For our transportable ²⁷Al⁺ optical ion clock setup we developed a simple and compact physics and laser package for manipulation of ⁴⁰Ca⁺. Important features are a segmented multi-layer trap with separate loading and probing zones, a compact titanium vacuum chamber, a near-diffraction-limited imaging system with high numerical aperture based on a single biaspheric lens, and an all-in-fiber  ⁴⁰Ca⁺ repump laser system. From measurements with a single calcium ion we derive a preliminary estimate of the trap-induced frequency shifts on ²⁷Al⁺ of 1.9x10^^-18.

Link to the paper.