Patent ID: 7916389

Claim:
A polarizer comprising: a translucent substrate; a diffraction grating which is formed on the translucent substrate, which has a plurality of convex portions that are aligned so as to have a frequency which is equal to or less than a wavelength to be used, and wherein each of the plurality of is made from an alternating layer consisting of high-refractive-index layers and low-refractive-index layers; and an intermediate-refractive-index region which is formed so as to have a portion, which, with a top surface thereof being exposed, is entirely buried except for the exposed top surface in said translucent substrate at a position between said convex portions that are adjacent to each other in the diffraction grating, said intermediate-refractive-index region having a refractive index which is higher than a refractive index of said low-refractive-index layer and which is lower than a refractive index of said high-refractive-index layer.