Position controller and position control method of optical system and recording/reproducing apparatus and driving method thereof

摘要

A position controller of an optical system comprising an optical system for forming a near-field with an optical recording medium and focusing converged light to the optical recording medium; an actuator for moving the optical system in a focal direction perpendicularly intersecting a recording surface of the optical recording medium; and a control circuit for controlling the actuator so as to shorten the distance between the optical system and the optical recording medium from outside to inside the range where the near-field is formed and further maintain it inside the range; a position control method of an optical system; and a recording/reproducing apparatus and driving method thereof.