| 摘要 |
Shape-wise thicknesses of a cover layer and first through (N−1)th intermediate layers of an optical recording medium having refractive indexes nr1, nr2 are converted into thicknesses t1, t2 of the respective layers having a predetermined refractive index which makes a divergent amount equal to a divergent amount of a light beam resulting from the thicknesses tr1, tr2, a difference DFF between the sum of a thickness“ti”through a thickness“tj”, and the sum of a thickness“tk”through a thickness“tm”is set to 1μm or more (where i, j, k, and m are each any positive integer satisfying i≰j<k≰m≰N), and the thicknesses t1, t2 are calculated by products of a function f(n) expressed by the following formula (1), and the thicknesses tr1, tr2: f(n)=−1.088n3+6.1027n2−12.042n+9.1007 (1) in the formula (1), n=nr1, nr2, . . . , and nrN.
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