| 摘要 |
Spherical aberration, astigmatism and coma can be corrected by a single liquid-crystal optical element, the electrode patterns in the optical element can be simplified, and the optical element can be controlled in a simple manner. The present invention provides an optical pickup including a light source to emit a light beam of a predetermined wavelength, an objective lens to focus the light beam emitted from the light source onto the signal recording surface of an optical disk, a liquid-crystal optical element provided between the light source and objective lens to correct spherical aberration, astigmatism and coma by varying the refractive index thereof, and a photodetector to detect return light from the signal recording surface of the optical disk. The liquid-crystal optical element has a pair of electrodes disposed opposite to each other in the optical-axial direction, and the liquid-crystal optical element has a pattern to correct spherical aberration, pattern to correct astigmatism and a pattern to correct coma, and the patterns are disposed dispersedly on the pair of electrodes to divide the electrode pair into a plurality of zones, and the plurality of zones resulted from division of the electrode pair by the patterns are used in combination to correct the spherical aberration, astigmatism and coma.
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