Tunable diode laser–integrating sphere systems: a study of their output intensity characteristics

Venkatesh, C. G.; Eng, R. S.; Mantz, A. W.

doi:10.1364/ao.19.001704

Cited by 9 publications

(5 citation statements)

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“…To our knowledge, the use of an integrating sphere for gas absorption measurements was first reported in 1980 by Venkatesh et al [6] for carbon monoxide monitoring around 5 µm. In 1988 Abdullin and Lebedev [7] used a copper sphere with a CO 2 laser to measure ammonia concentrations and in 1996 Tranchart et al [8] used a 10 cm diameter sphere in combination with tunable diode laser spectroscopy at 830nm and 1.2μm to detect water vapor and butane respectively.…”

Section: Introductionmentioning

confidence: 99%

Using integrating spheres as absorption cells: path-length distribution and application of Beer's law

2009

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We have modeled the path-length distribution in an integrating sphere used as a multipass optical cell for absorption measurements. The measured radiant flux as a function of analyte concentration is nonlinear as a result, deviating from that expected for a single path length. We have developed a full numerical model and introduce a new analytical relationship that describes this behavior for high reflectivity spheres. We have tested both models by measuring the optical absorption of methane at 1651 nm in a 50 mm diameter sphere, with good agreement with experimental data in the absorption range of 0-0.01 cm(-1). Our results compare well with previous work on the temporal response of integrating spheres.

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Section: Introductionmentioning

confidence: 99%

Using integrating spheres as absorption cells: path-length distribution and application of Beer's law

2009

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“…Integrating spheres (or cavities) consist of a hollow container with a diffusely reflective internal surface. These cells are traditionally used for measuring the power output of an incident light source, however they have also been adapted for use as gas absorption cells, first by Venkatesh et al in 1980 [32]. Typically, these cells possess two or more ports for light sources and detectors, with an additional two ports for gas inflow and exhaust.…”

Section: Integrating Spheresmentioning

confidence: 99%

Compact methane sensor using an integrating sphere and interband cascade laser at 3313 nm

Davis¹,

Francis²,

Hodgkinson³

et al. 2023

Sensors and Actuators B: Chemical

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“…The magnitude of the resulting signals was modelled by Arndt [20] . The modulation index m is defined as x m (8) In the linear regime of Eq. (1), the DC normalised signal level is…”

Section: Second Harmonic Wavelength Modulation Spectroscopymentioning

confidence: 99%

“…Integrating spheres have great promise as multipass gas cells that require minimal optical alignment in both broadband measurements [6,7] and tunable diode laser spectroscopy [8,9,10] . Light entering the sphere is scattered by the internal walls with very high levels of total diffuse reflectance.…”

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confidence: 99%

Using integrating spheres with wavelength modulation spectroscopy: effect of pathlength distribution on 2nd harmonic signals

2012

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We have studied the effect on 2 nd harmonic wavelength modulation spectroscopy of the use of integrating spheres as multipass gas cells. The gas lineshape becomes distorted at high concentrations, as a consequence of the exponential pathlength distribution of the sphere, introducing nonlinearity beyond that expected from the Beer-Lambert law. We have modelled this numerically for methane absorption at 1.651 μm, with gas concentrations in the range of 0-2.5%vol in air. The results of this model compare well with experimental measurements. The nonlinearity for the 2f WMS measurements is larger than that for direct scan measurements; if this additional effect were not accounted for, the resulting error would be approximately 20% of the reading at a concentration of 2.5 %vol methane. PACS codes07.07.Df sensorschemical 42.62.Fi laser spectroscopy 42.79.-e optical instruments, equipment and techniques 1 IntroductionThe detection and quantification of gas concentrations by measurement of their optical absorption is a technique with great scientific and commercial importance. Many methods have been devised to improve the signal to noise ratio (SNR) of this technique by extending the optical pathlength in gas sample cells. Multipass cells have been designed by White [1] , Herriott et al. [2] and Chernin and Barskaya [3] . As the description suggests, the light makes multiple passes across the cell, ideally without any overlap between beams at the detector. Cavity-enhanced techniques employing high quality dielectric mirrors (with reflectivity in excess of 99.999%) include integrated cavity output spectroscopy, ICOS, also termed cavity enhanced absorption spectroscopy [4] and cavity ringdown spectroscopy, CRDS [5] . Pathlengths of over 10 km can be reached within a physical length of 1 m [5] ). Here, beams are encouraged to overlap and over

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Tunable diode laser–integrating sphere systems: a study of their output intensity characteristics

Cited by 9 publications

References 0 publications

Using integrating spheres as absorption cells: path-length distribution and application of Beer's law

Using integrating spheres as absorption cells: path-length distribution and application of Beer's law

Compact methane sensor using an integrating sphere and interband cascade laser at 3313 nm

Using integrating spheres with wavelength modulation spectroscopy: effect of pathlength distribution on 2nd harmonic signals

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