METHOD FOR TREATING A MIRRORED OPTICAL ELEMENT

Description

[0001] The invention lies in the field of treatment of mirrored ophthalmic lenses, in particular those coated with a multi-layer interference coating. According to the invention, ophthalmic lens means a lens, corrective or not, which can be used as a spectacle lens, for example for glasses, in particular sunglasses or masks or the like.

[0002] Nowadays, ophthalmic lenses and more specifically, sunglasses not only protect the eyes from the sun, but also have an important aesthetic aspect for the wearer of these optical items.

[0003] For example, eyeglass wearers want personalized optical items that allow them to stand out through their external aspects, particularly their appearance in terms of color and reflection.

[0004] However, as is often the case in industry, customization significantly increases the cost of the items produced and generally opposes standardized production at lower cost.

[0005] In this case, a mirrored ophthalmic lens, i.e. one with a multi-layer interference coating, has a uniform external appearance.

[0006] To customize such an optical article, one could, for example, consider modifying the thickness of one or more layers of the multi-layer interference coating in certain areas by using a silicone pad printing mask. However, such a process lacks precision in terms of contours (burr problem) and repeatability. In addition, there are problems with the adhesion of layers subsequently deposited on buffered areas and therefore an increase in the reject rate.

[0007] Laser etching of certain layers of the multi-layer interference coating subsequently appears to be an attractive alternative. However, this laser etching can generate microcracks in the optical article which impair the lifetime of the optical article. In addition, such etching is not carried out under a controlled atmosphere and particles can be deposited on the optical article thus treated, subsequently leading to appearance defects and the adhesion, for example, of an anti-fouling treatment may no longer be achieved successfully.

[0008] WO2018015650 describes a method for marking an optical article using laser ablation. DE10 2011 119598 describes a multi-layer deposition method.

[0009] Removal of part of a layer by ion bombardment is also known, see for example US 2005 / 084626 and US 2019 / 302697.

[0010] The present invention therefore aims to at least partially overcome the aforementioned drawbacks by proposing a treatment method defined by the characteristics of claim 1.

[0011] Thus, from a standardized production, it is possible to customize a mirrored ophthalmic lens in a very precise and repeatable way.

[0012] The method according to the invention may have one or more of the following aspects taken alone or in combination: During the ion bombardment removal step, the initial thickness of the remote interference layer may be reduced by a value less than its initial thickness.

[0013] The mirror stack comprises, for example, two (exactly two) or at least three interference layers, and the thickness reduction of the remote interference layer is, for example, determined such that between the first and second colorations, the difference in the hue angle is less than 2% and the difference in the chromacity is greater than 10%.

[0014] The difference in brightness between the first and second coloring is notably less than 10%, and more particularly less than 5%.

[0015] The b* / a* ratio of the CIELAB space can be constant within a tolerance of 10%, notably 5%.

[0016] The thickness reduction can be uniform in each of the predetermined areas.

[0017] It can be provided that the step of removal by ion bombardment is preceded by a step of determining an ion bombardment duration to obtain the second coloration in the first predetermined zone.

[0018] The step of removal by ion bombardment is in particular such that the mirrored optical article exhibits, by an interferometry phenomenon, a mirroring having a reflection intensity in the first predetermined zone different from a zone not treated by the ion bombardment.

[0019] The mirrored article may comprise said first predetermined area and an area not treated by the ion bombardment, one of the two areas corresponding to a near vision area with a mirror having a lower reflection intensity than in the other area corresponding to a distance vision.

[0020] The surface of the first predetermined area is for example smaller than the surface of the mirrored optical article and the method may further comprise a second removal step (additional removal step) by ion bombardment at least in a second predetermined area of ​​the mirrored optical article which is different from the first predetermined area, during the second removal step a second predefined thickness of the remote interference layer is removed which is less than the first initial thickness of this remote interference layer and different from the thickness removed during the first removal step, in the second predetermined area, the mirrored optical article having by an interferometry phenomenon a third coloration according to the CIELAB space different from the first and second coloration according to the CIELAB space.

[0021] The removal step can be carried out by ion bombardment in a box coater equipped with an ion gun.

[0022] In particular, a mask is placed between the mirrored optical article and the ion gun preventing ions from reaching the interference layers outside the predetermined area.

[0023] The mask includes in particular an adhesive affixed to the mirrored optical article.

[0024] The mask may include a cover, in particular a metal one, placed between the ion gun and the mirrored optical article.

[0025] Ion bombardment can be carried out in a vacuum, or in an atmosphere containing an inert gas having a pressure less than or equal to atmospheric pressure.

[0026] After the ion bombardment removal step, an anti-fouling treatment is applied to the entire mirrored optical article.

[0027] The invention also relates to a mirrored ophthalmic lens obtained with a method presented above and having at least two different colorations according to the CIELAB space. The mirrored article comprises in particular said first predetermined zone and a zone not treated by ion bombardment, one of the two zones corresponding to a near vision zone with a mirroring having a lower reflection intensity than in the other zone corresponding to a distance vision.

[0028] Other characteristics and advantages of the invention will appear more clearly on reading the following description, given as an illustrative and non-limiting example, and the appended drawings among which: [ Fig 1A ] there figure 1A schematically shows a mirrored optical article, [ Fig 1B ] there figure 1B shows an exploded view along the axis of the mirrored article of the figure 1A , artificially separating the different layers forming the mirrored article, [ Fig 2 ] there figure 2 schematically shows a stack of layers of a mirrored optical article of figures 1A And 1B according to a first embodiment, [ Fig 3 ] there figure 3 schematically shows a stack of layers of a mirrored article according to a second embodiment, [ Fig 4 ] there figure 4 shows the mirrored optical article from the front according to the examples of the embodiments of the figures 1A , 1B , 2 And 3 , [ Fig 5 ] there figure 5 is a simplified side view, partially in cross-section, of a treatment enclosure which is capable of being implemented for the treatment of mirrored optical articles, [ Fig 6 ] there figure 6 shows a flowchart of an exemplary embodiment of the method for processing mirrored optical articles, [ Fig 7 ] there figure 7 is a first variant of the figure 4 , [ Fig 8 ] there figure 8 is a second variant of the figure 4 , [ Fig 9 ] there figure 9 is a third variant of the figure 4 , And [ Fig 10 ] there figure 10 shows, as an example, the reflectivity of an area of ​​a mirrored optical article before and after carrying out the treatment process.

[0029] An example of an embodiment will now be described with reference to the figures. In all the figures, the same references refer to the same elements.

[0030] So, from the examples of layer stacking diagrams of the figures 2 Or 3 , we can easily deduce figures similar to the figures 1A And 1B by adding or removing different layers.

[0031] The following embodiments are examples. Although the description refers to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment, or that the features apply only to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments.

[0032] The "front" or "back" side of a layer refers to the propagation of light rays towards the eye. Thus, a "front" side is always the one closest to the user's field of vision and a "back" side is always the one closest to the user's eye.

[0033] By "upstream" or "downstream" of two elements or layers, we refer to the propagation of light rays towards the eye. Thus, a first element is arranged "upstream" of a second element when the light passes through the first element on its way to the user's eye first, then the second element. Conversely, a first element is arranged "downstream" of a second element when the light passes through the second element on its way to the user's eye first, then the first element.

[0034] In this presentation, the UV range of ultraviolet includes wavelengths below 380nm.

[0035] In the present disclosure, the visible range includes wavelengths between approximately 380nm and approximately 800nm, and in particular wavelengths between approximately 400nm and 750nm.

[0036] Reflectivity is defined by the average light reflection factor ρv in the visible range as defined in ISO 12311:2013 point 7.7: The value of py in percentage is calculated by the ratio of the luminous flux reflected by the filter Φ R to the incident flux Φ I as follows: ρ V = 100 × I R I I = 100 × ∫ 380 780 ρ λ ⋅ V λ ⋅ S D 65 λ ⋅ d λ ∫ 380 780 V λ ⋅ S D 65 λ ⋅ d λ Or is the wavelength in nanometers; ρ ( λ ) is the spectral reflectance of the filter at the wavelength λ ; V ( λ ) is the relative sensitivity of the human eye, as defined in ISO 11664-1; S D65 ( λ ) is the spectral energy distribution of CIE standard illuminant D65, as defined in ISO 11664-2.

[0037] The hue angle and chromacity are defined by the standard NF ISO 11664-4:2011-07 point 4.2. Let a* and b* be the CIELAB colorimetric coordinates.

[0038] Chromacity is defined by C * ab = a * 2 + b * 2 1 / 2 The hue angle h ab = arctan (b* / a*) The hue angle must be between 0° and 90° if a* and b* are both positive, between 90° and 180° if b* is positive and a* negative, between 180° and 270° if b* and a* are both negative, and between 270° and 360° if b* is negative and a* positive.

[0039] Glossiness is defined by BYK calculation.

[0040] Also used is the term "reflection intensity" defined by or equivalent to the average light reflection factor as defined above.

[0041] The mirrored optical article 1 of the figures 1A And 1B is according to the invention intended to be used, in particular as an ophthalmic lens, for glasses, in particular sunglasses, or masks. To do this it is only necessary to shape the external edge 3 according to the desired shape of the frame of a frame or a mask.

[0042] On the figures 1A And 1B, the light incident on the mirrored article 1 and an eye 7 are represented by the arrow 5 to represent a user. The field of vision 13 is therefore located on the side of the arrow 7 and the user looks through the mirrored optical article 1 with his eye 7

[0043] By mirrored article 1, according to the invention, is meant an ophthalmic lens, corrective or not, finished or semi-finished, capable of being mounted in a frame, for example a spectacle frame, a mask or a visor intended to be placed in front of the eyes and forming a visual protection screen. The mirrored optical article 1 is the starting product which will be subjected to the process which will be described later.

[0044] The mirrored optical article 1 may be made of mineral glass or organic glass or a combination of both

[0045] The mirrored optical article 1 may be tinted or not, or have a tint gradient, and it may include other solar functions such as a polarizing function, photochromic alone or in combination as will be seen later. The mirrored article is for example class 2, 3 or 4 according to the ISO 12312 standard.

[0046] It may also include other additional functions, alone or in combination from the following non-exhaustive list: shockproof, anti-scratch, anti-abrasion, anti-reflective, anti-fouling, anti-fog, anti-static. These additional functions can be achieved using conventional methods (dipping, vacuum deposition, spin coating, spray coating, etc.).

[0047] In reference to the figures 1A And 1B , the mirrored optical article 1 comprises a transparent substrate 10.

[0048] This transparent substrate 10 has a rear face 10AR intended to be oriented towards the eye 7 of the user, intended to form the rear external surface of mirrored article 1 oriented towards the eye of the user, and a front face 10AV oriented towards the field of vision 13 of the user.

[0049] By transparent is meant a layer that allows incident light to pass through completely or at least partially. The transparent substrate 10 may be tinted, i.e. for example include dyes and / or pigments, or not.

[0050] More generally, the material(s) of certain layers of the mirrored optical article 1 may be made of any material commonly used in the field of optics and in particular in the ophthalmic field.

[0051] As thermoplastic material, one can for example choose from the following non-exhaustive group: polymethyl(meth)acrylate, polycarbonate, polycarbonate / polyester blends, polyamide, polyester, cyclic olefin copolymers, polyurethane, polysulfone, TAC (cellulose triacetate), polyimide, polyurethanes; poly(ethylene terephthalate) and polymethyl methacrylate (PMMA). and copolymers and their combination.

[0052] As thermosetting material, one can for example choose from the following non-exhaustive group of CAB (cellulose acetate butyrate), ethylene / norbornene or ethylene / cyclopentadiene copolymers; (homo and copolymers of allyl carbonates of linear or branched aliphatic or aromatic polyols, such as homopolymers of diethylene glycol bis(allyl carbonate) (CR 39 ®< ); (homo and copolymers of methacrylic acid and esters, which can be derived from bisphenol A; (polymers and copolymers of thiomethacrylic acid and esters, (polymers and copolymers of urethane and thiourethane), (polymers and copolymers of epoxy), (polymers and copolymers of sulfides and episulfides) and combinations thereof.

[0053] To color the thermoplastic material, it is possible to add pigments or dyes. Regarding pigments, these can be organic or mineral pigments.

[0054] The material of the substrate 10 is for example chosen from the group of the following materials: polymethyl(meth)acrylate, polycarbonate, mixed polycarbonate / polyester, polyamide, polyester, cyclic olefin copolymers, polyurethane, polysulfone, TAC (cellulose triacetate) or cellulose acetate butyrate and their combination.

[0055] The fact that the rear face 10AR forms an external face does not prevent it from being treated, for example, with an anti-scratch and / or anti-fouling and / or anti-reflective treatment on the rear face.

[0056] Upstream of the substrate 10 is arranged a mirror stack 21.

[0057] Depending on the method of implementation of the figures 1A , 1B And 2, a polarizing assembly 31 comprising for example a polarizing film, in particular of polyvinyl alcohol (PVA) doped with iodine and stretched axially, known for its polarizing properties, can be arranged between the mirror stack 21 on the one hand and the substrate 10 on the other hand and fixed to them by means of layers of glue 33 and 35. In the polarizing assembly 31, the polarizing film can be sandwiched by two thin layers, in particular made of thermoplastic material, in particular to protect the polarizing film. The polarizing assembly 31 can also be formed by a polarizing film only.

[0058] The polarizing assembly 31 is bonded to the rear face 21AR of the mirror stack 21 and to the front face 10AV of the substrate 10.

[0059] According to a first variant not shown, an adhesion layer is arranged between the polarizing assembly 31 and the substrate 10.

[0060] According to a second variant not shown, an anti-scratch treatment layer is arranged between the polarizing assembly 31 and the mirror stack 21.

[0061] Furthermore, a varnish may be disposed on the polarizing assembly 31, such that the varnish is located between the polarizing assembly 31 and the mirror stack 21.

[0062] If in the polarizing assembly 31, the polarizing film is sandwiched by two thin layers, in particular made of thermoplastic material, the most downstream layer can also serve as an adhesion layer as described above.

[0063] Mirror stack 21 is more detailed on the figure 2 . For example, it comprises a succession of thin layers M1, M2, M3, M4, M5 and M6. Adjacent thin layers have a different refractive index from each other. However, two non-adjacent thin layers can have identical refractive indices.

[0064] The layer M1 is the interference layer which is distant from the substrate 10 with a first initial thickness e 1-init and a first refractive index n 1 .

[0065] The layers M2 to M6 are close interference layers, arranged between the substrate 10 and the distant interference layer M1, each with an initial thickness e j-init and a refractive index nj (j being an integer from 2 to 6 in the present example). In particular, the layer M2 has a second initial thickness e 2-init and a refractive index n 2 which is different from the first refractive index n 1 .

[0066] The mirror stack 21 gives, by an interferometry phenomenon, a first coloring according to the CIELAB space to the mirrored optical article 1, of course in cooperation with the layers located further downstream in the direction of the user's eye 7. The number, indices and thicknesses of the layers of the stack are predetermined experimentally, by calculation or by means of a calculator or simulator so as to obtain said first coloring with a predetermined reflection rate.

[0067] Of course the number of thin layers M j can vary and include, for example, only two, four or eight layers.

[0068] The first thin layers M1, M3 and M5 are for example made of silica (SiO2) and the second thin layers M2, M4 and M6 are for example made of titanium oxide (Ti 3 O 5 ).

[0069] Other materials may be chosen, for example so that in the visible range, the first thin layers M1, M3 and M5 have a first refractive index n 1 less than or equal to 1.5, and the second thin layers M2, M4 and M6 have a second refractive index n 2 greater than 2, in particular equal to or greater than 2.3.

[0070] Generally, the first thin layers M1, M3 and M5 have a thickness between 70nm and 250nm, and the second thin layers M2, M4 and M6 have a thickness between 40nm and 80nm.

[0071] According to a very concrete example, the mirror stack 21 is formed as follows: Couche mince Matériaux Thickness e j (nm) M1 SiO 2 76,38 M2 Ti 2 O 3 58,21 M3 SiO 2 169,72 M4 Ti 2 O 3 61,57 M5 SiO 2 165,73 M6 Ti 2 O 3 71,86

[0072] As can be seen on the figure 2 , the first thin layers M1, M3 and M5 and the second thin layers M2, M4 and M6 are therefore arranged alternately.

[0073] The mirror stack 21 is typically produced by vacuum deposition of thin layers in a “box-coater” (installation for deposition of a coating by layers in French).

[0074] As a result, a polarizing assembly 31 comprising for example a polarizing film is bonded to the second thin layer M6 and to the front face 10AV of the substrate 10.

[0075] The method of realization of the figure 3 is only distinguished from that of the figure 2 by the fact that this embodiment does not provide a polarizer assembly 31. The substrate 10 is then fixed downstream of the rear face 21AR of the mirror stack 21.

[0076] It is possible to provide for the fixing of the substrate 10 on the rear face 21AR of the mirror stack 21 by an adhesive 35.

[0077] According to a variant not shown, an adhesion layer, in particular made of thermoplastic material, can be arranged between the mirror stack 21 and the substrate 10.

[0078] According to yet another embodiment not shown, it can be provided that the polarizing assembly 31 is replaced by a photochromic layer activatable in the UV range and / or in the visible range.

[0079] This photochromic layer may be a thermoplastic material comprising a known photochromic dye. Examples include the following families commonly used in ophthalmic lenses: spiro-oxazines, spiroindoline[2,3']benzoxazines, chromenes, spiroxazine homo-aza-adamantanes, spirofluorene-(2H)-benzopyrans, naphtho[2,1-b]pyrans and naphtho[1,2-b]pyrans.

[0080] There figure 4 shows the mirrored optical article 1 from the front according to the examples of the embodiments of the preceding figures, that is to say according to arrow 5.

[0081] In this figure, a first zone Z1 is drawn in dotted lines on which the treatment of the method according to the invention will be applied. In the present example, the zone Z1 is smaller than the surface area of ​​the mirrored optical article 1. Its extension is therefore smaller than the diameter of the mirrored optical article 1.

[0082] The untreated areas / zone(s) which are located outside the first zone Z1, are protected for example by at least one protective adhesive film Fp applied to the thin layer M1 before carrying out the treatment process. Thus, we see on this figure 4 the protective film Fp and the layer M1 of the mirror stack 21 in the zone Z1. According to another example, the zone Z1 covers the entire mirrored article 1 which will therefore, following the treatment process, change its external appearance and in particular its coloring. According to yet another example, several zones can be provided, for example Z1, Z2 etc., as will be seen later.

[0083] For this purpose, the mirrored optical article 1 is placed, for example, in an installation 220 for treatment by ion bombardment of mirrored optical articles 1.

[0084] This installation 220 comprises a treatment enclosure 221 and an ion-emitting source 222 for bombarding the mirrored optical articles 1 according to an evaporation cone 224 for example.

[0085] The treatment enclosure 221 may be hermetically sealed and connected to a vacuum unit (not shown), for example a vacuum pump, to lower the pressure inside the treatment enclosure 221 to a pressure suitable for the treatment to be applied, typically for example of the order of 3 * 10 -5 < mbar.

[0086] Alternatively, the ion bombardment may be carried out in an atmosphere containing an inert gas having a pressure less than or equal to atmospheric pressure. The emitting source 222 is for example constituted by an ion gun or a support on which a material to be evaporated is placed, an ion source or a plasma generator, for example a crucible or a plate, and, for its evaporation, the material is for example subjected to heating by the Joule effect, to electron bombardment, or to a cathode sputtering effect. The ion source may be a tungsten filament forming a cathode. The gas diffuser or plasma generator may be formed by a graphite anode. In this case, a crucible or a plate are not necessary for such an emitting source 222.

[0087] Above the emitting source 222 is arranged a rotating support 226 of the mirrored optical articles 1.

[0088] For this purpose, the rotary support 226 comprises individual housings 228 of the mirrored optical articles 10.

[0089] The 228 individual dwellings are arranged, for example, on concentric tracks.

[0090] It is understood that when the support 226 rotates, each of the individual housings 228 makes revolutions.

[0091] The rotating support 226 has, for example, a concave shape or more specifically a spherical cap shape so that the individual housings 228 of the mirrored optical articles 1 are arranged at an equal distance from the ion emitting source 222.

[0092] The rotating support 226 can rotate about an axis A which corresponds to the axis of symmetry of the rotating support and passes through the center thereof, which makes it possible to standardize the exposure of the mirrored optical articles to ion bombardment.

[0093] The installation 220 is for example a “box-coater” (installation for depositing a coating by layers in French) equipped among other things with an ion gun and which also allows other treatments to be applied, in particular finishing treatments of the mirrored optical article 1, such as an anti-fouling treatment. As mentioned above, the box-coater can also be used for producing the mirror stack 21.

[0094] The installation 220 therefore allows in the same machine the carrying out of various steps in the manufacture of an optical article, in particular even some which are prior to those concerned by the method of the invention.

[0095] Before being introduced into the installation 220, the area(s) of the mirrored optical article 1 which are not to be treated are therefore protected by a cover, for example the adhesive film Fp.

[0096] Alternatively, instead of the protective film Fp, a mask, in particular a cover, notably metallic, can be provided in the installation 220 between the mirrored optical article 1 and the ion gun preventing the ions from reaching the interference layers outside the predetermined zone Z1.

[0097] The method comprises a first step 103 (see figure 6 ) consisting of removing by ion bombardment at least in a first predetermined zone Z1 a thickness and of the mirrored stack 21 which is less than the sum of the initial thicknesses concerned by the removal step.

[0098] More specifically, the treatment method aims to remove a thin layer M j only partially and where appropriate completely the thin layer(s) M 1 to M j-1 furthest from the substrate 10. In the reference of the present application for i <j, la couche M i est plus éloignée du substrat 10 que la couche M j .

[0099] For example, according to a first embodiment, the installation 220 is configured to remove from the thin layer M1 a thickness and < e 1-init , that is to say the initial thickness e l-init of the remote interference layer M1 is reduced by a value and less than its initial thickness e 1-init . This therefore results in a residual thickness of the layer M1 er = e l-init - et . This example will generally be the most relevant in the case where the mirroring stack 21 has two or more than three thin interference layers M j .

[0100] More generally, if a part of the layer M k (k being an integer, in the present example k=1 to 6, preferably k=1 or 2) is removed, a thickness is removed by ion bombardment in the predetermined zone Z1: e t < ∑ j = 1 j = k e k − init

[0101] The Mk layer will therefore have a residual thickness e r = e k − init − e t + ∑ j = 1 j = k − 1 e j − init .

[0102] For example, the residual thickness er of the Mk layer can be predicted to be in the range 0.05 e k-init < er < 0.95 e k-init .

[0103] Thus, the mirrored optical article 1, presents in this predetermined zone Z1 by an interferometry phenomenon a second coloration according to the CIELAB space different from the first coloration of the untreated mirrored optical article 1 or of the untreated zones of the mirrored article 1.

[0104] The advantage of doing this is the precision of the process to remove a certain thickness and the repeatability on an industrial scale, which therefore allows to obtain a result in terms of predictable and good quality second coloring.

[0105] According to one example, in the case where the mirror stack 21 comprises at least three interference layers (such as for example according to the example of figures 2 And 3), and the ion bombardment removes only a part of the thin layer M1, the reduction in thickness and of the distant interference layer M1 is determined so that between the first and the second coloring, the difference in the hue angle is less than 2% and the difference in the chromacity is greater than 10%.

[0106] According to another example, the reduction in thickness and of the remote interference layer M1 is determined so that the difference in brightness between the first and the second coloring is less than 10%, in particular less than 5%.

[0107] According to yet another example, the reduction in thickness and of the distant interference layer M1 is determined so that the b* / a* ratio of the CIELAB space is constant within a tolerance of 10%, in particular 5% between the first and the second coloring.

[0108] After this first step 103, it is noted that the reduction in thickness is uniform in the or each of the predetermined zones Zi.

[0109] According to a variant, step 103 is preceded by an optional step 101 of determining a duration T of ion bombardment to obtain the second coloring in the first predetermined zone Z1.

[0110] According to yet another example, the reduction in thickness and of the remote interference layer M1 is determined such that the mirrored optical article 1 exhibits, by an interferometry phenomenon, a mirroring having a reflection intensity in the first predetermined zone Z1 different from a zone not treated by the ion bombardment.

[0111] According to the figure 7 which is a variant of the figure 4 , the mirrored optical article comprises said first predetermined zone Z1 and a zone not treated by ion bombardment, protected by the protective film Fp, and one of the two zones, here zone Z1, corresponds to a near vision zone with a mirroring having a lower reflection intensity than in the other zone (the untreated zone) corresponding to far vision.

[0112] According to another variant shown in figure 8 wherein the surface area of ​​the first predetermined area Z1 is smaller than the surface area of ​​the mirrored optical article 1, the method may further comprise a second removal step 105 by ion bombardment at least in a second predetermined area Z2 of the mirrored optical article 1 which is different from the first predetermined area Z1. During this second removal step 105, the area Z1 may be protected, for example by an additional adhesive film Fp, and a second predefined thickness of the remote interference layer M1 is removed which is less than the first initial thickness of this remote interference layer and different from the thickness removed during the first removal step 103.As a result, in the second predetermined zone Z2, the mirrored optical article 1 presents, by an interferometry phenomenon, a third coloration according to the CIELAB space different from the first and second coloration according to the CIELAB space. A three-color mirrored optical article is therefore obtained.

[0113] According to yet another variant shown in figure 9 , wherein the surface area of ​​the first predetermined area Z 1 is smaller than the surface area of ​​the mirrored optical article 1, the method may further comprise a second step 105 of removal by ion bombardment at least in a second predetermined area Z2 of the mirrored optical article 1 which is included in the first predetermined area Z 1 and smaller than the latter.

[0114] In the second removal step 105, an adhesive protective film Fp protects the entire mirrored optical article except the predetermined area Z2 and a second predefined thickness of the remote interference layer M1 is removed which is less than the difference between the first initial thickness of this remote interference layer and the thickness removed in the first removal step. In the second predetermined area, the mirrored optical article 1 consequently has, by an interferometry phenomenon, a third coloration according to the CIELAB space different from the first and second coloration according to the CIELAB space.

[0115] It is therefore understood that the method of treating the mirrored optical article 1 makes it possible to change certain parameters precisely and repeatably, in particular the coloring, to obtain a personalized product with a contained cost price.

[0116] There figure 10 shows for example the reflectivity as a function of the wavelength of a mirrored optical article 1 in the predetermined zone Z1 before, curve C1, and after, curve C2, step 103 of the treatment method. Before the treatment according to step 103, the mirrored optical article 1 has as a whole and more specifically in the predetermined zone Z1 a “blue” appearance, while after treatment, the predetermined zone Z1 has a “bronze” appearance as shown by the spectra of the figure 10 . From a mirrored optical article 1 of a predetermined color, we end up with a mirrored optical article of another color or having two or even three different colors. According to examples, the change in coloring can be less pronounced and result for example in a “pastel” effect.

[0117] Furthermore, by inspecting a mirrored optical article treated according to the method described above, in particular using an electron microscope, it can be observed that the removal in a predetermined area of ​​a thickness of the mirrored stack is carried out by ion bombardment. In particular, in a predetermined area Z1 for example, it is possible to locally observe a densification of the layers having undergone ion bombardment compared to an area where the layers have not undergone ion bombardment.

Claims

1. Process for treating a mirror-effect ophthalmic lens comprising: - a substrate (10), - a mirror stack (21) of at least two interferential layers (M1 to M6) borne by the substrate (10) thus increasing reflectance and having: * an interferential layer (M1) far from the substrate (10), with a first initial thickness and a first refractive index, and * at least one near interferential layer (M2) placed between the substrate (10) and the far interferential layer (M1), with a second thickness and a second refractive index which is different from the first refractive index, the mirror stack (21) giving, via an interference effect, a first colour in the CIELAB space to the mirror-effect ophthalmic lens (1), the process comprising a step (103) of removing, via ion bombardment, at least from a first predetermined region (Z1), a mirror-stack thickness that is smaller than the sum of the initial thicknesses concerned by the removing step, the mirror-effect ophthalmic lens exhibiting, via an interference effect, a second colour in the CIELAB space which is different from the first colour.

2. Process according to Claim 1, wherein, in the step (103) of removing via ion bombardment, the initial thickness of the far interferential layer is decreased by a value smaller than its initial thickness.

3. Process according to Claim 2, wherein the mirror stack (21) comprises two (M1, M2) or at least three interferential layers (M1 to M6), and wherein the decrease in thickness of the far interferential layer is determined so that, between the first and second colours, the difference in hue angle is smaller than 2% and the difference in chroma is larger than 10%.

4. Process according to Claim 2 or 3, wherein the difference in lightness between the first and second colours is smaller than 10%, and especially smaller than 5%.

5. Process according to any one of Claims 2, 3 and 4, wherein, between the first and second colours, the b* / a* ratio in the CIELAB space is constant within a tolerance of 10%, and especially of 5%.

6. Process according to one of the preceding claims, wherein the decrease in thickness is uniform in each of the predetermined regions.

7. Process according to one of the preceding claims, wherein the step of removing via ion bombardment is preceded by a step (101) of determining an ion-bombardment time required to obtain the second colour in the first predetermined region.

8. Process according to one of the preceding claims, wherein the step of removing via ion bombardment is such that the mirror-effect ophthalmic lens exhibits, via an interference effect, a mirror effect having a reflectance in the first predetermined region different from a region not treated by the ion bombardment.

9. Process according to one of the preceding claims, wherein the mirror-effect ophthalmic lens comprises said first predetermined region and a region not treated by the ion bombardment, one of the two regions corresponding to a near-vision region (Z1) with a mirror effect having a reflectance lower than in the other region, which corresponds to a far-vision region.

10. Process according to Claim any one of Claims 1 to 9, wherein the area of the first predetermined region is smaller than the area of the mirror-effect optical article and wherein the process further comprises a second step of removing via ion bombardment, at least from a second predetermined region (Z2) of the mirror-effect optical article (1) that is different from the first predetermined region, in the second removing step, a second predefined thickness of the far interferential layer is removed that is smaller than the first initial thickness of this far interferential layer and different from the thickness removed, in the first removing step, from the second predetermined region, the mirror-effect ophthalmic lens (1) exhibiting, via an interference effect, a third colour in the CIELAB space different from the first and second colours in the CIELAB space.

11. Process according to any one of Claims 1 to 10, wherein a mask is placed between the mirror-effect ophthalmic lens and an ion gun, preventing ions from reaching the interferential layers outside of the predetermined region.

12. Process according to any one of Claims 1 to 11, wherein the ion bombardment is carried out under vacuum conditions, or in an atmosphere containing an inert gas having a pressure lower than or equal to atmospheric pressure.

13. Process according to any one of Claims 1 to 12, wherein, after the step of removing via ion bombardment, an anti-smudge treatment is applied to the entirety of the mirror-effect ophthalmic lens.

14. Mirror-effect ophthalmic lens (1) obtained by a process according to any one of Claims 1 to 13 and exhibiting at least two different colours in the CIELAB space.

15. Mirror-effect ophthalmic lens according to Claim 14, wherein the mirror-effect article comprises said first predetermined region (Z1) and a region not treated by the ion bombardment, one of the two regions corresponding to a near-vision region with a mirror effect having a reflectance lower than in the other region, which corresponds to a far-vision region.