A dynamic fiber optic strain and power change sensor

A dynamic and quasi-distributed sensor principle for simultaneous measurement of length changes and optical power changes between reflection points in an optical fiber is presented. The technique is based on the incoherent optical frequency domain reflectometry (I-OFDR). Length change resolutions <1 mu m and measurement repetition rates up to 2 kHz can be achieved using standard single-mode and multi-mode optical fibers. Dynamic length change measurement results as well as field test results showing the deformation of a masonry building under seismic load are presented. Promising fields of application for this technique are the structural health monitoring sector and chemical process control.