Abstract
We report the construction of an atmospheric methane measurement instrument based upon a Zeeman‐split IR HeNe laser. The laser has a transverse magnetic field over ∼2/3 of its gain length, and can oscillate at an (unsplit) frequency (2947.9 cm−1) centered on a methane absorption line, or at ±0.055 cm−1 from the center, with low CH4 absorption. The laser is tuned to dwell sequentially at each frequency, giving two differential absorption measurements in each 46 ms tuning cycle. There are two atmospheric measurement channels, with fast (0.75 sec) and slow (5 sec) flow response times. Fluctuations in ambient CH4 of ∼20 ppb (RMS, 1 sec TC) are detected, with fringe effects the dominant noise source. The instrument has operated in a field experiment (NASA GTE/ABLE‐3A) in Alaska.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
