Multispecies Raman imaging in flames by use of an unintensified charge-coupled device

The application of an unintensified charge-coupled device (CCD) to one-dimensional multispecies Raman flame imaging is demonstrated. Relative signal strength is improved by the higher quantum efficiency of the unintensified CCD versus an intensified CCD generally used for Raman imaging. Experimental comparisons of unintensified and intensified CCD systems show ~40% improvement in the signal-to-noise ratios of major-species Raman signals for laboratory-scale H(2)-air flames. The maximum possible signal improvement is limited by the 40% transmission efficiency of the ferroelectric liquid-crystal light valve used to gate the CCD, although the light valve is demonstrated to be unnecessary for low-luminosity flames.