Measurement of optical and time-of-flight-gated 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. Speckle based flow measurements combined with time domain near-infrared spectroscopy enable the simultaneous measurement of optical and dynamic properties but such systems often suffer from low signal-to-noise ratio due to limited speckle collection. Camera based techniques being 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 time-of-flight-gated dynamic properties of turbid media. This method employs 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.