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Proceedings Paper

Measurements of absolute long distances
Author(s): Florian Pollinger; Nicolae Radu Doloca; Karl Meiners-Hagen; Martin Wedde; Ahmed Abou-Zeid
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Paper Abstract

The production of large components, e. g. in aerospace industries, requires flexible and yet highly precise measurement techniques to determine absolute lengths of up to one hundred metres. Two different approaches are presented in this paper. One is based on a time-of-flight measurement, using a femtosecond frequency comb as an advanced modulator. By the combined phase analysis of lines of different distinct frequencies in the Mega- and Gigahertz frequency range, a measurement distance of one hundred metres with a relative measurement uncertainty of 1x10-7 was achieved in laboratory conditions. In a second approach to long distance measurements, two standard interferometric measurement techniques, i.e. variable synthetic and fixed synthetic wavelength interferometry, were combined. The two interferometry techniques were realised within a single set-up, using two external cavity diode lasers as sources. Experimentally, lengths of up to twenty metres could thus be determined with relative uncertainties below 1x10-6, in good agreement with theoretical analysis. Both techniques, femtosecond fibre laser-based time-of-flight and diode laser-based multiwavelength interferometry, are therefore capable of absolute, guidance-free long distance measurements and have achieved demonstrated relative measurement uncertainties below 1x10-6 for distances over ten metres.

Paper Details

Date Published: 31 December 2010
PDF: 10 pages
Proc. SPIE 7544, Sixth International Symposium on Precision Engineering Measurements and Instrumentation, 754445 (31 December 2010); doi: 10.1117/12.885596
Show Author Affiliations
Florian Pollinger, Physikalisch-Technische Bundesanstalt (Germany)
Nicolae Radu Doloca, Physikalisch-Technische Bundesanstalt (Germany)
Karl Meiners-Hagen, Physikalisch-Technische Bundesanstalt (Germany)
Martin Wedde, Physikalisch-Technische Bundesanstalt (Germany)
Ahmed Abou-Zeid, Physikalisch-Technische Bundesanstalt (Germany)

Published in SPIE Proceedings Vol. 7544:
Sixth International Symposium on Precision Engineering Measurements and Instrumentation
Jiubin Tan; Xianfang Wen, Editor(s)

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