Broadband CARS measurement techniques of detecting species concentration in a flame were improved and applied to a laboratory flat flame burner. A novel phase-match method for generating CARS signal, which is dubbed Minimum Angle Crossed beam method (MAC), was employed to increase the S/N ratio under adverse conditions. This method gave rise to the signal enhancement of an order of magnitude higher than that of the BOXCARS arrangement. It was revealed that the single pulse method made it possible to measure O
2 concentration down to 2% fraction. A high-pressure Ar cell was required to compensate for the time-varying dye laser wavelength distribution. It was tentatively evaluated that the error introduced in the single pulse measurement was 1% in O
2 concentration of 2-10% and 1700-1900 K temperature range.
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