Phase-sensitive noise suppression in a photoacoustic sensor based on acoustic circular membrane modes

Lassen, Mikael; Brusch, Anders; Balslev-Harder, David; Petersen, J. C.

doi:10.1364/ao.54.000d38

Cited by 14 publications

(8 citation statements)

References 19 publications

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“…Detection and monitoring of hazardous chemicals and greenhouse gases is an increasingly important task [ 1 , 2 ]. Photoacoustic spectroscopy (PAS), in one of its many variations [ 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ], is highly suitable for this task due to its high sensitivity. One of the PAS variants, QEPAS, was introduced in 2002 [ 16 ], and is today an established spectroscopic technique [ 17 ].…”

Section: Introductionmentioning

confidence: 99%

Intrinsic Spectral Resolution Limitations of QEPAS Sensors for Fast and Broad Wavelength Tuning

Christensen¹,

Høgstedt²,

Friis³

et al. 2020

Sensors

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Quartz-enhanced photoacoustic sensing is a promising method for low-concentration trace-gas monitoring due to the resonant signal enhancement provided by a high-Q quartz tuning fork. However, quartz-enhanced photoacoustic spectroscopy (QEPAS) is associated with a relatively slow acoustic decay, which results in a reduced spectral resolution and signal-to-noise ratio as the wavelength tuning rate is increased. In this work, we investigate the influence of wavelength scan rate on the spectral resolution and signal-to-noise ratio of QEPAS sensors. We demonstrate the acquisition of photoacoustic spectra from 3.1 μm to 3.6 μm using a tunable mid-infrared optical parametric oscillator. The spectra are attained using wavelength scan rates differing by more than two orders of magnitude (from 0.3 nm s−1 to 96 nm s−1). With this variation in scan rate, the spectral resolution is found to change from 2.5 cm−1 to 9 cm−1. The investigated gas samples are methane (in nitrogen) and a gas mixture consisting of methane, water, and ethanol. For the gas mixture, the reduced spectral resolution at fast scan rates significantly complicates the quantification of constituent gas concentrations.

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Section: Introductionmentioning

confidence: 99%

Intrinsic Spectral Resolution Limitations of QEPAS Sensors for Fast and Broad Wavelength Tuning

Christensen¹,

Høgstedt²,

Friis³

et al. 2020

Sensors

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“…The mR cell was constructed based on finite element simulations in high-density PTFE as depicted in Figure 2b). 22,23 The dimensions and design of the optimal design is shown in figure 2b). The on-axis mR (absorption tube) is 9.5 mm-long with 1.5 mm inner diameter coupled to the off-axis mR with a 4.1 mm long tube with 1 mm inner diameter, where the QTF is placed.…”

Section: Methodsmentioning

confidence: 99%

Quartz-enhanced photo-acoustic spectroscopy for breath analyses

Petersen¹,

Lamard²,

Feng³

et al. 2017

SPIE Proceedings

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An innovative and novel quartz-enhanced photoacoustic spectroscopy (QEPAS) sensor for highly sensitive and selective breath gas analysis is introduced. The QEPAS sensor consists of two acoustically coupled microresonators (mR) with an off-axis 20 kHz quartz tuning fork (QTF). The complete acoustically coupled mR system is optimized based on finite element simulations and experimentally verified. Due to the very low fabrication costs the QEPAS sensor presents a clear breakthrough in the field of photoacoustic spectroscopy by introducing novel disposable gas chambers in order to avoid cleaning after each test. The QEPAS sensor is pumped resonantly by a nanosecond pulsed single-mode mid-infrared optical parametric oscillator (MIR OPO). Spectroscopic measurements of methane and methanol in the 3.1 µm to 3.7 µm wavelength region is conducted. Demonstrating a resolution bandwidth of 1 cm −1 . An Allan deviation analysis shows that the detection limit at optimum integration time for the QEPAS sensor is 32 ppbv@190s for methane and that the background noise is solely due to the thermal noise of the QTF. Spectra of both individual molecules as well as mixtures of molecules were measured and analyzed. The molecules are representative of exhaled breath gasses that are bio-markers for medical diagnostics.

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“…In the present work the OPO is optimized for operation in the spectral region between 3.1 µm and 3.8µm and with an average output power of approximately 400 mW and pulse durations of ∼ 18 nanoseconds at a repetition rate of 19.99 kHz, thus matching the QTF and mR tubes. The mR cell was constructed based on finite element simulations in high-density PTFE as depicted in Figure 2b) [22,23]. The dimensions and design of the optimal design is shown in figure 2b).…”

Section: Methodsmentioning

confidence: 99%

Quartz-enhanced photoacoustic spectroscopy as a platform for non-invasive trace gas analyser targeting breath analysis

Petersen,

Lamard,

Feng

et al. 2017

Preprint

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An innovative and novel quartz-enhanced photoacoustic spectroscopy (QEPAS) sensor for highly sensitive and selective breath gas analysis is introduced. The QEPAS sensor consists of two acoustically coupled micro-resonators (mR) with an off-axis 20 kHz quartz tuning fork (QTF). The complete acoustically coupled mR system is optimized based on finite element simulations and experimentally verified. Due to the very low fabrication costs the QEPAS sensor presents a clear breakthrough in the field of photoacoustic spectroscopy by introducing novel disposable gas chambers in order to avoid cleaning after each test. The QEPAS sensor is pumped resonantly by a nanosecond pulsed single-mode mid-infrared optical parametric oscillator (MIR OPO). Spectroscopic measurements of methane and methanol in the 3.1 µm to 3.7 µm wavelength region is conducted. Demonstrating a resolution bandwidth of 1 cm −1 . An Allan deviation analysis shows that the detection limit at optimum integration time for the QEPAS sensor is 32 ppbv@190s for methane and that the background noise is solely due to the thermal noise of the QTF. Spectra of both individual molecules as well as mixtures of molecules were measured and analyzed. The molecules are representative of exhaled breath gasses that are bio-markers for medical diagnostics.

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Phase-sensitive noise suppression in a photoacoustic sensor based on acoustic circular membrane modes

Cited by 14 publications

References 19 publications

Intrinsic Spectral Resolution Limitations of QEPAS Sensors for Fast and Broad Wavelength Tuning

Intrinsic Spectral Resolution Limitations of QEPAS Sensors for Fast and Broad Wavelength Tuning

Quartz-enhanced photo-acoustic spectroscopy for breath analyses

Quartz-enhanced photoacoustic spectroscopy as a platform for non-invasive trace gas analyser targeting breath analysis

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