| 摘要 |
<P>PROBLEM TO BE SOLVED: To suppress a decrease in SNR of a reproduction signal in the case that a recording system which forms a recording mark three-dimensionally having some extent especially like a void recording system is employed as a bulk recording system. <P>SOLUTION: When an optical recording medium is reproduced which includes a bulk-like recording layer and also has a mark recorded by focusing laser light on a predetermined position in the recording layer, information recorded with the mark is reproduced in a state in which a focusing position of first laser light emitted so as to reproduce the information recorded with the mark is shifted by a certain quantity from the focusing position of the laser light when the mark at the layer position to be reproduced is recorded. Consequently, the focusing position of the first laser light in the reproduction can be at the position shifting by the certain quantity toward an upper layer side from the focusing position of the laser light when the mark at the layer position to be reproduced is recorded, and consequently defocusing (ΔF) in the reproduction is suppressed to effectively suppress the decrease in SNR. <P>COPYRIGHT: (C)2012,JPO&INPIT |
