Fast numerical Fourier analysis of moiré pattern induced by a periodic metallic array on top of the microscopically patterned red-green-blue light sources.

An accurate and fast moiré pattern analysis algorithm is proposed for a periodic metallic array placed adjacent to a patterned red-green-blue (RGB) light source with a microscopic gap utilizing Fourier transform along with the human eye contrast sensitivity function. We analyzed how the moiré pattern evolved varying tilt angles and metal array periodicities placed on the top of RGB light sources, which have their own spatial periodicities. Based on multiplicative model, moiré patterns were numerically generated and the influences of 70 tilt angles and 60 periodicities on the moiré standard deviation were thoroughly analyzed to minimize moiré visibility. Our numerical results were compared to a prior analytical approach to obtain a good agreement, and the proposed scheme can be further applied to larger scale display systems with sophisticated touch screen metal arrays.

Experiment evaluation of speckle suppression efficiency of 2D quasi-spiral M-sequence-based diffractive optical element.

The quasi-spiral 2D diffractive optical element (DOE) based on M-sequence of length N=15 is designed and manufactured. The speckle suppression efficiency by the DOE rotation is measured. The speckle suppression coefficients of 10.5, 6, and 4 are obtained for green, violet, and red laser beams, respectively. The results of numerical simulation and experimental data show that the quasi-spiral binary DOE structure can be as effective in speckle reduction as a periodic 2D DOE structure. The numerical simulation and experimental results show that the speckle suppression efficiency of the 2D DOE structure decreases approximately twice at the boundaries of the visible range. It is shown that a replacement of this structure with the bilateral 1D DOE allows obtaining the maximum speckle suppression efficiency in the entire visible range of light.