| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical recording medium that suppresses variations in record sensitivity in three or more recording layers and that allows satisfactory recording even under the same recording power condition. <P>SOLUTION: An optical recording medium has a five-layer structure including five recording layers, namely an L<SB>0</SB>layer 16, an L<SB>1</SB>layer 18, an L<SB>2</SB>layer 20, an L<SB>3</SB>layer 22, and an L<SB>4</SB>layer 24 in this order from a side farthest away from a laser light incident surface. The materials of the respective recording layers are selected so that the rate of change in transmittance Tb/Ta as taken from the laser light incident surface satisfies 0.93<Tb/Ta<1.07 when recording on the L<SB>0</SB>layer 16 among the recording layers, where: Ta is transmittance of laser light to reach the L<SB>0</SB>layer 16 when the L<SB>0</SB>layer 16 is irradiated with the laser light of optimum recording power after recording marks are formed on all the recording layers closer to the laser light incident surface (being the L<SB>1</SB>to L<SB>4</SB>layers); and Tb is transmittance of laser light to reach the L<SB>0</SB>layer 16 when the L<SB>0</SB>layer 16 is irradiated with the laser light of optimum recording power with no recording mark formed on any of the recording layers closer to the laser light incident surface. <P>COPYRIGHT: (C)2008,JPO&INPIT |
