| 摘要 |
<p>An object of the invention is to improve the quality of a servo signal and a reproduction signal. Shape-wise thicknesses tr1, tr2, .multidot., and trN of a cover layer and first through (N-1)-th intermediate layers of an optical recording medium having refractive indexes nr1, nr2, .multidot., and nrN are converted into thicknesses t1, t2, .multidot., and tN of the respective layers having a predetermined refractive index "no" which makes a divergent amount equal to a divergent amount of a light beam resulting from the thicknesses tr1, tr2, .multidot., and trN, 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 1 µm or more (where i, j, k, and m are each any positive integer satisfying i.ltorsim.j < k.ltorsim.m.ltorsim.N), and the thicknesses t1, t2, .multidot., and tN are calculated by products of a function f(n) expressed by the following formula (1), and the thicknesses tr1, tr2, .multidot., and trN: f(n)=-1.088n3+6.1027n2-12.042n+9.1007 ...(1) in the formula (1), n=r1, nr2, .multidot., and nrN.</p> |
