Antenna-coupled microbolometer arrays with aerogel thermal isolation

Uncooled bolometric detectors used in infrared imaging systems have slow response times (similar to10 ms) which makes them impractical for fast-frame-rate applications. Antenna-coupled microbolometer arrays have been shown to have fast response times (similar to130 ns) and can be used as picture elements in infrared imaging systems but lack sufficient responsivity. Thermal isolation of antenna-coupled microbolometer arrays will increase its responsivity but will also increase its response time. Thermal isolation can be achieved using silica aerogel as a substrate, and its porosity can be used to modify the thermal conductivity down to values lower than air. In this paper antenna-coupled microbolometer arrays were fabricated on a substrate coated with a thin film of aerogel, noise, response and radiation characteristics were measured and compared to similar devices fabricated on a SiO2 substrate. The measured signal-to-noise ratio of devices fabricated on aerogel were one order of magnitude higher than devices fabricated on SiO2 and had time constants around 5 mus. (C) 2003 Elsevier B.V. All rights reserved.