Coherent Real-Time Terahertz Imaging for Packages and Personnel

A wide variety of non-intrusive optical sensing techniques in the ultra-violet, visible and near infrared spectral regions have become well-established tools for fundamental studies in combustion physics and chemistry in the laboratory. While these diagnostic techniques are well suited for visualizing complex reacting flow-fields and validating combustor design codes for advanced propulsion system development, the challenges posed by real-world propulsion systems limit their transition to on-board monitoring and control applications. Non-invasive remote sensors operating in the terahertz (THz) spectral region afford the promise of circumventing several limitations imposed by the harsh operating conditions of real-world combustors such as extreme ambient heat, pressure and vibration, limited optical access, two-phase flows, soot formation, background luminosity, and scattering. In addition, they offer significant potential for monitoring the health of gas-turbine engine components exposed to severe environments in situ. Foster-Miller proposes to develop novel THz sensors based on optoelectronic generation and coherent electro-optic detection of tunable monochromatic THz radiation using commercial off-the-shelf diode laser technology. The proposed SBIR Phase II effort will integrate mature laser and materials technologies into a compact, portable, rugged sensor that can perform rapid and accurate spectroscopic measurements on practical combustors over the widest possible range of THz frequencies. (P-040260)