Patents
Optically clear AR coatings on previously hard-coated plastic ophthalmic lenses and sheets have been developed following a two-layer (high and low index) quarter-wavelength coating design followed by deposition of one hydrophobic layer on top and cured by thermal and UV curing. High-index coating sol based on "SiO2-TiO2-PEO" or "SiO2-ZrO2-PEO" and low-index sol based on "SiO2-PEO" organic-inorganic polymeric networks have been used for the deposition of such AR coatings. About 98% of transmissions (reflective loss minimized to <2%) have been achieved after the deposition of such AR coatings. Deposition of a very thin hydrophobic coating derived from a mixture of alkyl chlorosilanes solution as a top layer further increased the overall hardness value to 5H plus (ASTM D 3363) and hydrophobic nature without affecting the optical property of AR coating. The reflection minima can be tuned at different wavelengths as per optical designs.