With the advent of methods for the pulsed annealing of materials using laser radiation, it has become increasingly important to achieve good beam uniformity. The authors describe a device based upon a diffusing screen coupled to a light guide which accepts a multimode beam directly from a laser and, irrespective of input beam inhomogeneities, yields an output beam with an exceptionally flat and uniform intensity distribution. The optical efficiency of the device is high and the output radiation power density can be controlled by adjusting diffuser design parameters. Deleterious speckle patterns in the output beam can be virtually eliminated.