Experimental research of speckle suppression efficiency in the entire visible spectrum using moving 3D composite diffraction grating

In this paper we present the results on speckle noise suppression in the entire visible spectrum using moving 3D diffractive optical element (DOE) based on the pseudorandom binary M-sequence. Spectral dependence of the speckle suppression efficiency as a function of moving speed and basic unit height of the DOE has been measured. The most effective 3D DOE structure for speckle reduction in the whole visible range has been determined. For the optimal DOE structure the speckle reduction coefficients of 21, 15 and 14 for light wavelengths of 633, 532 and 405 nm, respectively, have been obtained. Experimental results confirmed the high efficiency of the speckle noise suppression method in the entire visible spectrum.