Recent environmental concerns have greatly increased the need, application and scope of
real-time continuous emission monitoring systems. New techniques like Fourier
Transform Infrared have been applied with limited success for this application. However,
the use of well-tried and established techniques (Gas Filter Correlation and Single Beam
Dual Wavelength) combined with sophisticated microprocessor technology have
produced reliable monitoring systems with increased measurement accuracy.
David L. Dillehay,
"Multicomponent analysis using established techniques", Proc. SPIE 1434, Environmental Sensing and Combustion Diagnostics, (1 April 1991); doi: 10.1117/12.48461; https://doi.org/10.1117/12.48461