Uniformalization of Laser Beam Intensity

Abstract

A simple absorption filter is designed to obtain uniform intensity distribution of the laser beam, and uniformity within 3% is attained. This filter is made by filling the space between plano-concave lens and plane glass with refractive index-matched absorption liquid.
The intensity distribution of the beam incident to the filter should be of smooth Gaussian, which can be achieved by spatial frequency filtering. The optimum diameter of the pinhole for the filtering is obtained experimentally.