Abstract

In optical disk systems, when a spot scans a pitted spiral track, the orders diffracted by the pits interfere with one another on the detector, causing it to generate a signal. The signal can be approximated by a convolution of the pits with a line spread function. Since aberration degrades the line spread, it causes waveform distortion in the signal. This is particularly harmful to the digital signal, in which the length of the pits should be reproduced precisely. Experimentally, the largest waveform distortion is observed in the presence of coma. The next largest cause is spherical aberration. Consequently, an optical disk system must be aplanatic to reproduce a distortion-free signal.

© 1987 Optical Society of America