Optical disc drive and optical pickup

摘要

An apparatus for reading and/or writing data from/on a medium with a light beam includes: a light source for generating the light beam; an objective lens for focusing the beam onto the medium; a lens shift sensor for sensing how much the optical axis of the objective lens has shifted from that of the beam; a wavefront corrector, in which correcting elements are arranged as a two-dimensional array so as to locally correct the wavefront of the beam and to be driven independently of each other; a wavefront calculator for finding correlation between each coordinate on a cross section of the beam and the wavefront phase of the beam; a lens shift correction calculator for modifying the coordinate-wavefront phase correlation according to the output of the lens shift sensor; and a controller for controlling the wavefront corrector in accordance with the output of the lens shift correction calculator.