The Medium Intensity Approach Lighting System (MALSR) in use today at many airports throughout the United States employs many incandescent spot lamps. These lamps are relatively high wattage and, because of their relatively short life, require continual maintenance. Light emitting diodes (LEDs) have matured to the point that they can be considered to replace the inefficient incandescent lamps, especially when the latter are used with color filters. Under a Federal Aviation Administration (FAA) contract, Lighting Innovations Corporation (LIC) has developed LED based green runway threshold lamps for use in the MALSR. They already have been tested under flight conditions and are scheduled for full operational testing at several airports throughout the country. This paper addresses the advantages of LEDs over incandescents in this and other airfield lighting applications. Photometric, radiometric and spectral quantities are discussed, as are electrical, thermal and mechanical aspects of the project.
A fiber-optic hydrocarbon vapor sensor system was developed for environmental and industrial process monitoring in spill (alarm, level) and continuous (control) modes. The transducer consists of three optical fibers made reflective and optically coupled at their distal end, and mounted in a capillary. Light from an LED is launched in the source fiber, coupled to sensing and reference fibers at their distal ends, and fed back and monitored at the source. The optical transmission of a sensing fiber section is made sensitive to chemicals to be monitored and exposed to the ambient. Sensor system design and test results are presented. Its transductance can be altered easily by varying the geometry.
Simple, rugged intensity type fiberoptic vibration sensors have been developed and pre-production prototypes presently are being evaluated. The transduction element consists of a pair of multimode optical fibers, one mounted on a cantilever reed, the second on a fixed anvil. At frequencies well below the reed's resonant frequency, light coupled from one fiber to the other is directly proportional to the acceleration. The basic operating characteristics of the sensors, detailed laboratory test results and preliminary field data are presented.
Intensity type electric current sensors have been developed specifically for fault detection on electric power transmission lines. The transduction element consists of a pair of multimode optical fibers, one mounted on a ferromagnetic cantilever, the second on a fixed anvil such that light coupled from one fiber to the other is directly proportional to the magnetic field strength. The basic operating characteristics of the sensors, detailed laboratory test results and preliminary field data are presented. Their use for fault detection is also discussed.
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