In an optical disk system that uses a blue laser diode and a high numerical aperture objective lens, it is necessary to detect and correct a substrate thickness error and a radial tilt of the disk, because a spherical aberration and a coma aberration deteriorate the read/write characteristics. We present a newly developed method to detect the substrate thickness error and the radial tilt of the disk using a five-beam optical head. This detection method features a high signal-to-noise ratio for a readout signal and enables combination with differential focusing and tracking error detection methods. Experimental results demonstrate the validity of this detection method and a correction method using a liquid-crystal panel.
© 2009 Optical Society of America
Optical Data Storage
Original Manuscript: April 14, 2008
Revised Manuscript: October 28, 2008
Manuscript Accepted: March 12, 2009
Published: April 1, 2009
Ryuichi Katayama and Yuichi Komatsu, "Substrate thickness error and radial tilt detection using a five-beam optical head," Appl. Opt. 48, 2014-2026 (2009)