Abstract: Increasing levels of electromagnetic interference (EMI) coupled with the increasing use of composite materials on aircraft have created awareness and concern for susceptibility and weight of existing shielded electronics. Optical sensing techniques offer a solution due to their inherent immunity to EMI. Rosemount Inc.'s Aerospace Division has been developing an optical temperature sensor designed for aircraft and engine environments based on the fluorescent time rate of decay (TRD) principle. The TRD technique uses light from a source to excite fluorescence in an optical material. This fluorescence decays exponentially with a time constant which is a function of the temperature of the material. The key to this technique in aerospace applications is in the choice of the fluorescent material. The material properties must lend themselves to aerospace temperature ranges, the use of aerospace quality optical components, and high accuracy measurements. A demonstration system has been built and tested using 200 micron fiber and an LED light source. The fluorescent material is embedded in an element designed to allow the optical sensing element to replace the platinum resistance temperature sensing element in many of our existing military-qualified sensor products. The single fiber sensor is connected to an electro- optics unit which provides the excitation light, reads the fluorescent return signal, and calculates the temperature. This paper discusses the state of development of the current TRD demonstration system. !6
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