Patent ID: 7852718

Claim:
A compensation value setting device comprising: a changing section that sequentially changes a combination of a spherical aberration compensation value and a lens' position compensation value; a first index value calculation section that calculates, each time the combination of the spherical aberration compensation value and the lens' position compensation value is changed by the changing section and a trial process of correcting the spherical aberration and the position of the objective lens is performed, a first index value representing the evaluation of the combination of the spherical aberration compensation value and the lens' position compensation value for the trial process based on a signal acquired as a result of emitting the laser beam to the data recording surface of the optical disc via the objective lens that collects the laser beam; a second index value calculation section that calculates, each time the combination of the spherical aberration compensation value and the lens' position compensation value is changed by the changing section and a trial process of correcting the spherical aberration and the position of the objective lens is performed, a second index value representing the evaluation of the combination of the spherical aberration compensation value and the lens' position compensation value for the trial process based on data generated after a waveform equalization process for the signal; and a setting section that selects, based on the first and second index values calculated by the first and second index value calculation sections for each combination of the spherical aberration compensation value and the lens' position compensation value, one combination of the spherical aberration compensation value and the lens' position compensation value and then sets the selected combination for correcting the spherical aberration and the position of the objective lens.