光腔衰荡光谱技术及其应用综述

光腔衰荡光谱(CRDS)技术是近几年迅速发展起来的一种吸收光谱检测技术。在介绍光腔衰荡光谱检测原理的基础上,详细推导了CRDS技术用于反射率测量和痕量气体浓度检测的理论公式。分析了CRDS技术由于实际吸收光程长,检测精度不受光源强度及其变化的影响,因此具有检出限低,测量精度高,可靠性好等特性。综述了CRDS技术在微量污染气体监测中的应用及其发展趋势。最后提出了应用光腔衰荡光谱检测污染气体中不同有害成分浓度的一种新思路。     

基于衰荡腔技术的传感器设计与计算机分析

文中将痕量气体测量中衰荡腔技术引入到了SPR传感器中,提高了性能。理论上分析了衰荡腔光路及出射光强与衰荡腔扫描速度间的关系。分析发现:设计的新方法相对于直接测量SPR归一化光强的方法可以显著提高灵敏度,降低检出限。通过改变可调谐激光器的输入波长,并利用衰荡时间信号反馈调节可调掺铒光纤放大器放大,可以在保证灵敏度条件下追踪SPR吸收峰变化,因此兼具波长解调型SPR系统动态范围广,适应性强的优点。     

高灵敏度腔增强吸收式乙炔气体检测系统

基于超窄线宽激光特性和光源波长扫描技术,构建了高灵敏度腔增强吸收式乙炔气体检测系统。该系统采用超窄线宽可调谐半导体激光器作光源,使用两块高反射率平凹透镜组成的光学谐振腔作吸收池,通过扫描腔长使入射激光频率与谐振腔模式相匹配,利用激光失谐技术快速断开入射激光,从而实现对微量乙炔气体浓度的衰荡测量。利用腔增强吸收技术测得了激光衰荡时间和6 518.824 cm^-1附近的乙炔弱吸收光谱并进行了分析。结果表明,乙炔气体浓度线性相关系数优于0.999,最大相对误差小于2.5%,极限检测灵敏度为2×10^-6;逐次充入一定体积的乙炔气体,动态响应时间均小于10 s。该检测系统精确度好、灵敏度高,具有较好的动态响应特性,可用于电力变压器故障气体实时在线监测。     

用光腔衰荡法测量高反射率的实验研究

根据光腔衰荡光谱技术开展了测量镜片高反射率的研究,建立了测量实验装置。理论上给出了反射率测量的计算方法,在实验中测定了一对反射率相等的高反射腔镜的反射率,以及一块45°反射镜样品的反射率,并分析了影响光腔衰荡曲线的参数。     

高灵敏度光纤磁场传感器的设计与模型研究

根据磁致伸缩效应和光纤腔衰荡技术设计了高灵敏度的磁场传感器。基于Jiles-Atherton模型、二次畴转模型和光纤衰荡技术波长解调原理,建立了磁场传感器的数学模型,模型反映了磁场-应变-光纤腔衰荡时间之间的耦合机制。对不同预应力作用下Terfenol-D棒的磁致伸缩输出应变、衰荡时间、系统灵敏度与磁场之间的变化规律进行了理论分析和仿真研究,结果表明,该传感器具有很高的灵敏度,可通过改变预应力实现不同量程范围内的磁场测量,研究可为发展新型的高灵敏度磁场传感器提供了理论指导。     

原子吸收光谱概况

前言早在上一个世纪已经发现太阳光谱中有暗线光谱,试验证明这是高温下原子吸收的结果,并且吸收波长正是同种元素的发射波长。然而原子吸收光谱在分析上得到较大应用却迟到1955年 A.Walsh[1] 发表了一篇著名的论文《原子吸收光谱在分析上的应用》之后。经过以后几年的实践和研究,逐渐发现和解决了一些应用中的问题,原子吸收分光光度计的性能     

一次谐波锁频的快速光腔衰荡光谱检测

本文介绍了一种赫兹级响应速率的光腔衰荡光谱探测大气痕量气体的检测技术.将100 MHz正弦波调制信号加载在电光相位调制器上产生边带,用混频器提取载波与边带通过3m气体吸收池后拍频所产生的一次谐波作为误差信号,实现了1572 nm分布式反馈激光器对于二氧化碳气体分子6361.25 cm-1处超精细跃迁线的频率锁定.采用波...     

积分腔输出光谱技术及其应用综述

积分腔输出光谱（ICOS）技术是最近几年迅速发展起来的一种高精细腔吸收光谱技术。在介绍了积分腔输出光谱技术原理的基础上,推导了ICOS技术用于检测痕量气体时的理论公式,介绍了在ICOS技术中使用的波长调制光谱技术。指出了ICOS技术在环境监测方面的优势,包括装置简单、有效吸收光程长、检出限低、测量精度高等,而且给出了影响ICOS探测灵敏度的因素。最后综述了ICOS技术在痕量气体监测中的应用,指出了ICOS技术的发展趋势。     

基于光纤环形衰荡腔的甲烷传感研究

提出一种基于腔衰荡光谱技术的新型光纤甲烷传感方法,与传统的甲烷传感方式相比,它可以通过测量信号的相位移动来测量气体的浓度。实验中采用了环形的光纤结构,避免了小型渐变折射率透镜构成的微型气室产生的二次噪声,提高了系统的灵敏度。结果表明,该系统可以应用于低浓度气体的在线检测。     

AAS 9542C型原子吸收分光光度计

介绍了北京苏晖仪器有限公司生产的ＡＡＳ９５４２Ｃ型原子吸收分光光度计的特点，包括具有自动转换元素灯控制、波长扫描寻峰自动定位控制、光谱带宽自动控制、一体化自动控制、石墨炉的水气保护自动实现、石墨炉系统自动控制的特别自动控制功能和新颖的工作软件。     

REVIEW ON ADVANCES OF SENSORS BASED ON FIBER LOOP RING-DOWN SPECTROSCOPY

Fiber loop ring-down spectroscopy (FLRDS) is an absorption spectroscopic and detection technique. It makes use of an optical cavity, which not only realizes a long effective path length through a sample, but also eliminates the effects of fluctuations of the light intensity. In this article, research advances of FLRDS used for sensors, such as concentrations of gas, pressure, strain, and refractive index are presented. According to its different sensing properties, the working principles and the performances of each application in sensors are introduced in detail. Finally, the key problems of FLRDS in sensing technology are concluded and the future research directions are discussed.     

Pound-Drever-Hall-locked, frequency-stabilized cavity ring-down spectrometer

We describe a high sensitivity and high spectral resolution laser absorption spectrometer based upon the frequency-stabilized cavity ring-down spectroscopy (FS-CRDS) technique. We used the Pound-Drever-Hall (PDH) method to lock the probe laser to the high-finesse ring-down cavity. We show that the concomitant narrowing of the probe laser line width leads to dramatically increased ring-down event acquisition rates (up to 14.3 kHz), improved spectrum signal-to-noise ratios for weak O(2) absorption spectra at λ = 687 nm and substantial increase in spectrum acquisition rates compared to implementations of FS-CRDS that do not incorporate high-bandwidth locking techniques. The minimum detectable absorption coefficient and the noise-equivalent absorption coefficient for the spectrometer are about 2×10(-10) cm(-1) and 7.5×10(-11) cm(-1)Hz(-1/2), respectively.     

A rigid, monolithic but still scannable cavity ring-down spectroscopy cell

A novel cell for continuous wave cavity ring-down spectroscopy (cw-CRDS) is described and tested. The cell is monolithic and maintains a rigid alignment of the two cavity mirrors. Two high-resolution and high-force piezoelectric transducers are used to sweep the length of the cell by elastic deformation of the 2.86 cm outer diameter stainless steel tube that makes up the body of the cell. The cavity length is scanned more than 1/2 wavelength of the near-IR light used, which ensures that at least one TEM(00) mode of the cavity will pass through resonance with the laser. This allows the use of a frequency-locked-laser cw-CRDS technique, which increases the precision of the measurements compared to the alternative of sweeping the laser more than one free spectral range of the cavity. The performance of the cell is demonstrated by using it to detect the absorption spectrum of methane (CH(4)) at the wavenumber regions of around 6051.8-6057.7 cm(-1).     

Accurate measurements of water vapor transmission through high-performance barrier layers

We report a new approach to measuring very low rates of water vapor transmission through high-performance barrier layers, based on detection of the water vapor by cavity ring-down infrared spectroscopy. It provides accurate and traceable measurements with a detection limit for water vapor transmission significantly below 1 × 10(-4) g∕m(2)∕day. The system is underpinned by dynamic reference standards of water vapor generated between 5 and 2000 nmol∕mol with an estimated relative expanded uncertainty of ±2%. It has been compared with other methods and demonstrates good comparability.     

国产原子吸收光谱仪器的发展现状及新趋势

本文简要回顾了我国原子吸收光谱仪器的发展概况,论述了国产原子吸收光谱仪器的发展现状,简单介绍了原子吸收光谱仪器在多个领域进行的具体应用情况,同时从应用技术开发、软件功能、仪器可靠性和稳定性三个大的方面阐述了国内外原子吸收光谱仪产品的主要差距,提出国产原子吸收光谱仪器有待提高的方向和新的发展方向及趋势。     

Evaluation of carrier gases for high-precision water isotopic measurements by cavity ring-down laser spectroscopy

The carrier gas is important for obtaining stable, precise hydrogen and oxygen isotopic ratios in water samples using cavity ring-down laser spectroscopy. The δ²H and δ¹⁸O variations were investigated using four carrier gases under two microcombustion conditions. Although most deviations of δ²H and δ¹⁸O values were within the standard deviation of the instrument, statistical analysis indicated that carrier gas provided by a drying tube with higher water background was not suitable for cavity ring-down laser spectroscopy. In addition, the microcombustion on condition did not significantly improve the precision and accuracy of δ²H and δ¹⁸O measurements. Therefore, the best method for achieving highly precise results involved the use of low water containing compressed air as the carrier gas with the microcombustion warm condition.     

Coaxial arrangement of a scanning probe and an X-ray microscope as a novel tool for nanoscience

We report on the design and first tests of a novel instrument aimed at combining the benefits of scanning force microscopy with those of X-ray spectroscopy. For this we built an instrument combining a scanning transmission X-ray microscope with a beam-deflection atomic force microscope in a coaxial geometry. This allows to combine X-ray absorption spectroscopy and high resolution topography in-situ. When replacing the conventional scanning probe tip by a coaxially shielded tip the instrument will allow detection of the photoelectrons produced by resonant X-ray absorption. This could yield spectroscopic information with a spatial resolution approaching the values achievable with atomic force microscopy.