Dresden 2011 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 52: Precision Measurement and Metrology 3

Q 52.2: Talk

Thursday, March 17, 2011, 14:45–15:00, HÜL 386

Readout of satellite-satellite interferometer with 200km arms and nm precision — •Oliver Gerberding, Benjamin Sheard, Ioury Bykov, Joachim Kullmann, Gerhard Heinzel, and Karsten Danzmann — Max-Planck Institut for Gravitational Physics (Albert-Einstein Insitut) Hannover and QUEST, Leibniz University Hannover

In current geodesy mission like GRACE, Earth's gravity field is determined by measuring the precise variations in distance between two satellites in low Earth orbit. To improve this distance measurement, laser interferometry is the most promising candidate. A heterodyne interferometer between the satellites allows to measure their relative pointing and their distance variations with nm precision. The core of such an interferometer is the electronic phase readout system, called phasemeter. It tracks the phase with the required precision, while the heterodyne frequency is changing due to Doppler shifts introduced by relative satellite movements. The design of such a phasemeter is a very challenging task, since it needs to be able to handle technical noise, laser frequency noise and shot noise from receiving only a small amount of light.

Here we present our prototype design for such a phasemeter, able to measure heterodyne frequencies between 1 and 40MHz, and we show results from performance simulations and experiments.