Multiwavelength time-of-flight-resolved interferometric speckle contrast optical spectroscopy (multi-λ TOF iSCOS)

We present multi-wavelength time-of-flight-resolved interferometric speckle contrast optical spectroscopy (multi-λ TOF-iSCOS) for simultaneous, noninvasive measurement of blood flow and tissue oxygenation. The method combines a rapidly tunable laser with an ultrafast 2D camera operating at 1.1 million frames per second to acquire time-of-flight-resolved speckle contrast across two wavelengths. This enables depth-dependent estimation of blood flow index and cerebral metabolic rate of oxygen consumption (CMRO₂). Validation in liquid phantoms and human forearm measurements demonstrates the feasibility of compact, camera-based systems for real-time hemodynamics monitoring.