A high numerical aperture (NA = 0.92) objective lens for imaging and addressing of cold atoms

摘要

We have designed, built, and characterized a high-resolution objective lensthat is compatible with an ultra-high vacuum environment. The lens systemexploits the principle of the Weierstrass-sphere solid immersion lens to reacha numerical aperture (NA) of 0.92. Tailored to the requirements of opticallattice experiments, the objective lens features a relatively long workingdistance of 150 micrometers. Our two-lens design is remarkably insensitive tomechanical tolerances in spite of the large NA. Additionally, we demonstratethe application of a tapered optical fiber tip, as used in scanning near-fieldoptical microscopy, to measure the point spread function of a high NA opticalsystem. From the point spread function, we infer the wavefront aberration forthe entire field of view of about 75 micrometers. Pushing the NA of an opticalsystem to its ultimate limit enables novel applications in quantum technologiessuch as quantum control of atoms in optical microtraps with an unprecedentedspatial resolution and photon collection efficiency.