ABSORBING FILTER TO FLATTEN GAUSSIAN BEAMS

An absorbing filter that flattens the Gaussian intensity profile of a laser beam has been developed. The filter was fabricated by dc magnetron sputtering a thin tantalum film, by using a combination of substrate masking and motion. A model of the filter production has been developed that successfully predicts the film profile and performance. A typical filter produced by using these techniques results in a flat output to within +/-3% over a 2.2 mm with a transmission of 60% of the peak intensity of the Gaussian beam.