Offset Microlens Array Camera for Quantitative Flow Imaging via Single-Shot Multi-Exposure Speckle Acquisition

Multi-exposure speckle imaging (MESI) provides a method for quantitatively estimating blood flow velocity by analyzing speckle contrast across varying exposure times. However, conventional MESI relies on high speed cameras, or sequential acquisition at multiple exposure durations, which introduces motion artifacts and reduces temporal resolution. In this study, we propose an offset microlens array camera (oMAC) that captures and reconstructs speckle patterns corresponding to different exposure times in a single shot. The system consists of an offset microlens array and a rolling shutter CMOS image sensor. The offset microlens array allows the separation and reconstruction of speckle patterns associated with each row of the image sensor. The laser remains on for a predefined millisecond-scale interval, so that each sensor row is exposed for a different duration within a single frame. Our camera successfully estimated speckle decorrelation times under flow velocities ranging from 0 to 6.26 mm/s in a microfluidic channel. The proposed method supports compact, high-speed, and non-invasive quantitative blood flow imaging applicable to biomedical and microfluidic systems.