Title : Diode laser sensor for scramjet inlets

This work presents development of an oxygen-based diode laser absorption sensor designed to be used in a supersonic combustion ramjet engine inlet. The sensor uses free-space propagation of light from a vertical-cavity surface-emitting laser (VCSEL) to determine the temperature, velocity and angle of attack of an engine inlet in hypersonic flow. The report outlines the method of calculating these parameters based upon the absorption spectrum, calibrations of the system in a gas cell, tests of operation at high temperature and tests of the sensor in a hypersonic facility flow. The system in its current form is capable of measuring both freestream temperature and velocity at measurement rates of 150 Hz. Sensitivity to vibration and very low absorption values prevented the system from being able to determine the angle of attack. It is possible that, with more attention to reducing the effect of vibration, some information about the angle of attack may be obtained.