Diuse optical spectroscopy (DOS) is a technique that combines experimental measurements and model-based data analysis to measure the bulk absorption and scattering properties of highly scattering media. DOS typically uses red and near-infrared (NIR) light, especially from 600 to 1000 nm, where light propagation in tissue is heavily dominated by scattering . DOS measurements of tissue optical properties (i.e., absorption and scattering) are assumed to contain information about tissue structure and function. e term diuse optics refers to photons that propagate randomly throughout the tissue. DOS utilizes the photons that conventional optical techniques discard; instead of collimated or coherent photons, DOS measures incoherent, multiply scattered photons that are spread out over space and time. Diusive photons probe a large sample volume, providing macroscopically averaged absorption and scattering properties at depths up to a few centimeters in tissues.