Frankfurt 2006 – scientific programme

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Q: Quantenoptik und Photonik

Q 67: Präzisionsmessungen II

Q 67.6: Talk

Thursday, March 16, 2006, 15:15–15:30, HIV

Optical Metrology System of the LISA Gravitational Wave Detector — •Dennis Weise¹, Claus Braxmaier^1,2, Peter Gath¹, Hans-Reiner Schulte¹, Ulrich Johann¹, and Marcello Sallusti³ — ¹EADS Astrium GmbH, Claude-Dornier-Str., 88090 Immenstaad — ²Fachhochschule Konstanz, Brauneggerstr. 55, 78462 Konstanz — ³European Space Agency, P.O. Box 299, 2200 AG Noordwijk ZH, The Netherlands

We give an overview of the current status of the optical metrology system utilized within the Laser Interferometer Space Antenna (LISA) satellites for gravitational wave detection. In order to achieve a strain sensitivity in the range of 10⁻²⁰/√Hz at 5 mHz with a 5 million kilometer arm length, an absolute measurement accuracy of about 10 pm/√Hz is required. Heterodyne interferometry with differential wavefront sensing is employed as main metrology principle. The current design foresees a strap-down concept, in which an optical readout provides position as well as attitude information of the free floating proof mass with respect to the local optical bench (cf. talk by Thilo Schuldt, Humboldt-Universität zu Berlin). This measurement is combined with a second interferometric measurement of the distance between the local and the remote optical bench to yield the science signal for one interfermeter arm. A frequency swap between transmitted and local reference beam is introduced to reduce the effect of straylight on the 100 pW measurement beam.