M odern gas sensing systems capable of measuring concentrations of various types of gases are becoming more and more important in areas of fuel combustion or pollution control.
The gases of interest comprise trace gases like greenhouse gases carbon dioxide (CO2) or methane (CH4) but also chemically reactive gases like ozone (O3) or oxides from sulfur or nitrogen (SO2 or NOx). Optical gas sensor systems are particularly interesting for remote or in-situ sensing applications.
Here, SLEDs (together with spectrometers) in the visible or near-infrared wavelength regime, for example, are used to generate high-power broadband light emission. Certain gas species are then detected and their concentration is measured through the spectral position and the strength of certain absorption lines, typically related to specific vibrational transitions of the particular gas molecules .
Swept sources (ESS) of high power and narrow linewidths (together with a photo-receiver) can also be used for such applications. EXALOS offers high-power free-space or fiber-coupled SLEDs in the visible wavelength (400 to 800 nm) or in the near-infrared (800 to 1700 nm) for such applications.