| 摘要 |
An information reading and recording apparatus includes a super-resolution cut-off filter having an annular metal reflection film at its center portion and disposed immediately before one of two objective lenses with a higher NA. When reading DVD, the one objective lens with a higher NA with the super-resolution cut-off filter disposed therebefore is positioned at the optical path. When reading CD, the other objective lens with a lower NA is positioned at the optical path. The laser beam reflected by a disk follows backward the incoming optical path to pass through a half mirror, and is received by a photo-detector to be converted into an electrical signal.
|
