Differential optical shadow sensor for sub-nanometer displacement measurement and its application to drag-free satellites

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 b...

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Bibliographic Details
Published inOptics express Vol. 25; no. 21; pp. 25201 - 25211
Main Authors Zoellner, Andreas, Tan, Si, Saraf, Shailendhar, Alfauwaz, Abdul, DeBra, Dan, Buchman, Sasha, Lipa, John A
Format Journal Article
LanguageEnglish
Published United States 16.10.2017
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Summary: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 0.87nm/Hz at 1 Hz and 0.39nm/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.
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ISSN:1094-4087
1094-4087
DOI:10.1364/OE.25.025201