Antenna-coupled microbolometers for multi-spectral infrared imaging

Although the rapid development of 2-D focal plane arrays of thermal infrared (IR) detectors has led to remarkable progress in uncooled IR imaging technology, a major limitation of these sensors is the lack of true on-chip spectral discrimination. Multi-spectral detection capabilities enable rapid, efficient and multi-dimensional scene interpretation that is especially beneficial to advanced IR imaging systems for early threat warning and target recognition applications. We propose a novel design for a monolithic micromachined array of bolometric detectors capable of multi-spectral imaging in the long-wave IR (7-14 mu m) region. The central ingredient of this approach is to employ planar multi-mode antenna structures to efficiently couple incident electromagnetic radiation to a microbolometeric sensing element that is much smaller than the IR wavelength. The wavelength selectivity of such an antenna-coupled detector can be tuned by optimizing its multiple geometric parameters. We present a planar microbolometer design that can accomplish 3-color LWIR imaging with no moving parts analogous to solid-state color videography in the visible region. The proposed effort targets applications of uncooled color IR imaging where the benefits in space, power, weight and complexity will have a significant impact.