TY - JOUR A1 - Liehr, Sascha A1 - Muanenda, Y. S. A1 - Münzenberger, Sven A1 - Krebber, Katerina T1 - Relative change measurement of physical quantities using dual-wavelength coherent OTDR JF - Optics Express N2 - We propose the use of alternating pulse wavelengths in a direct-detection coherent optical time domain reflectometry (C-OTDR) setup not only to measure strain and temperature changes but also to determine the correct algebraic sign of the change. The sign information is essential for the intended use in distributed mode shape analysis of civil engineering structures. Correlating relative backscatter signal shifts in the temporal/signal domain allows for measuring with correct magnitude and sign. This novel approach is simulated, experimentally implemented and demonstrated for temperature change measurement at a spatial resolution of 1 m. KW - Fiber optics sensors KW - Backscattering KW - Rayleigh KW - C-OTDR KW - Distributed sensing KW - Temperature measurement KW - Strain measurement PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-389449 DO - https://doi.org/10.1364/OE.25.000720 SN - 1094-4087 VL - 25 IS - 2 SP - 720 EP - 729 PB - Optical Society of America CY - Washington, DC, USA AN - OPUS4-38944 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -