Patent ID: 6525332
Filing Date: 2003-02-25
Classification: G11B

Abstract:
An apparatus for detecting and compensating the disk tilt of an optical disk by adjusting the incident angle onto said optical disk of an incident laser beam generated from a laser source, comprising:a two-dimensional grating for diffracting said incident laser beam to a main laser beam and a plurality of minor laser beams, said two-dimensional grating is constructed such that said minor laser beams contain diffracted laser beams that are parallel to a radial direction of the optical disk and diffracted laser beams that are parallel to a tangential direction of the optical disk; a detection circuit for transferring the light intensities of said main and minor laser beams reflected from said optical disk to a radial-tilt signal denoting the radial tilt of said optical disk and a tangential-tilt signal denoting the tangential tilt of said optical disk; a reflective device for reflecting said main and minor laser beams to said optical disk and being able to tilt by rotating along the radial and tangential directions of said optical disk; and an actuation device for tilting said reflective device so as to change the incident angles of said main and minor laser beams according to said radial-tilt signal and said tangential-tilt signal; wherein said main laser beam is a zero-order diffracted laser beam, and said minor laser beams include a +1 first-order diffracted laser beam and a âˆ’1 first-order diffracted laser beam in the radial direction and a +1 first-order diffracted laser beam and a âˆ’1 first-order diffracted laser beam in the tangential direction.