Method of transferring a micron-scale pattern onto an optical article, and optical article obtained thereby
View Patent ↗A pattern (P) is transferred onto an optical article ( 1 ) in the form of one or more portions of a transferable material ( 3, 4 b ) retained by a layer of latex ( 2 ). The portion or portions of transferable material are applied with a stamp after the layer of latex has been formed on the article and before the latex is dry. By using latex as the adhesive material, the nature of the transferable material may vary widely. Such a method is particularly suitable for producing patterns such as holograms on optical lenses, especially ophthalmic lenses. The layer of latex may also protect the product against shocks which may subsequently be received.
1. A method of transferring a micron-scale pattern onto a surface of an optical article, the method comprising the following steps:
a) depositing a layer of at least one transferable material on a surface of a stamp having recesses and protuberances constituting micro-relief with micron-scale or submicron-scale definition, corresponding to the pattern to be transferred;
b) depositing a layer of a latex in the liquid form on the surface of the optical article;
c) before the layer of latex is dry, bringing the surface of the stamp that includes the layer of transferable material into contact with the layer of latex;
d) applying a pressure to the stamp; and
e) removing the stamp from the surface of the optical article comprising the layer of latex.
2. Method according to claim 1 , in which the micron-scale pattern comprises one or more individual patterns, each individual pattern having a dimension in the range 10 μm to 50 nm.
3. Method according to claim 1 , in which the dimensions of the recesses and the protuberances are in the range 10 micrometers to 50 micrometers, measured parallel to the surface of the stamp.
4. Method according to claim 1 , in which the depth of the recesses is in the range 0.1 μm to 30 μm.
5. Method according to claim 1 , in which the transferred pattern is a diffracting pattern when said pattern is illuminated by a beam of light.
6. Method according to claim 1 , in which the transferred pattern is a holographic pattern.
7. Method according to claim 6 , in which the transferred pattern is an amplitude hologram type holographic pattern.
8. Method according to claim 7 , in which in step c) the surface of the stamp is applied against the surface of the optical article carrying the layer of latex under conditions such that the layer of transferable material located on the protuberances of the surface of the stamp is selectively transferred onto the surface of said optical article.
9. Method according to claim 8 , in which in step c) the surface of the stamp is applied against the surface of the optical article carrying the layer of latex with pressure in the range 0.1 g/mm 2 to 60 g/mm 2 of surface of the protuberances of pattern P.
10. Method according to claim 6 , in which the transferred pattern is a phase hologram type holographic pattern.
11. Method according to claim 10 , in which in step c) the surface of the stamp is applied against the surface of the optical article carrying the layer of latex under conditions such that the protuberances on the surface of the stamp penetrate completely into the layer of latex, and such that the portions of the layer of transferable material that are located on the protuberances on the surface of the stamp as well as those located in the recesses of the stamp are jointly transferred onto the surface of said optical article.
12. Method according to claim 11 , in which in step c) the surface of the stamp is applied against the surface of the optical article carrying the layer of latex at a pressure of more than 60 g/mm 2 of the surface of the protuberances of pattern P.
13. Method according to claim 6 , in which the transferred pattern is a digital hologram type holographic pattern constituted by a set of contiguous pixels, each pixel having a surface area in the range 0.2 μm 2 to 25 μm 2 .
14. Method according to claim 1 , in which the transferred pattern occupies a small portion of a face of the optical article.
15. Method according to claim 14 , in which the transferred pattern occupies a portion of the face of the optical article of less than 25 mm 2 .
16. Method according to claim 1 , in which the transferred pattern occupies the entire face of the optical article.
17. Method according to claim 16 , in which the transferred pattern comprises an array of parallel electrically conductive wires.
18. Method according to claim 1 , in which the micron-scale pattern is adapted to form a reading image when a beam of light is passed through the optical article at a location of said pattern.
19. Method according to claim 1 , in which the layer of latex is deposited on the surface of the optical article using a spin-coating method.
20. Method according to claim 19 , in which the thickness of the layer of latex is in the range 0.2 μm to 50 μm.
21. Method according to claim 1 , further comprising the following step, carried out after step a) and/or step e):
f) covering the surface of the optical article with one or more functionalized coatings.
22. Method according to claim 21 , in which said one or more functionalized coatings comprise an anti-shock function, an anti-abrasion function, an antireflective function, a soil-repellent function, an anti-fogging function, an antistatic function, a polarizing function, a coloring function, or a photochromic function.
23. Method according to claim 21 , in which the additional step f) is carried out after step e).
24. Method according to claim 1 , in which the transferable material is a metallic material.
25. Method according to claim 24 , in which the transferable material is a metal selected from gold, aluminum, chromium, silver, copper, nickel, platinum, palladium, and an alloy comprising at least one of said metals.
26. Method according to claim 24 , in which the layer of transferable material is deposited in step a) onto the surface of the stamp by vacuum evaporation or vacuum cathodic sputtering.
27. Method according to claim 24 , in which the layer of transferable material comprises a stack of a plurality of respective layers of materials.
28. Method according to claim 27 , in which the material of at least one of the layers of the stack is refringent.
29. Method according to claim 1 , in which the stamp is based on polydimethylsiloxane at least at the locations of the protuberances of the surface of the stamp.
30. Method according to claim 1 , in which the stamp is approached parallel to the normal from a point of contact of the stamp surface with the optical article.
31. Method according to claim 1 , in which in step c) the surface of the stamp is adapted to deform during application against the surface of the optical article as a function of a curvature of said optical article surface.
32. Method according to claim 1 , further comprising a step of processing the surface of the optical article carried out before step b).
33. Method according to claim 1 , in which the optical article is selected from an instrumentation optical lens, a viewing lens, a visor, and an ophthalmic lens.
34. Method according to claim 33 , in which the optical article is an ophthalmic lens selected from afocal, single vision, bifocal, trifocal, and progressive power lenses.
35. An optical article comprising at least one transferred pattern on the surface of said optical article, transfer of said pattern being achieved by a method according to any one of the preceding claims.
36. Article according to claim 35 , representing an ophthalmic lens, said lens itself comprising:
a base lens comprising at least one organic or mineral substrate;
a dried layer of latex; and
portions of a transferable material forming the transferred pattern, by adhesion to the base lens via a layer of adhesive material.
37. Article according to claim 36 , in which the pattern is formed by several portions of printing material located at the same level on the layer of latex in a direction perpendicular to said layer and separated by gaps that are free of transferred material.
38. Article according to claim 36 , in which the pattern is embossed into the layer of latex and in which several portions of transferred material are located at different engraving depths into the layer of latex.
39. Article according to claim 36 , in which the layer of latex further forms a protection for the lens against shocks which may subsequently be received by said lens.