This invention greatly improves the quality of images obtained using optical systems illuminated by coherent light. It does so by removing the undesirable psuedo-random variations in the final image due to interference speckle and inhomogeneities in the spatial intensity distribution of the light source....http://www.google.de/patents/US6895149?utm_source=gb-gplus-sharePatent US6895149 - Apparatus for beam homogenization and speckle reduction
