Trace H2S monitoring based on off-axis integrated cavity output spectroscopy

The trace H2S in range of 0-20ppm has been measured by means of off-axis integrated cavity output spectroscopy (OA-ICOS) technology combined with tunable diode laser absorption spectroscopy (TDLAS) technology. The instrument uses off-axis alignment geometry to eliminate the problem of mode matching between laser and optical resonant cavity, in absenting the piezoelectric transducer. Combined with the high sensitivity of the TDLAS technology, sensitivity of the instrument is improved. The repeatability of instrument in H2S measurement achieves to 0.303ppm (3σ), linearity less than ±1% F.S., which meet the requirement of trace H2S measurement in petrochemical or natural gas industry.