Characterization of a Pixel-Level Binarized Autocorrelator for Large Array Multispeckle Diffuse Correlation...

Multispeckle Diffuse Correlation Spectroscopy (mDCS) is an optical technology for real-time measurement of deep-tissue microvascular blood flow. Its use in wearables is limited by the high computational cost of autocorrelation. We propose a resource-efficient 1-bit pixel-level autocorrelator that exploits sparse photon detection at long source-detector separations. Implemented on an FPGA, the design is validated using real Single Photon Avalanche Diode (SPAD) inputs against a conventional 5-bit baseline under identical conditions. Systematic characterization using a rotating diffuser identifies an empirical threshold of 0.7 for photon hit probability per lag bin, below which decay time constants are estimated with tolerable error. A qualitative cuff occlusion study is also demonstrated. Overall, this work presents a scalable solution for massively parallel, large array mDCS systems-on-chip for wearable healthcare devices.