Method to determine the speckle characteristics of front projection screens

We present a method to determine the speckle properties of front projection screens. Seven different screens are investigated in a backscattering geometry for 808 nm light. The speckle contrast reduction that results from polarization scrambling and reduced temporal coherence is modeled for the case of volume scattering in the screens. For this purpose, the screen's volume scattering path length distributions and depolarization characteristics are determined. This is done via a streak camera setup to measure the temporal broadening of ultrashort 50 fs light pulses scattered in the screens. We show that it is essential to properly select a projection screen with large volume roughness in order to achieve low speckle contrast values for moderate illumination bandwidths.