Close-bonded diffractive optical element, optical material used therefor, resin precursor, and resin precursor composition

摘要

To obtain a close-contact multi-layer type diffractive optical element having a homogeneous high-refractive-index and low-dispersion resin layer, an acrylate-terminated oligomer, obtained by allowing excess bifunctional acrylate to react with bifunctional thiol, is used as a resin precursor for the high-refractive-index and low-dispersion resin layer.