Patent ID: 7023630

Claim:
An optical element comprising: a base member; and a resin layer which is formed on the base member and has a linear expansion coefficient different from a linear expansion coefficient of the base member, wherein the resin layer has a minute periodic structure which has a period smaller than a wavelength of incident light on the optical element, wherein the resin layer has an aspherical surface on which the minute periodic structure is formed, and wherein the following condition is satisfied: 20°<θ<90°, where, when R represents an approximate radius of curvature of the aspherical surface in the resin layer, θ represents an angle between effective maximum peripheral portions of the optical element, which is viewed from a center of the approximate radius of curvature R, and the approximate radius of curvature refers to a radius of curvature of a circle defined by a center of the aspherical surface and the effective maximum peripheral portions.