Enabling High-Resolution Photon-Counting Measurements Near Cloud Edges

^(a) University of Colorado Boulder, Aerospace Engineering Sciences Department Boulder, CO, USA 80303
^(b) NSF National Center for Atmospheric Research, Earth Observing Lab Boulder, CO, USA 80303
^(c) University of Wisconsin Madison, Space Science & Engineering Center Madison, WI, USA 53706
^(d) NASA Langley Research Center Hampton, VA, USA 23681 This email address is being protected from spambots. You need JavaScript enabled to view it.

Published online: 9 April 2026

Abstract

Single-photon avalanche diodes exhibit a nonlinear bias known as deadtime, in which high-density backscatter signals can saturate the detector. This results in missed counts and measurements that are biased low, thus limiting the detector's dynamic range. Unfortunately, traditional deadtime correction (via post-processing) is limited only to applications where the scene of interest is uniform over the sampling bin. This means it fails to accurately estimate dynamic or heterogeneous scenes that exhibit high backscatter, posing a significant challenge. This presentation introduces a novel deadtime-correction technique that overcomes these limitations, enabling high-resolution measurements at high (and low) fluxes. We leverage this new capability in combination with an ultra-high-resolution acquisition system (< 1 cm) to generate high-resolution measurements of clouds. This will be demonstrated using simulations and measurements.