Optical head, optical information recording/reproducing apparatus, computer, video recording/reproducing apparatus, video reproducing apparatus, server and car navigation system

摘要

An optical head is provided that increases the light utilization efficiency and that can be adapted to high-speed recording and double-layer disks. A beam-shaping lens that shapes an elliptical beam emitted from a light source into a substantially circular beam has a pair of cylindrical surfaces that are curved in the same direction. The cylindrical surface that is closer to the light source is an aspherical surface, and the cylindrical surface that is closer to the light source is a spherical surface. Thus, an optical head is obtained, with which aberrations can be kept low, even when the beam-shaping magnifying power is about a factor 2.