Multi-layer optical recording medium and method and apparatus for reproducing optical data

Abstract

An optical disc having a protection layer for protecting a recording layer located farther from a substrate and having a first recording layer and a second recording layer stacked on one side of the substrate, wherein the reflectance of one of the first and second recording layers is made higher than the reflectance of the other recording layer, and a reproducing device which uses this optical disc. The reproducing device casts a light beam emitted from a single light source onto the first recording layer or the second recording layer via a single objective lens, discriminates which of the first recording layer and the second recording layer the light beam emitted from the light source is cast on, on the basis of the result of detection of a reflected beam from the first recording layer or the second recording layer, moves the objective lens in a direction parallel to the optical axis of the objective lens on the basis of the result of discrimination, and condenses the light beam on the first recording layer or the second recording layer so as to carry out reproduction of information.