Information recording/reproduction apparatus

Abstract

An optical information recording/reproduction apparatus includes a correction device that corrects aberration, due to a change in thicknesses of a transparent substrate and spherical aberration generated by inserting an optical attenuation device into an optical path or retreating the optical attenuation device from the optical path, by changing intervals between a plurality of lenses. The correction device is disposed between an objective lens and a light source. The correction device also functions as a collimator lens. The optical attenuation device is provided in an optical path of diverging light flux from the light source to the correction device, for attenuating an optical output from the light source. A discrimination circuit discriminates (i) a kind of the optical recording medium and (ii) an insertion of the optical attenuation device into the optical path or a retreating of the optical attenuation device from the optical path, and produces a discrimination result. A learning circuit performs a learning process by searching for a correction amount, while the correction device changes the intervals between the plurality of lenses, and a circuit changes initial positions of the intervals between the plurality of lenses at a start of the learning process performed by the learning circuit, in accordance with the discrimination result produced by the discrimination circuit.