A fiber optic Raman sensor for hydrocarbon detection

This paper reports an all-optical sensor for concentration ratio monitoring of ethanol and methanol from their mixture sample in water/gasoline on the basis of spectrum analysis for various sample compositions. A fiber optic Raman sensor is developed as a probe indicator for component detection of such hydrocarbon mixtures. The sensor employs a frequency doubled 532 nm continuous Nd:YAG laser and a specially designed fiber optic Raman probe. Attractiveness of reported scheme lies in the online determination of sample constituents without employing specially designed IR fiber with much-complicated and expensive IR spectroscopy, and with no alteration in sample physico-chemical structure. Spectral investigation techniques based on spectral shape band intensities and areas as well as multi-component analysis are tested to find the most effective tool for measuring ethanol and methanol from the mixture. This work has demonstrated that this sensor is capable to monitor the methanol and ethanol in water and gasoline solution.