Absorption spectroscopy in hollow-glass waveguides using infrared diode lasers

Thomas A. Blake; James F. Kelly; Timothy L. Stewart; John S. Hartman; Steven W. Sharpe; Robert L. Sams

doi:10.1117/12.453761

23 September 2002 Absorption spectroscopy in hollow-glass waveguides using infrared diode lasers

Thomas A. Blake, James F. Kelly, Timothy L. Stewart, John S. Hartman, Steven W. Sharpe, Robert L. Sams

Proceedings Volume 4817, Diode Lasers and Applications in Atmospheric Sensing; (2002) https://doi.org/10.1117/12.453761
Event: International Symposium on Optical Science and Technology, 2002, Seattle, WA, United States

Abstract

Hollow-glass waveguides may be a viable technology that, in some cases, may supplant heavier multi-pass cells such as White or Herriott cells for performing trace detection using tunable diode laser absorption spectroscopy. We report here a series of experiments for testing the suitability of waveguides for infrared spectroscopy. The loss characteristics of 1 mm bore diameter waveguides have been measured for straight and coiled lengths. The minimum linear loss coefficient is 0.46 (+/- 0.10) dB/m while the bending loss coefficient is 0.42 dB. Using a flow of 1 ppm nitric oxide in nitrogen mixture through a coiled 3 meter length of waveguide (coil diameter 50 cm) we could detect the fundamental R(8.5), Ω = 3/2 transition of NO with a signal-to-noise (RMS) ratio of 44:1 in direct absorption using a single mode, lead-salt diode laser with six minutes of signal averaging. Using direct absorption spectroscopy we have found that the absorption pathlength is approximately equal to the physical length of the waveguide. Broadband FM diode laser spectroscopy produces for the same transition and waveguide sample conditions a comparable signal-to-noise ratio with less than a second of signal averaging. Finally, we have also performed near-infrared spectroscopy of nitrous oxide flowing through a waveguide using a telecommunications diode laser. The RMS baseline noise for these measurements, in absorbance units, was 2 x 10^-5.

Citation Download Citation

Thomas A. Blake, James F. Kelly, Timothy L. Stewart, John S. Hartman, Steven W. Sharpe, and Robert L. Sams "Absorption spectroscopy in hollow-glass waveguides using infrared diode lasers", Proc. SPIE 4817, Diode Lasers and Applications in Atmospheric Sensing, (23 September 2002); https://doi.org/10.1117/12.453761

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available