Progress in the Development of an Enhanced Cavity Absorption Sensor for Spacecraft Air Monitoring 2002-01-2449
The progress in the development of a sensor for the detection of trace air constituents to monitor spacecraft air quality is reported. A continuous wave, external-cavity tunable diode laser centered at 1.55 μm is used to pump an optical cavity absorption cell in cw-Cavity Ringdown Spectroscopy (cw-CRDS). This technique exploits the sensitivity enhancements provided by the long effective pathlength from the optical cavity created between two highly reflective mirrors (R>0.9999). Preliminary results are presented that demonstrate the sensitivity, selectivity, and reproducibility of this method. Detection limits of 2.0 ppm for CO, 2.5 ppm for CO2, 1.8 ppm for H2O, 19.4 ppb for NH3, 7.9 ppb for HCN, and 4.0 ppb for C2H2 are calculated.