title: Understanding interferometry for micro-cantilever displacement detection.
abstract: Interferometric displacement detection in a cantilever-based non-contact atomic force microscope (NC-AFM) operated in ultra-high vacuum is demonstrated for the Michelson and Fabry-Pérot modes of operation. Each mode is addressed by appropriately adjusting the distance between the fiber end delivering and collecting light and a highly reflective micro-cantilever, both together forming the interferometric cavity. For a precise measurement of the cantilever displacement, the relative positioning of fiber and cantilever is of critical importance. We describe a systematic approach for accurate alignment as well as the implications of deficient fiber-cantilever configurations. In the Fabry-Pérot regime, the displacement noise spectral density strongly decreases with decreasing distance between the fiber-end and the cantilever, yielding a noise floor of 24 fm/Hz(0.5) under optimum conditions.
authors.affiliation: Fachbereich Physik, Universität Osnabrück, Barbarastraße 7, 49076 Osnabrück, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: von Schmidsfeld
authors.affiliation: Fachbereich Physik, Universität Osnabrück, Barbarastraße 7, 49076 Osnabrück, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Nörenberg
authors.affiliation: Fachbereich Physik, Universität Osnabrück, Barbarastraße 7, 49076 Osnabrück, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Temmen
authors.affiliation: Fachbereich Physik, Universität Osnabrück, Barbarastraße 7, 49076 Osnabrück, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Reichling
keywords: displacement noise spectral density; interferometer; non-contact atomic force microscope (NC-AFM); opto-mechanic effects