Dynamic information storage or retrieval – With servo positioning of transducer assembly over track... – Optical servo system
Reexamination Certificate
2005-03-29
2005-03-29
Klimowicz, William (Department: 2652)
Dynamic information storage or retrieval
With servo positioning of transducer assembly over track...
Optical servo system
C369S112070
Reexamination Certificate
active
06873581
ABSTRACT:
The semiconductor laser device includes a signal light diffraction grating, and a light receiving portion having a pair of photodiodes extending as two strips with a parting portion or a zonal gap interposed therebetween and receiving a focus error detecting beam from the signal light diffraction grating. The light receiving portion is arranged such that its longitudinal direction is orthogonal to the direction of diffraction grooves of the signal light diffraction grating. The pair of photodiodes is arranged such that a spot of the focus error detecting beam moves, due to temperature changes, in a range essentially limited to the parting portion therebetween. Thus, a semiconductor laser device and an optical pickup apparatus suppressing focus errors due to temperature changes and preventing reduction in signal strength can be obtained.
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Battaglia Michael V.
Klimowicz William
Morrison & Foerster / LLP
Sharp Kabushiki Kaisha
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