Patent ID: 8531770
Filing Date: 2013-09-10
Classification: G02B

Abstract:
1. A diffractive optical element, comprising: a first optical member including a first diffraction grating having a sawtooth cross section; and a second optical member which includes a second diffraction grating having an inverted shape of the first diffraction grating and which has a refractive index different from that of the first optical member, wherein the first and second optical members are stacked in a state in which the first and second diffraction gratings closely contact each other, and a diffraction surface of the first diffraction grating satisfies the following expression (1): where “Ra_a” represents arithmetical mean roughness (μm) of the diffraction surface, “Δn “Ra_s” represents arithmetical mean roughness (μm) of a surface causing the largest scattering among light entering surfaces other than the diffraction surface in the diffractive optical element, and “Δn