Читать книгу Continuous Emission Monitoring - James A. Jahnke - Страница 129

Light sources used in CEM system analyzers emit in the ultraviolet, visible, and infrared regions of the spectrum. Advances in semiconductor electronics have led to the application of light emitting diodes (LEDs) and lasers in CEM analyzers. LEDs have largely supplanted the incandescent lamps once used in opacity monitors, and diode and quantum cascade lasers, alternatives to earlier broadband infrared light sources, have led to a new generation of extractive and in‐situ CEM system gas analyzers.