Patent ID: 8619365

Claim:
A multilayer anti-reflective coating for a substrate, comprising: (a) a first layer having a refractive index n 1 , where n 1 <1.4, and an optical thickness of (0.25Â±5%) Î» o nm, which in expanded form is a range of (0.25-5% of 0.25) Î» o nm to (0.25+5% of 0.25) Î» o nm, where Î» o is a wavelength in the visible light range; (b) a second layer adjacent to the first layer, the second layer having a refractive index n 2 , where n 2 â‰§1.8, and an optical thickness of (0.5Â±5%) Î» o nm, which in expanded form is a range of (0.5âˆ’5% of 0.5) Î» o nm to (0.5+5% of 0.5) Î» o nm, where Î» o is a wavelength in the visible light range; (c) a third layer adjacent to the second layer, the third layer having a refractive index n 3 , where 1.4â‰¦n 3 <1.6, and an optical thickness of (0.1Â±5%) Î» o nm, which in expanded form is a range of (0.1-5% of 0.1) Î» o nm to (0.1+5% of 0.1) Î» o nm, where Î» o is a wavelength in the visible light range; and (d) a fourth layer adjacent to the third layer, the fourth layer having a refractive index n 4 , where n 4 â‰§1.8, and an optical thickness of (0.05Â±10%) Î» o nm, which in expanded form is a range of (0.05âˆ’10% of 0.05) Î» o nm to (0.05+10% of 0.05) Î» o nm, where Î» o is a wavelength in the visible light range; the anti-reflective coating having a coating order of first layer/second layer/third layer/fourth layer, with the first layer being the outermost layer relative to the substrate.