Measurement of optical and depth-dependent dynamic properties of turbid media with photon-counting sensitivity using frequency-modulated scattering holography

Diffuse optical techniques which can non-invasively measure cerebral blood flow require the knowledge of tissue optical properties for accurate quantification. Eventhough speckle based flow measurement combined with time domain near-infrared spectroscopy enables the simultaneous measurement of optical and dynamic properties, such systems often suffer from low signal-to-noise ratio due to limited speckle collection. Camera based techniques being highly parallel improve the signal-to-noise but cannot assess optical properties due to hardware constraints. Here, we introduce frequency-modulated scattering holography, a technique that enables the measurement of optical and depth-dependent dynamic properties of turbid media. This method employs highly parallel interferometric detection with photon-counting sensitivity, achieving a 21.6 dB improvement over the previous single-detector system. It offers a simple and integrated solution for flow imaging in complex media.