Simultaneous temperature and relative [O.sub.2]-[N.sub.2] concentration measurements by single-shot pure rotational coherent anti-Stokes Raman scattering for pressures as great as 5 MPa

Dual-broadband pure rotational coherent anti-Stokes Raman scattering is a valuable nonintrusive tool for gas diagnosis that provides simultaneous and time-resolved information about temperature and relative species concentration. A systematic investigation of single-shot precision and accuracy of simultaneous measurement of temperature and [O.sub.2]/[N.sub.2] concentration is presented. Various 02 concentrations(1.0-15.6%) in binary mixtures with [N.sub.2] have been investigated in a temperature range from 300 to 773 K and for pressures of 1-50 bars (0.1-5 MPa). A comparison of two least-sum-squared differences fit evaluation procedures for the spectral shape, weighted constantly or inversely with respect to the relative signal intensity, is given. The results yielded good accuracy and precision for measuring temperature as well as concentration. The influence of temperature, [O.sub.2] concentration, pressure, and evaluation techniques on both accuracy and precision is discussed. [C] 2000 Optical Society of America OCIS codes: 120.0120, 120.6780, 300.6230, 300.6420, 290.5860.