For the first time, to our knowledge, optical diffraction is shown to
be a wavelet transform with the electromagnetic wavelets. Pde show tha
t the optical wavelets proposed by Onural [Opt. Lett. 18, 846 (1993)]
are the Huygens wavelets under a Fresnel approximation, and the electr
omagnetic wavelets proposed by Kaiser [A Friendly Guide tp Wavelets (B
irkhauser, Boston, Mass., 1994)] reduce to Hyugens wavelets in the cas
e of a monochromatic field. (C) 1998 Optical Society of America.