Patent ID: 8098555

Claim:
An optical disc apparatus comprising: an optical head for irradiating a light beam onto an optical disc; an optical head moving means for moving the optical head in a radial direction of the optical disc; a coma aberration correcting means for correcting a coma aberration of the light beam in the radial direction on the optical disc; and a tilt detecting means for detecting a tilt of the optical disc in the radial direction, wherein an amount of the correction performed by the coma aberration correcting means is a predetermined value regardless of a position of the optical head, and the optical head is moved by the optical head moving means in a predetermined moving range, the predetermined value is determined based on the mean value of the tilt detected by the tilt detection means at a substantially innermost circumference position on the optical disc and the tilt detected by the tilt detection means at a substantially outermost circumference position on the optical disc; and wherein the tilt detection means detects the tilt at the substantially innermost circumference position by calculating a mean value of focus driving values detected at two locations on the optical disc, said two locations being equidistant from and on opposite sides of the substantially innermost circumference position along the radial direction the tilt detection means detects the tilt at the substantially outermost circumference position by calculating a mean value of focus driving values detected at two other locations on the optical disc, said two other locations being equidistant from and on opposite sides of the substantially outermost circumference position along the radial direction; and the predetermined moving range is a range between an innermost of two said locations and an outermost of said two other locations along the radial direction.