The authors would like to gratefully acknowledge L. J. Mawst and M. A. Emanuel for historical purposes;
and L. M. Miller and Y .S. Moroz for helpful discussions and technical support. This work was supported in part by the National Science Foundation (DMR 83-16981 and CDR 85-22666);
the McDonnell Douglas Corporation;
the U.S. Naval Research Laboratory (N00014-88-K-2005);
and the U.S. Army Night Vision and Electro-Optics Laboratory (DAAK 20-84-K-0225);