Patent ID: 8130603
Filing Date: 2012-03-06
Classification: G11B

Abstract:
1. An optical disk driving apparatus comprising: an optical head device having a laser light source, a converging optical system converging a light beam emitted by the laser light source onto an optical disk, a photo detector receiving reflected light reflected by the optical disk, and an aberration correcting optical system controlling aberration of the converging optical system; a motor rotating the optical disk; and a control section receiving a signal from the photo detector, wherein the converging optical system has an objective lens formed using resin as a main material, the aberration correcting optical system has a spherical aberration correcting element correcting spherical aberration of the objective lens, the control section evaluates a quality of a reproduction signal for information in the optical disk by using the reflected light received by the photo detector, and utilizes a result of the evaluation to control the spherical aberration correcting element, and for the resin that is the main material of the objective lens, a change rate of a refractive index with respect to a change in temperature ranges from −1.5×10E−4 per degree centigrade to −0.8×10E−4 per degree centigrade.