Site-resolved imaging of ytterbium atoms in a two-dimensional optical   lattice
  We report a high-resolution microscope system for imaging ultracold ytterbium atoms trapped in a two-dimensional optical lattice. By using the ultraviolet strong transition combined with a solid immersion lens and high-resolution optics, our system resolved individual sites in an optical lattice with a 544-nm spacing. Without any cooling mechanism during the imaging process, the deep potential required to contain the atoms was realized using a combination of a shallow ground-state and a deep excited-state potentials. The lifetime and limitations of this setup were studied in detail. 
Martin Miranda, Ryotaro Inoue, Yuki Okuyama, Akimasa Nakamoto, and   Mikio Kozuma
cond-mat.quant-gas physics.atom-ph