OPTICAL DISK, REPRODUCING HEAD FOR OPTICAL DISK, LIGHT RECEIVING ELEMENT UNIT AND OPTICAL DISK REPRODUCING METHOD

摘要

PROBLEM TO BE SOLVED: To provide a method and a reproducing head independently and simultaneously reproducing plural signal lines on an optical disk for quickening an information reading speed. SOLUTION: This reproducing head is constituted so that when a laser beam for reading a signal on the optical disk 16 is made incident nearly perpendicularly to the signal surface of the rotating optical disk 16 by a reproducing lens 15, a laser beam wavelength and the numerical aperture are selected so as to have plural signal lines in the spot of the laser beam emitted on the signal surface of the optical disk 16, and a reproducing beam reflected from the optical disk 16 is projected onto a light receiving element unit constituted of plural light receiving elements with a size nearly equal to the beam spot, and independently and simultaneously detecting at every signal line.