| 摘要 |
In an optical head, a polarized laser beam is converged by an objective lens onto a magnetooptical disk to which a magnetic field is applied by a magnet unit in recording or erasing mode. The laser beam reflected from the disk is reflected by a half prism, passes through a half wave plate, and is applied to a polarizing beam splitter. The laser beam is splitted into first and second laser beams, which are applied to first and second photodetectors having a same structure, through cylindrical lenses. The detection signals output from the photodetectors are processed into a focusing error signal. The objective lens is moved along its optical axis by a voice coil driver in response to the focusing error signal.
|
