Patent ID: 8526292

Claim:
A manufacturing method for an optical recording medium having N (where N is a positive integer of 3 or more) information recording surfaces, actual thicknesses of a cover layer and first through (N−1)-th intermediate layers of the optical recording medium being respectively tr 1 , . . . , trj, . . . , and trN in an order from a surface of the optical recording medium where light is incident, at least one layer out of the cover layer and the first through (N−1)-th intermediate layers including k layers, actual thicknesses of the k layers being respectively dj 1 , dj 2 , . . . , and dj k , and refractive indexes of thickness portions of the k layers being respectively, nrj 1 , nrj 2 , . . . , and nrjk, and 1≦j≦N, the manufacturing method comprising: defining, a thickness tj by the following formula: tj=ΣdjM×f ( nrjM ) where Σ represents an integration from 1 through k with respect to “M”; and setting the thickness tj to 10 μm or more, a function f(n) is expressed by the following formula (1): f ( n )=−1.088 n 3 +6.1027 n 2 −12.042 n +9.1007 (1) in the formula (1), n=nr 1 , . . . , nrM, . . . , and nrk, wherein the manufacturing method produces the optical recording medium with layers having thicknesses that prevent light from forming an image on a backside of a surface of the optical recording medium, suppress coherence between reflected light from the information recording surfaces, and improve the quality of a servo signal and a reproduction signal.