We describe and demonstrate a trace gas detector using a variation of cavity ring down spectroscopy (CRDS) in which
we modulate the laser frequency and use off-axis alignment to simplify the sensor design and make it more suitable for
deployment in vibration-prone environments. The use of off-axis alignment reduces the sensitivity to vibration and
optical feedback. Modulation of the laser frequency eliminates signal fluctuations that can arise due to laser drift and
incomplete averaging of the cavity modes, and thus removes the need for precision locking or frequency stabilization of
the laser.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Andreas Karpf and Gottipaty N. Rao
"Detection of trace gases using frequency modulated off-axis cavity ring-down spectroscopy", Proc. SPIE 8358, Chemical, Biological, Radiological, Nuclear, and Explosives (CBRNE) Sensing XIII, 83581D (May 1, 2012); doi:10.1117/12.920814; http://dx.doi.org/10.1117/12.920814