Optical system for optical pickup employing coma compensating element
AssigneeHitachi, Ltd.
InventorsShuichi Takeuchi, Koichi Maruyama, Takeshi Shimano
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Abstract
A coma compensating element has two refraction surfaces. The refraction surfaces provide, as a whole, no aberration with respect to rays perpendicularly incident thereon, while the refraction surfaces provide coma with respect to rays obliquely incident thereon.
Claims10
A coma compensating element having two refraction surfaces, the refraction surfaces providing no aberrations with respect to rays incident thereon perpendicularly, the refraction surfaces providing coma with respect to rays incident obliquely thereon, the coma provided by the two refraction surfaces being the same quantity in opposite directions.
An optical system for a optical pickup, comprising:
- a light source that emits a light beam;
- an objective lens that converges the light beam emitted by said light source on a data recording surface of an optical disc;
- at least one coma compensating element having two refraction surfaces, the refraction surfaces providing no aberrations with respect to rays perpendicularly incident thereon, the refraction surfaces providing coma with respect to rays obliquely incident thereon, the coma provided by the two refraction surfaces being the same quantity in opposite directions.
Dependencies are inferred from the claim text.