Optical pickup device and optical disk device

Abstract

An optical pickup device or an optical disk device includes: a light sourcethat emits a laser beam toward an optical disk; an optical receiverthat detects light reflected from the optical disk; and an astigmatism-generating elementthat generates light used for focus control in a condition where a focusing position on one of two perpendicular cross sections including an optical axis of the light reflected from the optical diskis located ahead of the optical receiverand a focusing position on the other cross section is located behind the optical receiver. The astigmatism-generating elementis a Fresnel mirrorconfigured to include a plurality of reflecting mirrors, and an imaginary surfacethat connects the tips of the reflecting mirrors is curved in a concave shape toward a light incidence side.