| 摘要 |
PROBLEM TO BE SOLVED: To enable one optical head to reproduce or record/reproduce a data of an optical disk in accordance with its kind of recording density by changing a ratio D/W of a diameter W of a collimated light beam to be incident upon an objective lens to an effective diameter D of the objective lens in accordance with high or low recording density of the optical disk. SOLUTION: The collimated light beam transmitted through a beam splitter 4 is splitted by 4-th beam splitter 16, and a splitted collimated light beam reflected in the perpendicular direction is enlarged in diameter via a mirror 17 by a beam diameter converting optical system 18, while the other splitted collimated light beam transmitted in the straight direction is not changed in diameter as it is. The objective lens 5 is moved in accordance with the low recording density optical disk 6 to be recorded/reproduced and the high recording density optical disk 19 to be reproduced, and a vignetting coefft. D/W is changed over to 0.93 and 0.4 respectively. Reproducing data of the high recording density optical disk 19 such as the DVD and recording/reproducing data of the low recording density optical disk 6 such as the M0 can be carried out by the same one optical head in a magneto-optical disk device. |
