Bichromatic UV detection system for atomically-resolved imaging of ions

Abstract

We present a compact bichromatic imaging system, located outside of the vacuum chamber of a trapped ion apparatus that collects the fluorescence of 230.6 and 369.5 nm photons simultaneously on a shared electron-multiplying charge-coupled device (EMCCD) camera. The system contains two lens doublets, consisting of a sphere and an asphere. They provide a numerical aperture of 0.45 and 0.40 at 230.6 and 369.5 nm, respectively, and enable spatially resolved state detection with a large field of view of 300 μm for long 115In+/172Yb+ Coulomb crystals. Instead of diffraction-limited imaging for one wavelength, the focus in this system is on simultaneous single-ion resolved imaging of both species over a large field, with special attention to the deep UV wavelength (230.6 nm) and the low scattering rate of In+ ions. The introduced concept is applicable to other dual-species applications.