Читать книгу Continuous Emission Monitoring - James A. Jahnke - Страница 137

Lasers, of course, are used in gas analyzers to monitor at specific wavelengths. Before the advent of lasers, it was necessary to restrict or separate the wavelengths at which molecules absorb from the spectra emitted from broadband radiation sources. Optical filters and diffraction gratings were and still are used to do this in spectroscopic CEM system analyzers. To manufacture an analyzer, it is often easier and less expensive to utilize broadband emission sources, coupled with spectral limiters such as gratings and filters.