TitleDifferential optical shadow sensor for sub-nanometer displacement measurement and its application to drag-free satellites
Publication TypeJournal Article
Year of Publication2017
AuthorsZoellner A, Tan S
Secondary AuthorsSaraf S, Alfauwaz A, DeBra D, Buchman S, Lipa J
JournalOptics Express
Start Page25201
Date Published10/2017

We present a method for 3D sub-nanometer displacement measurement using a set of differential optical shadow sensors. It is based on using pairs of collimated beams on opposite sides of an object that are partially blocked by it. Applied to a sphere, our 3-axis sensor module consists of 8 parallel beam-detector sets for redundancy. The sphere blocks half of each beam’s power in the nominal centered position, and any displacement can be measured by the differential optical power changes amongst the pairs of detectors. We have experimentally demonstrated a displacement sensitivity of 0.87 nm/Hz at 1 Hz and 0.39 nm/Hz at 10 Hz. We describe the application of the module to the inertial sensor of a drag-free satellite, which can potentially be used for navigation, geodesy and fundamental science experiments as well as ground based applications.

Last modified Mon, 17 Dec, 2018 at 17:03