Program written by Gorden Videen and modified by Dat Ngo. The program follows the derivation of Gorden Videen given  in his dissertation and the articles Videen, Opt. Comm. 115, p. 1 (1995);  Videen, JOSA A 8, p. 483 (1991); 9, p. 844 (1992).

• Link (local copy, 25 Feb 1998)