Optical pickup apparatus

Details Optical pickup apparatus Optical pickup apparatus

2011-07-05

2011-07-05

Haley, Joseph (Department: 2627)

Dynamic information storage or retrieval

Specific detail of information handling portion of system

Radiation beam modification of or by storage medium

C369S112030, C369S112040, C369S112050, C369S112070, C369S112230, C369S124030, C369S044370, C369S044380

Reexamination Certificate

active

07974172

ABSTRACT:
An optical-pickup apparatus comprising: a laser-light source; a diffraction grating including first-and-second regions of periodic structures different in phase from each other and a third region whose periodic structure is different in phase from the first-and-second regions; an objective lens focusing main-and-sub-luminous fluxes generated by the diffraction grating on the same optical-disc track; and a photodetector to receive reflected light of the main-and-sub-luminous fluxes from an optical disc and output a detection signal for generating main-and-sub-push-pull signals, a relationship between an incident light width in the objective lens corresponding to the third region and pupil diameters of the objective lens corresponding to first-and-second wavelengths of laser lights being adjusted so that a ratio of minimum value to maximum value of a differential-push-pull-signal is at substantially 50% or more and a ratio of sub-push-pull-signal level to main-push-pull-signal level is at substantially 15% or more, in both cases of the laser lights.

REFERENCES:
patent: 2009/0022032 (2009-01-01), Kawasaki et al.
patent: 2004-145915 (2004-05-01), None
patent: 2007-220175 (2007-08-01), None

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