THz Differential Absorption Radar for Bioparticulate Detection

Recent measurements of the electromagnetic transmission through bacillus subtillus, an anthrax facsimile, have revealed absorption resonances in the THz region. A system-level analysis previously carried out by the proposer has shown that at least oneof the resonances (centered at 14.05 cm-1, or 421 GHz) is located at a frequency of low enough atmospheric absorption to be detectable by an active remote sensor at a significant stand-off. The proposed STTR effort would construct such a sensor as adifferential absorption radar using all solid-state components. All components are commercially available except the highly-tunable, mW-level coherent source required to make a useful transmitter for field applications. The transmitter will be developedthrough this STTR project in collaboration with the Jet Propulsion Laboratory (JPL) who have in-house solid-state source technology that can produce up to approximately 10 mW cw in the 420-GHz region with a tunability of at least 5 %. In Phase I, theproposer will integrate the JPL source into a working bench-top 420 GHz transmitter, construct a working direct (incoherent) receiver with off-the-shelf electronics, and combine the transmitter and receiver in a working sensor demonstration. Thisdemonstration will be carried out with innocuous bioparticles (e.g., baccilus subtillus) that may be provided by the Government Sponsor. If successful this project will produce the first known sensor capable of measuring low densities of bioparticle at alarge stand-off. The commercial applications of such a sensor would be in counter-terrorism and in public health (monitoring the movement of human disease).