Neutral atom imagers, such as those on IBEX, cover energies from 0.01 to 100 keV, encompassing the entire energy range of neutral atoms (and their parent ion populations) in the magnetosphere, heliosphere, and interstellar medium. To measure neutrals over this broad energy range, different types of imagers are required. Most imagers have a key subsystem that converts an incoming neutral atom into an ion. Then, the ion can be deflected away from the initial neutral direction. This deflection is critical for separating the original signal from much higher backgrounds (e.g., ultraviolet radiation) that are present in space. The conversion subsystem is the least efficient subsystem in a neutral atom imager, especially at energies below 1 keV. The state-of-the-art neutral atom camera IBEX-Hi22 demonstrates this point. This system uses an ultrathin carbon foil1,23 to convert an incident neutral atom into a positive ion. The foil has a thickness of the order of atoms, allowing transmission down to energies of several hundreds of eV. However, the probability of producing a charged particle decreases dramatically for neutral atom energies below 1 keV. Furthermore, the probability of transmission through the foil also decreases dramatically below about 0.5 keV [e.g., at 0.2 keV (20)], resulting in very low overall efficiencies at energies of a few hundreds of eV.