Speckle suppression by a quasi-spiral 2D diffractive optical element based on the binary pseudorandom M-sequence
The method based on suppressing speckle noise by a rotating quasi-spiral 2D diffractive optical element (DEO) created using binary pseudo-random sequences is presented. The unique DOE structure for the case of M-sequence code 15 in length was fabricated. Speckle suppression for green, purple, and red lasers by a factor more than 11.6 and 4, respectively, was obtained. Numerical simulations have shown that strong dispersion of photoresist (DOE structure medium) results in a significant decrease of the efficiency of the method on the borders of the visible range of electromagnetic radiation, and the use of material with anomalous dispersion can significantly improve the parameters of suppression of speckles on the borders of the visible range of wavelengths.