The use of an astigmatic lens to generate a position error signal (PES) suitable for servo control is discussed. A simple computer model was written that can predict adequately the performance of an astigmatic system. The effect of various system parameters on the PES is presented.
© 1984 Optical Society of America
Donald K. Cohen, Wing Ho Gee, M. Ludeke, and Julian Lewkowicz, "Automatic focus control: the astigmatic lens approach," Appl. Opt. 23, 565-570 (1984)