Detection of elemental mercury by multimode diode laser correlation spectroscopy

Lou, Xiutao; Somesfalean, Gabriel; Svanberg, Sune; Zhang, Zhiguo; Wu, Shaohua

doi:10.1364/oe.20.004927

Cited by 26 publications

(11 citation statements)

References 21 publications

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“…In these systems, high reflection mirrors (>99.99%) are used as the window of the gas cell, and consequently the maintenance of the mirrors has always been an important issue. Non-dispersive infrared (NDIR) [12,13] and tunable diode laser absorption spectroscopy (TDLAS) [14][15][16][17][18] have also been well developed for optical gas detection over these years. Despite the relatively low stability, more and more products have been developed based on NDIR because of its low cost and fast response.…”

Section: Introductionmentioning

confidence: 99%

High Sensitivity Continuous Monitoring of Chloroform Gas by Using Wavelength Modulation Photoacoustic Spectroscopy in the Near-Infrared Range

et al. 2021

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An optical system for gaseous chloroform (CHCl3) detection based on wavelength modulation photoacoustic spectroscopy (WMPAS) is proposed for the first time by using a distributed feedback (DFB) laser with a center wavelength of 1683 nm where chloroform has strong and complex absorption peaks. The WMPAS sensor developed possesses the advantages of having a simple structure, high-sensitivity, and direct measurement. A resonant cavity made of stainless steel with a resonant frequency of 6390 Hz was utilized, and eight microphones were located at the middle of the resonator at uniform intervals to collect the sound signal. All of the devices were integrated into an instrument box for practical applications. The performance of the WMPAS sensor was experimentally demonstrated with the measurement of different concentrations of chloroform from 63 to 625 ppm. A linear coefficient R2 of 0.999 and a detection sensitivity of 0.28 ppm with a time period of 20 s were achieved at room temperature (around 20 °C) and atmosphere pressure. Long-time continuous monitoring for a fixed concentration of chloroform gas was carried out to demonstrate the excellent stability of the system. The performance of the system shows great practical value for the detection of chloroform gas in industrial applications.

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Section: Introductionmentioning

confidence: 99%

High Sensitivity Continuous Monitoring of Chloroform Gas by Using Wavelength Modulation Photoacoustic Spectroscopy in the Near-Infrared Range

et al. 2021

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“…Osticioli et al 9 used shift excitation difference spectroscopy and subtracted shifted Raman spectroscopy methods to reject the baseline caused by fluorescence in spectra of painting materials. More recently, excitation with specific wavelengths, 10 standard addition-based derivative spectra, 11 single-shot interferometric approach, 12 and the gas correlation method 13 have been common choices. However, these algorithms can work only for certain types of spectra, which limits the extent of their applications.…”

Section: Introductionmentioning

confidence: 99%

Joint Baseline-Correction and Denoising for Raman Spectra

et al. 2015

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Laser instruments often suffer from the problem of baseline drift and random noise, which greatly degrade spectral quality. In this article, we propose a variation model that combines baseline correction and denoising. First, to guide the baseline estimation, morphological operations are adopted to extract the characteristics of the degraded spectrum. Second, to suppress noise in both the spectrum and baseline, Tikhonov regularization is introduced. Moreover, we describe an efficient optimization scheme that alternates between the latent spectrum estimation and the baseline correction until convergence. The major novel aspect of the proposed algorithms is the estimation of a smooth spectrum and removal of the baseline simultaneously. Results of a comparison with state-of-the-art methods demonstrate that the proposed method outperforms them in both qualitative and quantitative assessments.

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“…Among these recent advances, we may mention novel research achievements on remote sensing of greenhouse gases, by using a broadband laser source instead of a narrowband laser. Examples of these new advances are the broadband differential absorption lidar [13][14][15][16][17][18][19] and the optical correlation spectroscopy lidar (OCS-lidar) methodology, introduced by B. Thomas et al [20]. The OCS-lidar methodology is a new differential absorption spectroscopy method based on pioneer work performed on gas correlation lidar [21].…”

Section: Introductionmentioning

confidence: 99%

Remote sensing of atmospheric gases with optical correlation spectroscopy and lidar: first experimental results on water vapor profile measurements

et al. 2013

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In this paper, the first experimental demonstration of the optical correlation spectroscopy lidar (OCS-lidar) is proposed. It is a new active remote sensing methodology to measure range-resolved atmospheric gas concentrations, based on broadband laser spectroscopy and light amplitude modulation. As a first step, a numerical study is performed for OCS-lidar measurements to optimize the accuracy of the range-resolved gas concentration measurement. Then, we demonstrate the ability of the OCS-lidar methodology to monitor the water vapor in the planetary boundary layer using the 4m 720-nm absorption band. In addition to this first experimental proof, two different experimental configurations are proposed. The amplitude modulation, related to the optical correlation spectroscopy, is operated either at the emission with an active amplitude modulator before the backscattering process, or with passive optical filters on the laser backscattered light. For both configurations, range-resolved gas concentration measurements, achieved with a micro-pulse ground-based OCS-lidar, are presented. An extended discussion presents the mixing-ratio accuracy, which reaches ±1,000 ppm at a 2,000-m range for a range resolution of 200 m. The differences between the two experimental configurations are also discussed.

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Detection of elemental mercury by multimode diode laser correlation spectroscopy

Cited by 26 publications

References 21 publications

High Sensitivity Continuous Monitoring of Chloroform Gas by Using Wavelength Modulation Photoacoustic Spectroscopy in the Near-Infrared Range

High Sensitivity Continuous Monitoring of Chloroform Gas by Using Wavelength Modulation Photoacoustic Spectroscopy in the Near-Infrared Range

Joint Baseline-Correction and Denoising for Raman Spectra

Remote sensing of atmospheric gases with optical correlation spectroscopy and lidar: first experimental results on water vapor profile measurements

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