HWG-CRDS

Goal:

Develop a trace gas sensor with ~1 second sampling resolution and  > 10 times improvement in minimum detection limit over more traditional absorption spectroscopy techniques. Our proposed technique is to incorporate pulsed cavity ring down laser absorption spectroscopy in a hollow waveguide (HWG-CRDS). In conventional CRDS, a gas cavity is charged with a laser (typically mid-IR), and the time rate of decay of laser energy is observed as light “bounces” between two highly reflective end mirrors (99.9% to 99.999% typical). The rate of decay is dependent on the rate of energy loss due to gas absorption in the cell at a particular wavelength. In the HWG-CRDS approach, a ~10³-10⁴ signal enhancement is made my injecting light energy through an aperture into a cavity constrained by the hollow waveguide. Pulsed light is used to remove the requirement for precision tuning of the cavity normally used to prevent constructive/destructive wave interference. A portion of this work includes the development of a very high-speed data acquisition system to effectively monitor the laser light pulses bouncing between the two end mirrors.

 

Principal Investigator:

Dr. Christopher Dryer, Colorado School of Mines

 

Institutional Principal Investigator:

Greg Mungas

 

Patents:

-One Filed U.S. Patent

 

Publications:

G. Mungas, C. Dreyer. “Pulsed Cavity Ringdown Spectroscopy in a Hollow Waveguide.” 2006 IEEAC#1476.

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