Patent ID: 9454987
Filing Date: 2016-09-27
CPC Classification: G11B

Claim Text:
1. An optical information processing apparatus comprising: 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; a focus adjustment unit that adjusts, based on a focus adjustment value, a focus position of the light radiated onto the optical disc; and an adjustment unit that measures 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 unit and the focus adjustment value, obtains, 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 adjusts the amount of spherical aberration correction and the focus adjustment value based on the at least five estimated positions; wherein the adjustment unit 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.