Diffuse correlation spectroscopy (DCS), a popular optical technique for fast noninvasive measurement of blood flow, is commonly implemented using expensive fiber-coupled long coherence length laser systems. Here, we report the development of a portable and fiber-less approach that can be used as a low-cost alternative to illuminate tissue in DCS instruments. We validate the accuracy and noise characteristics of the fiber-less DCS laser source, by comparisons against traditional DCS light sources, with experiments on controlled tissue-simulating phantoms and in humans.

We demonstrate a new coherence gated Diffuse Correlation Spectroscopy (DCS) instrument for pathlength resolved measurement of flow, and tissue optical properties, using a continuous wave low coherence source and a Mach-Zehnder interferometer.

We demonstrate heterodyne demodulation of Frequency Domain Diffuse Optical Spectroscopy (FD-DOS) over a broad frequency range (50 - 400 MHz), for single distance estimation of tissue optical properties.

Using finite element simulations of photon diffusion, we show that Frequency Domain (FD) and Continuous Wave (CW) Diffuse Optical Spectroscopy provide different estimates of hemodynamic changes due to functional activation.

This paper demonstrates a novel approach for fast, single-shot Multi-Exposure Speckle Imaging of blood flow with a simplified imaging setup. Our method can transform existing single-exposure speckle images to quantitative flow images.