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5 July 2000 Demonstration of nanometer-level active metrology for long-range interferometric displacement measurements
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We report on the laboratory demonstration of an active linear metrology scheme using two separate lasers. In `active' metrology, the passive retroreflector in one arm of a typical heterodyne interferometer is replaced with an active optical transponder. The Transponder can dramatically boost the returned signal strength, thereby providing a way to perform metrology and pathlength control over long (> km) distances. Two Lightwave Electronics non-planar ring oscillator lasers at a wavelength of 1.319 micrometers were used as the Source and Transponder. The frequency of the Transponder is offset locked to the signal received from the Source using the Lightwave Laser Offset Locking Accessory, and the Transponder beam is sent back to the Source. The phases of the beat signals are measured locally at the Source and Transponder by appropriately demodulating the signal, and post-processed to determine displacement. In initial experiments, the standard deviation of the measurement errors was less than three nanometers.
© (2000) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Muthu Jeganathan and Serge Dubovitsky "Demonstration of nanometer-level active metrology for long-range interferometric displacement measurements", Proc. SPIE 4006, Interferometry in Optical Astronomy, (5 July 2000);

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