Compatible optical pickup

Abstract

An optical pickup compatible between a digital video disc read only memory (DVD-ROM) and a compact disc rewritable (CD-RW), which is a member of the CD family media. The compatible optical pickup includes: a first light source for emitting a first light having a predetermined wavelength; a second light source for emitting a second light having a long wavelength relative to the first light; an optical path changing unit for changing the traveling path of an incident light; an objective lens for condensing the first and second lights onto optical discs having different thicknesses, respectively; and a main photodetector for detecting an information signal and error signals from the first and second lights which have been reflected by the optical discs and passed through the optical path changing unit. The optical path changing unit includes a planar first beam splitter disposed on the optical path between the first light source and the objective lens, for changing the traveling path of the first light from the first light source, and a planar second beam splitter disposed on the optical path between the first beam splitter and the objective lens, for changing the optical paths of the first and second lights. The main photodetector comprises a first photodetector having four divided regions, a second photodetector having two divided regions, and a third photodetector having two divided regions, the second and third photodetectors being disposed at both sides of the first photodetector.