Patent ID: 8854939
Filing Date: 2014-10-07
Classification: G11B

Abstract:
1. An optical information apparatus that records and/or reproduces information using an information recording medium, comprising: a light source that outputs light; an optical system that forms a predetermined sized beam spot on the information recording medium using the light from the light source; a power detection unit that detects output power of the light source and generates a power detection signal; a power control unit that controls the output power of the light source using the power detection signal; a gap detection unit that detects a gap length between the information recording medium and the optical system, and generates a gap detection signal; a correction unit that generates a corrected gap detection signal by removing, from the gap detection signal, a fluctuation component which is not due to fluctuation of the gap between the information recording medium and the optical system; and a gap control unit that controls the gap length between the information recording medium and the optical system using the corrected gap detection signal, wherein the power control unit has a gain crossover frequency greater than a gain crossover frequency of the gap control unit, and the correction unit includes: a filter unit that extracts a fluctuation component of the output power of the light source from the power detection signal; and a fluctuation component removal unit that generates the corrected gap detection signal by removing, from the gap detection signal, the fluctuation component extracted by the filter unit.