Photonics Maintaining Competitiveness in the Information Era (1988) / Chapter Skim
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5. Opportunities in Sensor Technology
5. Opportunities in Sensor Technology
Pages 51-64
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From page 51... ...
As the push toward automation continues, the demands on the types, performance, and cost of sensors will grow. Optical sensors appear to offer performance and cost advantages that will enable many new applications to become possible.
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From page 52... ...
In process control applications such as are found In chemical processing plants or in power generation plants, it is desired to be able to determine fluid flow rates, liquid levels, temperatures, pressure, rates of mung, status of various components such as valves and switches, and electrical currents and voltages; to inspect remotely various pieces of equipment; and to monitor personnel status. Sensors to perform these functions must be tied together with a robust telemetry system capable of providing the required bandwidth and, in some cases, able to survive such adverse processes as electromagnetic interference (EMI)
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From page 53... ...
FIBER SENSORS After 8 years of development, optical fiber sensors are begs ng to emerge as competitive devices for performing sensing tasks such as those required for aircraft engine and flight controls, for shipboard machinery and damage controls, for medical probing, and for industrial process controls. Fiber sensors operate by having the perturbation to be measured (e.g., temperature, pressure, or displacement)
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From page 54... ...
Additionally, the compatibility of optical sensors with optical telemetry makes possible the development of all-optical, multielement sensor systems capable of supporting large numbers of high-bandwidth sensor elements while at the same time eliminating the requirement for transmitting electrical power to the sensor site from the monitoring site.4 This combination of compatible fiber sensors and fiber telemetry represents an intrinsic advantage over conventional electrical technology. In Appendix E, the operation of fiber sensors is detailed, and the state of the art outlined.
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From page 55... ...
Two types of fiber-optic magnetic sensors have been demonstrated, the Faraday effect sensors, which are useful for measurement of large magnetic fields ~ ~ 1 Oe) , and interferometric sensors utilizing magnetostrictive materials for high-sensitivity devices (<1 mOe)
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From page 58... ...
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From page 60... ...
These f~ber-optic devices replace conventional resistive bridges or magnetic induction position sensors. The first industrial application of these devices will undoubtedly be in hazardous/explosive environments where the all-dielectric nature of fiber sensors enhances safety.
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From page 61... ...
Devices resulting from these advances are finding application in strategic, tactical, and ecological reconnaissance and surveillance, both from the ground and from the air, as well as in consumer products such as miniature video cameras for various uses. Silicon technology was the early basic technology used in charge-coupled devices, and the first imaging CCDs were sensitive in the spectral region of 0.4 microns to 1.0 microns.
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From page 62... ...
While several fiber sensors are commercially available, compatibility among the sensor types has not been realized, and serious packaging of laboratory devices has occurred in only a few cases. Most of the fiber sensors listed in previous sections perform adequately in laboratory environments; however, drifts in calibration, due to environmental changes and other problems, have been encountered when poorly engineered or packaged devices have been fielded.
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From page 63... ...
laboratories, the difficulty in commercializing the technology rapidly relative to foreign competition is a major concern in the optical fiber sensor area. Projects to standardize fiber sensors, so that compatibility issues are resolved, and to integrate fiber telemetry are desirable.
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From page 64... ...
1982. Optical fiber sensor technology.
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