| 摘要 |
PROBLEM TO BE SOLVED: To make the recording density of an optical disk higher by narrowing a track pitch in the manner of cancelling the crosstalk from adjacent tracks. SOLUTION: The detection is executed by making eight light receiving areas to four areas with the use of the optical disk arranging the unrecording areas on every other two tracks, in such a manner that the crosstalks of the inner/ outer circumferences are discriminated thereby the polarities of the crosstalks are changed over and aλ/2 plate 18 is inserted only to the one side area divided by the diameter of a luminous flux in the radial direction. A differential signal of the recorded track and a differential signal of the crosstalk of the adjacent tracks are simultaneously detected, and the subtraction is made for differential signals for each other.
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