Patent ID: 7522485

Claim:
An optical disc device that performs recording and reproduction with a focusing lens applying a light beam to an information surface of an information medium that has been surface coated with a light transmitting layer, comprising: a storage unit operable to store information of a drive value which makes spherical aberration that can occur due to the light transmitting layer become zero; a spherical aberration correction unit having a spherical aberration correction element and operable to pre-correct spherical aberration occurring in the light beam by driving the spherical aberration correction element based on the drive value information; a focus detection unit operable to detect a focus error signal corresponding to the focal state of the light beam on the information medium; a focus error signal gain adjustment unit operable to adjust a gain of the focus error signal and output the focus error signal the gain of which has been adjusted as an adjusted focus error signal; a total optical quantity detection unit operable to detect an AS signal corresponding to the total quantity of light from an optical disc; an automatic amplitude control unit operable to automatically control the amplitude of the adjusted focus error signal based on the AS signal and the adjusted focus error signal, and output the automatically amplitude controlled signal as an AGC focus error signal; a focusing lens drive unit operable to drive the focusing lens; and a control unit operable to set a gain value for gain adjustment by the focus error signal gain adjustment unit and to execute focus control by driving the focusing lens drive unit, wherein, after the spherical aberration correction unit corrects spherical aberration occurring in the light beam, the control unit pulls in focus control by executing gain adjustment of the focus error signal gain adjustment unit so as to keep an amplitude value of the adjusted focus error signal constant irrespective of a reflectivity of the optical disc, and adjusting the amplitude of the focus error signal.