Abstract

The development and application of a range of absorption spectrometers, which operate in the 3.2 - 4.6 μm spectral region, are presented. The sensors are based on difference frequency mixing two cw diode lasers in periodically poled LiNbO₃ to generate narrow linewidth light (<60 MHz). Ruggedness and increased power is achieved by the use of fiber optics for beam delivery and inline fiber amplifiers. Species detected in air include H₂CO, CO, CO₂, CH₄, H₂O, HCl with sensitivities down to the parts-per-billion level with direct absorption detection or < 100 ppt using 2-f modulation spectroscopy.

© 2001 IEEE