Importance

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Abstract

An optical disc device includes: a diffraction element receiving as input reflected light from an optical disc recording medium, including a first diffraction area formed in a position where light in the center portion of incident light flux is diffracted, a second diffraction area formed so as to be in contact with an outer edge of the first diffraction area, and a third diffraction area formed so as to be in contact with an outer edge of the second diffraction area; and a light receiving/signal generating unit which generates a focus error signal and a lens error signal based on light diffracted at the third diffraction area; with the light receiving/signal generating unit receiving light diffracted at the second diffraction area, and generating the focus error signal based on the received light signal thereof and a received light signal obtained by receiving light diffracted at the third diffraction area.

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First Claim