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/Hz0.5 under optimum conditions.
Highlights
A common method for measuring the displacement of a microcantilever or another micro-mechanical device is interferometric displacement detection
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
A related interferometric setup based on multi-beam interference in an optical cavity is the Fabry-Pérot interferometer typically used in form of an etalon in spectroscopy, lasers, and optical telecommunication [3] for precise wavelength selection within a certain free spectral range [4]
Summary
A common method for measuring the displacement of a microcantilever or another micro-mechanical device is interferometric displacement detection. The Fabry–Pérot interferometer is characterized by the finesse , defined as the ratio between the spectral selectivity and the free spectral range [5]. Both types of interferometers are suitable for precisely detecting small movements of one of the involved mirrors [6]. In contrast to a classical interferometer, the setup commonly involving a fiber end and a cantilever is characterized by a significant beam divergence and a small mirror area.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
