The principle of a specific optical device which was
designed to homogenize the power density distribution of a CO2 laser
beam is described in the paper. The detailed formulas to express the
relation between power density distribution of converted beam and optical
parameters of device are given. Based on this relation, a scheme to optimize
the device is presented. The power density distributions simulated by
computer before and after optimization are given. A tentative criterion to
estimate the uniformity of a beam spot in which there are interference
fringes, is put forward.