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Investigation of self-adaptive algebraic tomography for gas reconstruction in larger temperature range by multiple wavelengths absorption spectroscopy

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Chinese Optics Letters 2014年第12期12卷 52-58页

作者：李宁吕晓静翁春生 National Key Laboratory of Transient Physics Nanjing University of Science and Technology

We develop a self-adaptive algebraic tomography algorithm （SAATA） to investigate the simultaneons reconstruction of concentration and temperature distributions in larger temperature range from two views. The simplified optical arrangement with fewer projections is realized by extension of spectral information at multiple wavelengths, resulting in great potential in applications of practical combustion diagnosis. Tile results show SAATA can perform much better reconstructions in 300 3000 K temperature range than genetic simulated annealing algorithm and least-square orthogonal-triangular decomposition method with two- wavelength scheme. More phantoms are created to demonstrate the capability of SAATA to capture the peaks and adapt for both flat and sharp temperature distributions. Meanwhile, the advantage of high stability ensures better reconstruction performance at noise levels from 0.1% to 10% in projections.

关键词： absorption spectroscopy Algebra Algorithms Least squares approximations Simulated annealing Temperature distribution Tomography

absorption spectroscopy of cold caesium atoms confined in a magneto-optical trap

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Chinese Physics B 2004年第10期13卷 1669-1673页

作者：闰树斌刘涛耿涛张天才彭堃墀王军民 StateKeyLaboratoryofQuantumOpticsandQuantumOpticsDevices andInstituteofOpto-ElectronicsShanxiUniversityTaiyuan030006China

absorption spectra of cold caesium atoms confined in a magneto-optical trap are measured around D2 line at 852nm with a weak probe beam. absorption reduction dip due to electromagnetically induced transparency (EIT)effect induced by the cooling/trapping field in a V-type three-level system and a gain peak near the cycling transition are clearly observed. Several mechanisms mixed with EIT effect in a normal V-type three-level system are briefly discussed. A simple theoretical analysis based on a dressed-state model is presented for interpretation of the absorption spectra.

关键词： absorption spectroscopy caesium atoms magneto-optical trap (MOT) V-type three-level system electromagnetically induced transparency (EIT)

Fiber-distributed multi-channel open-path H_2S sensor based on tunable diode laser absorption spectroscopy

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Chinese Optics Letters 2007年第2期5卷 121-124页

作者：陈东刘文清张玉钧刘建国阚瑞峰王敏方曦崔益本 Key Laboratory of Environmental Optics & Technology Anhui Institute of Optics and Fine MechanicsChinese Academy of SciencesHefei 230031

Tunable diode laser based gas detectors are now being used in a wide variety of applications for safety and environmental interest. A fiber-distributed multi-channel open-path H2S sensor based on tunable diode laser absorption spectroscopy （TDLAS） is developed, the laser used is a telecommunication near infrared distributed feed-back （DFB） tunable diode laser, combining with wavelength modulation spectroscopy technology, a detection limit of 20 ppm-m is demonstrated. Multi-channel detection is achieved by combining optical fiber technique. An on-board reference cell provides on-line sensor calibration and almost maintenance-free operation. The sensor is suitable for large area field H2S monitoring application.

关键词： absorption spectroscopy Hydrogen sulfide Optical fibers Semiconductor lasers

Observation on the aerosol and ozone precursors in suburban areas of Shenzhen and analysis of potential source based on MAX-DOAS

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Journal of Environmental Sciences 2023年第10期132卷 109-121页

作者： Hairong Zhang Ang Li Zhaokun Hu Hongmei Ren Hongyan Zhong Jianfeng Guo Long Yun Mingdi Zhang Key Laboratory of Environmental Optics and Technology Anhui Institute of Optics and Fine MechanicsHefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031China University of Science and Technology of China Hefei 230026China Institutes of Physical Science and Information Technology Anhui UniversityHefei 230601China Shenzhen Environmental Monitoring Center Station Shenzhen 518049China

Long-term stereoscopic observations of aerosol,NO2,and HCHO were carried out at the Yangmeikeng(YMK)site in Shenzhen.Aerosol optical depths and NO2 vertical column concentration(NO2 VCD)derived from MAX-DOAS were found to be consistent with other datasets.The total NO2 VCD values of the site remained low,varying from 2×10^(15)to 8×10^(15)mol/cm^(2),while the HCHO VCD was higher than NO2 VCD,varying from 7×10^(15)to 11×10^(15)mol/cm^(2).HCHO VCD was higher from September to early November than that was from mid-late November to December and during February 2021,in contrast,NO2 VCD did not change much during the same period.In January,NO2 VCD and HCHO VCD were both fluctuating drastically.High temperature and HCHO level in the YMK site is not only driving the ozone production up but alsomay be driving up the ozone concentration as well,and the O_(3)production regime in the YMK site tends to be NOx-limited.At various altitudes,backward trajectory clustering analysis and Potential Source Contribution Function(PSCF)were utilized to identify possible NO2 and HCHO source locations.The results suggested that the Huizhou-Shanwei border and the Daya Bay Sea area were the key potential source locations in the lower(200 m)and middle(500 m)atmosphere(WPSCF>0.6).The WPSCF valuewas high at the 1000maltitude whichwas closer to the YMKsite than the near ground,indicating that the pollution transport capability in the upper atmosphere was limited.

关键词： Multi-axial differential optical absorption spectroscopy (MAX-DOAS) Nitrogen dioxide(NO2) Formaldehyde(HCHO) Potential source contribution function(PSCF)

Effects of Gyroresonance absorption and Self absorption on the Gyrosynchrotron Radiation Spectrum

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Chinese Physics Letters 2004年第10期21卷 2067-2070页

作者：周爱华宿英娜黄光力 PurpleMountainObservatory ChineseAcademyofSciencesNanjing210008 GraduateSchool ChineseAcademyofSciencesBeijing100039

Effects of gyroresonance absorption and self absorption on the gyrosynchrotron radiation spectrum are investigated with a model in a magnetic dipole field. It is found that the gyroresonance absorption and self absorption suppress substantially the gyrosynchrotron radiation at lower frequencies where the radio source is optically thick. The suppression of the gyroresonance absorption on the spectrum increases with the increasing temperature and density of thermal electrons. The suppression of the self absorption on the spectrum increases as increasing number density of the nonthermal electrons. The influences of the gyroresonance absorption and the self one on the spectrum are compared quantitatively. It is shown that only when the number density of the nonthermal electron reaches a higher value of about 3×104cm−3 above 10keV, can the effect of the self absorption on the spectrum compare with the effect of the gyroresonance absorption.

关键词： absorption spectroscopy

Raman and optical absorption spectroscopic investigation of Yb-Er codoped phosphate glasses containing SiO_2

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Chinese Optics Letters 2009年第1期7卷 56-59页

作者：陈尤阔温磊胡丽丽陈伟 Y.Guyot G.Boulon Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Physical Chemistry of Luminescent Materials University of LyonUMR CNRS 5620Villeurbanne 69622France

Yb-Er codoped Na2O-Al2O3-P2O5-xSiO2 glasses containing 0 - 20 mol% SiO2 were prepared successfully. The addition of SiO2 to the phosphate glass not only lengthens the bond between pS＋ and non-bridging oxygen but also reduces the number of P=O bond. In contrast with silicate glass in which there is only four-fold coordinated Si4＋, most probably there coexist [SiO4] tetrahedron and [SiO6] oetahedron in our glasses. Within the range of 0 - 20 mol% SiO2 addition, the stimulated emission cross-section of Era＋ ion only decreases no more than 10%. The Judd-Ofelt intensity parameters of Er3＋, Ω2 does not change greatly, but Ω4 and Ω6 decrease obviously with increasing SiO2 addition, because the bond between Er3＋ and O2- is more strongly eovalently bonded.

关键词： absorption spectroscopy Erbium Fiber lasers Glass Oxygen Silicates Ytterbium

Optical heterodyne Herriott-type multipass laser absorption spectrometer

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Chinese Optics Letters 2015年第1期13卷 97-99页

作者：李传亮刘路路邱选兵魏计林邓伦华陈扬骎 Department of Physics School of Applied ScienceTaiyuan University of Science and Technology State Key Laboratory of Precision spectroscopy East China Normal University

We present a Herriott-type multipass laser absorption spectrometer enhanced by optical heterodyne detection. The proposal is demonstrated by measuring the spectra of water vapor molecule in the region from 12247.6873 to 12249.6954 cm^-1. Compared with direct absorption spectroscopy, the signal-to-noise ratio is improved nearly one magnitude of factor by combining with the optical heterodyne spectroscopy and extra weak absorption lines are observed. The minimum detectable absorption is estimated at 4.36×10^-8 cm^-1 and the measured line shape dominated by Doppler broadening can be precisely recovered by direct transformation of experimental optical heterodyne spectral profile.

关键词： absorption spectroscopy Heterodyning Signal to noise ratio

Simultaneous measurement of gas distribution in a premixed flame using adaptive algebraic reconstruction technique based on the absorption spectrum

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Chinese Optics Letters 2016年第11期14卷 66-70页

作者：张立芳王飞张海丹严建华岑可法 State Key Laboratory of Clean Energy Utilization Zhejiang University

Four tomography algorithms,including the algebraic reconstruction technique,simultaneous iterative reconstruction technique,the multiplicative algebraic reconstruction technique,and the adaptive algebraic reconstruction technique（AART）,are compared with each other based on the tunable diode laser absorption spectroscopy technique;the determination of the relaxation parameter is discussed to improve reconstruction quality and shorten computational time as much as possible.The calculated results demonstrate that the AART algorithm can produce the reconstruction results with better quality and less computational time.In the experimental measurement,the AART algorithm with a two-line thermometry scheme is adopted to measure the spatial distribution of H2O temperature and concentration,two H2O absorption lines near 1397.8 nm are selected,the temperature and H2O concentration in the McKenna plat premixed flames are experimentally reconstructed and analyzed,and the results of integrated tomography reconstruction are consistent with the thermocouple traverse measurement.

关键词： absorption spectroscopy Algebra Image reconstruction Thermocouples Tomography

Bragg suppression for optical absorption in multi-quantum well structures

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Chinese Optics Letters 2003年第5期1卷 299-301页

作者：肖万能周建英赵霁王维江李润华 State Key Laboratory of Optoelectronic Materials and Technologies Sun Yat-sen UniversityGuangzhou 510275

Direct calculations of absorption spectra for multi-quantum well structures by extracting field distributions at well positions are performed. Results demonstrate the previously reported Bragg suppression, and agree exactly with the indirect calculation by linear dispersion theory. This reveals that Bragg suppression effect in fact originates from the remarkably decreased intensities at well positions by Bragg interference condition, rather than from the formation of supperradiant modes.

关键词： absorption spectroscopy