PURPOSE: To accurately grasp each displacement quantity, and to obtain efficient calibration with high accuracy, by providing either an axial direction displacement calibrating part, a radial direction displacement calibrating part, or a focus error output voltage calibrating part.
CONSTITUTION: The displacement quantity of an axial azimuth detector in an axial direction is calibrated from an output DC value by irradiating a beam spot on an axial direction displacement calibrating part 4. Also, a track control is performed so that the beam spot follows to some track groove in a radial direction displacement calibrating part 5, and by setting the output of a radial direction displacement detector at that time as a reference output, the displacement quantity in a radial direction is calibrated from the DC value of the output of the detector jumped by a constant value to the inside/outside of a certain track. And an objective lens is driven so that beams are focused on a calibration reference position in a focus error output voltage calibrating part 6, and an optical head is moved in the inside and the outside directions, and a focus error corresponding to an inclined angle is generated, thereby, a focus error output voltage is varied, and a focus error output characteristic is calibrated.
YOSHIZAWA TAKASHI
KINOSHITA KANAE
SHINDENSHI KOGYO KK
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