| 摘要 |
A multiple-layer optical information recording medium is provided. An information recording layer that is the farthest from the reading side is denoted by L 0, L 1, L 2, . . . and L 5 information recording layers are successively formed in the direction of the optical axis. Five spacers having thicknesses t<SUB>0 </SUB>to t<SUB>4 </SUB>are interposed between the information recording layers. The spacers satisfy the relationships [Deltat<SUB>m</SUB>>A<SUB>CCT</SUB>xR<SUB>m+1</SUB>xR<SUB>m+2</SUB>xT<SUB>m+1</SUB><SUP>2</SUP>xnlambda/(2NA<SUP>2</SUP>)] and [Deltat<SUB>m-sum</SUB>>A<SUB>CCT</SUB>xR<SUB>m+a</SUB>xR<SUB>m+b</SUB>xT<SUB>ab</SUB><SUP>2</SUP>xnlambda/(2NA<SUP>2</SUP>)]. The thicknesses of the spacers of the six-layer disc satisfy the relationship t<SUB>1</SUB>>t<SUB>3</SUB>>t<SUB>0</SUB>>t<SUB>2</SUB>>t<SUB>4</SUB>. In addition, the thicknesses of the spacers are properly designated so that the influence of multiple reflections is removed.
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