OPTICAL PICKUP HEAD DEVICE AND INFORMATION RECORDING/REPRODUCING DEVICE

摘要

PROBLEM TO BE SOLVED: To detect a tracking error signal of limited offset even when a recordable optical storage medium having two information recording surfaces is used.

SOLUTION: A diffraction means receives a beam emitted from a light source to generate a plurality of 0-order and primary or more diffracted lights. A converging means receives a plurality of beams from the diffraction means to converge them on an optical storage medium. A branch means receives the plurality of beams reflected on the storage medium to branch them. A light detecting means receives the plurality of beams to output signals according to the received light quantity. The diffraction means is provided with grating patterns different in center parts and both sides. The directions and the cycles of the grating patterns disposed on both sides of the center are similar, but phases are different.

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