An investigation into the use of an integrating sphere as a gas absorption cell

Hawe, Eamonn; Fitzpatrick, Colin; Chambers, Paul; Lewis, Elfed

doi:10.1088/1464-4258/9/6/s03

Cited by 9 publications

(7 citation statements)

References 17 publications

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“…The internal surface of the sphere was covered with a diffuse white spray pain (13) A theoretical pressure of about 810 bar was found for the oxygen A-band to remain in the linear operating regime. This pressure is four times greater than the maximum working pressure of 200 bar used in our experiment which provides a certain safety margin.…”

Section: Methodsmentioning

confidence: 99%

An Investigation into the Effects of Pressure on Gas Detection Using an Integrating Sphere as Multipass Gas Absorption Cell: Analysis and Discussion

Ducanchez

Bendoula²,

Roger³

2016

Journal of Near Infrared Spectroscopy

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The approach adopted in the present work was to increase the pressure within an integrating sphere system to increase the number density of molecules in the gas cell and hence to obtain a significant absorption in order to improve the sensitivity of the measurement system. This feasibility study has allowed an assessment of the net absorption gain with the rise of pressure and highlights the validity domain of the linear operating regime relative to Beer's law. Experiments were conducted on the oxygen A-band. The absorption peaks of oxygen at 760 nm typically were measured with a 50 mm diameter integrating sphere system under various pressures. Tests were performed up to 200 bar, the pressure for which the linear regime was operative, and analysed from a theoretical and experimental point of view. An experimental net absorption gain of 160 was achieved in this pressure range with the possibility of up to 650 bar while remaining in the linear regime. Finally, the experimental data obtained, in particular the absorption evolution due to the contribution of oxygen gas, seem consistent with the simulated results and are discussed in this paper.

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Section: Methodsmentioning

confidence: 99%

An Investigation into the Effects of Pressure on Gas Detection Using an Integrating Sphere as Multipass Gas Absorption Cell: Analysis and Discussion

Ducanchez

Bendoula²,

Roger³

2016

Journal of Near Infrared Spectroscopy

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“…And so, for diffuse paths in an integrating sphere, the incident flux term is expressed as Φ d , the flux incident on the detector, as detailed in Eq. (7). Here, Φ d12 and Φ d21 have been expressed in terms of the sphere throughput and incident flux, as derived in Eq.…”

Section: Adaptation To An Integrating Sphere -Theorymentioning

confidence: 99%

“…Integrating cavities as multipass cells have been demonstrated to be a useful tool for absorption measurements [7][8][9][10]. An integrating cavity consists of an inner surface made from a material providing uniformly diffuse (Lambertian) reflection, such that beams make multiple passes throughout the cavity, providing a long, mean effective pathlength.…”

Section: Introductionmentioning

confidence: 99%

Integrating cavity based gas cells: a multibeam compensation scheme for pathlength variation

et al. 2016

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We present a four beam ratiometric setup for an integrating sphere based gas cell, which can correct for changes in pathlength due to sphere wall contamination. This allows for the gas absorption coefficient to be determined continuously without needing to recalibrate the setup. We demonstrate the technique experimentally, measuring methane gas at 1651nm. For example, contamination covering 1.2% of the sphere wall resulted in an uncompensated error in gas absorption coefficient of ≈41%. With the ratiometric scheme, this error was reduced to ≈2%. Potential limitations of the technique, due to subsequent deviations from mathematical assumptions are discussed, including severe sphere window contamination.

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“…In fact, the design of gas cells benefits from a rich research background. Gas cells' classification includes White [14], Herriott [10], an astigmatic Herriott [15], a multi-pass matrix system [16], circular gas cells [17] and an integrating sphere [18]. Circular multi-pass cells can be implemented using flat concentric mirrors (mirror for each reflection) [19], spherical concentric mirrors (light hits each mirror more than once) [20], a single toroidal mirror (different radius of curvature in the sagittal and tangential plane to correct astigmatism aberration) [21] or circular cell of multiple rows in the vertical direction [22].…”

Section: Introductionmentioning

confidence: 99%

Silicon Multi-Pass Gas Cell for Chip-Scale Gas Analysis by Absorption Spectroscopy

et al. 2020

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Semiconductor and micro-electromechanical system (MEMS) technologies have been already proved as strong solutions for producing miniaturized optical spectrometers, light sources and photodetectors. However, the implementation of optical absorption spectroscopy for in-situ gas analysis requires further integration of a gas cell using the same technologies towards full integration of a complete gas analysis system-on-chip. Here, we propose design guidelines and experimental validation of a gas cell fabricated using MEMS technology. The architecture is based on a circular multi-pass gas cell in a miniaturized form. Simulation results based on the proposed modeling scheme helps in determining the optimum dimensions of the gas cell, given the constraints of micro-fabrication. The carbon dioxide spectral signature is successfully measured using the proposed integrated multi-pass gas cell coupled with a MEMS-based spectrometer.

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An investigation into the use of an integrating sphere as a gas absorption cell

Cited by 9 publications

References 17 publications

An Investigation into the Effects of Pressure on Gas Detection Using an Integrating Sphere as Multipass Gas Absorption Cell: Analysis and Discussion

An Investigation into the Effects of Pressure on Gas Detection Using an Integrating Sphere as Multipass Gas Absorption Cell: Analysis and Discussion

Integrating cavity based gas cells: a multibeam compensation scheme for pathlength variation

Silicon Multi-Pass Gas Cell for Chip-Scale Gas Analysis by Absorption Spectroscopy

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