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US 2010/0135143 A1Published application
Optical system, optical pickup apparatus, and optical disc apparatus for extracting signal beams
AssigneeRicoh Company, Ltd.
InventorTetsuya Ogata
Life of this patent
Estimating the term…
Abstract
An optical system for efficiently extracting plural signal beams from a bundle of rays reflected from a multilayer optical disc.
Claims17
An optical system for extracting a plurality of signal beams from a bundle of rays reflected from a multilayer optical disc, the reflected bundle of rays including the plural signal beams and a plurality of stray beams, the optical system comprising:
- a polarizer situated on an optical path of the reflected bundle of rays for splitting the reflected bundle of rays;
- a condensing optical element situated in front or in back of the polarizer for condensing the reflected bundle of rays;
- a first polarization converting optical element situated between a first imaginary plane and a second imaginary plane, the first imaginary plane including condensing areas at which the plural signal beams are condensed by the condensing optical element, the second imaginary plane including condensing areas at which the plural stray beams are condensed by the condensing optical element, the first polarization converting optical element having a plurality of divided areas for dividing the plural signal beams and the plural stray beams into two bundle of rays and converting polarization of the divided bundle of rays so that one of the divided bundle of rays has a polarization different from the other divided bundle of rays;
- a second polarization converting optical element situated between the first imaginary plane and a third imaginary plane located farther from the condensing optical element than the first imaginary plane, the third imaginary plane including condensing areas at which the plural stray beams are condensed, the second polarization converting optical element having a plurality of divided areas facing the plural divided areas of the first polarization converting optical element for converting the polarization of the plural signal beams and the plural stray beams transmitted through the first polarization converting optical element so that the plural signal beams has a polarization different from the plural stray beams;
- and
- an analyzer for extracting the plural signal beams from the reflected bundle of rays transmitted through the second polarization converting optical element based on the difference of polarization.
3 more elements
An optical system for extracting a plurality of signal beams from a bundle of rays reflected from a multilayer optical disc, the reflected bundle of rays including the plural signal beams and a plurality of stray beams, the optical system comprising:
- a polarizer situated on an optical path of the reflected bundle of rays for splitting the reflected bundle of rays;
- a condensing optical element situated in front or in back of the polarizer for condensing the reflected bundle of rays;
- a polarization converting optical element situated between a first imaginary plane and a second imaginary plane, the first imaginary plane including condensing areas at which the plural signal beams are condensed by the condensing optical element, the second imaginary plane including condensing areas at which the plural stray beams are condensed by the condensing optical element, the polarization converting optical element having a plurality of divided areas for dividing the plural signal beams and the plural stray beams into two bundle of rays and converting polarization of the divided bundle of rays so that one of the divided bundle of rays has a polarization different from the other divided bundle of rays;
- and
- a reflecting member situated on the first imaginary plane for reflecting the reflected bundle of rays transmitted through the polarization converting optical element to the polarization converting optical element;
- wherein the reflected bundle of rays reflected from the reflecting member are incident on the polarizer and has the plural signal beams extracted therefrom based on the difference of polarization by the polarizer.
3 more elements
17-19. (canceled)
Dependencies are inferred from the claim text.