Device and process for manufacturing an optical lens with liquid molds

Abstract

The invention relates to a device (10) for manufacturing an optical lens, comprising: - a tank (100) defining internally a chamber (101) suitable for being filled with a liquid, - a ring (150) that defines internally a formation volume (151) suitable for receiving a material of formation of the optical lens, and that is held into said tank, and - a compartment divider (140) surrounding said ring and dividing said chamber into an upper subdivision and a lower subdivision.

Description

[0001] DEVICE AND PROCESS FOR MANUFACTURING AN OPTICAL LENS WITH LIQUID MOLDS

[0002] TECHNICAL FIELD OF THE INVENTION

[0003] The present invention generally relates to the field of eyeglasses.

[0004] It more particularly relates to a device and a process for manufacturing an optical lens.

[0005] BACKGROUND INFORMATION AND PRIOR ART

[0006] A traditional mold assembly for molding ophthalmic lenses comprises two molding shells at the periphery of which is disposed an annular closure member that defines with these shells a molding cavity.

[0007] The two molding shells are generally made of a solid and transparent material while the closure member is made of a tape.

[0008] The main function of the tape is to close the space between the molding shells and to maintain these shells at a distance from each other when the mold assembly is filled of a monomer to be polymerized.

[0009] The molding shells have internal faces, the curvatures of which are selected so that once polymerized, the lens has the required optical power.

[0010] This traditional technology has many drawbacks.

[0011] First of all, to manufacture lenses with distinct optical powers, the manufacturer has to store a great number of expensive molding shells, which require a big storage space.

[0012] Moreover, these molding shells have to be manufactured through a process requiring high precision cutting and polishing, and then treated either thermally or chemically, which represents a significant cost in the overall lens casting process.

[0013] Before the molding process, the mold assembly must be prepared in advance in a clean environment to avoid any dust or foreign material contaminating the lens, which requires time and precaution.

[0014] A too low adhesion between the polymerized material and the molding shells would lead to a pre-release defect, jeopardizing the quality of the optical surface. Consequently, the material is chosen to adhere to the molding shells. Therefore, after the molding process, when the mold assembly has to be manually disassembled, it can be difficult to release the lens.

[0015] Once disassembled from the lens, the molding shells need to be submitted to washing so as to remove any remaining polymer, which is tedious and time consumer. Then, it has to be machined to the exact required shape and polished. Moreover, the lens has to be grinded and polished to exhibit the required surface smoothness (the opposite of roughness), and this smoothness is limited by grinding and polishing particles size.

[0016] Last, the molding shells are typically made from glass and can be scratched, shattered, or broken when used, leading to additional costs for manufacturing new molding shells.

[0017] In this context, document US2021362445 teaches a very different technical solution to cast optical lenses, requiring no solid molding shell.

[0018] This solution requires a device comprising a tank and a ring located horizontally inside the tank. This tank is first filled with a liquid so as to immerse the entire ring. Then, a monomer having a density close from that of the liquid is injected inside the ring, so as to create a kind of monomer "bubble" attached to the edge of the ring. The monomer is then cured, resulting in a lens.

[0019] Theoretically, the obtained lens has a very accurate surface finish (that is to say a very high smoothness, at the atomical level) since this finish only depends on the size of fluid molecules. Consequently, the grinding and polishing steps are no longer required.

[0020] Moreover, the release of the lens is easier since it only consists in removing the lens from the ring.

[0021] But in practice, this technical solution is difficult to implement, especially in mass production.

[0022] It is indeed extremely difficult to load the ring with the liquid monomer, as the monomer doesn't evenly spread within the annular space of the ring but rather tends to retract to form thick lumps hanging partly on the ring edge.

[0023] Consequently, a tool must be used to try to spread the material and eventually form a continuous film that spreads over the whole ring’s inside area. This process is very tedious, not always successful, and creates striations on the lenses.

[0024] Another disadvantage is that, for a given mass of monomer loaded in the ring, the curvature of the lens is defined by a passive buoyancy equilibration driven by the actual density mismatch between the liquid in the reservoir and the monomer. Consequently, it is difficult to obtain lenses with the exact required optical powers. SUMMARY OF THE INVENTION

[0025] In this context, the present invention provides an improved technical solution to cast optical lenses without solid molding shells.

[0026] This solution consists in using a device for manufacturing an optical article, comprising:

[0027] - a tank defining internally a chamber suitable for being filled with a equilibration liquid,

[0028] - a receiving element having an aperture that defines internally a formation volume suitable for receiving a hardenable liquid composition for the formation of the optical article, said receiving element being held into said tank, and

[0029] - a compartment divider surrounding said receiving element and dividing said chamber into an upper subdivision and a lower subdivision.

[0030] It is noted that the receiving element and the compartment divider can be formed in a single piece.

[0031] The compartment divider forms a barrier between the chamber subdivisions, preventing the occurrence of large flows of liquid between these compartments.

[0032] Therefore, the device makes it possible to fill more easily the internal volume of the apertured receiving element with the monomer.

[0033] Moreover, thanks to the compartment divider, when the lower subdivision is full of liquid, the monomer can be loaded at the surface of the liquid, in the internal volume of the apertured receiving element when the latter is semi-emerged and when the upper subdivision is empty. The compartment divider indeed ensures the liquid to remain as stable as possible during this monomer loading step.

[0034] In this way, the monomer is floating atop the liquid’s surface, and it spreads freely up to fill the whole area defined by the apertured receiving element’s wall. Then, the liquid level can be rosed to cover the compartment divider (without generate any perturbation in the lower compartment) and the upper air-exposed surface of the monomer, leading to the full submersion of the monomer bubble. The compartment divider ensures here again the liquid to remain as stable as possible during this step.

[0035] The filling process is simple and intuitive.

[0036] The device is compact and does not require any heavy-duty equipment for the process allowing flexibility in the manufacturing operation. It can be used to mold a wide variety of lens geometry, and it results into lenses having very smooth surfaces.

[0037] Additionally, the used liquid is common and inexpensive (brine or a mix of water and bio-sourced glycerol can be used).

[0038] Preferably, a surfactant solution can be used to prevent the formation of any floater during the submersion of the monomer bubble.

[0039] In a preferred embodiment, said upper subdivision and lower subdivision are in fluid communication (through a way not passing through said formation volume), but this communication can be blocked when filling the formation volume or the upper subdivision.

[0040] Consequently, thanks to the compartment divider, the monomer can be smoothly poured on the liquid contained into the lower subdivision. And after, the liquid can move between the upper and lower subdivisions in order to adjust the curvature of the monomer bubble. In other words, the liquid volumes in the subdivisions form liquid molding shells of varying curvature. This enables an active or passive control of the curvature of the monomer (the active control being not dependent on the density equilibrium, contrary to the passive one that depends on buoyancy equilibration).

[0041] Other preferential characteristics of this device are the following:

[0042] - the device comprises communication means to make said upper subdivision and said lower subdivision communicating with each other through a way other than through said formation volume.

[0043] - the communication means comprises a valve suitable, in a first position, to prevent the equilibration liquid from communicating from any one of said upper and lower subdivisions to the other one of said upper and lower subdivisions and suitable, in a second position, to enable the equilibration liquid to communicate from at least one of said upper and lower subdivisions to the other one of said upper and lower subdivisions.

[0044] - said communication means comprises a pipe located outside said formation volume or a hole located into said compartment divider.

[0045] - when the valve is in the second position, said upper subdivision and said lower subdivision are in free fluid communication.

[0046] - the device comprises a liquid modulating system suitable to suck equilibration liquid from and / or to inject equilibration liquid into any one of said upper and lower subdivisions.

[0047] - said liquid modulating system is suitable to suck equilibration liquid from any one of said upper and lower subdivisions and to inject an equivalent amount of equilibration liquid into the other of said upper and lower subdivisions.

[0048] - said compartment divider is adapted to be removed from the tank.

[0049] - said receiving element is fixed in position in the tank by said compartment divider.

[0050] The invention also proposes a process for manufacturing an optical article, using such a device and comprising the following steps:

[0051] - filling said lower subdivision with an equilibration liquid until said equilibration liquid reaches at least a lower end of said formation volume,

[0052] - filling said formation volume, onto a surface of said equilibration liquid, with a hardenable liquid composition (a liquid composition that can be transformed into a solid one),

[0053] - filling said upper subdivision with an equilibration liquid having properties distinct from that of the equilibration liquid filling said lower subdivision or not, to submerge the hardenable liquid composition,

[0054] - adjusting the shapes of surfaces of equilibration liquid in contact with said hardenable liquid composition, to modify the shapes of surfaces of the hardenable liquid composition,

[0055] - hardening said hardenable liquid composition, for instance by curing said material by light radiation exposure, and

[0056] - extracting the hardened optical article.

[0057] Other preferential characteristics of this process are the following:

[0058] - said step of adjusting is performed by said liquid modulating system, by sucking equilibration liquid from and / or injecting equilibration liquid into any one of said upper and lower subdivisions.

[0059] - during said step of adjusting, said upper subdivision and said lower subdivision are set in free fluid communication (passive buoyancy).

[0060] - said equilibration liquid is not miscible with the hardenable liquid composition.

[0061] - said hardening step being carried out by curing said hardenable liquid composition by light radiation exposure, said equilibration liquid is transparent to said light radiation. - the equilibration liquid filling said lower subdivision has a density equal to or higher than the density of the hardenable liquid composition.

[0062] - just before or after said step of filling said formation volume, a step of adding a surface-active agent, preferably non-foaming, onto the hardenable liquid composition is provided.

[0063] - during the step of filling said upper subdivision, the equilibration liquid is poured at a distance from the hardenable liquid composition, preferably on an internal face of the tank.

[0064] The invention also relates to a process for manufacturing an optical article, comprising the following steps:

[0065] - providing a tank that defines internally a chamber suitable for being filled with an equilibration liquid and that houses into said chamber a receiving element having an aperture that defines internally a formation volume suitable for receiving a hardenable liquid composition,

[0066] - filling a first part of said chamber with an equilibration liquid until said equilibration liquid reaches at least a lower end of said formation volume,

[0067] - filling said formation volume, onto a surface of said equilibration liquid, with a hardenable liquid composition,

[0068] - filling another part of said chamber with an equilibration liquid having properties distinct from that of the equilibration liquid filling said lower subdivision or not, to submerge the hardenable liquid composition,

[0069] - hardening said hardenable liquid composition, for instance by curing said hardenable liquid composition by light radiation exposure, and

[0070] - extracting the hardened optical article.

[0071] This process does not necessarily use a compartment divider. The main idea of this process is rather to pour the hardenable liquid composition into the tank, at the surface of the equilibration liquid and, when this hardenable liquid composition has been poured, to complete the tank with a new volume of equilibration liquid.

[0072] It can be noted that the first example described at the end of the description can be carried-out according to this process, and without a compartment divider. The following four examples can also be carried-out according to this process, but with a compartment divider.

[0073] Preferably, this process comprises, after the filling of said formation volume and before filing said another part of said chamber, a step of adding a surface-active agent (“surfactant”), preferably non-foaming, onto the hardenable liquid composition.

[0074] DETAILED DESCRIPTION OF EXAMPLE(S)

[0075] The following description with reference to the accompanying drawings, given by way of non-limiting example makes it clear what the invention consists in and how it can be reduced to practice.

[0076] In the accompanying drawings:

[0077] - Figure 1 is a schematic view of a first embodiment of a device according to the invention,

[0078] - Figure 2 shows a perspective view and a cross-sectional view of a tank of the device of Figure 1 ,

[0079] - Figure 3 shows a perspective view and a cross-sectional view of the device of Figure 1 ,

[0080] - Figure 4 is a flowchart of a process according to the invention, and

[0081] - Figure 5 is a schematic view of a second embodiment of a device according to the invention.

[0082] Figure 1 shows a device 10 suitable for molding an optical article without using solid molding shells.

[0083] In the represented embodiment, this optical article to be molded is an ophthalmic optical lens 200 (Fig.2) such as, for instance, a single vision lens, a progressive addition lens, a bifocal lens or a trifocal lens. Such a lens is adapted to be mounted in a rim of an eyeglass frame. But in a variant, the optical article may be a sunglass lens (tinted or not, polarized or not), a lens suitable for being mounted in a google, a lens for an optic device, a microscope lens, a telescope lens...

[0084] This optical lens 200 is intended to be casted into liquid moldings shells.

[0085] To this end, the device 10 shown in Figure 1 comprises a tank 100 defining internally a chamber 101 in which the optical lens 200 is to be molded. Here, this chamber 101 is tight but in a variant, only a bottom part of this chamber could be tight, an air vent being provided in the upper part of this chamber.

[0086] In the embodiment of Figure 1 , this tank has a cylindrical shape but, in a variant, it may have a distinct shape.

[0087] It comprises a lateral wall 110 closed on its lower side by a bottom wall 120. This bottom wall has a disc shape.

[0088] The lateral wall 110 could be opened on its upper side but it is preferably closed by a lid 130.

[0089] This lid 130 is suitable to be tightly closed to avoid the introduction of dirt. It is suitable to be opened to enable the introduction of a material of formation of the optical lens 200 (a hardenable liquid composition) and the extraction of the obtained optical lens.

[0090] The tank 100 is thus designed so as to be filled with an equilibration liquid and hermetically closed.

[0091] The device 10 also comprises an apertured receiving element (called hereinafter “apertured element 150”) defining internally a formation volume (called hereinafter “lumen 151”) suitable for receiving the hardenable liquid composition.

[0092] In a preferred embodiment, this apertured element 150 has a ring shape, with an internal face which is preferably cylindrical and which defines the lumen 151 . Here, this internal face has a symmetry of revolution around a main axis A1 . Here, this internal face has a height comprised between 1 and 10 mm.

[0093] Here, this internal face is not perfectly smooth. On the contrary, it has a texture that improves the adhesion of the hardenable liquid composition. Here, it comprises reliefs such that the hardenable liquid composition can grip to it. The mean height of the reliefs is here comprised between 25 and 500pm.

[0094] This apertured element 150 is located inside the tank 100, preferably at a distance from its bottom wall 120, from its lid 130 and from its lateral wall 110. In a preferred embodiment, it is centered inside the tank 100.

[0095] This apertured element 150 is held in position into said tank 100. To this end, it is here fixed to the lateral wall 110 of the tank 100 by a mounting support.

[0096] Here this support also has a function of compartment divider 140.

[0097] This compartment divider 140 is located at least in part inside the tank 100, so as to surround the apertured element 150 and to separate the chamber 101 into two compartments: an upper subdivision 101 U located above the apertured element 150 and the compartment divider 140, and a lower subdivision 101 L located under the apertured element 150 and the compartment divider 140.

[0098] In the embodiment of Figure 1 , this compartment divider 140 is liquid- tightly. Consequently, inside the tank 100, the upper subdivision 10111 and lower subdivision 101 L can only communicate with each other through the lumen 151 (if no hardenable liquid composition has been introduced into this lumen).

[0099] Here, this compartment divider 140 has an annular shape defining a central opening, and it houses the apertured element 150 into its central opening. The apertured element 150 can be fitted inside the compartment divider 140 by means of a press or glued to it or fixed by any other means.

[0100] In a variant, the compartment divider 140 and the apertured element 150 can form a single piece.

[0101] Here, the material of formation of the optical lens 200 (the hardenable liquid composition) that is to be poured into the lumen 150 is curable. Here, it is a polymer or a monomer composition suitable to be cured by light preferably UV light exposure. In an embodiment, the monomers are methacrylate monomers and / or oligomers. Preferred methacrylate monomers are bisphenol A poly(alkoxylated) dimethacrylates such as 2,2 -bis (4-methacroyloxydiethoxyphenyl)propane. Examples of polymerizable monomer compositions are described in US5,702,825. Other monomers such as MR7™ and MR8TMsold by Mitsui, or TRIVEX® sold by PPGmay be used. We will consider below that the material used is a monomer.

[0102] Before curing and hardening this monomer, the entire tank 100 is filled with the equilibration liquid so as to maintain the monomer inside the lumen 151 and to give it a desired shape (that is why the liquid volumes included in the subdivision are called liquid molding shells).

[0103] For this purpose, the equilibration liquid is preferably less viscous than the monomer.

[0104] Moreover, this equilibration liquid has a density that is preferably equal to or higher than that of the monomer. However, its density is preferably at most 20% higher than that of the monomer.

[0105] The used equilibration liquid is selected to be not miscible with the monomer and to be transparent to the light radiations used for curing the monomer.

[0106] Preferably, its surface tension is as low as possible to avoid any deformation of the monomer and the occurrence of floaters in the equilibration liquid.

[0107] To enable this monomer to be cured into the tank 100, a UV light source may be housed into this tank. But in a preferred embodiment, this UV light source 40 is located outside the tank 100 and at least one of the lid 130 and the bottom wall 120 of the tank 100 is made in a material transparent to UV.

[0108] In the embodiment of Figure 1 , only one UV light source 40 is used, above the tank lid 130.

[0109] But in a variant, two UV light sources can be used, a first one above the tank and the other one under the tank. This variant is preferred if an element such as a waveguide is positioned into the lumen 151 , so as to be embedded into the monomer.

[0110] When the monomer has just been poured into the lumen 150 but is not yet cured, the shape of the monomer “bubble” can be adjusted by removing some equilibration liquid from one of the subdivisions 101 L, 10111 and by adding a corresponding volume of equilibration liquid into the other one.

[0111] To this end, in the first embodiment shown in Figure 1 , a pipe system 30 is provided outside this chamber, to make these subdivisions communicate. Consequently, the upper subdivision and lower subdivision are in fluid communication through the apertured element 150 and through the pipe system 30.

[0112] This pipe system 30 comprises two ducts 33, 33 that are respectively connected to the upper subdivision 10111 and lower subdivision 101 L through two ports.

[0113] In a preferred embodiment, the pipe system 30 further includes a valve to block any communication between the upper subdivision and lower subdivision (at least during the filling of the lumen 151 by the monomer and of the upper subdivision by the equilibration liquid).

[0114] Here, this valve is formed by a liquid modulating system 31 connected to the subdivisions through the ducts 33, 33. This liquid modulating system 31 is designed to be able to suck an amount of equilibration liquid from any one of said upper subdivision and lower subdivision and to inject an equal amount of equilibration liquid in the other subdivision. In practice, this liquid modulating system 31 is a pump called “inter-compartment pump”. In a variant, it may be a plunger. This variant is preferred if the liquids used in the upper subdivision 10111 and lower subdivision 101 L are of distinct nature.

[0115] The device 10 also comprises means 20 for filling the chamber 101 with the equilibration liquid.

[0116] These means 20 comprise for instance a liquid storage reservoir 21 that is connected to the upper subdivision 10111 and lower subdivision 101 L through two ports by means of two distinct pipes 22, 23. Preferably, both pipes comprise a pump 24, 25 suitable to fill the subdivisions with equilibration liquid before the molding step, and to drain the equilibration liquid from the subdivisions after the molding step. These pumps can also be controlled during the introduction of monomer in the apertured element lumen, to maintain the equilibration liquid level inside the tank 100.

[0117] Figures 2 and 3 represent more detailed and less schematic views of the tank 100 and of the device 10 of Figure 1 .

[0118] Figure 2 shows a perspective view and a cross-sectional view of the tank 100.

[0119] In this embodiment, the tank 100 comprises three superimposed metallic annular pieces connected to each other by four bolts 160. All the pieces are positioned horizontally.

[0120] The upper piece 131 forms an outside part of the lid 130 of the tank 100. The lower piece 121 forms an outside part of the bottom wall 120 of the tank 100. And the intermediate piece forms the compartment divider 140.

[0121] These annular pieces are hold at a distance from each other by two tubes. These tubes are preferably transparent, to let the user see the inside of the tank 100. They are for instance made from glass or from plastic material.

[0122] In a preferred embodiment, all these annular pieces have the same dimensions.

[0123] The upper and lower annular pieces 121 , 131 are both closed by a disc shaped wall that is made from a material transparent to UV. This wall has for instance a diameter of 60mm and a thickness of 10mm.

[0124] The intermediate annular piece holds the apertured element 150 that delimits the lumen 151 . Its lower and upper faces extend at the same height as the apertured element ones.

[0125] A sealing material can be used between the various components of the tank 100, for instance a silicone Dragon Skin™ 30.

[0126] Figure 3 shows the entire device 10, including the tank 100.

[0127] This device comprises a frame 11 , here made of metallic beams, that supports the tank 100 and other accessories.

[0128] As shown in this Figure, the device frame 11 supports for instant the filling unit 20 suitable to inject the equilibration liquid inside the subdivisions 101 L, 101 U. This filling unit is here located aside the tank 100.

[0129] The frame 11 also supports a UV curing unit comprising two UV light sources 40, 41 suitable to cure the monomer located inside the ring. These UV light sources are here located under and above the tank 100. The frame 11 supports the curvature adjustment unit. This unit is here formed by the filling unit 20 in the sense in that the above-mentioned pumps can be driven so as to suck an amount of equilibration liquid from one subdivision and to fill the other subdivision with an equivalent amount of equilibration liquid so as to deform the monomer bubble as required.

[0130] The frame 11 can also be equipped with other accessories, as described in the following examples (that can be combined with each other).

[0131] As a first example, the tank 100 can comprise a port connected to a vacuum pump controlled to remove bubbles from the equilibration liquid and from the monomer, if any.

[0132] As a second example, the tank 100 can comprise a piezoelectric system or a moving system, suitable to make the liquid vibrate so as to cause the bubbles to rise to the surface.

[0133] As a third example, the tank 100 can comprise a filter on at least a part of its ports, to prevent any dust from entering in the equilibration liquid or in the monomer bubble.

[0134] As a fourth example, the tank 100 can be equipped with optical properties measurement means, suitable to measure for instance the transmission and / or the transmittance and / or the haze and / or a number of air bubbles and / or a sharpness and / or a clarity of the monomer (before curvature adjustment and polymerization of this monomer).

[0135] As a fifth example, the tank 100 can be fitted with a camera for determining the curvature of the monomer inside the lumen 151 , in live.

[0136] As a sixth example, the tank 100 can be provided with a heating and / or cooling unit to vary the temperature of the equilibration liquid (especially if production cycles create a heat-sink effect from the monomer in the equilibration liquid).

[0137] As a seventh example, the tank 100 may include venting valves for introducing air into the tank or extracting it out of the tank when the pumps are activated.

[0138] Finally, the device comprises a control module (not represented in the figures).

[0139] This module comprises a processing unit, such as a CPU, a programmable logic device (DSP, FGPA... ) or a controller, or any combination thereof. It also comprises a memory and various input and output interfaces.

[0140] Thanks to its input interfaces, the processing unit is suitable for receiving instructions from an individual.

[0141] Thanks to its output interfaces, the processing unit is suitable for controlling the filling unit, the UV curing unit, and the curvature adjustment unit.

[0142] Thanks to its memory, the processing unit stores either a computer application, consisting of computer programs comprising instructions, the execution of which by the processor enables the processing unit to implement the process described below, or logic gates designed to perform this process.

[0143] This process aims at manufacturing the optical article 200 by using the device 10.

[0144] Distinct embodiments can be used to carry out this process.

[0145] In a main embodiment, the process comprising six steps S1 to S6 shown in Figure 4.

[0146] The first step S1 consists in filling the lower subdivision 101 L of the chamber 101 with the equilibration liquid, by means of the pump 25 (figure 1 ).

[0147] This step is performed until the equilibration liquid reaches the lower face of the apertured element 150 and of the compartment divider 140.

[0148] A sensor can be used to stop the pump when this subdivision 101 L is full of equilibration liquid. In a variant, the control module can memorize a duration required to fill this subdivision and switch on the pump only during this duration.

[0149] The second step S2 consists in filling the lumen 151 , by pouring the monomer at the surface of the equilibration liquid.

[0150] The volume of requested monomer can be calculated by the control module, according to the desired characteristics of the lens to be molded.

[0151] In a preferred embodiment, the monomer and / or the liquid has a low surface tension, preventing these fluids to mix which each other.

[0152] The loading can be done by an automatic filling unit. It can also be done manually, with a syringe or by pouring. In any case, the monomer is first poured along the internal face of the apertured element 150, then the lumen 151 is gradually and slowly filled. This lumen is, in a preferred embodiment, entirely filled with the monomer. That is why the thickness of the apertured element 150 is selected according to the required thickness of the lens to be molded.

[0153] During the third step S3, the upper subdivision 10111 of the chamber 101 is filled with the equilibration liquid to cover the compartment divider 140 and the surface of monomer. To this end, the pump 24 is activated.

[0154] At that step, special precautions are taken to avoid the formation of floating bodies of monomer that would detach from the monomer upper surface while the equilibration liquid level rise. The geometry of the lens is indeed guaranteed by the amount of monomer in the lumen 151 .

[0155] To avoid such formation, the surface tension of the equilibration liquid and / or of the monomer is minimized either by the choice of its nature or by the use of a surface-active agent (preferably non-foaming) that is poured onto the top surface of the monomer.

[0156] Moreover, the equilibration liquid is introduced in the upper subdivision by pouring it directly on the monomer (to prevent the liquid from reaching the monomer from the sides and detaching portions of monomer).

[0157] In a variant, the equilibration liquid is poured at a distance from the monomer, on an internal face of the tank 100, which prevent the liquid from causing turbulence.

[0158] In an embodiment, the equilibration liquid covers the monomer inside the lumen from its periphery to its center.

[0159] The introduction of the equilibration liquid can be made from a shower or through pulverization to wet the monomer surface.

[0160] During this introduction, the compartment divider 140 and the liquid modulating system 31 act as a closed valve and avoid the formation of floaters on each face of the monomer.

[0161] The use of an equilibration liquid having a density lower than that of the monomer to fill the upper subdivision 101 U limits monomer drawing.

[0162] Here, the equilibration liquid used to fill both subdivisions is the same, but in a variant, they may have distinct properties. For instance, the density of the liquid in the lower subdivision may be greater than that of the monomer, to avoid the monomer to sink into the tank.

[0163] Here, the equilibration liquid has a density slightly equal to that of the monomer (for instance comprised between 90 and 110% of the monomer density).

[0164] The liquid comprises a mix of glycerol and water the ratio of which is selected to find the required density. Here, the fluid density is 1.124 kg / m3at 50°C.

[0165] But in a variant, if the monomer composition M as described hereafter (with a density of 1 .124 kg / m3), the liquid may comprise a first mix of Glycerol and Water (55% of the total weight) and a second mix of sodium chloride and Water (20% of the total weight), the liquid density being of 1.124 kg / m3at 50°C.

[0166] In another variant, if the monomer is of the reference MR7™ (with a density of 1.26 kg / m3), the liquid may only comprise glycerol so as to have a liquid density of 1 .25 kg / m3at 50°C .

[0167] In another variant, if the monomer is of the reference TRIVEX® (with a density of 1.03 kg / m3), the liquid may comprise a first mix of Glycerol and Water (20% of the total weight) and a second mix of sodium chloride and Water (4% of the total weight).

[0168] The following step S4 consists in adjusting the curvature of the upper and lower surfaces of the monomer.

[0169] The required curvature is determined according to the optical power required for the lens.

[0170] In this embodiment, this step S4 is performed by the control module, by sucking an amount of equilibration liquid in one of the subdivisions and by injecting a same amount of equilibration liquid in the other subdivision. This operation is called “active equilibration”.

[0171] This step is performed by controlling the inter-compartment pump (i.e. the liquid modulating system 31 ).

[0172] In a variant, if the tank does not comprise any liquid modulating system 31 , this step can be performed by using the pumps 24, 25.

[0173] In another variant, if the tank comprises in the upper subdivision an air vent, only one of these pumps can be used. For instance, only the pump 25 can be used to adjust the shape of the monomer bubble.

[0174] Then, during a fifth step S5, the monomer is polymerized by light radiation exposure. To this end, the control module activates the UV light sources during the duration necessary to polymerize all the monomer. The duration may be of 1 minute with a wavelength of 365 nm in a UV oven “Height-LED HTBX II”.

[0175] Finally, during a last step S6, the lens is extracted from the tank 100, by sucking all the equilibration liquid out of the tank and by removing the lid 130 to enable an individual to remove the lens from the lumen 151.

[0176] Figure 5 shows another embodiment of the device 10.

[0177] Because most of the components of this device 10 are identical to those of the first embodiment shown in Figure 1 , they are referenced by the same numbers and they will not be described again.

[0178] This device 10 differs from that illustrated in Figure 1 in that it does not have a liquid modulating system 31.

[0179] As explained above, the curvature of the monomer bubble could then be adjusted using the pump 25. However, in this embodiment, this adjustment will preferably be carried out passively, by “buyoancy equilibrium”.

[0180] To this end, a pipe or an opening is provided to make the upper and lower subdivisions communicate, and a valve is fitted into this pipe or opening so as to, in a first position, block this communication and, in a second position, open this communication.

[0181] The pipe may be located outside the tank (as shown in the first embodiment). But here, as shown in Figure 5, the communication is ensured by an opening 147 provided in the compartment divider 140. This opening is fitted with a two-positions valve 148.

[0182] In this embodiment, the curvature of the surfaces of the monomer will depend on the buoyancy equilibration (that is to say on the densities of monomer and liquid).

[0183] To this end, in a first example, the lower subdivision 101 L is filled with a first equilibration liquid. Then, the valve 148 is closed and the lumen 151 is filled with a monomer (the monomer being poured onto the surface of the first equilibration liquid). After, the upper subdivision 10111 is filled with a second equilibration liquid having properties distinct from that of the first equilibration liquid, to submerge the monomer. Finally, the valve 148 is controlled to open.

[0184] Because of the distinct densities of the equilibrium liquids, the curvature of the monomer automatically varies. Then, the monomer is cured, and the obtained lens has a final curvature that depends on the densities differences.

[0185] At this step of the description, we can list some of the parameters that have an impact on the monomer curvature.

[0186] As explained above, the first parameters are the density of the monomer and the densities of the equilibration liquids.

[0187] The second parameters relate to the shape of the device 10. For instance, the diameter and the height of the lumen 151 have an influence on the final shape of the lens. Other parameters can be taken into account, such as the pressure inside the tank 100 (if the upper subdivision is hermetic).

[0188] At this step, we can give five detailed examples of implementing the process for manufacturing optical lenses. In these examples, the lumen 151 has a height of 10mm and a diameter of 60mm.

[0189] The curvature radii of lenses obtained in the examples are measured by using the profilormeter Form-Talyserf PGI 1240. The analysis software is Talor Hobson pltra. The lens measurement is done on X and Y axis and the value is the average of the two. The probe is then set to the center of the peak of the lens by using auto crest function. By select this option, the measurement will run Auto-Crest routine. This procedure automatically finds the crown (or valley) of a convex (or concave) surface by travel back and forth on the lens surface until the probe find the spot where the difference of the travel distance in Z axis is zero.

[0190] Then the measurement the travel distance is set to 6mm. The probe will travel along the surface of the lens 6mm between the auto crest spot and collect the data of the lens surface from the displacement of the probe in Z thus create the curvature profile of the lens. The probe then stop after 6mm have been traveled. The lens curvature radius is then calculated using the Talor Hobson pltra analysis tool.

[0191] The power of lenses obtained in the examples is obtained by DPT measurements using The Dual Lens Mapper or DLM (Automation & Robotics, Verviers, Belgium). The lens is placed on the tray of DLM machine then the button is pressed to load the lens inside the machine. The measurements of the lens power are based on local distortion of a reflection and transmission grid of the lens captured with camera sensors. The machine then outputs the lens power in the mapping which can select the area to distract the power form. The value of the power is extracted from the optical center of the lens.

[0192] In a first example, the lens to be manufactured is piano.

[0193] During the first step S1 of filling the lower subdivision 101 L of the chamber 101 , the used equilibration liquid is a mixture of sodium chloride (24% of the total weight) and distilled water. Its density is of 1 .178 g.crrr3at 25°C.

[0194] During the second step S2 of filling the lumen 151 with monomer composition M (for instance with a syringe), this monomer composition M comprises bisphenol A tetraethoxydimethacrylate and photoinitiator CGI1850 (from Ciba Geigy) 0.175 % by weight of composition M.. Its density is of 1 .124 g.crrr3at 25°C. The volume of poured monomer composition is of 30 mL.

[0195] During the third step S3 of filling the upper subdivision 10111 of the chamber 101 to cover the surface of monomer, a surfactant is first sprayed onto this surface. This surfactant comprises here sodium dodecylbenzene sulfonate (at 0.1 %w / w). Then, the upper subdivision 10111 is filled with equilibration liquid, here pure water (its density is of 1 .000 g.crrr3at 25°C).

[0196] The following step S4, consisting in adjusting the curvature of the upper and lower surfaces of the monomer, is here not performed. In other words, the connection between the lower subdivision 101 L and the upper subdivision 10111 of the chamber 101 remains closed.

[0197] During the fifth step S5, the monomer is polymerized by light radiation exposure. The exposure duration may be of 2 minutes with a wavelength of 365 nm, at 100% in a UV oven “Height-LED HTBX II”.

[0198] Finally, during the last step S6, the lens is extracted from the tank 100, by sucking all the equilibration liquid out of the tank and by removing the lid 130 to enable an individual to remove the lens from the lumen 151.

[0199] The obtained lens exhibits two plane main optical faces, a diameter of 60 mm and a constant thickness of 10 mm. The curvature radius of its lower optical face is of 3554 mm. The curvature radius of its upper optical face is of 3654 mm.

[0200] In a second example, the lens to be manufactured is said to be of the kind “negative meniscus”.

[0201] During the first step S1 of filling the lower subdivision 101 L of the chamber 101 , the used equilibration liquid is a mixture of sodium chloride (24% of the total weight) and distilled water. Its density is of 1 .178 g.crrr3at 25°C.

[0202] During the second step S2 of filling the lumen 151 with the monomer composition M as described above. Its density is of 1.124 g.crrr3at 25°C. The volume of poured monomer is of 30 mL.

[0203] During the third step S3 of filling the upper subdivision 101 U of the chamber 101 to cover the surface of monomer, a surfactant is first sprayed onto this surface. This surfactant comprises here sodium dodecylbenzene sulfonate (at 0.1 %w / w). Then, the upper subdivision 101 U is filled with equilibration liquid, here pure water (its density is of 1 .000 g.crrr3at 25°C).

[0204] During the fourth step S4 of adjusting the curvature of the surfaces of the monomer, an addition volume of the same mixture of sodium chloride (having a density of 1.178 g.crrr3at 25°C) is injected into the lower subdivision 101 L of the chamber 101. This volume is here of 15mL. During this step, the connection between the lower subdivision 101 L and the upper subdivision 101 U of the chamber 101 remains closed.

[0205] During the fifth step S5, the monomer is polymerized by light radiation exposure. The exposure duration may be of 2 minutes with a wavelength of 365 nm, at 100% in a UV oven “Height-LED HTBX II”.

[0206] Finally, during the last step S6, the lens is extracted from the tank 100, by sucking all the equilibration liquid out of the tank and by removing the lid 130 to enable an individual to remove the lens from the lumen 151.

[0207] The obtained lens exhibits a convex optical face and a concave optical face having a radius of curvature greater than that of the other face, a diameter of 60 mm and a thickness of 10 mm along its edge. The curvature radius of its lower optical face is of 105 mm. The curvature radius of its upper optical face is 523 mm. Consequently, the lens has an optical power of -4.34 diopters.

[0208] In a third example, the lens to be manufactured is said to be of the kind “positive meniscus".

[0209] During the first step S1 of filling the lower subdivision 101 L of the chamber 101 , the used equilibration liquid is a mixture of sodium chloride (20% of the total weight) and distilled water. Its density is of 1 .145 g.crrr3at 25°C.

[0210] During the second step S2 of filling the lumen 151 with the monomer composition M as described above. Its density is of 1.124 g.crrr3at 25°C. The volume of poured monomer is of 30 mL.

[0211] During the third step S3 of filling the upper subdivision 10111 of the chamber 101 to cover the surface of monomer, a surfactant is first sprayed onto this surface. This surfactant comprises here sodium dodecylbenzene sulfonate (at 0.1 %w / w). Then, the upper subdivision 10111 is filled with equilibration liquid, here pure water (its density is of 1 .000 g.crrr3at 25°C).

[0212] Here, the equilibration liquid is poured at a distance from the monomer, on an internal face of the tank 100, which prevent the liquid from causing turbulence.

[0213] During the fourth step S4 of adjusting the curvature of the surfaces of the monomer, a volume of the mixture of sodium chloride is removed from the lower subdivision 101 L of the chamber 101 . This volume is here of 15mL. During this step, the connection between the lower subdivision 101 L and the upper subdivision 101 U of the chamber 101 remains closed.

[0214] During the fifth step S5, the monomer is polymerized by light radiation exposure. The exposure duration may be of 2 minutes with a wavelength of 365 nm, at 100% in a UV oven “Height-LED HTBX II”.

[0215] Finally, during the last step S6, the lens is extracted from the tank 100, by sucking all the equilibration liquid out of the tank and by removing the lid 130 to enable an individual to remove the lens from the lumen 151.

[0216] The obtained lens exhibits a nearly plane concave optical face and a convex optical face having a radius of curvature lower than that of the other face, a diameter of 60 mm and a thickness of 10 mm along its edge. The curvature radius of its lower optical face is 1100 mm and the curvature radius of its upper optical face is 61 mm. Consequently, the lens has an optical power of + 8.78 diopters.

[0217] In a fourth example, the lens to be manufactured is said to be of the kind “positive meniscus”.

[0218] During the first step S1 of filling the lower subdivision 101 L of the chamber 101 , the used equilibration liquid is a mixture of sodium chloride (20% of the total weight) and distilled water. Its density is of 1 .145 g.crrr3at 25°C.

[0219] During the second step S2 of filling the lumen 151 with the monomer composition M as described above. Its density is of 1.124 g.crrr3at 25°C. The volume of poured monomer is of 30 mL.

[0220] During the third step S3 of filling the upper subdivision 10111 of the chamber 101 to cover the surface of monomer, a surfactant is first sprayed onto this surface. This surfactant comprises here sodium dodecylbenzene sulfonate (at 0.1 %w / w). Then, the upper subdivision 10111 is filled with equilibration liquid, here the same as the one used during the firsts step S1 .

[0221] During the fourth step S4 of adjusting the curvature of the surfaces of the monomer, the connection between the lower subdivision 101 L and the upper subdivision 10111 of the chamber 101 is opened, enabling a passive equilibrium connection. The lens curvature will gradually shifted from negative to positive, this process taking approximately 5 minutes. If any, the air is purged first.

[0222] During the fifth step S5, the monomer is polymerized by light radiation exposure. The exposure duration may be of 2 minutes with a wavelength of 365 nm, at 100% in a UV oven “Height-LED HTBX II”. Finally, during the last step S6, the lens is extracted from the tank 100, by sucking all the equilibration liquid out of the tank and by removing the lid 130 to enable an individual to remove the lens from the lumen 151.

[0223] The obtained lens exhibits a concave optical face and a convex optical face having a radius of curvature lower than that of the other face, a diameter of 60 mm and a thickness of 10 mm along its edge. The curvature radius of its lower optical face is of 145 mm. The curvature radius of its upper optical face is of 75 mm. Consequently, the lens has an optical power of 3.74 diopters.

[0224] In a fifth example, the lens to be manufactured is said to be of the kind “negative meniscus”.

[0225] During the first step S1 of filling the lower subdivision 101 L of the chamber 101 , the used equilibration liquid is a mixture of sodium chloride (24% of the total weight) and distilled water. Its density is of 1.178 g.crrr3at 25°C.

[0226] During the second step S2 of filling the lumen 151 with the monomer composition M as described above. Its density is of 1.124 g.crrr3at 25°C. The volume of poured monomer is of 30 mL.

[0227] During the third step S3 of filling the upper subdivision 10111 of the chamber 101 to cover the surface of monomer, a surfactant is first sprayed onto this surface. This surfactant comprises here sodium dodecylbenzene sulfonate (at 0.1 %w / w). Then, the upper subdivision 10111 is filled with equilibration liquid, which is a mixture of sodium chloride (19% of the total weight) and distilled water. Its density is of 1 .138 g.crrr3at 25°.

[0228] During the fourth step S4 of adjusting the curvature of the surfaces of the monomer, the connection between the lower subdivision 101 L and the upper subdivision 10111 of the chamber 101 is opened, enabling a passive equilibrium connection. The lens curvature will gradually shifted from negative to positive, this process taking approximately 5 minutes. If any, the air is purged first.

[0229] During the fifth step S5, the monomer is polymerized by light radiation exposure. The exposure duration may be of 2 minutes with a wavelength of 365 nm, at 100% in a UV oven “Height-LED HTBX II”.

[0230] Finally, during the last step S6, the lens is extracted from the tank 100, by sucking all the equilibration liquid out of the tank and by removing the lid 130 to enable an individual to remove the lens from the lumen 151.

[0231] The obtained lens exhibits a concave optical face and a convex optical face having a radius of curvature greater than that of the other face, a diameter of 60 mm and a thickness of 10 mm along its edge. The curvature radius of its lower optical face is of 100 mm. The curvature radius of its upper optical face is of 314 mm. Consequently, the lens has an optical power of -3.95 diopters. In a sixth example, the aim is to obtain a lens having specific characteristics (in this case the lens power) that can be adjusted thanks to determined parameters. Here, these parameters are the density of the equilibration fluid in the lower subdivision 101 L and the volume extracted from the lower subdivision 101 L.

[0232] During the first step S1 of filling the lower subdivision 101 L of the chamber 101 , the used equilibration liquid is poured in this lower subdivision 101 L until the lower border of the apertured element 150.

[0233] This equilibration liquid is a mixture of sodium chloride and distilled water. Distinct ratio (determined with the density machine Density Kit MS-DNY-

[0234] 54) can be used. Some of them are showed in Table 1 :

[0235] During the second step S2, the lumen 151 is filled with the monomer composition as described above. The volume of poured monomer is of 30 mL. The loading is done with a syringe because of the ease of use but it could also be done by other methods such as pouring. The used monomer is known under the reference MR7TMor MR8™.

[0236] During the third step S3 of filling the upper subdivision 10111 of the chamber 101 to cover the surface of monomer, a surfactant is first sprayed onto this surface. This surfactant comprises here sodium carbonate at 0.01 % of the total weight. Then, the upper subdivision 10111 is filled with equilibration liquid, which is a mixture of sodium chloride and distilled water. Its density is of 0.997 kg.rrr3at 25°.

[0237] During the fourth step S4 of adjusting the curvature of the monomer, only the volume of equilibration liquid in the lower subdivision 101 L is adjusted. Here, a volume of liquid is sucked from the lower subdivision 101 L.

[0238] During the fifth step S5, the monomer is polymerized by light radiation exposure. The exposure duration may be of 1 minute with a wavelength of 365 nm, at 100% in a UV oven “Height-LED HTBX II”.

[0239] Finally, during the last step S6, the lens is extracted from the tank 100, by sucking all the equilibration liquid out of the tank and by removing the lid 130 to enable an individual to remove the lens from the lumen 151.

[0240] The obtained lens exhibits a flat optical face (on the top side) and a convex optical face having a radius of curvature that depends of the used parameters (here the density of the equilibration fluid and the volume extracted from the lower subdivision 101 L during the fourth step S4).

[0241] The results are shown in the following Table 2:

[0242] The present invention is in no way limited to the embodiments described and shown.

[0243] In particular, the process used to manufacture the lens may be slightly different from the one described above.

[0244] In this variant (not shown), the apertured element is provided on its internal face with a removable sleeve. Such a sleeve is advantageous for several reasons. It eases the lens extraction process because this sleeve can be removed from the ring with the polymerized lens. It can be made from a material or with a texture that improve monomer adhesion. It can form an adapter ring, the internal diameter of the sleeve being different from a sleeve to another one to vary the diameter of the lens.

[0245] In another variant, the compartment divider (40) may be an interface not strictly sealed but enabling to limit the liquid exchanges between the two subdivisions.

[0246] This compartment divider is preferably rigid, but in a variant, it may be formed by a flexible membrane.

[0247] In another variant, the compartment divider (40) can be fixed to the tank and to the receiving element (150) in a removable manner. In this variant, there is no need to use a valve: this compartment divider can indeed have a function of closed valve when it is fixed to the tank, and a function of opened valve when it is removed from the tank.

[0248] In another embodiment, the volume of the equilibration liquid in the upper and / or lower subdivisions can be adjusted by making the size of these subdivisions vary (and not by making the volume of liquid vary into the subdivision as explained in the previous embodiments). To this end, the bottom of the lower subdivision can for instance move along the side wall of this lower subdivision, like a “a piston system”, enabling a volume displacement and creating a curvature of the monomer attached to the receiving element (150). In a variant or in addition, the top wall of the upper subdivision can move along the side wall of this upper subdivision.

Claims

CLAIMS1 . A process for manufacturing an optical article (200), using a device (10) comprising:- a tank (100) defining internally a chamber (101 ) suitable for being filled with an equilibration liquid,- a receiving element (150) having an aperture that defines internally a formation volume (151 ) suitable for receiving a hardenable liquid composition for the formation of the optical article (200), and that is held into said tank (100), and- a compartment divider (140) surrounding said receiving element (150) and dividing said chamber (101 ) into an upper subdivision (101 U) and a lower subdivision (101 L),. the process comprising the following steps:- filling said lower subdivision (101 L) with an equilibration liquid until said equilibration liquid reaches at least a lower end of said formation volume (151 ),- filling said formation volume (151 ), onto a surface of said equilibration liquid, with a hardenable liquid composition,- filling said upper subdivision (10111) with an equilibration liquid having properties distinct from that of the equilibration liquid filling said lower subdivision (101 L) or not, to submerge the hardenable liquid composition,- adjusting the shapes of surfaces of equilibration liquid in contact with said hardenable liquid composition, to modify the shapes of surfaces of the hardenable liquid composition,- hardening said hardenable liquid composition, for instance by curing said material by light radiation exposure, and- extracting the hardened optical article (200).

2. The process according to claim 1 , using the device (10) claimed in claim 6, wherein said step of adjusting is performed by said liquid modulating system (24, 25, 31 ), by sucking equilibration liquid from and / or injecting equilibration liquid into any one of said upper and lower subdivisions (101 U, 101 L).

3. The process according to any one of claims 1 and 2, wherein, during said step of adjusting, said upper subdivision (101 U) and said lower subdivision (101 L) are set in free fluid communication.

4. The process according to any one of claims 1 to 3, wherein said equilibration liquid is not miscible with the hardenable liquid composition.

5. The process according to any one of claims 1 to 4, wherein said hardening step being carried out by curing said hardenable liquid composition by light radiation exposure, said equilibration liquid is transparent to said light radiation.

6. The process according to any one of claims 1 to 5, wherein the equilibration liquid filling said lower subdivision (101 L) has a density equal to or higher than the density of the hardenable liquid composition.

7. The process according to any one of claims 1 to 6, comprising, just before or after said step of filling said formation volume (151 ), a step of adding a surface-active agent, preferably non-foaming, onto the hardenable liquid composition.

8. The process according to any one of claims 1 to 7, wherein, during the step of filling said upper subdivision (101 U), the equilibration liquid is poured at a distance from the hardenable liquid composition, preferably on an internal face of the tank (100).

9. A device (10) for manufacturing an optical article (200), comprising:- a tank (100) defining internally a chamber (101 ) suitable for being filled with an equilibration liquid,- a receiving element (150) having an aperture that defines internally a formation volume (151 ) suitable for receiving a hardenable liquid composition for the formation of the optical article (200), and that is held into said tank (100), and- a compartment divider (140) surrounding said receiving element (150) and dividing said chamber (101 ) into an upper subdivision (101 U) and a lower subdivision (101 L).

10. The device according to claim 9, comprising communication means to make said upper subdivision (10111) and said lower subdivision (101 L) communicating with each other through a way other than through said formation volume (151 ).

11. The device according to claim 10, wherein the communication means comprises a valve (31 , 148) suitable:- in a first position, to prevent the equilibration liquid from communicating from any one of said upper and lower subdivisions (101 U, 101 L) to the other one of said upper and lower subdivisions (101 U, 101 L) and- in a second position, to enable the equilibration liquid to communicate from at least one of said upper and lower subdivisions (101 U, 101 L) to the other one of said upper and lower subdivisions (101 U, 101 L).

12. The device according to any one of claims 10 and 11 , wherein said communication means comprises a pipe (32, 33) located outside said tank (100) or a hole (147) provided into said compartment divider (140).

13. The device according to any one of claims 11 and 12, wherein, when the valve (148) is in the second position, said upper subdivision (101 U) and said lower subdivision (101 L) are in free fluid communication.

14. The device according to any one of claims 9 to 13, comprising a liquid modulating system (24, 25, 31 ) suitable to suck equilibration liquid from and / or to inject equilibration liquid into any one of said upper and lower subdivisions (101 U, 101 L).

15. The device according to claim 14, wherein said liquid modulating system (24, 25, 31 ) is suitable to suck equilibration liquid from any one of said upper and lower subdivisions (101 U, 101 L) and to inject an equivalent amount of equilibration liquid into the other of said upper and lower subdivisions (101 U, 101 L).

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