Patent ID: 8040774

Claim:
An optical disk device, comprising: an optical head that has a light source, and a condensing system including a solid immersion lens; a plurality of photoelectric conversion units that convert a reflected light from an information recording/reproducing surface formed on an optical disk and a reflected light of an incident light from the light source side of the solid immersion lens, into electric signals and output the signals; a tilt detection unit that outputs, as a tilt detection signal, a result of computing output signals of each of the plurality of photoelectric conversion units according to a predetermined rule; a tilt control unit that performs tilt control for controlling the tilt of the solid immersion lens with respect to the optical disk, using the tilt detection signal from the tilt detection unit; and a gap adjustment unit that performs gap adjustment for changing a gap between the solid immersion lens and the optical disk, the tilt control unit enabling the tilt control according to the tilt detection signal that is output from the tilt detection unit in a process of adjusting the gap between the solid immersion lens and the optical disk by the gap adjustment unit, wherein: the plurality of photoelectric conversion units include two photoelectric conversion units that convert the reflected light from the information recording/reproducing surface formed on the optical disk and the reflected light of the incident lights from the light source side of the solid immersion lens into electric signals and output the signals, the tilt detection unit outputs a result of subtracting one of the output signals of the two photoelectric conversion units from the other one of the output signals as the tilt detection signal, the gap adjustment unit moves the solid immersion lens closer to the optical disk in the gap adjustment process, and the tilt control unit enables the tilt control according to the tilt detection signal that is output from the tilt detection unit, and the gap adjustment unit moves the solid immersion lens closer to the optical disk in the gap adjustment process, and the tilt control unit enables the tilt control when the absolute value of the tilt detection signal that is output from the tilt detection unit, exceeds a predetermined level.