A novel fly's eye homogenizer for single mode laser diodes is presented. Laser speckle has been removed and a uniform laser line illumination has been obtained for the first time with the proposed fly's eye homogenizer incorporating a single mode laser diode by introducing a staircase element and short pulse switching of the injection current. The former degrades the spatial coherence of the adjacent beamlets emanating from the microlens arrays while the latter simultaneously shortens the temporal coherence time so that the necessary optical path lengths in the staircase element become realistic in size. An average speckle contrast of 5% was achieved with the new fly's eye homogenizer whereas the standard fly's eye homogenizer at a CW driving yielded a high contrast of 87%. The diffraction theory for partial coherent light based on Wolf's formulation was extended to a simplified model of the new fly's eye homogenizer. The effect of the pulse width on the speckle contrast of the laser line illumination is experimentally shown and is discussed through a detailed analysis of the power spectrum and the fringe visibility, and a numerical study on the Dirichlet kernel based on the derived formulation for the intensity.