Very efficient speckle suppression in the entire visible range by one two-sided diffractive optical element

The impact of the precision and direction of motion of a two-dimensional (2D) diffractive optical element (DOE) based on binary pseudo-random sequences on speckle suppression efficiency is investigated experimentally. The experimental data show a large speckle suppression efficiency and agree qualitatively with the theoretical results. The experimental results confirm that the wavelength range for the speckle suppression of a two-level 2D DOE based on binary random sequences is narrower than the visible range. The experimental data confirm the theoretical prediction that the wavelength range for the speckle suppression for a double-sided one-dimensional (1D) DOE is wider than the visible range. The large speckle suppression coefficient k>16 and a speckle contrast below 2.6% are obtained in the entire visible range by using one two-sided 1D M-sequence-based DOE with code length N=15. The proposed method has potential applications in laser projection display systems.