Bichromatic UV detection system for atomically-resolved imaging of ions

TL;DR

This paper introduces a compact, dual-wavelength imaging system for simultaneous, high-resolution detection of ions at UV wavelengths, enabling detailed spatial imaging of mixed ion species.

Contribution

A novel bichromatic imaging system with high NA and large field of view, optimized for simultaneous UV detection of different ion species outside the vacuum chamber.

Findings

Achieves spatially resolved imaging of ions at 230.6 nm and 369.5 nm.

Provides a large field of view of 300 μm for Coulomb crystals.

Demonstrates effective dual-species ion imaging with high spatial resolution.

Abstract

We present a compact and bichromatic imaging system, located outside of the vacuum chamber of a trapped ion apparatus, that collects the fluorescence of 230.6 nm and 369.5 nm photons simultaneously on a shared EMCCD camera. The system contains two lens doublets, consisting of a sphere and an asphere. It provides a numerical aperture of 0.45 and 0.40 at 230.6 nm and 369.5 nm, respectively, and enables spatially resolved state detection with a large field of view of 300 $\mu$m for long $^{115}$In$^+$/$^{172}$Yb$^+$ 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.