Fast Neutral Atom Microscopy: An Optimisation Framework for Stagnation Detectors

Abstract The nascent field of neutral helium microscopy, as well as many applications within atomic and molecular beam research, are currently restricted by low detector sensitivity. To compensate, system designers have relied on forming a stagnation volume around the detector to artificially increase local helium density and thus collected signal. As a consequence, the signal level and temporal response for these instruments are coupled, with higher signal coming at the cost of response time. Here we develop a theoretical model to derive an optimum balance between signal and temporal response, so as to resolve a desired level of contrast within an image. Our model was validated against an implementation of neutral helium microscopy – namely the Mk II scanning helium microscope (SHeM). For an indicative topographic sample, utilising the same imaging time, a 27% improvement in collected signal was achieved as compared to existing practice.