Patent ID: 8081382

Claim:
A reflective screen comprising: a substrate having a first refractive index; and a periodic structure provided on a major surface of the substrate and including a periodic film, the periodic film having a period Λ and being made of a material having a second refractive index being higher than the first refractive index, the period Λ being not less than 400/(N+1) nanometers and not more than 680/(N−1) nanometers, the N being an equivalent refractive index of the periodic film, wherein for K light wavelengths λ k which produce an achromatic color upon color mixing, the periodic structure includes a stacked layer of K periodic films, each having an equivalent refractive index N k associated with the wavelength λ k , and having regularity of period Λ k which is not less than λ k /(N k +1) and not more than λ k /(N k −1).