Optical head and disk recording and reproducing apparatus

Details Optical head and disk recording and reproducing apparatus Optical head and disk recording and reproducing apparatus

2006-06-13

2006-06-13

Wellington, Andrea (Department: 2652)

Dynamic information storage or retrieval

With servo positioning of transducer assembly over track...

Optical servo system

C369S112230

Reexamination Certificate

active

07061834

ABSTRACT:
An optical head and a disk recording and reproducing apparatus using the same. The optical head can realize a stable recording and reproducing with less cross-talk and can be made small and thin by making the objective lens to be small and thin. The optical head includes an optical system including a light source having astigmatic difference and an objective lens that forms an optical spot on an information recording medium. The optical system has optical properties in that the optical spot has an initial astigmatism on the design optical axis, the direction of the initial astigmatism is a direction in which a back-side line focus is substantially perpendicular to the radial direction of the information recording medium, and astigmatism is generated in the direction in which the initial astigmatism of the optical spot is reduced as the objective lens moves in the direction in which the objective lens is more distant from the design optical axis in the radial direction. The direction of astigmatism of the optical spot formed by the objective lens is a direction in which a back-side line focus is substantially perpendicular to the radial direction in the radial direction movement range of the objective lens.

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