Optical element and optical pickup device used therewith

摘要

An optical element for reflecting light has a substrate and a thin film formed on the substrate. The thin film reflects light in a predetermined reflection wavelength band so that the thin film adjusts a difference in phase differences between a P-polarized light component and S-polarized light component of an incident light to the thin film and between P-polarized light component and S-polarized light component of the reflected light to 180°±10° at an absolute value.