A Raman cell based on hollow optical fibers for breath analysis

Okita, Yuji; Kubo, Takashi; Matsuura, Yuji

doi:10.1117/12.841414

Cited by 16 publications

(16 citation statements)

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“…However, it is recommended to keep the capillary fiber straight in order to minimize the attenuation. Okita et al 30 showed that the total power loss of this capillary fiber setup (1.1 m long) can be up to more than 80% for a bending radius ∼14 cm. This implies that the strong attenuation of the capillary fiber due to bending would constrain the smallest possible size of the analyzer.…”

Section: C Comparing Hc-pcf To Capillary Fiber-based Breath Analyzermentioning

confidence: 98%

“…The specifications and performance of this prototype HC-PCF gas analyzer were compared to another gas analyzer with a capillary fiber-based Raman cell recently reported by Okita et al 30 In that published experiment, a polycarbonate based hollow capillary optical fiber with a silver inner coating was used as a light guide and gas cell. The 532 nm laser excitation light was focused to the capillary fiber (700 μm diameter) by a 70 mm focal length lens, while the other end of the fiber was open to the atmosphere.…”

Section: C Comparing Hc-pcf To Capillary Fiber-based Breath Analyzermentioning

confidence: 99%

“…The SNR was calculated as the ratio of peak intensity to the respective statistical standard deviation which was calculated from 150 repeated measurements of the peak intensity and the background noise. Following Buric et al and Okita et al, 30,37 the measurable noise level (where the SNR is equal to 1) was taken as the minimum detectable signal, and using the known concentration of carbon dioxide in atmospheric air, the minimum detectable concentration was calculated as approximately 15 ppmv. Note that the vibrational lines of hydrogen gas at 4161 cm −1 , nitrogen gas at 2331 cm −1 , and water vapor at 3652 cm −1 were not observed in any spectra because they are out of the spectral range of our system.…”

Section: A Testing Of the Forward-scattering Raman Cellmentioning

confidence: 99%

“…HC-PCF can be thought of as a new type of hollow light guide, with a major improvement on transmission loss over coated capillary optical fibers. [30][31][32] This improvement is achieved by fabricating the photonic crystal (PC) cladding with many microstructured holes to provide band-gap guidance of light in the hollow core. 33 The width of the band-gap ensures that propagation is only favorable for a range of photon wavelengths typically ±50 nm from the center of the band.…”

Section: Introductionmentioning

confidence: 99%

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A Raman cell based on hollow core photonic crystal fiber for human breath analysis

Chow

Short²,

Lam³

et al. 2014

Medical Physics

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The results of this study were compared to a previous study using HC-PCF to trap industrial gases and backward-scatter 514.5 nm light from them. The authors found that the method presented in this paper has an advantage to enhance the signal-to-noise ratio (SNR). This SNR advantage, coupled with the better transmission of HC-PCF in the near-IR than in the visible wavelengths led to an estimated seven times improvement in the detection sensitivity. The authors' prototype device also demonstrated a 100-fold improvement over a recently reported detection limit of a reflective capillary fiber-based Raman cell for breath analysis. Continued development is underway to increase the detection sensitivity further to reach practical clinical applications.

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Section: C Comparing Hc-pcf To Capillary Fiber-based Breath Analyzermentioning

confidence: 98%

Section: C Comparing Hc-pcf To Capillary Fiber-based Breath Analyzermentioning

confidence: 99%

Section: A Testing Of the Forward-scattering Raman Cellmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A Raman cell based on hollow core photonic crystal fiber for human breath analysis

Chow

Short²,

Lam³

et al. 2014

Medical Physics

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“…With their device they succeeded in human breath analysis, achieving detection limits of 0.2% variation in the O 2 content. 19 Other fibre enhancement techniques have been investigated recently using hollow core photonic crystal fibres (PCF) as the Raman gas cell to extend the interaction length. 20,21 Hanf et al 20 utilise a purpose-manufactured fibre with a hollow-core diameter of about 7 μm, with the laser directly focussed into the core.…”

Section: And Csontos Et Almentioning

confidence: 99%

Trace gas and dynamic process monitoring by Raman spectroscopy in metal-coated hollow glass fibres

2015

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Quantitative capillary Raman spectroscopy measurements are described, in which improved speed and sensitivity for atmospheric trace gas analysis and real-time monitoring of catalytic hydrogen-exchange reactions were demonstrated. ARTICLE accepted for publicationT.M. James et al -Raman trace gas and process monitoring using metal-coated hollow glass fibres Results on using capillary Raman spectroscopy as an approach for improving the speed, sensitivity and limit of detection for quantitative analysis of gases are reported. Specifically, its potential for trace component identification and rapid process control has been explored. Using a metal-lined hollow glass capillary configuration, its Raman signal was found to be two orders of magnitude larger than that from a conventional 90° Raman implementation. However, the actual improvement in the signal-to-noise ratio and thus the limit of detection was markedly lower, due to an increase in the fluorescence background generated in optical components in the laser beam path and the capillary body itself. Using careful, systematic suppression strategies, the signal-tonoise ratio of our capillary setup increased by a further factor of 3-4, now yielding detection limits for trace gases well below the 100 ppm level. In a "dynamic" measurement series the time evolution of catalytic gas mixing of H 2 and D 2 , to form HD, has been recorded, in which sub-mbar detection limits in sub-second recording times were achieved.

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Optimization of parabolic cell for gas Raman analysis

Zuo

Wang

2019

J Raman Spectroscopy

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Raman spectroscopy is a widely practicable technique in gas analysis, but the application in simultaneous detection of multiple‐trace gas is still a challenge for its weak signal level. To extend the application of Raman gas analysis to detection of trace gas constituents, a closed parabolic sample cell proposed in our previous work is optimized by optical analysis and experimental verification. The optical analysis shows that for a parabolic reflector with rim diameter 6p (p, semi‐latus rectum), the collecting solid angle can be as large as 90% of full space (4π) and the power‐collecting efficiency can be as high as 80%. The variation of the Raman signal level with the position of collecting aperture and the parameter p of parabolic reflector was verified by the experimental results. At the optimized structure parameters, we get a signal‐to‐background ratio of 122 and a signal‐to‐noise ratio of 305 in the Raman spectra of ambient air with exposure time of 1 s. From the results of standard analytic gaseous samples, the limits of detection of 33 ppm‐bar for H2, 38 ppm‐bar for CO, 19 ppm‐bar for CH4, 27 ppm‐bar for C2H6, 23 ppm‐bar for C2H4, and 20 ppm‐bar for C2H2 were obtained with exposure time of 200 s. These results indicate that the parabolic sample cell is a competitive Raman collector, which showing good balance in signal enhancement and background level.

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A Raman cell based on hollow optical fibers for breath analysis

Cited by 16 publications

References 0 publications

A Raman cell based on hollow core photonic crystal fiber for human breath analysis

A Raman cell based on hollow core photonic crystal fiber for human breath analysis

Trace gas and dynamic process monitoring by Raman spectroscopy in metal-coated hollow glass fibres

Optimization of parabolic cell for gas Raman analysis

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