| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical disk reproducing device discriminating unevenness on an optical disk where a recessed type and a projected type recording pits are provided relative to lands on an information recording surface. SOLUTION: A sub-beam 23 of a +1st order diffracted beam being a reproduction beam is emitted so that the beam is off-tracked to the right side of a pit sequence (A). By the diffraction effect of light by the side edge part of the pit, a reflection return beam 34 has the maximum intensity in the direction tilted to the left side (B). On photo-detectors 32e, 32f for detecting it, a beam spot is emitted to a position deviated to the left side relative to its boundary, and a difference signal (e-f) becomes negative. Since the (e-f) becomes positive inversely in the case of the projected type recording pit, the unevenness is discriminated by the polarity of the difference signal.
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