said other additional layer (52) of hardenable coating liquid (46) is only partially cured,at least partially uncured or have an extreme portion or sublayer inhibited so as to promote adhesion of the additional coating liquid layer (52) to it., 2. Method according to claim 1, characterized in that the unfinished surface (42) is at least partially uncured before the coating step. Petition 870260031685, dated 06 / 04 / 2026, p. 8 / 15 2 / 4 3. Method, according to claim 2, characterized in that the unfinished surface (42) is formed by the external volume elements (14) that form the optical element (40) and said external volume elements (14) have a non-zero polymerization rate less than or equal to having received 2 times a light possessing a surface energy of cure representative of the Jacobs energy (Ej), wherein the Jacobs energy Ej is obtained from the Jacobs equation as follows: Ej = Ec * exp ( th / Dp ), wherein th is the thickness of the optical element 40, Dp is the light penetration depth value of the surface energy of cure within the curable material and Ec is the critical Jacobs energy defined for the curable material.

4. Method according to claim 2, characterized in that the unfinished surface (42) is an inhibited layer formed by the extreme portion of the bulk elements (14) forming a surface part of the optical element (40) and in which polymerization was inhibited during the additive manufacturing process.

5. Method, according to any one of claims 1 to 4, characterized in that the hardenable coating liquid (46) is a polymerizable coating liquid.

6. Method according to claim 5, characterized in that the hardenable coating liquid (46) comprises at least one type of initiator adapted to initiate a polymerization of the polymerizable material used to manufacture the optical element (40).

7. Method, according to any one of claims 1 to 6, characterized in that the polymerizable material of the external predetermined volume elements (14) that form the optical element (40) and the hardenable coating liquid (46) comprise the same monomer.

8. Method, according to any one of claims 1 to 6, characterized in that the absolute difference in refractive index between the polymerizable material of the external predetermined volume elements that form the optical element, in a hardened state, and the hardenable coating liquid (46), in a hardened state, is less than 0.

02.

9. Method according to claim 8, characterized in that the absolute difference in refractive index between the polymerizable material of the external predetermined volume elements forming the optical element, in a hardened state, and the hardenable coating liquid (46), in a hardened state, is less than or equal to 0.

01.

10. Method, according to any one of claims 1 to 9, characterized in that the coating layer (50) and the potential additional coating layer (52) are such that the optical element (40) is coated with a smoothing layer with a total thickness (54) greater than a depth dimension (56) of the depression (18), and / or greater than a mean thickness dimension of the predetermined volume element (14), preferably greater than or equal to at least one and a half times such depth dimension (56).

11. Method, according to any one of claims 1 to 10, characterized in that the unfinished surface (42) of the optical element (40) is not fully cleaned before the coating step, so that the surface (42) comprises a layer or sublayer of curable liquid material before applying and spreading on said unfinished surface (42) a layer (50) of hardenable coating liquid.

12. A method according to any one of claims 1 to 11, characterized in that the application and spreading steps are carried out by at least one of an immersion process, a spraying process, a rotary coating process, an inkjet process, and a polymer blasting process.

13. Method, according to any one of claims 1 to 12, characterized in that the optical element (40) comprises a plurality of layers formed by said plurality of volume elements (14) and forming a curved profile, the relief pattern (44) of said surface (42) being a stepped pattern formed by edges (58) of said layers.

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