Patent ID: 8270265

Claim:
An optical pickup device, comprising: a light source which emits a laser beam toward an optical disk; an optical receiver which detects light reflected from the optical disk; and an astigmatism-generating element which generates light used for focus control in a condition that a focusing position on one of two perpendicular cross sections including an optical axis of the light reflected from the optical disk is located ahead of the optical receiver and a focusing position on the other cross section is located behind the optical receiver; wherein the astigmatism-generating element is a Fresnel mirror configured to have a plurality of orbicular band shaped reflecting mirrors, and an imaginary surface that connects tips of the orbicular band shaped reflecting mirrors is curved in a concave shape toward a light incidence side, the light source emits laser beams with two wavelengths from adjacent positions, and the laser beam with one of the wavelengths is emitted toward a DVD and the laser beam with the other wavelength is emitted toward a CD, and a level difference of the orbicular band shaped adjacent reflecting mirrors in a central portion of the Fresnel mirror has a depth almost equal to a half wavelength of reflected light from the CD.