Abstract

An experimental comparison of the ring-lens and the astigmatic techniques of generating a focus-error signal (FES) in optical disk systems reveals that the ring lens generates a FES curve over two times steeper than that produced by the astigmat. Partly because of this large slope and partly because of its diffraction-limited behavior, the ring-lens scheme exhibits superior performance characteristics. In particular, the undesirable signal known as feedthrough (induced on the FES by track crossings during the seek operation) is substantially lower than that observed with the astigmatic method. The ring lens is easy to align and has reasonable tolerance for positioning errors.

© 1994 Optical Society of America

Causes of focus-error feedthrough in optical-disk systems: astigmatic and obscuration methods

Bruce E. Bernacki and M. Mansuripur
Appl. Opt. 33(5) 735-743 (1994)

Characterization of a novel focusing/tracking technique with increased feedthrough immunity for optical-disk applications: the double-astigmatic method

Bruce E. Bernacki, Keith Bates, M. Mansuripur, Delbert Hansen, and Daniel Cisneros
Appl. Opt. 32(29) 5789-5796 (1993)

Ring-toric lens for focus-error sensing in optical data storage

Michael R. Descour, Daniel I. Simon, and Wei-Hung Yeh
Appl. Opt. 38(8) 1388-1392 (1999)

Analysis of astigmatic focusing and push–pull tracking error signals in magnetooptical disk systems

Masud Mansuripur
Appl. Opt. 26(18) 3981-3986 (1987)

Effects of substrate birefringence on focusing and tracking servo signals in magneto-optical disk data storage

Satoshi Sugaya and M. Mansuripur
Appl. Opt. 33(22) 5073-5079 (1994)