A laser beam delivery apparatus for a microscope comprises first and second optical diffusers that are configured to move in a periodic manner with a respective different frequency. Each optical diffuser may comprise a spinning disk. The laser light is spatially randomized by the first spinning diffuser and its spatial pattern is further randomized by the second diffuser. The second diffuser prevents any spatial pattern from repeating after one revolution of the first diffuser, which prevents beating patterns from forming when the light is imaged through a spinning confocal disk and increases the uniformity in other cases.