Patent ID: 7864638

Claim:
An optical disk apparatus capable of reading data from an optical disk which has a plurality of information recording layers, including a first information recording layer whose distance from a disk surface is relatively small and a second information recording layer whose distance from the disk surface is relatively large, comprising: a light source for radiating a light beam; a lens for converging the light beam radiated from the light source; focus control means for causing a converging point of the light beam to be positioned on an arbitrary information recording layer of the optical disk; tracking control means for causing the converging point of the light beam to be positioned on a predetermined track of the information recording layer; and gain setting means capable of changing gain characteristics of at least one of the focus control means and the tracking control means, wherein, the gain setting means prescribes a first gain crossover frequency when reading data from the first information recording layer to be a value which is lower than a second gain crossover frequency when reading data from the second information recording layer; and a depth of the first information layer from the disk surface is between 50 Î¼M and 100 Î¼m.