Optical head with reduced aberration

Abstract

An optical head device for recording and/or reproducing information by using an optical recording medium includes a light source, an objective lens, a photo detector, an optical system including a collimator lens, a beam splitter, a convergent lens and a cylindrical lens, a housing for accommodating the light source, the photo detector and the optical system, and an optical glass plate for reducing aberration of the optical system and the objective lens. A light beam from the light source is turned to a parallel beam flux by the collimator lens to irradiate the objective lens, which provided drivably converges the parallel beam flux on the optical recording medium. The light beam reflected from the optical recording medium passes through the objective lens and reflected by the beam splitter in the optical system toward the photo detector. The light beam reflected by the beam splitter is converged on the photo detector by the convergent lens and the cylindrical lens. The characteristic of the present invention is that the optical glass plate for reducing the aberration seals the housing to protect the light source and the optical system from dust. The optical glass plate is set rotated about the axis of the parallel beam flux to a position reducing the aberration of the optical system and of the objective lens.