Patent ID: 7519979

Claim:
An optical head comprising: a laser light source emitting a flux of light; an objective lens, the flux of light from the laser light source to an optical disk passing through the objective lens; a lens holder holding an aberration correction lens in a space between the laser light source and the objective lens; a drive shaft disposed to extend in a direction parallel to an optical axis of the flux of light, the drive shaft guiding the lens holder in the extended direction; a piezoelectric element provided at an end portion of the drive shaft, the piezoelectric element being capable of extending and contracting in a drive shaft direction in response to an applied voltage; a base including a bottom portion, and a pair of supporting portions provided to stand on the bottom portion while being spaced apart in a direction of the optical axis, each of the supporting portions having a through hole in which the drive shaft is inserted; and a position detection portion detecting a position of the aberration correction lens in the drive shaft direction, the position detection portion including a magnetic field generation portion and a magnetic field detection portion disposed to be allowed to undergo displacement with respect to the magnetic field generation portion in the direction of the optical axis, one of the magnetic field generation portion and the magnetic field detection portion being arranged on the base and the other of the magnetic field generation portion and the magnetic field detection portion being arranged on the lens holder, wherein the lens holder is movable relatively with respect to the drive shaft in the drive shaft direction by varying a change rate when the applied voltage to the piezoelectric element is increased and decreased.