Optical pickup apparatus for performing multi-focusing

Abstract

An optical pickup apparatus for performing multi-focusing on two disks having different thicknesses by using a beam separating unit to simultaneously read out data of the two disks. The apparatus includes a laser emitting unit for radiating a linearly-polarized laser beam, a diffraction grating for forcing the beam radiated from the laser emitting unit to a main beam and two sub-beams, a collimator lens for changing the beams having passing through the diffraction grating into parallel beams, a first beam separating unit for transmitting and reflecting the parallel beams passed through the collimator lens to separate the parallel beams into two beams, an objective lens for focusing the beams separated via the first beam separating unit, a second polarized beam splitter for separating the beams focused by the objective lens to be reflected from the surface of a disk and separated again by the first beam separating unit, a sensor lens for sensing to radiate the beams separated by the second polarized beam splitter, and photodetector for providing a control signal to enable the reproduction of information of the disk by the beams radiated after passing through the sensor lens.

Dependencies are inferred from the claim text.