Patent ID: 8638646

Claim:
An optical information processing method comprising: a light irradiating and receiving step of irradiating an information recording surface of an optical disc with laser light as a light collecting spot and detecting reflected light from the information recording surface of the optical disc; a signal processing step of detecting shift amount of a first control device for controlling amount of a spherical aberration at the light collecting spot and shift amount of a second control device for controlling amount of a focus offset indicating a shift of the light collecting spot from a correct focal point, from a detection signal of the reflected light outputted in the light irradiating and receiving step, generating a reproduction signal, and detecting a performance evaluation value which indicates characteristic of the reproduction signal; and an adjusting step of adjusting the spherical aberration on the basis of the shift amount of the first control device and the performance evaluation value and adjusting the focus offset on the basis of the shift amount of the second control device and the performance evaluation value; wherein said signal processing step includes a detecting process of the performance evaluation values form a first point, a second point, a third point and a fourth point in an x and y coordinate system, in which an x-coordinate is one of the shift amount of the first control device and the shift amount of the second control device and a y-coordinate is the other, the first point, the second point and the third point having the same y-coordinate and different x-coordinates with each other, the fourth point being provided on a first straight line which passes through the first point, the fourth point and the first point having different x-coordinates and different y-coordinates with each other.