Patent ID: 7667286

Claim:
A light-collecting device comprising an aggregate of light-transmitting films having different refractive indexes, wherein one light-transmitting film in said aggregate has a concentric circle shape with a predetermined thickness and a width which is equal to or smaller than a wavelength of incident light, another light-transmitting film in said aggregate concentrically fills all or a part of a space of said aggregate in which said one light-transmitting film is not positioned, in said aggregate, Δn(x)=Δn max [(Ax 2 +Bx sin θ)/2π+C] is approximately satisfied, where θ is an incident angle of the incident light, Δn max is a maximum value of a difference between a refractive index of said aggregate and a refractive index of a light-incoming side medium, and A, B and C are predetermined constants, and where Δn(x) is a difference between the refractive index of said aggregate and the refractive index of the light-incoming side medium, the difference depending on a distance x in an in-plane direction in said aggregate, and Δn max L=λ is approximately satisfied where L is a thickness of said aggregate and λ is a wavelength of the incident light.