Diffractive optical element, objective optical system including the same, and optical pickup including the same
AssigneePanasonic Corporation
InventorsYasuhiro Tanaka, Michihiro Yamagata, Katsuhiko Hayashi
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Abstract
A diffractive optical element includes a first optical part and a second optical part bonded to each other with a bonded surface therebetween configured as a diffraction surface. In this diffractive optical element, the diffraction order of diffracted light with the largest quantity of light out of diffracted light for one of a plurality of kinds of laser beams obtained on the diffraction surface is different from the diffraction order for at least another laser beam.
Claims6
A diffractive optical element, comprising:
- a first optical part and a second optical part bonded to each other with a bonded surface therebetween formed as a diffraction surface for diffracting a plurality of kinds of laser beams of different wavelengths on said diffraction surface,
- wherein diffracted light with the largest quantity of light out of diffracted light for a laser beam of the smallest wavelength obtained on said diffraction surface of said diffractive optical element has a second or higher diffraction order.
An objective optical system for focusing each of a plurality of kinds of laser beams of different wavelengths on an information recording surface of an optical information recording medium, the objective optical system comprising:
- a diffractive optical element including a first optical part and a second optical part bonded to each other with a bonded surface therebetween formed as a diffraction surface for diffracting said plurality of kinds of laser beams on said diffraction surface,
- wherein diffracted light with the largest quantity of light out of diffracted light for a laser beam of the smallest wavelength obtained on said diffraction surface of said diffractive optical element has a second or higher diffraction order.
An optical pickup for focusing a laser beam on an information recording surface of an optical information recording medium, the optical pickup comprising:
- a light source for emitting a plurality of kinds of laser beams of different wavelengths;
- and
- an objective optical system for focusing each of said plurality of kinds of laser beams emitted from said light source onto said information recording surface,
- wherein said objective optical system comprises a diffractive optical element including a first optical part and a second optical part bonded to each other with a bonded surface therebetween formed as a diffraction surface for diffracting each of said plurality of kinds of laser beams emitted from said light source on said diffraction surface, and
- diffracted light with the largest quantity of light out of diffracted light for a laser beam of the smallest wavelength obtained on said diffraction surface of said diffractive optical element has a second or higher diffraction order.
Dependencies are inferred from the claim text.