摘要 |
An optical pick-up unit is suitable for scanning a first type of record carrier having a first information density and at least a second type of record carrier, the second type of record carrier having a second information density different from the first information density. The optical pick-up unit comprises a first radiation source ( 16, 86 ) for emitting a first diverging radiation beam ( 24 ) for scanning the first type of record carrier, and at least a second radiation source ( 48, 96 ) for emitting a second radiation beam ( 50 ) for scanning the second type of record carrier. The optical pick-up unit also comprises a first beam splitter ( 58, 93, 104 ) for combining the first radiation beam and the second radiation beam on a common optical path. The first beam splitter is a plane-parallel plate-type beam splitter. A correcting element ( 20, 22, 72 ) for astigmatism and coma correction is arranged between the first radiation source and the first beam splitter.
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