Patent ID: 8289828
Filing Date: 2012-10-16
Classification: G11B

Abstract:
1. An optical data recording/reproduction apparatus comprising: a laser light source; an objective lens for focusing a light beam emitted from the laser light source on a data recording surface of a data recording medium; a spherical aberration correcting unit located in a light path between the laser light source and the objective lens; an optical pickup with a driving unit for tilting the objective lens; and a controller for the optical pickup, wherein: where SCD denotes coma aberration which occurs at a focused light spot on the data recording surface when the data recording medium is tilted by unit angle and SCO denotes coma aberration which occurs at a focused light spot on the data recording surface when the objective lens is tilted by unit angle, a relation between a cover layer thickness of the data recording surface and ratio α of SCO to SCD (SCO/SCD) is previously calculated and stored in a storage unit; where alpha and where α