Monitoring N2 & O2 concentration ratios in a high-pressure gas mixture by fiber optic Raman Sensor

We proposed and developed a fiber-optic Raman gas sensor for in situ, online concentration ratio monitoring of Nitrogen and Oxygen in a high-pressure gaseous mixture. The sensor employs a frequency doubled 532 nm continuous wave (CW) Nd:YAG laser and a modified In-Photonics fiber optic state-of-art miniaturized Raman Probe. Optimum performance of Raman sensor, for long term detection of gaseous mixture sample, is achieved by maximizing Raman signals of N2/O2, while minimizing the noise from other sources. A signal processing technique is developed to filter the sensor response from the broad fluorescence background. Sensor performance was analyzed in terms of relative intensity and area of N2 and O2 Raman spectra. Efficient light collection optics and uncomplicated design of the probe facilitate it as a promising tool in gas sensing application for rugged field use. Proposed sensor offers a cost effective solution for qualitative as well as quantitative analysis of gaseous phase N2/O2 mixture in enclosure where sampling would be hazardous or otherwise undesirable and finds diverse industrial applications.