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US 5,633,852 AGranted
Optical data recording and reproducing apparatus including chromatic aberration correction
AssigneeAsahi Kogaku Kogyo Kabushiki Kaisha
InventorsKoichi Maruyama, Junji Kamikubo
Life of this patent
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Abstract
An optical data recording and reproducing apparatus includes a laser source, a collimating lens made of a single lens having a positive power to collimate the divergent laser beams emitted from the laser source, and an objective lens which is to converge the collimated light onto a data recording surface of a data recording medium. The chromatic aberration of the objective lens is corrected to reduce the back focal distance thereof as the wavelength increases to cancel the chromatic aberration of the collimating lens.
Claims6
An optical data recording and reproducing apparatus, comprising;
- a laser source;
- a collimating lens having a positive power to collimate divergent laser beams emitted from said laser source;
- and
- an objective lens adapted to converge the beams collimated by said collimating lens onto a data recording surface of a data recording medium;
- wherein,
- said collimating lens is a single lens;
- and
- said objective lens is provided with an over correction of chromatic aberration to reduce a back focal distance of said objective lens as a wavelength increases to thereby cancel a chromatic aberration of said collimating lens.
5 more elements
Dependencies are inferred from the claim text.