Development of a rugged, fuel tank compatible, oxygen concentration sensor

We propose to engineer a compact, robust, optically-based sensor for measuring local oxygen concentration in aircraft fuel tanks. This system will utilize absorption of rapidly scanned Vertical Cavity Surface Emitting Diode Lasers (VCSELs) by molecular oxygen. This proposed system can measure 100 ppm to 100% oxygen in ambient temperatures from -100 to 300 F utilizing a new spectroscopic frequency domain detection scheme known as the wavelength agile spectral-harmonic (WASH) technique. The wavelength agile aspect of the laser source allows for temperature insensitive measurements of oxygen concentration over a wide range of pressures (0.1 atm to 50 atm). The system will also possess auto-calibration capabilities, the ability to withstand temporary immersion in all liquid fuels, fast time response (100 msec), and long operating life (> 10,000 hrs).