Novel miniature spectrometer for remote chemical detection. 1998 annual progress report

'This research will develop an entirely new class of chemical sensing technology that will enable qualitative and quantitative remote, real-time optical diagnostics of chemical species in hazardous gas, liquid, and semi-solid phases through a completely novel implementation of evanescent wave spectroscopy. The sensor design uses a tiny, solid block (< 1 cm{sup 3}) of ultra-high purity optical material that is fabricated into a regular, planar polygon with a convex facet to form a total-internal-reflection ring cavity. Cavity ring-down detection measures the absorption of evanescent waves by chemical species in contact with the cavity. By interfacing the cavity to a remotely located light source and detection system (e.g., 0.1 to 10 Km away), this new technology will permit remote, high-sensitivity, broadband chemical sensing with a rugged, cost-effective, miniature spectrometer. This report summarizes work conducted after 1 year of a 3-year project.