| 摘要 |
An optical pickup apparatus is provided for recording and/or reproducing information on an optical disc including at least one reference layer and at least one recording layer in which information can be recorded at recording positions each located at a different distance from an optical disc surface. The optical pickup apparatus includes: a light source; a relay lens system for emitting a converged light flux; an objective lens arranged at a predetermined distance from the reference layer, for converging the converged light flux onto one of the recording positions; and a photodetector. The relay lens system changes a convergence angle of the converged light flux to enter the objective lens by moving in a direction of an optical axis thereof so as to select a recording position where information is recorded and/or reproduced. |
