Patent ID: 7489617
Filing Date: 2009-02-10
Classification: G11B

Abstract:
1. An optical head device for use in at least one of recording and reading of information to or from an optical recording medium, comprising: a light source for emitting a light beam; and a prism for converging the light beam from the light source, the prism comprising: a first surface through which the light beam advancing along a first direction enters into the prism, the first direction being parallel to a recording surface of the optical recording medium; a second surface for reflecting the light beam which has entered into the prism through the first surface within the prism; a third surface for reflecting the light beam reflected by the second surface within the prism; and a fourth surface through which the light beam reflected by the third surface is emergent from the prism for at least one of recording and reading of information, wherein, the third surface further converges the light beam and forms a beam spot in the vicinity of the fourth surface, a central beam reflected and converged by the third surface being perpendicular to the fourth surface.