title: High numerical aperture (NA = 0.92) objective lens for imaging and addressing of cold atoms.
abstract: We have designed, built, and characterized a high-resolution objective lens that is compatible with an ultrahigh vacuum environment. The lens system exploits the principle of the Weierstrass sphere solid immersion lens to reach a numerical aperture (NA) of 0.92. Tailored to the requirements of optical lattice experiments, the objective lens features a relatively long working distance of 150 μm. Our two-lens design is remarkably insensitive to mechanical tolerances in spite of the large NA. Additionally, we demonstrate the application of a tapered optical fiber tip, as used in scanning near-field optical microscopy, to measure the point spread function (PSF) of a high NA optical system. From the PSF, we infer the wavefront aberration for the entire field of view of about 75 μm. Pushing the NA of an optical system to its ultimate limit enables novel applications in quantum technologies such as quantum control of atoms in optical microtraps with an unprecedented spatial resolution and photon collection efficiency.
authors.forename: Carsten
authors.initials: C
authors.lastname: Robens
authors.forename: Stefan
authors.initials: S
authors.lastname: Brakhane
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Alt
authors.forename: Felix
authors.initials: F
authors.lastname: Kleißler
authors.forename: Dieter
authors.initials: D
authors.lastname: Meschede
authors.forename: Geol
authors.initials: G
authors.lastname: Moon
authors.forename: Gautam
authors.initials: G
authors.lastname: Ramola
authors.forename: Andrea
authors.initials: A
authors.lastname: Alberti