OPTICAL SPECKLE-FIELD VISIBILITY DIMINISHING BY REDUCTION OF A TEMPORAL COHERENCE
2024
Mikhaylo Vasnetsov | Valeriy Voytsekhovich | Vladislav Ponevchinsky | Nataliia Kachalova | Alina Khodko | Oleksanr Mamuta | Volodymyr Pavlov | Vadym Khomenko | Natalia Manicheva
The paper is a report of an experimental study to suppress the speckle structure of a coherent optical field. The technique proposed is based on the reduction of the temporal coherence utilizing enriching the output spectrum of Nd:YVO4 laser with intra-cavity second harmonic generation by additional emission lines. Temperature-controlled simultaneous emission of two components at 1.063 mm and 1.066 mm with nearly equal intensities in IR is achived. In the second-harmonic output the emission lines 531.7 nm, 532.3 nm and 532.8 nm were recorded. The influence of the spectrum variation on the formation of a speckle field was checked. Successfully removed intensity zeros and reduced contrast (visibility) from 0.92 to 0.65 in a light scattered by a ground glass diffuser at the angle 35°. A simple consideration of the speckle field dumping mechanism is presented.
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