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Scintillation index of optical wave propagating in turbulent atmosphere

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Chinese Physics B 2009年第2期18卷 581-587页

作者：饶瑞中 anhui institute of optics and fine mechanics Chinese Academy of Sciences

A concise expression of the scintillation index is proposed for a plane optical wave and a spherical optical wave both propagating in a turbulent atmosphere with a zero inner scale and a finite inner scale under an arbitrary fluctuation condition. The expression is based on both the results in the Rytov approximation under a weak fluctuation condition and the numerical results in a strong fluctuation regime. The maximum value of the scintillation index and its corresponding Rytov index are evaluated. These quantities are affected by the ratio of the turbulence inner scale to the Fresnel size.

关键词： atmospheric optics scintillation atmospheric turbulence

Haze observations by simultaneous lidar and WPS in Beijing before and during APEC, 2014

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Science China Chemistry 2015年第9期58卷 1385-1392页

作者： Zhenyi Chen Jiaoshi Zhang Tianshu Zhang Wenqing Liu Jianguo Liu anhui institute of optics and fine mechanics Chinese Academy of Sciences

We present combined Mie lidar, ozone lidar and wide-range particle spectrometer observations which were carried out in Beijing, north China during two periods—one haze period before the Asia-Pacific Economic Cooperation(APEC) meeting and one moderate pollution period during the meeting in 2014. High extinction coefficient, moderate ozone concentration and variable particle number concentration were obtained throughout the first haze observation period. The mean extinction coefficients in the two pollution periods were 0.52 and 0.23 km?1, respectively, at 532 nm. The ozone concentration during the first haze phase was more various with a higher average value of 49 ppb compared with that in the second pollution observations(32 ppb). Compared with the same metrological condition occurring at the end of October, the sharply decreased aerosol extinction coefficient and ozone concentration show the effectiveness of the emission-cutting measures implemented during APEC in November. The comparison of aerosols and ozone in different heights indicate different pollution sources and the complicated ozone process of generation and disappearance. The correlation between the scattering coefficient and particle number concentrations of various diameter depended on the ambient humidity. Especially the particle number concentration(500 nm–1 ?m) contributed most to PM2.5 concentration. The four-day back trajectories from a Hybrid Single-particle Lagrangian Integrated Trajectory(HYSPLIT) model indicate that the air masses in the lower boundary layer before and during APEC were advected from the densely populated south regions of China and the long pollution transportation passing through northern China.

关键词： haze aerosol ozone lidar WPS

General optical scintillation in turbulent atmosphere

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Chinese optics Letters 2008年第8期6卷 547-549页

作者：饶瑞中 anhui institute of optics and fine mechanics Chinese Academy of Sciences

A general expression of the scintillation index is proposed for optical wave propagating in turbulent atmosphere under arbitrary fluctuation conditions. The expression depends on extreme behaviors of the scintillation indices under both weak and strong fluctuations. The maximum scintillation index in the onset region and the corresponding Rytov index can be evaluated from the general expression. Plane and spherical waves in the cases of zero and non-zero turbulence inner scale are given as examples for illustration of the general behaviors of scintillation indices.

关键词： Light emission Turbulence

Preparation and Characterization of Gd_3Sc_2Ga_3O_(12) Polycrystalline Material by Co-Precipitation Method

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Journal of Rare Earths 2007年第2期25卷 158-162页

作者：邵淑芳张庆礼苏静孙敦陆王召兵殷绍唐 anhui institute of optics and fine mechanics Chinese Academy of Sciences

Gd3Sc2Ga3O12 polycrystalline material for single crystal growth was prepared with Ga, Gd2O3 and Sc2O3 as starting materials and aqueous ammonia as the precipitator by co-precipitation method. The precursors sintered at various temperatures were characterized by infrared spectra （IR）, X-ray diffractometry （XRD） and transmitted electron microscopy （TEM）. The results showed that pure GSGG phase could be obtained at 900 ℃. The sintered powders were well-dispersed and less-aggregated in the sintered temperature range of 900 - 1000 ℃. XRD and TEM show that the polycrystalline particle sizes of the polycrystalline powders were about 20 - 50 nm. Compared with the method that Ga2O3, Gd2O3 and Sc2O3 were mixed directly and sintered to get polycrystalline materials, the synthesized temperature was lower and sintered time was shorter. Thus co-precipitation was a good method to synthesize GSGG polycrystalline material.

关键词： Gd3Sc2Ga3O12 co-precipitation laser crystal rare earths

Simulation studies of multi-line line-of-sight tunable-diode-laser absorption spectroscopy performance in measuring temperature probability distribution function

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Chinese Physics B 2014年第12期23卷 209-214页

作者：张光乐刘建国阚瑞峰许振宇 Key Laboratory of Environmental optics & Technology Anhui Institute of Optics and Fine Mechanics Chinese Academy of Sciences

Line-of-sight tunable-diode-laser absorption spectroscopy（LOS-TDLAS） with multiple absorption lines is introduced for non-uniform temperature measurement. Temperature binning method combined with Gauss–Seidel iteration method is used to measure temperature probability distribution function（PDF） along the line-of-sight（LOS）. Through 100 simulated measurements, the variation of measurement accuracy is investigated with the number of absorption lines, the number of temperature bins and the magnitude of temperature non-uniformity. A field model with 2-T temperature distribution and15 well-selected absorption lines are used for the simulation study. The Gauss–Seidel iteration method is discussed for its reliability. The investigation result about the variation of measurement accuracy with the number of temperature bins is different from the previous research results.

关键词： TDLAS temperature non-uniformity Gauss–Seidel iteration method simulation

Ground-based remote sensing of atmospheric total column CO_2 and CH_4 by direct sunlight in Hefei

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Chinese Physics B 2013年第12期22卷 563-569页

作者：程巳阳徐亮高闽光李胜金岭童晶晶魏秀丽刘建国刘文清 Key Laboratory of Environment optics & Technology Anhui Institute of Optics and Fine Mechanics Chinese Academy of Sciences

Fourier transform spectrometry has played an important role in the three-dimensional greenhouse gas monitoring as the focus of attention on global warming in the past few years. In this paper, a ground-based low-resolution remote sensing system measuring the total columns of CO2 and CH4 is developed, which tracks the sun automatically and records the spectra in real-time and has the advantages of portability and low cost. A spectral inversion algorithm based on nonlinear least squares spectral fitting procedure for determining the column concentrations of these species is described. Atmospheric transmittance spectra are computed line-by-line in the forward model and observed on-line by direct solar radiation. Also, the wavelength shifts are introduced and the influence of spectral resolution is discussed. Based on this system and algorithm, the vertical columns of O2, CO2, and CH4 are calculated from total atmospheric observation transmittance spectra in Hefei, and the results show that the column averaged dry-air mole fractions of CO2 and CH4 are measured with accuracies of 3.7% and 5%, respectively. Finally, the H2O columns are compared with the results observed by solar radiometer at the same site and the calculated correlation coefficient is 0.92, which proves that this system is suitable for field campaigns and used to monitor the local greenhouse gas sources under the condition of higher accuracy, indirectly.

关键词： carbon dioxide methane ground-based remote sensing solar absorption spectroscopy

High Resolution and High Sensitivity Measurement of Methane at 1.51μm

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Chinese Physics Letters 2006年第9期23卷 2415-2417页

作者：邓伦华高晓明曹振松赵卫雄张为俊 Laboratory of Atmospheric optics Anhui Institute of Optics and Fine Mechanics Chinese Academy of Sciences Hefei 230031 Laboratory of Environmental Spectroscopy Anhui Institute of Optics and Fine Mechanics Chinese Academy of Sciences Hefei 230031

The high-resolution absorption spectrum of CH4 at 1.51μm is observed by direct absorption spectroscopy technique with a White absorption cell. Multi-peak fitting technique is adopted to reveal line positions and line intensities of CH4 from 6608cm^-1 to 6625 cm^-1. Special attention is paid on the determination of the line positions, and the accuracy is better than ±0.002cm^-1. A minimum measurable absorption of 2.1×10^-8 （3σ） has been achieved based on the measured direct absorption spectroscopy.

关键词： High Resolution Measurement of Methane

Temperature-dependent Raman spectroscopic study of bismuth borate Bi_2ZnOB_2O_6

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Chinese Physics B 2015年第1期24卷 503-506页

作者：张季张德明张庆礼殷绍唐 anhui Xin Hua University anhui institute of optics and fine mechanics Chinese Academy of Sciences

A temperature-dependent Raman spectroscopic study on Bi2 Zn OB2O6crystal was carried out to investigate the structure change of the crystal with the increase of temperature. Raman spectra of crystal Bi2 Zn OB2O6were recorded in the spectral range 10–1600 cm-1at room temperature first. Compared with the vibrational spectra of the referred compounds,satisfactory assignment of most of the high-energy modes to vibrations of Bi–O, B–O, and Zn–O bonds was achieved. In particular, the Raman high-frequency peak located at 1344 cm-1was attributed to the B–O vibration in the BO3 *** temperature-dependent Raman spectroscopic study was carried out up to 600°C. It was found that all the Raman lines exhibit decreases in frequency and the widths of the Raman peaks increase with increasing temperature. No phase transition was observed under 600°C.

关键词： Bi2ZnOB2O6 crystal high temperature Raman spectroscopy vibrational mode

Accuracy improvement of calibration-free laser-induced breakdown spectroscopy

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Plasma Science and Technology 2019年第3期21卷 6-15页

作者： Hongbo FU Zhibo NI Huadong WANG Junwei JIA Fengzhong DONG anhui Provincial Key Laboratory of Photonics Devices and Materials Anhui Institute of Optics and Fine Mechanics Chinese Academy of Sciences Key Laboratory of Environmental optics & Technology Anhui Institute of Optics and Fine MechanicsChinese Academy of Sciences University of Science and Technology of China

Calibration-free laser-induced breakdown spectroscopy can overcome the matrix effect and the huge application prospects of in situ and on-line measurement, so it has been studied and applied to many analytical samples by numerous researchers since it was first proposed in ***, its accuracy is always lower than other analytical techniques and traditional quantitative analysis methods of laser-induced breakdown spectroscopy. The goal of this paper is to review the improvement of accuracy in the experimental setup and spectral analysis,especially after 2010, but not limited to it. The main contents include the accurate measurement of spectral intensity, the spatial and temporal window of local thermodynamic equilibrium and the accurate calculation of temperature and electron density. Due to the requirement of one or more standard samples, the combination of standard samples and CF-LIBS is discussed as a separate section. Finally, a simple conclusion is offered to relevant researchers who want to use CF-LIBS for quantitative analysis.

关键词： CF-LIBS quantitative analysis accuracy self-absorption local thermodynamic equilibrium