Coupling characterization and noise studies of the Optical Metrology System on-board the LISA Pathfinder Mission

摘要

In this article we describe the first investigations of the completeengineering model of the Optical Metrology System (OMS), a key subsystem of theLISA Pathfinder science mission to space. The latter itself is a technologicalprecursor mission to LISA, a space-borne gravitational wave detector. At itscore, the OMS consists of four heterodyne Mach Zehnder interferometers, ahighly stable laser with external modulator and a phase-meter. It is designedto monitor and track the longitudinal motion and attitude of two floatingtest-masses in the optical reference frame with a (relative) precision in thepicometer and nanorad range, respectively. We analyze sensor signalcorrelations and determine a physical sensor noise limit. The couplingparameters between motional degrees of freedom and interferometer signals areanalytically derived and compared to measurements. We also measure adversecross-coupling effects originating from system imperfections and limitationsand describe algorithmic mitigation techniques to overcome some of them. Theirimpact on system performance is analyzed in the context of the Pathfindermission.