| 摘要 |
An optical head apparatus comprises: a light source for emitting light; a front-end converging optical system for converging the light emitted from the light source onto a multi-layer information storage medium; a back-end converging optical system for reconverging the light reflected from a layer on the multi-layer information storage medium; wavefront converting means for accepting the reconverged light, and for forming an wavefront to enable detection of a focus error signal and/or a tracking error signal; and a photodetector for receiving the light from the wavefront converting means, and for outputting a signal proportional to the amount of the received light. |
