P3.2 - Robust, High-Performance Raman-OFDR System for Distributed Temperature Sensing

SENSOR+TEST Conferences 2011
2011-06-07 - 2011-06-09
Proceedings SENSOR 2011
P3 - Temperature / Humidity
W. Hill, M. Busker, B. Callsen, A. Dreß, M. Fromme, D. Gavrila, S. Ketzer, J. Kübler, M. Löbbert, I. Roda, B. Sagirkaya, M. Wildenauer - LIOS Technology GmbH, Köln (Germany)
725 - 725


Distributed temperature sensing (DTS) using Raman optical frequency domain reflectometry (Raman-OFDR) is known as a field-proven, reliable and economic technology for fire detection in tunnels and for temperature monitoring in power cables, pipelines, industrial ovens and oil wells. The semiconductor laser of the device does not show any wear because of the smooth modulation in continuous wave mode without high peak intensities.

We developed a novel, light-noise limited detection scheme for the Raman-OTDR DTS resulting in a clear improvement of sensing capabilities. The new system reaches comparable temperature and spatial resolutions an order of magnitude faster than conventional systems.

The increased sensitivity and speed can be used for extended distance ranges up to 40 km.

Spatial resolution has also been improved, and temperatures can be sampled every 10 cm. This enables DTS monitoring of industrial processes and plants such as metal melting, baking of composites, chemical processes, power generation, turbines and combustion engines.

The DTS is designed without any moving parts and with completely passive cooling. Therefore, it is basically maintenance-free and well-suited for permanent installations at remote locations.

The minimum measuring time for a complete temperature profile along an optical fibre is about 1 s. This high speed enables further applications in industry. Fire detection applications also benefit from the fast measurements. An approval for fire detection according to EN 54-22 is pending with a distance range being three times larger than for previous systems.