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Monitoring ammonia through cavity-enhanced absorption spectroscopy

Based on near infrared cavity-enhanced absorption spectroscopy (CEAS), we develop an optical off-axis enhanced cavity sensor system for ammonia monitoring. A tunable DFB laser scanned around 1510.44nm is used to probe absorption spectrum of ammonia gas at a vacuum pressure of 25kPa. Traceable standard ammonia gas is injected into the sensor system cavity at a gas flow of 600ml/min to calibrate the sensor system. And then the linearity and sensitivity of the sensor system are investigated for ammonia at the same working conditions. Maximum measuring error of only is achieved ranging from 0 to 1000 ppm, showing a higher performance for ammonia gas detection than traditional commercial electrochemical sensor systems. It offers a combination of sensitivity, robustness, dynamic range and easy operation in practical application.