Diffractive optic elements for forming scanning beams

A novel approach for designing quasi non-diffracting beams is presented. When using these beams for scanning images, the resulting signals have low contrast levels that are maintained over distances far exceeding depth-of-focus distances obtainable with Gaussian beams. A system using two phase-only diffractive optics filters separated by a free space region is sufficient to generate such beams. Gerchberg-Saxton algorithms are applied for determining the phase functions necessary for transforming the input laser beam into the desired beam distribution. The characteristics of the beams are presented.