Hazardous gas detection with an integrating sphere in the near-infrared

Hawe, Eamonn; Lewis, Elfed; Fitzpatrick, Colin

doi:10.1088/1742-6596/15/1/042

Cited by 10 publications

(8 citation statements)

References 7 publications

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“…Luminescent sensors often have long delay times and so are not suited to exhaust gas sensing where the concentrations change rapidly. A wide range of absorption-based techniques exist including a whole range of evanescent wave gas sensors [8]- [11], single-pass cell sensors [12], [13] and multipass cell sensors [14]- [16]. Evanescent wave gas sensors can have sensitivity issues as the interaction between the optical light and the test gas is often very limited.…”

Section: Introductionmentioning

confidence: 99%

Low Concentration Monitoring of Exhaust Gases Using a UV-Based Optical Sensor

et al. 2007

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The development of an ultra-violet (UV) differential optical absorption spectroscopy (DOAS) fibre-optic sensor for the monitoring of vehicle exhaust gases is described in this paper. Experimental results describing the operation of this sensor with NO 2 SO 2 , and NO are shown. These experimental results are compared with existing published spectroscopic absorption measurements. It is shown that the minimum detectable concentration of NO 2 is 1 ppm, SO 2 is 1 ppm, and NO is 26 ppm. The sensor was found to have a low susceptibility to interference between the detection of these gases. Index Terms-differential optical absorption spectroscopy (DOAS), exhaust gas sensing, pollution monitoring, spectroscopy, ultra-violet (UV).

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Section: Introductionmentioning

confidence: 99%

Low Concentration Monitoring of Exhaust Gases Using a UV-Based Optical Sensor

et al. 2007

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“…With the improvement of light power, the PA signal also increases, but high-power light sources usually have high cost and large volumes. Some researchers have used devices in which light beams are reflected multiple times to achieve the equivalent effects [ 30 , 31 , 32 , 33 , 34 ]. Lassen reported a photoacoustic sensor based on an integrating sphere.…”

Section: Introductionmentioning

confidence: 99%

Highly Sensitive Sphere-Tube Coupled Photoacoustic Cell Suitable for Detection of a Variety of Trace Gases: NO2 as an Example

Liu

et al. 2021

Sensors

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The concentration of trace gases in the atmospheric environment is extremely low, but it has a great impact on the living environment of organisms. Photoacoustic spectroscopy has attracted extensive attention in the field of trace gas detection because of its high sensitivity, good selectivity, and fast response. As the core of a photoacoustic detection setup, the photoacoustic cell has a significant impact on detection performance. To improve detection sensitivity, a sphere-tube coupled photoacoustic cell (STPAC) was developed, which was mainly composed of a diffuse-reflective sphere and an acoustic resonance tube. Modulated light was reflected multiple times in the sphere to increase optical path, and photoacoustic (PA) signals were further amplified by the tube. Based on STPAC, a PA gas detection setup was built with a laser diode (LD) at 450 nm as the light source. The experimental results showed that the minimum detection limit (noise equivalent concentration, NEC) of NO2 was ~0.7 parts per billion (ppb). Compared with the T-type PA cell (TPAC) in which the modulated light passed through the sphere, the signal-to-noise ratio of STPAC was increased by an order of magnitude at the same concentration of the NO2 sample.

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“…In 1996, Tranchart et al 9 used an integrating sphere in combination with tunable diode laser spectroscopy at l = 830 nm and 1200 nm to detect water vapour and butane, respectively. A significant number of works launched by Hawe of the University of Limerick has resulted in a broadband spectroscopic sensor for CO 2 in 2005 (at 1590 nm) 10 and in 2007 (at 1570 nm and 2000 nm) 11 with a detection limit of 200 ppm as well as NO 2 , SO 2 and O 3 (in the UV-visible) in 2006, 12 2000 13 and 2008 14 with limits of detection of 5 ppm, 10 ppm and 500 ppm, respectively. More recent work performed by Hodgkinson et al 15,16 has enabled the realisation of spectroscopic sensor for CH 4 (at 1.65 µm) with limits of detection of 75 ppm and 0.4 ppm for a sphere diameter of 50 mm using direct scan and 100 mm using wavelength modulation spectroscopy, respectively.…”

Section: Introductionmentioning

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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Hazardous gas detection with an integrating sphere in the near-infrared

Cited by 10 publications

References 7 publications

Low Concentration Monitoring of Exhaust Gases Using a UV-Based Optical Sensor

Low Concentration Monitoring of Exhaust Gases Using a UV-Based Optical Sensor

Highly Sensitive Sphere-Tube Coupled Photoacoustic Cell Suitable for Detection of a Variety of Trace Gases: NO2 as an Example

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

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