OPTICAL DETECTOR, OPTICAL PICKUP AND OPTICAL INFORMATION REPRODUCING APPARATUS USING OPTICAL PICKUP

摘要

PURPOSE: An optical detector, an optical pickup, and an optical disc drive using an optical pickup capable of recording/reproducing an information signal in/from a plurality type of optical discs are provided in a manner that the structure of an optical system is simpler than that of a conventional optical system. CONSTITUTION: The optical system constitution of the optical pickup consisting of the semiconductor laser having two laser beam sources of different wavelengths within one casing, one diffraction grating and one optical detector is adopted to a means to dissolve this theme. The optical pickup is provided with light receiving regions quadrisected to plurality of shapes, each of which is a square with a cross inside, in the positions irradiated with the light beam reflected from the optical disk and simultaneously, the focus error signals by an astigmatism system are formed respectively independently from these light receiving regions and the tracking error signals by a differential phase detection system are formed from one or both of the light receiving regions.