A Compact, Real-Time Optical Pyrometer for Hot Gun Barrel Detection

We propose a hot gun barrel detector utilizing a monolithic dual-waveband InGaAsP optical pyrometer for bore temperature measurement, combined with thermistors for barrel external temperature measurement. The unique aspect of this approach is theincorporation of a monolithic semiconductor pyrometer for non-contact temperature measurement using near-infrared radiation, using two (rather than one) wavelength bands to limit errors from varying emissivity and ambient conditions. Dual-waveband sensingwithout external optics is obtained by monolithically integrating two vertically-stacked InGaAsP PIN photodiodes, with the upper photodiode sensitive to shorter wavelengths and the lower photodiode sensitive to longer wavelengths. A hermetic package withlensed cap yields a complete dual-waveband pyrometer in a single miniature, rugged device with low manufacturing cost. Previous results demonstrate that low-noise temperature sensing can be achieved with un-cooled InGaAsP photodiodes. In Phase I, we willdevelop a prototype optical pyrometer, characterize its performance, and refine our device model. In Phase II we will develop prototype sensors for sub-scale testing, in collaboration with the Navy and a commercial defense electronics manufacturer. InPhase III we will demonstrate accuracy and reliability of the sensor system during extended gun firings and introduce a commercial system, in collaboration with a commercial defense electronics manufacturing partner. The output of this program will be acommercial dual-waveband pyrometer that is much smaller, more rugged, and lower in cost than comparable devices that are commercially available today. This product will displace single-waveband pyrometer assemblies from many industrial applications,providing both cost and performance advantages for non-contact temperature measurements above 200¿F, as widely employed in industries such as primary metals, glass, paper, and energy.