Patent ID: 7411882
Filing Date: 2008-08-12
Classification: G11B

Abstract:
1. An optical head device comprising a light source, an objective lens for focusing onto an optical recording medium the light which is emitted from said light source and travels on a going path, a photodetector for detecting the light which is reflected from said optical recording medium and travels on a returning path, and a liquid crystal panel for producing wave aberration by which the wave aberration of the light traveling on the going path is canceled, wherein said liquid crystal panel further produces wave aberration by which the wave aberration of the light traveling on the returning path is canceled, further comprising: a polarization beam splitter for separating an optical path extending from said light source to said optical recording medium and an optical path extending from said optical recording medium to said photodetector, and a quarter wavelength plate provided between said polarization beam splitter and said objective lens, wherein said liquid crystal panel comprises a first liquid crystal panel disposed between said light source and said polarization beam splitter or between said polarization beam splitter and said quarter wavelength plate, and a second liquid crystal panel disposed between said polarization beam splitter and said photodetector or between said polarization beam splitter and said quarter wavelength plate.