| 摘要 |
Diffractive optical elements (DOEs) consisting of a sandwich of two materials are described with an interfacial surface whose relief height impresses the desired optical phase. The two materials have nearly matched indices of refraction, so the interfacial surface has a profile that varies by many wavelengths and is easily fabricated. The materials are chosen such that the refractive index difference and dispersion obey a matching condition that renders the optical path difference (OPD) across the element constant across a broad band of wavelengths. This achromatizes the DOE in that the diffraction efficiency is independent of wavelength. This achromatic property and the fabrication ease allowed by the nearly index matched (NIM) materials enables hybrid refractive-diffractive elements to be fabricated by molding processes for broadband applications.
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