Gas spectroscopy and optical path-length assessment in scattering media using a frequency-modulated continuous-wave diode laser.

Simultaneous assessment of the spectroscopic absorption signal of gas enclosed in a scattering medium and the corresponding optical path length of the probing light is demonstrated using a single setup. Sensitive gas absorption measurements are performed by a tunable diode laser using wavelength-modulation spectroscopy, while the path length is evaluated by the frequency-modulated cw technique commonly used in the field of telecommunication. Proof-of-principle measurements are demonstrated with water vapor as the absorbing gas and using polystyrene foam as an inhomogeneously scattering medium. The combination of these techniques opens up new possibilities for straightforward evaluation of gas presence and exchange in scattering media.

[1]  Sune Svanberg,et al.  Food monitoring based on diode laser gas spectroscopy , 2008 .

[2]  E. Brinkmeyer,et al.  Coherent frequency-domain reflectometry for characterization of single-mode integrated-optical waveguides , 1993 .

[3]  Sune Svanberg,et al.  Spectroscopic studies of wood-drying processes. , 2006, Optics express.

[4]  Sune Svanberg,et al.  Simultaneous detection of molecular oxygen and water vapor in the tissue optical window using tunable diode laser spectroscopy. , 2008, Applied optics.

[5]  Jesse Zheng,et al.  Optical Frequency-Modulated Continuous-Wave (Fmcw) Interferometry , 2005 .

[6]  Coherence addressing of quasi-distributed absorption sensors by the FMCW method , 2000 .

[7]  Luc Thévenaz,et al.  Wavelength modulation spectroscopy: combined frequency and intensity laser modulation. , 2003, Applied optics.

[8]  Stefan Andersson-Engels,et al.  Concentration measurement of gas embedded in scattering media by employing absorption and time-resolved laser spectroscopy. , 2002, Applied optics.

[9]  S Andersson-Engels,et al.  Analysis of gas dispersed in scattering media. , 2001, Optics letters.

[10]  Sune Svanberg,et al.  Diode laser absorption spectroscopy for studies of gas exchange in fruits , 2006 .

[11]  S. Svanberg,et al.  VCSEL-based oxygen spectroscopy for structural analysis of pharmaceutical solids , 2008 .

[12]  Sailing He,et al.  Multiplexing Scheme of Long-Period Grating Sensors Based on a Modified Optical Frequency Domain Reflectometry , 2008 .

[13]  Sune Svanberg,et al.  Assessment of photon migration in scattering media using heterodyning techniques with a frequency modulated diode laser. , 2009, Optics express.

[14]  Kyuseok Song,et al.  Recent Developments in Modulation Spectroscopy for Trace Gas Detection Using Tunable Diode Lasers , 2003 .