An illumination apparatus for reducing speckle effect in light reflected off an illumination target includes a laser; diffuser positioned in an optical path between an illumination target and the laser to diffuse collimated laser light in a planar fan of diffused light that spreads in one dimension across at least a portion of the illumination target; and a beam deflector to direct the collimated laser light incident on the beam deflector to sweep across different locations on the linear diffuser within an exposure time for illumination of the illumination target by the diffused light. The different locations span a distance across the linear diffuser that provides sufficient uncorrelated speckle patterns, at an image sensor, in light reflected from an intersection of the planar fan of light with the illumination target to add incoherently when imaged by the image sensor within the exposure time.