Advanced imaging and spectroscopy of biological and chemical agents at terahertz frequencies

We are developing hot electron bolometer (HEB) mixer receivers for heterodyne detection at terahertz frequencies. HEB detectors provide unprecedented sensitivity and spectral resolution at terahertz frequencies. Terahertz imagers based on HEB technology have sufficient sensitivity to operate in a passive imaging mode, thus eliminating the need for active illumination. HEB mixers have, therefore, become the detectors of choice for applications requiring low noise temperatures at frequencies from 0.5 THz to 10 THz. Previously, we have developed receivers and focal plane arrays operating near the quantum noise limit for astrophysical applications. We have demonstrated a low-noise heterodyne focal plane array (FPA) operating at 0.85 THz. HEB technology is becoming the basis for advanced terahertz imaging and spectroscopic technologies for the study of biological and chemical agents over the entire terahertz spectrum. We also demonstrated a fully automated passive imaging system based on our HEB technology. Our high spectral resolution terahertz imager has a noise equivalent temperature difference (NE Delta T) value of better than 0.5 K and a spatial resolution of a few millimeters.