Speckle reduction in laser displays using a MEMS tandem modulator

This paper reports a novel idea of using a tandem grating modulator for speckle reduction in laser displays. The modulator was designed based on finite-element method simulations, fabricated using micromachining technology, and characterized for speckle reduction. Two types of modulator were fabricated with different shape of gratings. Experiments showed that these modulators reduced the speckle contrast to 0.57 and 0.37, respectively. The results agreed with theoretical analysis. With some modification of this modulator, the speckle noise can be reduced to 0.07 according to the theory. The despeckle modulator is flexible for system implementation and can be a promising component in display system with coherent light source to restrain the speckle noise.