Patent ID: 6831886
Filing Date: 2004-12-14
Classification: G11B

Abstract:
An optical head device comprising:a light source which emits a light beam; and a prism which comprises: a first surface through which a light beam advancing along a first direction enters into the prism; a second surface for reflecting and converging the light beam entered through the first surface, the light beam reflected and converged by the second surface advancing along a second direction different from the first direction; a third surface having an area on or in vicinity of which the light beam reflected and converged by the second surface forms a beam spot; and a light shutter layer, provided on the third surface, having a minuscule opening formed at the area of the third surface, wherein the minuscule opening is smaller than the beam spot, and the light shutter layer except the minuscule opening prevents the light beam from passing through the third surface.