31 December 2010 Measurements of absolute long distances
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Proceedings Volume 7544, Sixth International Symposium on Precision Engineering Measurements and Instrumentation; 754445 (2010); doi: 10.1117/12.885596
Event: Sixth International Symposium on Precision Engineering Measurements and Instrumentation, 2010, Hangzhou, China
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.
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Florian Pollinger, Nicolae Radu Doloca, Karl Meiners-Hagen, Martin Wedde, Ahmed Abou-Zeid, "Measurements of absolute long distances", Proc. SPIE 7544, Sixth International Symposium on Precision Engineering Measurements and Instrumentation, 754445 (31 December 2010); doi: 10.1117/12.885596; https://doi.org/10.1117/12.885596
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KEYWORDS
Distance measurement

Interferometry

Semiconductor lasers

Frequency combs

Femtosecond phenomena

Interferometers

Diodes

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