OPTICAL PICKUP AND OPTICAL ELEMENT USED THEREFOR

摘要

A diffraction grating pattern is formed on a region other than a desired region provided in a substantially central portion of a double refraction plate, and this diffraction grating pattern comprises ion exchange regions having predetermined width, length and thickness and formed cyclically, and dielectric films formed on the upper surfaces of the ion exchange regions. The thickness of the ion exchange region and the thickness of the dielectric films are set so that ordinary rays of light advancing toward the double refraction plate pass through the diffraction grating pattern with a zero-order diffracted wave of extraordinary rays of light interrupted by the diffraction grating pattern. This enables an optical pickup contributing to the miniaturization of a reproducer and capable of being handled easily, and an optical element used therefor to be provided.