Patent ID: 7170845

Claim:
An aberration correcting apparatus for correcting aberration in an optical path of an optical system which irradiates a recording medium with a light beam and guides the light beam reflected from said recording medium, comprising: an object lens for focusing the light beam on said recording medium; a first aberration correction element movable along the optical axis of said light beam for performing coarse correction of the aberration of the light beam; a driver for positioning said first aberration correction element along the optical axis in response to a drive control signal; a second aberration correction element having a plurality of phase adjustment portions each generating an amount of phase change in the light beam to perform fine correction for a residual aberration of said first aberration correction element, the amount corresponding to an adjustment signal and said second aberration correction element being integrally formed with said object lens so as to be in alignment with each other; a phase adjuster for supplying said adjustment signal to the respective adjustment portions in response to a phase control signal; a light receiver for receiving the light beam reflected from said recording medium to generate a light-receiving signal; and a controller for generating said drive control signal and said phase control signal based on said light-receiving signal, wherein said phase adjuster corrects the residual aberration of said first aberration correction element.