OPTICAL PICK-UP USING OPTICAL PHASE PLATE

PURPOSE: An optical pickup using an optical phase plate is provided to be flexibly used for both DVD(Digital Video Disk) and CD-R(Compact Disk-Recordable) by eliminating a spherical aberration with a phase plate. CONSTITUTION: Plural LDs(Laser Diodes,31,40) emit first laser beams having relatively short waves and second laser beams having relatively long waves respectively. An objective lens(37) has a predetermined focal length for meeting the focus of the objective lens by the first laser beams with the data recording face of a first optical disk. Both beam splitters(32,33) reflects the laser beams of the LDs toward the objective lens and the laser beams of the objective lens toward a photodetector(39). A phase plate(36) reduces the size of beams spot on the recording face of a second optical disk through phase shift of the second laser beams emitted to the objective lens. An optical pickup is flexibly used for both DVD(8) and CD-R(9) with a single objective lens by using a phase plate.