Optics comprise key subsystems for hypersonic vehicles. They are used in targeting and communications and have the potential to be applied to directed energy (or laser) systems. Aaron Fassler's research concerns optical window performance in hypersonic conditions. To weather the extreme temperatures of hypersonic flow, an optical window may be cooled by blowing another gas (nitrogen, e.g.) across it. This, however, creates a mixing layer that produces high levels of optical distortion. Through use of Schlieren and Shack-Hartman Wavefront Sensor (SHWFS) measurement techniques, Aaron's research aims to produce a better model for aero-optical distortions in these kind of mixing layers.
Schlieren image showing cooling flow blown over a window and interacting with the supersonic freestream flow.
Wind tunnel with the Schlieren system setup.