Patent ID: 8154803

Claim:
A diffractive optical element comprising: a substrate; a protective film; and a diffraction grating disposed between the substrate and the protective film; wherein the diffraction grating is formed of a first composite material comprising a first resin and first inorganic particles, a volume ratio of the first inorganic particles with respect to the first composite material is 5% to 50% by volume, the diffraction grating has a thickness of equal to or smaller than 20 μm, the protective film is formed of a material comprising a second resin, one of the diffraction grating and the protective film is formed of a material having a high refractive index and a low dispersion and the other is formed of a material having a low refractive index and a high dispersion, a first-order diffraction efficiency in a wavelength band of 400 to 700 nm is equal to or higher than 80%, and a light transmittance at a wavelength of 400 nm is equal to or higher than 90%.