| 摘要 |
<p>An optical disc apparatus for recording, reproducing, or erasing an information signal by converging a light flux onto a recording layer through a transparent substrate comprises: an optical head (30) having a plurality of objective lenses (36, 46) whose aberrations have respectively been corrected for a plurality of disc substrates of different thicknesses; and means (8, 9) for discriminating the thickness of the disc substrate. In accordance with the result of the discrimination of the thickness of the disc substrate of the loaded optical disc (1), the objective lens in which the occurrence of the aberration is smallest is used, so that the information signal can preferably be recorded, reproduced, or erased onto/from the optical discs (1) having different substrate thicknesses. <IMAGE></p> |
