A Simple, Inexpensive Approach to Real-Time Calibration of Radiometric Instrumentation

40208 Ion Optics, Inc. Infrared instruments, used to measure solar fluxes and map atmospheric pollutants, require frequent calibration to correct for thermal drift and other sources of error, and to maximize instrumental sensitivity. This is done with blackbody sources that depend upon large size and thermal mass to achieve uniform temperature; therefore, they are unsuitable for incorporation directly into the instrument. Also, calibration is infrequent and difficult, particularly for instruments stationed at inaccessible locations. This project will develop a miniature, electrically-modulated blackbody source weighing a few grams and occupying a fraction of a cubic centimeter. The heart of this source is an ion-beam textured filament which achieves temperature stability by heating and cooling on a time scale much faster than thermal diffusion. Its low thermal mass, near-perfect emissivity, and high temperature coefficient of resistivity cause it to precisely follow its drive current, permitting instantaneous feedback and temperature control. Its low power demand will permit remote, battery-powered operation under computer control. Anticipated Results/Potential Commercial Applications as described by the awardee: The proposed device is a simple, light-weight alternative to traditional benchtop blackbody sources. By reducing weight, complexity, and cost, it should enable applications beyond the reach of current infrared devices. These applications range from simple IR-absorption gas monitoring to in-flight calibration of complex astronomical instruments.