Friday, 4 May 2012

Specialty Optical Fiber Design for Commercial Intrinsic Fiber Sensors

Your opportunity to read the paper presented by Dr Chris Emslie at the SPIE Defense, Security & Sensing Conference in Baltimore on Friday 27th April.

Below is the introduction to Chris' White Paper, the full copy can be downloaded from our website.
After 30 years of promise, and in some cases one or more false-starts, intrinsic fiber sensors based on 'Specialty' optical fibers are at last becoming a genuine, commercial reality.  The first sensor to achieve this status is undoubtedly the fiber optic gyroscope (FOG) which has grown steadily in volume over the past decade and has now gained widespread acceptance as a high reliability alternative to both conventional, spinning-mass and also ring-laser gyroscopes.  FOG is now being joined by both current-sensors and sensors for a broad-range of measureands, based on well-established acoustic, seismic and non-linear scattering techniques, primarily for oil-extraction and civil engineering.  It is safe to say that this 30 year gestation has proved far longer than anyone had either expected or hoped.  However, scientists and engineers should take some comfort that this delay owes little, if anything, to the strength or state of the underlying technology.
Fiber Hydrophone Schematic
In some cases, for example FOG, the root-cause lies in the conservatism of a customer base dominated by Defence and Aerospace that necessarily views 'new' technologies as un-tested and therefore potentially unreliable.  In others, product development has been slowed by significant and global skills shortages, when one project has taken clear precedent over another - a phenomenon that led to the commercialisation of the erbium doped fiber amplifier an entire decade before the fiber laser.  In others still, such as fiber optic current sensors and hydrophones, the market simply has not been ready - either because existing technologies fulfilled the current need, or were too well-entrenched for easy (or willing) substitution.  Although the road to commercial acceptance has been a long and difficult one, the path has been eased significantly by the availability of 'Specialty Fibers' either adapted, or designed specifically for sensors.  This paper identifies seven principal fiber design considerations, bend-insensitivity, jointing characteristics, reliability, birefringence and mechanical stiffness and references their significance in the context of three types of fiber sensor that have either achieved, or are close to achieving commercial accpetance:  FOG, acoustic and seismic sensors and current-sensors.
Copies of the presentation are available by contacting