Patent ID: 7351447

Claim:
A method of producing an anti-reflection film, comprising: selecting a first material having a-reflective index of n 1 , coating the first material on a transparent substrate having a reflective index of n s to form a first layer having a thickness of d 1 , selecting a second material having a reflective index of n 2 , coating the second material on the first layer to form a second layer having a thickness of d 2 so that an optical admittance Y at a surface of the second layer opposite to the first layer is represented by, Y = H E = ( x + iy ) where i is the imaginary number unit, [ E H ] = [ cos ⁢ ⁢ δ 2 ( i / n 2 ) ⁢ ⁢ sin ⁢ ⁢ δ 2 i ⁢ ⁢ n 2 ⁢ ⁢ sin ⁢ ⁢ δ 2 cos ⁢ ⁢ δ 2 ] ⁡ [ cos ⁢ ⁢ δ 1 ( i / n 1 ) ⁢ sin ⁢ ⁢ δ 1 i ⁢ ⁢ n 1 ⁢ sin ⁢ ⁢ δ 1 cos ⁢ ⁢ δ 1 ] ⁡ [ 1 n s ] δ 1 =2π n 1 d 1 /λ 0 δ 2 =2π n 2 d 2 /λ 0 where λ 0 is a wavelength of incident light in vacuum, selecting a third material having a reflective index of n 3 , and coating the third material on the second layer to form a third layer having a thickness of d 3 , wherein said reflective index of the transparent substrate, the reflective index and the thickness of the first layer, the reflective index and the thickness of the second layer, and the reflective index of the third layer are selected so that x and y satisfy the following formula, 0.9 x{ ( n 3 2 −n 0 2 )/2 n 0 } 2 <{x −( n 3 2 +n 0 2 )/2 n 0 } 2 +y 2 <1.1 x {( n 3 2 −n 0 2 )/2 n 0 } 2 where n 0 is a refractive index of an outer region at an outside of the anti-reflection film.