Patent ID: 8094531
Filing Date: 2012-01-10
Classification: G11B

Abstract:
1. A method of extracting a phase difference between a pair of optical signals among a plurality of input optical signals corresponding to detected light beams, the method comprising: detecting the plurality of input optical signals based on received light beams reflected from an optical disc; repeatedly moving a first graph representing one optical signal from among the pair of optical signals by a predetermined distance with respect to a second graph representing another optical signal from among the pair of optical signals, the first and second graph representing optical signal values with respect to a t-axis; adding differences between optical signal values of the first graph and optical signal values of the second graph corresponding to predetermined positions of the t-axis, the adding differences being repeated for each of the repeatedly moved positions of the first graph; outputting a moved distance of a position where the added value is smallest as a phase difference.