High-resolution imaging of Rydberg atoms in optical lattices using an aspheric-lens objective in vacuum

We present a high-resolution, simple, and versatile system for imaging ultracold Rydberg atoms in optical lattices. The imaging objective is a single aspheric lens [with a working distance of 20.6 mm and a numerical aperture (NA) of 0.51] placed inside the vacuum chamber. Adopting a large-working-distance lens leaves room for electrodes and electrostatic shields to control electric fields around Rydberg atoms. With this setup, we achieve a Rayleigh resolution of 1.10 mu m or 1.41 lambda(lambda= 780 nm), limited by the NA of the aspheric lens. For systems of highly excited Rydberg states with blockade radii greater than a few mu m, the resolution achieved is sufficient for studying many physical processes of interest.