A HOLOGRAPHIC INTERFEROMETER SPECTROMETER FOR HYPERSONIC FLOW

HOLOGRAPHIC INTERFEROMETRY, WIDELY USED FOR DIAGNOSIS OF FLOW FIELDS, PROVIDES AN INSTANTANEOUS, THREE-DIMENSIONAL DENSITY DISTRIBUTION BY OBSERVATION OF THE FRINGE VARIATIONSOF AN INTERFEROGRAM. WHEN OPTICAL PATH-LENGTH CHANGES ARE MUCH LESS THAN A WAVELENGTH OF LIGHT, THE FLOW FIELD CAN BE EASILY OBSERVED. WHEN OPTICAL PATH-LENGTH CHANGES ARE MUCH LESS THAN A WAVELENGTH OF LIGHT, THE PROBLEM IS COMPLICATED SINCE FRINGE SHIFTS ARE BARELY VISIBLE. A PROBLEM OF CURRENT CRITICAL INTEREST IN AERODYNAMICS IS THE DIAGNOSIS OF HYPERSONIC FLOWS INVOLVING LOW DENSITIES, SHORT PATH- LENGTHS, AND THE MIXING OF FLOWS. AS A RESULT, IMPROVED SENSITIVITY AND THE ABILITY TO DISTINGUISH CONSTITUENTS ARE NEEDED. THIS PROJECT COMBINES UNIQUE AND INNOVATIVE CONCEPTS WITH STATE-OF-THE-ART HARDWARE TO IMPROVE SENSITIVITY AND INFORMATION CONTENT BY ORDERS OF MAGNITUDE OVER CURRENT SYSTEMS. SPECIFICALLY, THE INNOVATIONS INCLUDERECORDING THE FOURIER TRANSFORM AT RESONANCE WITH TURNABLE OR MULTIPLE WAVELENGTH LASERS AND RECONSTRUCTING WITH A NEW PHASE SHIFTING TECHNIQUE. THIS SYSTEM WILL HAVE APPLICATIONS IN INDUSTRIES REQUIRING FLOW DIAGNOSES IN HYPERSONIC WIND TUNNELS, COMBUSTION FACILITIES, AND OTHER TYPES OF TEST FACILITIES.