Patent ID: 6175450
Filing Date: 2001-01-16
Classification: B32B,C03C,G02B,G02C

Abstract:
A transparent photochromic article includinga transparent substrate including a photochromic material; andan anti-reflection surface coating thereon, produced with a plurality of overlapping layers incorporating, alternatively a first and a second material having respectively higher and lower refractive indices, the anti-reflection coating includinga first layer including said first material having an optical thickness of about 20 to 40 nm;a second layer including said second material having an optical thickness of about 40 to 55 nm;a third layer including said first material having an optical thickness of about 65 to 85 nm;a fourth layer including said second material having an optical thickness of about 30 to 45 nm;a fifth layer including said first material having an optical thickness of about 50 to 65 nm; anda sixth layer including said second material having an optical thickness of about 110 to 135 nm, wherein the mean reflectance at the external surface is less than or equal to about 1% in the UV range.