| 摘要 |
Optical pick-up apparatus for retrieving data stored on an optical storage disc having a plurality of record layers (6, 7), the radiation beam reflected back from the disc when a first layer (7) is irradiated comprising radiation reflected back from the first layer (7) and radiation reflected back from one or more of the other layers(6). A spatial filter (8) is provided which is arranged and configured to spatially filter the radiation beam so as to cause the radiation reflected by the first record layer (7) and the radiation reflected by any of the other record layers (6) of the optical storage disc to be spatially separated, such that at least a substantial portion of the radiation reflected back from the other layers (6) can be selectively eliminated from the radiation beam prior to retrieval therefrom of the data.
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