A number of fiber optic sensors for geophysical applications have been developed over the past two decades at the Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography. These include: a strain sensor to monitor ice flow in Antarctica, a strain sensor to track sediment creep on the ocean bottom, a borehole strain sensor to monitor fault movement during earthquakes, a pressure sensor to detect low frequency acoustic waves, and a seismometer. All of these sensors utilize one of two interrogation techniques. The first is a commercially made electronic distance meter which, by measuring the transit time of light pulses through the sensing fiber, can track changes in a 1000-m-long fiber with a precision of about 1 mm. The second technique is interferometry. For this purpose, a quadrature fringe resolver based on a digital signal processor has been developed. It combines wide dynamic range (centimeters) with high resolution (picometers). Continuous records spanning days to years have been obtained with these instruments.

Date Published: 12 October 2007
PDF: 9 pages
Proc. SPIE 6770, Fiber Optic Sensors and Applications V, 67700Q (12 October 2007); doi: 10.1117/12.735921

Published in SPIE Proceedings Vol. 6770:
Fiber Optic Sensors and Applications V
Eric Udd, Editor(s)