Optical information processing apparatus and optical information processing method, and adjustment device, adjustment method, and adjustment program for optical information processing apparatus

An optical information processing method comprising:

• a light radiation reception step for radiating light onto an optical disc and detecting light reflected from the optical disc to output a reproduced signal;
• a spherical aberration correction step for correcting spherical aberration of the light radiated onto the optical disc;
• a focus adjustment step for adjusting, based on a focus adjustment value, a focus position of the light radiated onto the optical disc;
• and
• an adjustment step for measuring a signal characteristic of the reproduced signal at each of at least three measurement positions on each of at least three straight lines on a plane with coordinate axes representing an amount of spherical aberration correction by the spherical aberration correction step and the focus adjustment value, obtaining, from the results of the measurements, as estimated positions, at least five positions on the plane at which the signal characteristic has substantially the same value, and adjusting the amount of spherical aberration correction and the focus adjustment value based on the at least five estimated positions;
• wherein
• the adjustment step performs an ellipse approximation on the at least five estimated positions, obtains a center of the ellipse from the result of the ellipse approximation, and determines the amount of spherical aberration correction and the focus adjustment value based on the center of the ellipse.

An adjustment method for an optical information processing apparatus including a light radiation reception unit that radiates light onto an optical disc and detects light reflected from the optical disc to output a reproduced signal, a spherical aberration correction unit that corrects spherical aberration of the light radiated onto the optical disc, and a focus adjustment unit that adjusts a focus position of the light radiated onto the optical disc based on a focus adjustment value, the adjustment method comprising

• an adjustment step for measuring a signal characteristic of the reproduced signal at each of at least three measurement positions on each of at least three straight lines on a plane with coordinate axes representing an amount of spherical aberration correction by the spherical aberration correction means and the focus adjustment value, obtaining, from the results of the measurements, as estimated positions, at least five positions on the plane at which the signal characteristic has substantially the same value, and adjusting the amount of spherical aberration correction and the focus adjustment value based on the at least five estimated positions, wherein
• the adjustment step performs an ellipse approximation on the at least five estimated positions, obtains a center of the ellipse from the result of the ellipse approximation, and determines the amount of spherical aberration correction and the focus adjustment value based on the center of the ellipse.