In this work we have demonstrated the development of long wavelength, interferometric diffuse correlation spectroscopy. Using a fiber optic probe with collocated detection fibers, we were able to directly compare measured blood flow and signal-to-noise ratio between the long wavelength diffuse correlation spectroscopy (LW-DCS) and long wavelength interferometric diffuse correlation spectroscopy (LW-iDCS) instruments.

For both single photon detection and interferometric detection, the availability of cost-effective, high-power fiber optic amplifiers, an engineering benefit of making measurements at 1,064 nm, allows for an increased signal-to-noise ratio (SNR) beyond the intrinsic benefits of using light at 1,064 nm.

By sacrificing spatial resolution, multiple sources spaced > 3.5 mm apart could be used, allowing for an even higher SNR for high quality pulsatile blood flow measurements.

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