Patent ID: 8081544

Claim:
A method for deciding a spherical aberration compensation (SAC) value for an optical storage medium comprising at least one recoding layer and a cover layer, the SAC value being suitable for a selected recording layer among the at least one recording layer, the method comprising the steps of: (a) performing at least one focus search on the optical storage medium to derive at least one focus error (FE) signal in response to at least one testing SAC value, the FE signal comprising a plurality of s-curves, each of the s-curves corresponding to one of the at least one recording layer and the cover layer respectively; (b) calculating a center basis corresponding to the testing SAC value according to the FE signal; (c) calculating a center level corresponding to the testing SAC value according to the s- curve corresponding to the selected recording layer; and (d) deciding the SAC value according to the center level, the center basis, and the testing SAC value.