scholarly journals Absorption detection using optical waveguide cavities

2010 ◽  
Vol 88 (5) ◽  
pp. 401-410 ◽  
Author(s):  
Hans-Peter Loock ◽  
Jack A. Barnes ◽  
Gianluca Gagliardi ◽  
Runkai Li ◽  
Richard D. Oleschuk ◽  
...  
Keyword(s):  
Optical Cavity ◽  
Spectroscopic Method ◽  
Optical Loss ◽  
Wavelength Shift ◽  
Cavity Ring Down Spectroscopy ◽  
Mode Spectrum ◽  
Waveguide Cavities ◽  
High Finesse ◽  
Absorption Measurements ◽  
Cavity Ring Down

Cavity ring-down spectroscopy is a spectroscopic method that uses a high quality optical cavity to amplify the optical loss due to the light absorption by a sample. In this presentation we highlight two applications of phase-shift cavity ring-down spectroscopy that are suited for absorption measurements in the condensed phase and make use of waveguide cavities. In the first application, a fiber loop is used as an optical cavity and the sample is introduced in a gap in the loop to allow absorption measurements of nanoliters of solution at the micromolar level. A second application involves silica microspheres as high finesse cavities. Information on the refractive index and absorption of a thin film of ethylene diamine on the surface of the microresonator is obtained simultaneously by the measurements of the wavelength shift of the cavity mode spectrum and the change in optical decay time, respectively.

scholarly journals Cavity ring-down spectroscopy sensor for detection of hydrogen chloride

2013 ◽  
Vol 6 (4) ◽  
pp. 7217-7250
Author(s):  
C. L. Hagen ◽  
B. C. Lee ◽  
I. S. Franka ◽  
J. L. Rath ◽  
T. C. VandenBoer ◽  
...  
Keyword(s):  
Hydrogen Chloride ◽  
Near Infrared ◽  
Limit Of Detection ◽  
Optical Cavity ◽  
High Specificity ◽  
Ionization Mass ◽  
Cavity Ring Down Spectroscopy ◽  
Mist Chamber ◽  
Hcl Concentration ◽  
Cavity Ring Down

Abstract. A laser-based cavity ring-down spectroscopy (CRDS) sensor for measurement of hydrogen chloride (HCl) has been developed and characterized. The instrument uses light from a distributed-feedback diode laser at 1742 nm coupled to a high finesse optical cavity to make sensitive and quantifiable concentration measurements of HCl based on optical absorption. The instrument has a (1σ) limit of detection of < 20 pptv in 1 min and has high specificity to HCl. The measurement response time to changes in input HCl concentration is < 15 s. Validation studies with a previously calibrated permeation tube setup show an accuracy of better than 10%. The CRDS sensor was preliminarily tested in the field with two other HCl instruments (mist chamber and chemical ionization mass spectrometry), all of which were in broad agreement. The mist chamber and CRDS sensors both showed a 400 pptv plume within 50 pptv agreement. The sensor also allows simultaneous sensitive measurements of water and methane, and minimal hardware modification would allow detection of other near-infrared absorbers.

scholarly journals Cavity ring-down spectroscopy sensor for detection of hydrogen chloride

2014 ◽  
Vol 7 (2) ◽  
pp. 345-357 ◽  
Author(s):  
C. L. Hagen ◽  
B. C. Lee ◽  
I. S. Franka ◽  
J. L. Rath ◽  
T. C. VandenBoer ◽  
...  
Keyword(s):  
Hydrogen Chloride ◽  
Near Infrared ◽  
Limit Of Detection ◽  
Optical Cavity ◽  
High Specificity ◽  
Ionization Mass ◽  
Cavity Ring Down Spectroscopy ◽  
Mist Chamber ◽  
Hcl Concentration ◽  
Cavity Ring Down

Abstract. A laser-based cavity ring-down spectroscopy (CRDS) sensor for measurement of hydrogen chloride (HCl) has been developed and characterized. The instrument uses light from a distributed-feedback diode laser at 1742 nm coupled to a high finesse optical cavity to make sensitive and quantifiable concentration measurements of HCl based on optical absorption. The instrument has a (1σ) limit of detection of <20 pptv in 1 min and has high specificity to HCl. The measurement response time to changes in input HCl concentration is <15 s. Validation studies with a previously calibrated permeation tube setup show an accuracy of better than 10%. The CRDS sensor was preliminarily tested in the field with two other HCl instruments (mist chamber and chemical ionization mass spectrometry), all of which were in broad agreement. The mist chamber and CRDS sensors both showed a 400 pptv plume within 50 pptv agreement. The sensor also allows simultaneous sensitive measurements of water and methane, and minimal hardware modification would allow detection of other near-infrared absorbers.

scholarly journals Toward real-time measurement of atmospheric mercury concentrations using cavity ring-down spectroscopy

2010 ◽  
Vol 10 (6) ◽  
pp. 2879-2892 ◽  
Author(s):  
X. Faïn ◽  
H. Moosmüller ◽  
D. Obrist
Keyword(s):  
Temporal Resolution ◽  
Time Resolution ◽  
Pulse Repetition Frequency ◽  
Ambient Air ◽  
Atmospheric Mercury ◽  
Dye Laser ◽  
High Temporal Resolution ◽  
Cavity Ring Down Spectroscopy ◽  
Absorption Measurements ◽  
Cavity Ring Down

Abstract. Cavity ring-down spectroscopy (CRDS) is a direct absorption technique that utilizes path lengths up to multiple kilometers in a compact absorption cell and has a significantly higher sensitivity than conventional absorption spectroscopy. This tool opens new prospects for study of gaseous elemental mercury (Hg0) because of its high temporal resolution and reduced sample volume requirements (<0.5 l of sample air). We developed a new sensor based on CRDS for measurement of (Hg0) mass concentration. Sensor characteristics include sub-ng m−3 detection limit and high temporal resolution using a frequency-doubled, tuneable dye laser emitting pulses at ~253.65 nm with a pulse repetition frequency of 50 Hz. The dye laser incorporates a unique piezo element attached to its tuning grating allowing it to tune the laser on and off the Hg0 absorption line on a pulse-to-pulse basis to facilitate differential absorption measurements. Hg0 absorption measurements with this CRDS laboratory prototype are highly linearly related to Hg0 concentrations determined by a Tekran 2537B analyzer over an Hg0 concentration range from 0.2 ng m−3 to 573 ng m−3, implying excellent linearity of both instruments. The current CRDS instrument has a sensitivity of 0.10 ng Hg0 m−3 at 10-s time resolution. Ambient-air tests showed that background Hg0 levels can be detected at low temporal resolution (i.e., 1 s), but also highlight a need for high-frequency (i.e., pulse-to-pulse) differential on/off-line tuning of the laser wavelength to account for instabilities of the CRDS system and variable background absorption interferences. Future applications may include ambient Hg0 flux measurements with eddy covariance techniques, which require measurements of Hg0 concentrations with sub-ng m−3 sensitivity and sub-second time resolution.

scholarly journals Aligning an optical cavity: with reference to cavity ring-down spectroscopy

2020 ◽  
Vol 59 (30) ◽  
pp. 9464
Author(s):  
Hamzeh Telfah ◽  
Anam C. Paul ◽  
Jinjun Liu
Keyword(s):  
Optical Cavity ◽  
Cavity Ring Down Spectroscopy ◽  
Cavity Ring Down

scholarly journals Toward a real-time measurement of atmospheric mercury concentrations using cavity ring-down spectroscopy

2009 ◽  
Vol 9 (5) ◽  
pp. 22143-22175
Author(s):  
X. Faïn ◽  
H. Moosmüller ◽  
D. Obrist
Keyword(s):  
Temporal Resolution ◽  
Time Resolution ◽  
Pulse Repetition Frequency ◽  
Elemental Mercury ◽  
Atmospheric Mercury ◽  
Dye Laser ◽  
High Temporal Resolution ◽  
Cavity Ring Down Spectroscopy ◽  
Absorption Measurements ◽  
Cavity Ring Down

Abstract. A new sensor based on cavity ring-down spectroscopy (CRDS) has been developed for the measurement of gaseous elemental mercury (Hg0) mass concentration with sub-ng m−3 detection limit and high temporal resolution. Cavity ring-down spectroscopy is a direct absorption technique that utilizes path lengths of up to multiple kilometers in a compact absorption cell and has a significantly higher sensitivity than conventional absorption spectroscopy. Our prototype uses a frequency-doubled, tuneable dye laser emitting pulses at ~253.65 nm with a pulse repetition frequency of 50 Hz. The dye laser incorporates a unique piezo element attached to its tuning grating allowing it to tune the laser on and off the Hg0 absorption line on a pulse to pulse basis to facilitate differential absorption measurements. Hg0 absorption measurements with this CRDS laboratory prototype are highly linearly related to Hg0 concentrations determined by a Tekran 2537B analyzer over a Hg0 concentration range of four orders of magnitude, from 0.2 ng m−3 to 573 ng m−3 implying excellent linearity of both instruments. The current CRDS instrument has a~sensitivity of 0.10 ng m−3 at 10 s time resolution. This tool opens new prospects for the study of Hg0 because of its high temporal resolution and reduced limited sample volume requirements (<0.5 l of sample air). Future applications may include ambient Hg0 flux measurements with eddy covariance techniques, which require measurements of Hg0 concentrations with sub-ng m−3 sensitivity and sub-second time resolution.

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