OPTIC HEAD

摘要

PURPOSE: An optical head is provided to perform a focus error detection and a tracking error detection in one optical system. CONSTITUTION: A laser beam is generated from a chip(100) of a laser diode. The laser beam penetrates a protect glass(300) for being reflected by a beam splitter(500). The reflected beam passes through a protect plate(700) by an object lens(600) for being concentrated on a recording surface(720) of media(700). The beam is reflected for being inputted to the beam splitter by passing through the protect substrate and the object lens. A portion of the beam is focused on a quadrant photo-detector(130). The other portion of the beam progresses toward a cutting mirror(800) for reaching a total reflection film(820). Then, the beam is focused on the quadrant photo-detector by passing through the beam splitter. Moreover, another portion of beam is absorbed in a total absorb film(830). The beam passes a substrate(510) of the beam splitter for two times to compensate aberration by using the substrate with a specific thickness.