| 摘要 |
An optical recording/reproducing apparatus is arranged so that, upon recording or reproducing a recording medium having a plurality of recording layers, the gap of the lens groups at the time of forming a converged light spot on this first recording layer is DIS( 1 ), the gap of the lens groups at the time of forming the converged light spot on the N-th layer (the farthest layer from the surface of the recording medium) is DIS(N) and the neutral point of the spherical-aberration correcting mechanism is set at a position satisfying the following expression: lens group gap dst( 3 )=((DIS ( 1 )+DIS(N))/2.
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