Compact FPGA-based software correlator for real-time blood flow measurement with diffuse correlation spectroscopy

Diffuse correlation spectroscopy (DCS) enables noninvasive measurement of deep tissue blood flow, but high-speed and multi-channel implementations are often constrained by data throughput. We present an FPGA-based compressed DCS architecture for fast, high-throughput real-time measurements of intensity autocorrelation functions that leverages parity-based 1-bit photon counting to exploit sparse photon arrivals. The system is validated by direct comparison with a conventional research-grade DCS instrument with experiments on solid and liquid tissue-simulating phantoms and in vivo forearm measurements during arm-cuff occlusion. Results demonstrate $96.875\%$ data compression with preservation of autocorrelation fidelity and blood flow estimation performance over practical acquisition rates, enabling compact and scalable real-time DCS instrumentation.