Development of a Rugged, Fuel Tank Compatible, Oxygen Concentration Sensor

The objective of the proposed Phase II effort is to transfer proven sensor technology from the laboratory breadboard to a functional flight-ready prototype for installation in an aircraft fuel tank. In the Phase I effort, a novel spectroscopic technique was shown to be an effective method for measuring oxygen concentration in harsh environments with sufficient accuracy for use in an OBIGGS system. This system utilizes rapidly scanned Vertical Cavity Surface Emitting Diode Lasers (VCSELs) to measure oxygen concentration by molecular absorption. This system can measure 1000 ppm to 100% oxygen in ambient temperatures from -60 to 150 F utilizing as the wavelength agile spectral-harmonic (WASH) technique. The wavelength agile aspect of the laser source/detection technique allows for temperature insensitive measurements of oxygen concentration over a wide range of pressures (0.3 atm to 2 atm) with high accuracy as well as with auto-calibration capabilities. The Phase II effort is focused on packaging this sensor technology in a form that is able to be inserted into an operational aircraft fuel tank and conform to a set of environmental and operational requirements as defined by both the OBIGGS needs as well as the fuel tank environment. Furthermore, achievement of the Phase II goal requires the miniaturization of the laser driver, data collection, and data processing functions into flight-scale electronic hardware.