Investigating the effects of vibration and subject motion on fiber based-speckle contrast optical spectroscopy (Invited Paper)

Speckle contrast optical spectroscopy (SCOS) has transformed deep-tissue blood flow measurements by offering signal-to-noise ratios that are orders of magnitude greater than those achieved with diffuse correlation spectroscopy. In fiber-based SCOS systems, the parallel detection of thousands of speckles relies on multi-mode fibers. However, motion within these fibers introduces fluctuations that can interfere with signals originating from the sample of interest. In this study, we integrate a state-of-the-art single-photon avalanche diode (SPAD) array with a conventional SCOS setup to recover spatially resolved normalized intensity autocorrelation functions and their corresponding speckle contrast values simultaneously. This approach will enable us to better understand the impact of fiber motion on blood flow measurements using multi-mode fibers and determine methods to minimize measurement artifacts.