Speckle and Spatial Coherence
Speckle is a ubiquitous phenomenon that arises during any quasi-monochromatic interrogation of biological specimens, whether by spatial scanning of focused beams or broad-field illumination, and whether using laser sources or low-coherence illumination. It is a direct manifestation of spatial interference among multiple waves that have been scattered or refracted from a complex target sample. Speckle is detrimental to high-resolution optical imaging, and many techniques are applied to mitigate its effects. However, speckle is a form of self interference and hence is intrinsically an interferometric phenomenon, and due to its interferometric sensitivity, speckle carries information from the smallest scales of the target (organelles, membranes, vesicles, etc.) to provide statistical information on subcellular structure and dynamics.
KeywordsDynamic Light Scattering Autocorrelation Function Spatial Coherence Paraxial Approximation Speckle Contrast
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