PHASE-TYPE DIFFRACTION ELEMENT, MANUFACTURING METHOD THEREOF, AND IMAGE PICKUP APPARATUS

摘要

A phase-type diffraction element comprises a transparent substrate (2) having a front surface and a rear surface, and solid liquid crystal layer (3) which is provided on the front surface of the transparent substrate and is comprised of a continuous layer containing at least a liquid crystal compound. The solid liquid crystal layer is comprised of periodically arranged first areas (3a) and second areas (3b) and third areas (3m) formed between the first and second areas. The first areas are optically anisotropic, the second areas are optically isotropic, and the third areas are not optically isotropic. The degree of orientation of a mesogen of the liquid crystal compound is lower in the third areas than in the first areas. The in-plane mean refractive index ni and the in-plane mean refractive index na of the first areas are different from one another, and the third areas have an in-plane mean refractive index nm between the indices ni and na.