TRANSFORMATION OF GAUSSIAN TO COHERENT UNIFORM BEAMS BY INVERSE-GAUSSIAN TRANSMITTIVE FILTERS

Several plano-convex aluminum thin films, similar to 30 nm thick in th e center and similar to 2 mm in diameter, were deposited on microscope cover slides to function as inverse-Gaussian transmittive filters. By placing one of these filters in front of the Gaussian He-Ne laser, we can modify the beam intensity profile in the downstream direction. To yield a uniform beam, the position of the filter must be aligned in t he transverse plane for maximum intensity at the output of the filter. These filters are easy to fabricate and are inexpensive. Most importa nt, they can help produce collimated phase-coherent uniform beams, whi ch are useful in high-precision fringe-analysis techniques. (C) 1998 O ptical Society of America.