Patent ID: 7864425
Filing Date: 2011-01-04
Classification: C08J,C08K,C08L,C09D,G02B

Abstract:
1. A diffractive optical element comprising: a substrate made of a first material and having a diffraction grating pattern formed on its surface; and a protective film made of a second material and covering the diffraction grating pattern, wherein the first material comprises a first resin; the second material is a composite material that comprises a second resin and first inorganic particles dispersed in the second resin and containing at least zirconium oxide, has a refractive index at the d line n the weight ratio of the first inorganic particles to the composite material as a whole is not less than 50 wt % and not more than 85 wt %; the diffraction grating pattern has a depth of not more than 20 μm; and the diffractive optical element has a first-order diffraction efficiency of not less than 85% at a wavelength of 400 to 700 nm.