A method and apparatus for converting a Gaussian laser beam into a propagating
far field diffraction pattern using an off-axis diffractive optic. This propagating
far field pattern is focused by a lens to obtain a flattop intensity at the focal
plane. The technique is based on the idea of Fourier transform pairs and produces
a small spot diameter with a useable depth of field. A focused uniform intensity
profile can be useful for many laser applications.