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Fang B, Zhao W, Xu X, Zhou J, Ma X, Wang S, Zhang W, Venables DS, Chen W. Portable broadband cavity-enhanced spectrometer utilizing Kalman filtering: application to real-time, in situ monitoring of glyoxal and nitrogen dioxide. OPTICS EXPRESS 2017; 25:26910-26922. [PMID: 29092174 DOI: 10.1364/oe.25.026910] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 10/17/2017] [Indexed: 06/07/2023]
Abstract
This article describes the development and field application of a portable broadband cavity enhanced spectrometer (BBCES) operating in the spectral range of 440-480 nm for sensitive, real-time, in situ measurement of ambient glyoxal (CHOCHO) and nitrogen dioxide (NO2). The instrument utilized a custom cage system in which the same SMA collimators were used in the transmitter and receiver units for coupling the LED light into the cavity and collecting the light transmitted through the cavity. This configuration realised a compact and stable optical system that could be easily aligned. The dimensions and mass of the optical layer were 676 × 74 × 86 mm3 and 4.5 kg, respectively. The cavity base length was about 42 cm. The mirror reflectivity at λ = 460 nm was determined to be 0.9998, giving an effective absorption pathlength of 2.26 km. The demonstrated measurement precisions (1σ) over 60 s were 28 and 50 pptv for CHOCHO and NO2 and the respective accuracies were 5% and 4%. By applying a Kalman adaptive filter to the retrieved concentrations, the measurement precisions of CHOCHO and NO2 were improved to 8 pptv and 40 pptv in 21 s.
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Niu MS, Han PG, Song LK, Hao DZ, Zhang JH, Ma L. Comparison and application of wavelet transform and Kalman filtering for denoising in δ 13CO 2 measurement by tunable diode laser absorption spectroscopy at 2.008 µm. OPTICS EXPRESS 2017; 25:A896-A905. [PMID: 29041300 DOI: 10.1364/oe.25.00a896] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 07/27/2017] [Indexed: 06/07/2023]
Abstract
We propose to use the wavelet transform and Kalman filter methods for processing noise in δ13CO2 measurement using laser absorption spectroscopy at 2.008 µm and they have been shown to be useful tool for reducing the intrinsic noise of the optical system. Through the performance comparison and analysis of these two denoising techniques for the intrinsic noise reduction of optical system, it can be found that the Kalman filter is a more suitable approach for the extraction of gas isotope measurement signal from a contaminated signal.
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Wu T, Chen W, Fertein E, Masselin P, Gao X, Zhang W, Wang Y, Koeth J, Brückner D, He X. Measurement of the D/H, ¹⁸O/¹⁶O, and ¹⁷O/¹⁶O isotope ratios in water by laser absorption spectroscopy at 2.73 μm. SENSORS 2014; 14:9027-45. [PMID: 24854363 PMCID: PMC4063013 DOI: 10.3390/s140509027] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2014] [Revised: 05/12/2014] [Accepted: 05/15/2014] [Indexed: 01/10/2023]
Abstract
A compact isotope ratio laser spectrometry (IRLS) instrument was developed for simultaneous measurements of the D/H, 18O/16O and 17O/16O isotope ratios in water by laser absorption spectroscopy at 2.73 μm. Special attention is paid to the spectral data processing and implementation of a Kalman adaptive filtering to improve the measurement precision. Reduction of up to 3-fold in standard deviation in isotope ratio determination was obtained by the use of a Fourier filtering to remove undulation structure from spectrum baseline. Application of Kalman filtering enables isotope ratio measurement at 1 s time intervals with a precision (<1‰) better than that obtained by conventional 30 s averaging, while maintaining a fast system response. The implementation of the filter is described in detail and its effects on the accuracy and the precision of the isotope ratio measurements are investigated.
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Affiliation(s)
- Tao Wu
- Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nanchang 330063, China.
| | - Weidong Chen
- Laboratoire de Physicochimie de l'Atmosphère, Université du Littoral Côte d'Opale, 189A, Av. Maurice Schumann, 59140 Dunkerque, France.
| | - Eric Fertein
- Laboratoire de Physicochimie de l'Atmosphère, Université du Littoral Côte d'Opale, 189A, Av. Maurice Schumann, 59140 Dunkerque, France.
| | - Pascal Masselin
- Laboratoire de Physicochimie de l'Atmosphère, Université du Littoral Côte d'Opale, 189A, Av. Maurice Schumann, 59140 Dunkerque, France.
| | - Xiaoming Gao
- Anhui Institute of Optics & Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China.
| | - Weijun Zhang
- Anhui Institute of Optics & Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China.
| | - Yingjian Wang
- Anhui Institute of Optics & Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China.
| | - Johannes Koeth
- Nanoplus Nanosystems and Technologies GmbH, Oberer Kirschberg 4, 97218 Gerbrunn, Germany.
| | - Daniela Brückner
- Nanoplus Nanosystems and Technologies GmbH, Oberer Kirschberg 4, 97218 Gerbrunn, Germany.
| | - Xingdao He
- Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nanchang 330063, China.
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Riris H, Rodriguez M, Allan GR, Hasselbrack W, Mao J, Stephen M, Abshire J. Pulsed airborne lidar measurements of atmospheric optical depth using the Oxygen A-band at 765 nm. APPLIED OPTICS 2013; 52:6369-6382. [PMID: 24085100 DOI: 10.1364/ao.52.006369] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 07/24/2013] [Indexed: 06/02/2023]
Abstract
We report on an airborne demonstration of atmospheric oxygen optical depth measurements with an IPDA lidar using a fiber-based laser system and a photon counting detector. Accurate knowledge of atmospheric temperature and pressure is required for NASA's Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) space mission, and climate modeling studies. The lidar uses a doubled erbium-doped fiber amplifier and single photon-counting detector to measure oxygen absorption at 765 nm. Our results show good agreement between the experimentally derived differential optical depth measurements with the theoretical predictions for aircraft altitudes from 3 to 13 km.
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Wu T, Chen W, Kerstel E, Fertein E, Gao X, Koeth J, Rössner K, Brückner D. Kalman filtering real-time measurements of H2O isotopologue ratios by laser absorption spectroscopy at 2.73 microm. OPTICS LETTERS 2010; 35:634-636. [PMID: 20195302 DOI: 10.1364/ol.35.000634] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Kalman adaptive filtering was applied for the first time, to our knowledge, to the real-time simultaneous determination of water isotopic ratios using laser absorption spectroscopy at 2.73 microm. Measurements of the oxygen and hydrogen isotopologue ratios delta(18)O, delta(17)O, and delta(2)H in water showed a 1-sigma precision of 0.72 per thousand for delta(18)O, 0.48 per thousand for delta(17)O, and 0.84 per thousand for delta(2)H, while sampling the output of the tuned Kalman filter at 1 s time intervals. Using a standard running average technique, averaging over approximately 30 s is required to obtain the same level of precision.
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Affiliation(s)
- Tao Wu
- Laboratoire de Physicochimie de l'Atmosphère, Université du Littoral Côte d'Opale, 189A Avenue, Maurice Schumann, 59140 Dunkerque, France
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Werle PW, Mazzinghi P, D'Amato F, De Rosa M, Maurer K, Slemr F. Signal processing and calibration procedures for in situ diode-laser absorption spectroscopy. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2004; 60:1685-1705. [PMID: 15248940 DOI: 10.1016/j.saa.2003.10.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2003] [Revised: 10/07/2003] [Accepted: 10/07/2003] [Indexed: 05/24/2023]
Abstract
Gas analyzers based on tunable diode-laser spectroscopy (TDLS) provide high sensitivity, fast response and highly specific in situ measurements of several atmospheric trace gases simultaneously. Under optimum conditions even a shot noise limited performance can be obtained. For field applications outside the laboratory practical limitations are important. At ambient mixing ratios below a few parts-per-billion spectrometers become more and more sensitive towards noise, interference, drift effects and background changes associated with low level signals. It is the purpose of this review to address some of the problems which are encountered at these low levels and to describe a signal processing strategy for trace gas monitoring and a concept for in situ system calibration applicable for tunable diode-laser spectroscopy. To meet the requirement of quality assurance for field measurements and monitoring applications, procedures to check the linearity according to International Standard Organization regulations are described and some measurements of calibration functions are presented and discussed.
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Affiliation(s)
- P W Werle
- National Institute for Applied Optics, 50125 Florence, Italy.
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Kosterev AA, Curl RF, Tittel FK, Köhler R, Gmachl C, Capasso F, Sivco DL, Cho AY. Transportable automated ammonia sensor based on a pulsed thermoelectrically cooled quantum-cascade distributed feedback laser. APPLIED OPTICS 2002; 41:573-578. [PMID: 11905584 DOI: 10.1364/ao.41.000573] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A compact ammonia sensor based on a 10-microm single-frequency, thermoelectrically cooled, pulsed quantum-cascade laser with an embedded distributed feedback structure has been developed. To measure NH3 concentrations, we scanned the laser over two absorption lines of its fundamental v2 band. A sensitivity of better than 0.3 parts per million was achieved with just a 1-m optical path length. The sensor is computer controlled and automated to monitor NH3 concentrations continuously for extended periods of time and to store data in the computer memory.
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Riris H, Carlisle CB, McMillen DF, Cooper DE. Explosives detection with a frequency modulation spectrometer. APPLIED OPTICS 1996; 35:4694-4704. [PMID: 21102890 DOI: 10.1364/ao.35.004694] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
An explosives detection instrument was designed and tested at SRI International. The instrument uses frequency modulation spectroscopy with midinfrared lead-salt diode lasers to perform high-sensitivity detection of characteristic nitrogen-containing decomposition products of explosives. Ultimately, the instrument should be capable of detecting and identifying subpicogram levels of plastic explosives, which would be suitable for screening passengers at airports. Using the laboratory breadboard instrument and two different explosive vapor generators, we demonstrated a lower limit of detection of 5-10 pg for cyclotrimethylene trinitramine and linearity of the signal over an order of magnitude.
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