fiber-optic sensor

Fiber-optic sensor

A sensor that uses thin optical fibers to carry light to and from a location to be probed. In performing the sensing, light can be lost from the fibers or modified in velocity by the action of the phenomena on the fiber. Fiber-optic sensors are ideal for probing in remote or hostile locations, where miniature sensors are required such as in the body, or where extreme sensitivity is required. Two classes of fiber sensors have evolved: intensity sensors, in which the amplitude of light in the fiber is changed during sensing, and interferometric sensors, in which the velocity of light or its phase is modified during sensing. The latter class has proved to be extremely sensitive; intensity sensors are used where moderate performance is acceptable and lower cost is important. Depending on their design, intensity sensors can respond to pressure, temperature, liquid level, position, flow, smoke, displacement, electric and magnetic fields, chemical composition, and numerous other conditions.

Optical interferometry is one of the most sensitive means of detecting displacements as small as 10-13 m. Interferometric fiber sensors apply this technology to sense many physical phenomena. A fiber gyro based on the Sagnac effect is formed by making a fiber loop which, when rotated, causes the light traveling in both directions in the loop to experience different velocities with or against the rotation. A second type of interferometric sensor is constructed by using the Mach-Zehnder interferometer. Sensitivities equal to or surpassing the best conventional technologies have been achieved in these sensors. See Interferometry

fiber-optic sensor

[′fī·bər ¦äp·tik ′sen·sər]
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References in periodicals archive ?
Omron Electronics has introduced the E3X-DAG, a one-of-a-kind white LED fiber-optic sensor for detecting true colors in marks and workpieces.
A new and reportedly unique control system uses a fiber-optic sensor for real-time monitoring and control of both film color and layer thicknesses.
Since the fiber-optic sensor operates with light waves rather than electrons, it has several advantages over conventional electronic strain gauges: ruggedness, absence of drift, and immunity to electromagnetic noise.
The Pyrofiber single-axis fiber-optic sensor head for measuring precise IR temperatures and emissivity values of miniature targets is now available.
It combines the effectiveness and strength of a decorative metal fence with a fiber-optic sensor that is impossible to see.
The fiber-optic sensor system functionality is described and a comparison is made between the three techniques.
The fiber-optic sensor does not depend on the intensity of the signal, which can change with the bending of the fiber, Belleville said.
In the short term, fiber-optic sensor systems do involve increased costs; however, FHWA is attempting to discover what increased benefits and cost-saving advantages they may have for the long term.
NIST research associate Dara Woerdeman says that until now, application of fiber-optic sensor technology in process applications such as RTM has been limited by the low refractive index of the optical fiber relative to the matrix resin.

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