Optical head and optical disk apparatus
AssigneePanasonic Corporation
InventorYuuichi Takahashi
Life of this patent
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Abstract
An optical head comprises first and second light sources which are arranged next to each other and emit lights of different wavelengths and an optical device which is arranged between the first and second light sources and a conversing lens for reducing the spherical aberration caused by combination of the conversing lens and at least one of first and second optical recording media which correspond to at least one of the lights of first and second wavelengths. The optical axis of the optical device is shifted with respect to the optical axis of the conversing lens in order to reduce the coma aberration that is caused since at least one of optical axes of the lights of first and second wavelengths does not coincide with the optical axis of the conversing lens.
Claims16
An optical head for use in an optical disk apparatus which performs recording and/or reproduction of information for first and second optical recording media by using, respectively, light of a first wavelength and light of a second wavelength which is different from the first wavelength, comprising:
- a first light source for emitting light of the first wavelength;
- a second light source for emitting light of the second wavelength which is different from the first wavelength, the second light source being disposed adjacent to the first light source;
- a converging lens for converging the light emitted from the first and second light sources toward the first and second optical recording media;
- and
- an optical device disposed between:
- the first and second light sources;
- and the converging lens, the optical device reducing a spherical aberration which occurs due to a combination of:
- at least one of the light of the first wavelength and light of the second wavelength;
- at least corresponding one of the first;
- and second optical recording media to and the converging lens,
- wherein an optical axis of the optical device is shifted with respect to an optical axis of the converging lens so as to reduce a coma which occurs due to an optical axis of at least one of the light of the first wavelength and light of the second wavelength not coinciding with the optical axis of the converging lens.
A beam spot formation method for forming first and second light beam spots by converging light respectively emitted from adjoining first and second light sources with a single converging lens,
- wherein an optical device for correcting a spherical aberration which occurs in at least one of the first and second light beam spots due to the converging lens and the first and second optical recording media is disposed between:
- the first and second light beam spots;
- and the converging lens, and an optical axis of the optical device is shifted with respect to an optical axis of the converging lens so as to reduce a coma which occurs due to optical axes of the first and second light sources not coinciding with the optical axis of the converging lens.
Dependencies are inferred from the claim text.