A new technique for speckle noise reduction of laser projection displays using waveplates

In laser projection displays, countermeasure technique against glares on the screen called speckle noise is one of the focuses. In the experiments, a quarter-waveplate with slow axis rotated by 45 degrees against the polarization axis of the incident green laser source was inserted into the optical path of our laser projection display system. Only in such a setup, an enough coherence alleviation was attained. We have also carried out quantitative evaluations of the speckle noise by overlaying the projected images using a CCD camera on the histogram-based estimations of speckle noise intensities. Noise reduction of about 20% was accomplished.