Fibers Laugh at Danger
Light, sturdy fiber optic sensors can help monitor conditions in power plants, on airplane wings,
on dams and in other hard-to-reach places.
BY MARIE FREEBODY, CONTRIBUTING EDITOR
The composition of fiber optic sensors enables them to be placed in areas where traditional point sensors simply cannot go. “If you can glue it, wrap it,
wind it, bury it, encase it or bond it, fiber
optic sensing can monitor it,” said Paul
Richardson, senior product manager at Oz
Optics Ltd. of Ottawa, Ontario, Canada.
Today, fiber optic sensors are cropping
up in a variety of places, including turbine blades, power cables, airplane wings,
dams and levees, where they can be used
to measure strain, temperature, light intensity or even air pressure.
Compared with electrical sensors, fiber
optic sensors are lighter in weight and can
operate in extreme environments – and the
lack of electrical current running through
them means that they are not a spark hazard and are immune to electromagnetic
interference. This expands the number of
places in which this technology can be deployed to include power plants and other
highly sensitive environments.
“Hazardous or explosive environments
are fine for fiber optics, as there is no risk
of generating a spark,” Richardson said.
“Caustic environments are also acceptable,
since the fibers are made of silica glass.
High-EMF [electromagnetic force] areas
are good candidates for fiber optic sensing, since the method of measurement
is essentially immune to electromagnetic
“When properly designed, they are
also suitable for placement in areas of
ionizing radiation. We’ve even performed
measurements using fiber optics at 20
degrees Kelvin inside a cryostat.”
Thanks to decreasing instrumentation
A self-healing fiber optic sensor: (a) the polymer
filament connecting the glass fibers in the sensor;
(b) the filament has snapped off; (c) the resin has
rushed into the gap, been exposed to UV light and
reconnected the filament – effectively repairing itself.
Images courtesy of North Carolina State University.
costs and the ability to make measurements over increasingly long distances of
the fiber itself, these sensors are making
their way into some unusual places.
One such application with which engi-
neers at Oz Optics were tasked was to
monitor the strain when firing a large
gun. In this case, extreme levels of force
were being used to launch each round,
and the customer wanted to ensure that
the weapon was safe to fire.