SHIELDS -- A Spatial Heterodyne Interferometer for Emergent Line Discrimination Spectroscopy

This proposal advocates the development of the Spatial Heterodyne Interferometer for Emergent Line Discrimination Spectroscopy (SHIELDS), a camcorder-sized spectrometer unit which detects chemical, biological, and radiological contaminants using Fraunhofer Line Discrimination. Rapid detection of contaminants is a vital part of battlespace terrain reasoning and awareness. The Spatial Heterodyne Spectrometer (SHS) at the heart of SHIELDS combines the high resolution and throughput of conventional interferometers with the robustness of grating spectrometers, making SHIELDS the ideal instrument for this application. SHIELDS easily attains the 0.2-Å resolution required to assuredly detect the Fraunhofer lines in question (the prototype will be designed for the sodium doublet at 589 nm). It also much more robust than conventional interferometers (Michelson, Fabry-Perot), which require scanning mechanisms to work at their full resolving power. It is thus much more robust, especially in the monolithic configuration used in SHIELDS, where the interferometer's main optical elements are fused into a single block. The SHIELDS unit will detect contaminants in real time (at least 30 measurements per second) at sensitivities 100 times higher than what standard grating spectrometers can achieve. It will also detect simultaneous reference frames, for immediate calculation and detection of contaminants.