| 摘要 |
PURPOSE: An optical pickup device is provided to decenter a sensor lens interposed between a half mirror and a photo diode from an optical center axis, and to compensate for a coma in accordance with an optical aberration caused from the half mirror, thereby forming a symmetrical beam. CONSTITUTION: A CL(Collimator Lens)(109) progresses a beam passing through a prism(107) in parallel. An objective lens(110) condenses the optical beam that transmits the CL(109) into one point on a surface of a CD(112) or a DVD(111). When the beam reflected from the CD(112) or the DVD(111) is incident through the objective lens(110), the CL(109), the prism(107), and a half mirror(106), a sensor lens(115) decenters the beam from an optical center axis in order to compensate for an optical aberration. A PD(Photo Diode)(113) converts the compensated beam into an electrical signal. An MPD(Monitor PD)(108) detects the transmitted/reflected beam, and uses the beam as a monitor signal. |
