OPTICAL INFORMATION REPRODUCING METHOD AND DEVICE THEREFOR

PROBLEM TO BE SOLVED: To prevent crosstalk from adjacent ID from rapidly increasing even when a focus is offset when an optical system has aberration by detecting reflected light corresponding to a mark column showing sector information and reproducing based on a detected signal with a largest signal amplitude corresponding to the mark of a plurality of the detected signals. SOLUTION: From reproduced signals A 109, B 110 outputted by photo- detectors A 107, B 108, a summed signal 113 is produced by an adder 111, and a differential signal 114 is produced by a subtracter 112. Next, an envelope signal 116 of the differential signal 114 is produced through a band-pass filter 115, and the envelope signal 116 is binarized by a gate generation circuit 117 to produce ID gates A 118, B 119. A multiplexer 120 selects one of the reproduced signals A 108, B 109, and the summed signal 113 according to ID gates A 118, B 119 and outputs a reproduced signal 121 to a logical processing circuit 124. Thus, precise ID detection becomes possible.