Stuttgart 2012 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 28: Präzisionsmessungen und Metrologie 4
Q 28.7: Vortrag
Dienstag, 13. März 2012, 15:30–15:45, V47.02
Highly Reproducible Sub-Nanometer Surface Characterisation of Laser Mirrors for Satellite-to-Satellite Picometer Metrology — •Harald Kögel1, Martin Gohlke1,3, Thilo Schuldt2, Ulrich Johann1, Claus Braxmaier1,2, and Dennis Weise1 — 1Astrium GmbH - Satellites, Friedrichshafen, Germany — 2University of Applied Sciences Konstanz, Germany — 3Humboldt-Universität zu Berlin, Germany
Within the alternative payload concept IFP (In-Field Pointing) for the LISA (Laser Interferometer Space Antenna) space mission seasonal angular changes in the triangular formation of the three spacecraft are compensated by changing the line of sight of their telescopes with a small actuated mirror, the IFP-Mechanism. This mechanism is located in a pupil plane of each telescope. During actuation the laser beam is scanning over the surface of the optical components in its path. This leads to changes in optical path length due to their surface roughness and could negatively influence the targeted picometer-sensitivity of the optical metrology system. We present a measurement setup developed to characterise the surface of laser mirrors within sub-nanometer accuracy at a high level of reproducibility. As measuring device a heterodyne interferometer is used. The optical components are accommodated in a pendulum specifically designed for this purpose that is suspended on a monolithic hinge and driven by a linear piezo-stepping actuator. With this pendulum the optical components can be precisely moved through the laser beams of the interferometer whereby the surface is measured highly reproducible with a deviation < 0.2nm (rms).