Image Reconstruction from Readout-Multiplexed Single-Photon Detector Arrays

TL;DR

This paper introduces a probabilistic inverse imaging framework for resolving multiple photon events in readout-multiplexed single-photon detector arrays, significantly improving image reconstruction quality and efficiency.

Contribution

It develops a novel estimator that resolves up to four coincident photons and demonstrates improved PSNR, reduced frame requirements, and theoretical optimality over conventional methods.

Findings

Increases PSNR by 3-4 dB compared to conventional methods.

Reduces required readout frames by a factor of ~4.

Matches the Cramer-Rao bound for detection probability estimation.

Abstract

Readout multiplexing is a promising solution to overcome hardware limitations and data bottlenecks in imaging with single-photon detectors. Conventional multiplexed readout processing creates an upper bound on photon counts at a very fine time scale, where frames with multiple detected photons must either be discarded or allowed to introduce significant bias. We formulate multiphoton coincidence resolution as an inverse imaging problem and introduce a solution framework to probabilistically resolve the spatial locations of photon incidences. Specifically, we develop a theoretical abstraction of row--column multiplexing and a model of photon events that make readouts ambiguous. Using this, we propose a novel estimator that spatially resolves up to four coincident photons. Monte Carlo simulations show that our proposed method increases the peak signal-to-noise ratio (PSNR) of reconstruction by 3 to 4 dB compared to conventional methods under optimal incident flux conditions. Additionally, this method reduces the required number of readout frames to achieve the same mean-squared error as other methods by a factor of ~4. Finally, our method matches the Cramer--Rao bound for detection probability estimation for a wider range of incident flux values compared to conventional methods. While demonstrated for a specific detector type and readout architecture, this method can be extended to more general multiplexing with different detector models.