title: Background suppression in near-field optical imaging.
abstract: In several recent studies, antenna-based optical microscopy has demonstrated its potential to resolve features as small as 10 nm. Most studies are concerned with well-separated features on flat surfaces, and there are only few studies that deal with samples of high feature density or even three-dimensional objects. The reason is that the external laser irradiation of the optical antenna (e.g., tip or particle) also directly irradiates the sample and therefore gives rise to a background. Here we introduce an efficient background suppression scheme that makes use of feedback modulation. The method is widely applicable and not restricted to cantilever-based scanning schemes. We apply this technique to both dense samples of dye molecules and ion channel proteins in plasma membranes and demonstrate effective background suppression and strongly improved sensitivity. The feedback modulation scheme is expected to find application for biological studies in liquid environments and for investigations of subsurface features in material science.
authors.affiliation: Institute of Optics, University of Rochester, Rochester, New York 14627, USA.
authors.forename: Christiane
authors.initials: C
authors.lastname: Höppener
authors.forename: Ryan
authors.initials: R
authors.lastname: Beams
authors.forename: Lukas
authors.initials: L
authors.lastname: Novotny
mesh_terms: D006046:Gold / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry; D055095:Optics and Photonics / Q000295:instrumentation* / Q000379:methods*
chemical_list: D006046:Gold