| 摘要 |
An optical pick-up is provided to remove interlayer noise in a multi-layer disk and to remove influence of a dead zone by diffracting some of the projected beams through first and second diffraction devices. An optical pick-up comprises a light source(110), an objective lens(170), a beam splitter(130), first and second diffraction devices, a sensor lens(180), and a beam detecting unit(190). The first diffraction device generates the second beam from the beam reflected from a beam storage medium. The beam detecting unit includes a first detecting unit for receiving the first beam, and two sub detecting units for receiving the second beam. The second diffraction device diffracts some of the beam reflected by another layer to prevent the beam from entering the beam detecting unit. The first and second diffraction devices include first and second areas for diffracting some of the projected beam.
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