Readout for intersatellite laser interferometry: Measuring low frequency phase fluctuations of high-frequency signals with microradian precision

Oliver Gerberding, Christian Diekmann, Joachim Kullmann, Michael Troebs, Ioury Bykov, Simon Barke, Nils Christopher Brause, Juan Jose Esteban Delgado, Thomas S. Schwarze, Jens Reiche, Karsten Danzmann, Torben Rasmussen, Torben Vendt Hansen, Anders Enggaard, Søren Møller Pedersen, Oliver Jennrich, Martin Suess, Zoran Sodnik, Gerhard Heinzel

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Precision phase readout of optical beat note signals is one of the core techniques required for inter-satellite laser interferometry. Future space based gravitational wave detectors like eLISA require such a readout over a wide range of MHz frequencies, due to orbit induced Doppler shifts, with a precision in the order of µ rad/root Hz at frequencies between 0.1 mHz and 1 Hz. In this paper, we present phase readout systems, so-called phasemeters, that are able to achieve such precisions and we discuss various means that have been employed to reduce noise in the analogue circuit domain and during digitisation. We also discuss the influence of some non-linear noise sources in the analogue domain of such phasemeters. And finally, we present the performance that was achieved during testing of the elegant breadboard model of the LISA phasemeter, which was developed in the scope of a European Space Agency technology development activity. (C) 2015 AIP Publishing LLC.
Original languageEnglish
Article number074501
JournalReview of Scientific Instruments
Issue number7
Number of pages12
Publication statusPublished - 2015

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