An Investigation of the Use of the Fabry-Perot Interferometer for Flow Field Diagnostics Using Raman Scattering
Final rept. 1 Jul 1974-21 Jul 1975
ARNOLD ENGINEERING DEVELOPMENT CENTER ARNOLD AFB TN
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A new interferometric technique for the detection of rotational Raman scattering was demonstrated. The technique involves the use of a Fabry-Perot interferometer to simultaneously pass all of the rotational lines from a single molecular specie while at the same time rejecting interfering light from other molecular species and that of Rayleigh scattered light. Data were obtained for total ground state rotational Raman scattering intensity versus interferometer plate separation. Calculations are presented which predict the rotational temperature dependence of the transmitted intensity of the Fabry-Perot interferometer. The use of the technique for both rotational and vibrational temperature measurements as well as determination of molecular number density is discussed. The results of this study indicate that a significant increase in sensitivity for a Raman scattering measurement of both density and temperature can be obtained using Fabry-Perot interferometry. Additionally, it was found that, for a wide temperature range, the N2 density measurement can potentially be made without knowledge of the gas temperature.
- Test Facilities, Equipment and Methods
- Fluid Mechanics