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18 June 2007 Adopting our heterodyne interferometer with sub-nm sensitivity for industrial position metrology
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The laser interferometer space antenna (LISA) mission utilizes as current baseline a high sensitivity optical readout for measuring the relative position and tilt of a free flying proof mass with respect to the satellite housing. The required sensitivities are ~5pm/&sqrt; Hz for the translation measurement and ~20 nrad/&sqrt;Hz for the tilt measurement. For this purpose, EADS Astrium GmbH - in collaboration with the Humboldt-University Berlin and the University of Applied Sciences Konstanz - develops a fiber-coupled heterodyne interferometer including differential wavefront sensing for the tilt measurement. The interferometer is based on a highly symmetric design where both, measurement and reference beam have the same optical pathlength, frequency and polarization. We realized a mechanically highly stable and compact setup which is located in a temperature stabilized vacuum chamber and utilizes frequency stabilization of the laser and intensity stabilization of the heterodyne frequencies at the fibre outputs. Noise levels below 5 pm/&sqrt; Hz in translation movement and below 10 nrad/&sqrt;Hz in tilt movement (both for frequencies above 10-2 Hz) were measured. While this setup is developed with respect to the requirements of the LISA space mission, it also has potential applications beyond: In industry, high precision position measurements - with ever increasing sensitivity - are needed e.g. for guaranteeing very small tolerances for automobile industry components. While current systems developed for this purpose use for instance whitelight-interferometry with resulting sensitivities in the nm-range, our interferometer opens the possibility to further improve the sensitivity. Here, we discuss possible implementations of our interferometer for industrial applications.
© (2007) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Thilo Schuldt, Martin Gohlke, Dennis Weise, Achim Peters, Ulrich Johann, and Claus Braxmaier "Adopting our heterodyne interferometer with sub-nm sensitivity for industrial position metrology", Proc. SPIE 6616, Optical Measurement Systems for Industrial Inspection V, 661649 (18 June 2007);

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