OPTICAL PICKUP UNIT

摘要

PURPOSE: An optical pickup unit is provided to employ a polarized beam splitter as an optical path converter, and to increase optical efficiency by using a 1/4 wavelength plate. CONSTITUTION: The first and the second light sources(10,20) irradiate lights having different wavelength corresponding to the first and the second disks(23,25) having different thickness. A polarized beam splitter(15) transmits or reflects the light irradiated from the first light source according to a polarized state. An optical path converter(16) transmits the light passing through the polarized beam splitter, and converts a path of the light irradiated from the second light source. A 1/4 wavelength plate(17) converts the polarized state of the light passing through the optical path converter. An objective lens(21) focuses the irradiated lights on the first and the second disks. An optical detector(30) detects the lights reflected from the first and the second disks.