Raman Gas Analyzer Based on a Multimode Diode Laser

The article presents the concept of gas analyzer based on Raman spectroscopy where a multimode blue diode laser is used as an excitation source. Methods for reducing the spectral width of the radiation of such a laser due to external feedback have been investigated. It has been shown that, when an optical scheme based on Fabry–Pero interferometer is used for this purpose, the resolution of the recorded Raman spectra can reach 8 cm–1. The performance of the developed Raman gas analyzer is presented and discussed. It was established that the achieved signal-to-noise ratio at the analysis time of 2 s allows detection of any type of molecule with concentration of >1%.