吸收式光纤乙炔气体传感器的研究

基于乙炔气体的光谱吸收特性,采用一种带有参考通道的光纤乙炔气体在线实时检测系统.在设计过程中采用了双光路结构解决系统不稳定问题,消除随机因素的影响,提高测量准确度.给出了该光纤乙炔气体浓度测量的实验结果.     

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。     

油中溶解C2H4气体的光声探测

光声光谱气体分析技术灵敏度高,不消耗被测气体,克服了传统的变压器检测的气相色谱分析方法的缺点。文中采用了光声光谱法对C2H4气体进行探测,论述了光声信号的产生原理,用CO2激光器作光源对C2H4气体浓度进行了测量,证实了该技术在油中溶解气体浓度测量中的实用价值。     

应用单一超窄线宽激光器的多气体检测系统设计

应用超窄线宽半导体激光器的波长扫描和光谱调制技术,设计了一种高精度多组分气体实时在线检测系统.系统采用单一超窄线宽可调谐半导体激光器作为光源,设计了新型串联式气室结构减小横向空间、增加光程长,并通过三角波信号对光源光谱进行调制;结合时分复用和空分复用技术,利用超窄线宽激光的特性实现了CO,CO2,CH4多组分气体浓度的...     

体布拉格光栅外腔倍频半导体激光器研究

为提高绿光激光器的输出特性,设计了一种体布拉格光栅外腔倍频半导体激光器。采用反射型体布拉格光栅作为反馈元件构成外腔半导体激光器,并使用三硼酸锂晶体进行倍频,研究了基频光的光束及光谱特性对倍频光的光束及光谱特性的影响。实验结果表明,使用体布拉格光栅进行外腔锁波时,所得到的倍频光同样能实现窄带宽输出,同时倍频光的远场分布与基频光的远场分布一致。使用衍射效率为10%的体布拉格光栅作为外腔输出镜,可将半导体激光器的输出波长稳定锁定在1 064 nm,所得到的倍频光波长稳定在532 nm附近,光谱线宽压缩至0.4 nm左右,输出功率可达73 mW。     

基于TDLS的光谱吸收型CO_2传感器仿真与实验研究

文中采用可调谐半导体激光器光谱吸收技术(TDLS),针对激光调制参数设置问题,建立CO_2气体光谱吸收理论模型,分析光谱吸收后产生基波、二次谐波信号与气体浓度的关系。使用Simulink进行仿真,研究激光器调谐系数对谐波强度的影响,并优化了实验系统的设计参数。通过搭建CO_2检测系统,进行气体浓度定标测试,得到气体浓度与谐波强度的关系,采用叠加平均和积分的方法处理检测信号,使系统性能得到显著提高。由此实现了CO_2气体高精度检测,为谐波检测技术的实际应用提供了参考。     

湿度和SF_6在石英增强光声光谱中对CO分子弛豫率的影响

为了研究六氟化硫(SF_6)气体分子和水汽(H_2O)对一氧化碳(CO)气体分子的弛豫率的影响,建立了一个基于石英增强光声光谱(QEPAS)技术的痕量气体传感器系统。采用1.57μm的近红外分布式反馈二极管激光器作为激励光源,并对不同SF_6和H_2O气体浓度下的CO的光声信号进行对比研究。首先用CO传感器系统探测CO与N_2的气体混合物中CO的光声信号,然后在CO与N_2气体混合物中加入不同浓度的SF_6气体,分别探测不同浓度SF_6气体下的CO光声信号强度。最后在CO与N_2的气体混合物中加入不同浓度H_2O,探测加入H_2O后的CO的光声信号强度。实验结果表明随着CO和N_2气体混合物中SF_6气体浓度的增加,CO的光声信号幅值几乎没有变化,而在混合物中加入2.5%的H_2O后,发现CO的光声信号提高了约5倍。因此,SF_6对CO气体的弛豫率没有明显的影响,然而H_2O的添加能够有效缩短CO气体的弛豫时间。     

运用光声光谱技术的变压器油中溶解气体检测研究

根据我们国家目前城市变压器运行情况,对光声光谱技术在变压器油中溶解气体检测的应用进行了研究,对试验的机理和数据惯性进行了探索论证。建立了光声光谱法的试验系统模型,并确定了采用的光声腔和光源,研究了氢气组分的检测方法。对不同组分含量的气体进行了试验,并与气体色谱法试验获得的结果进行了对比,认为光声光谱法用于变压器油中气体检测是可行的。     

光声光谱技术的发展与应用

光声光谱(PAS)是基于光声效应的新兴光谱技术。近年来,光声光谱仪已成为物理、化学、生物、医药等方面研究分析的有用工具。光声光谱技术,目前正以广泛的应用潜力而受到人们的重视。在气体光声光谱技术研究方面,美国贝尔试验室很早就提出将光声光谱技术应用于气体分析仪器上的方案。由于条件的局限,近年来随着红外激光光源的研制成功以及光声光谱分析灵敏度的显著提高,才出现了商     

计算机监控FBG-ECLD乙炔吸收稳频技术

报道了基于计算机监控的光纤光栅外腔半导体激光器(FBG-ECLD)乙炔吸收稳频,设计了计算机信号监测和设备控制的平台,实现了在计算机界面上对信号的监测和对稳频控制设备的控制。系统将光纤光栅外腔半导体激光器的输出光频率稳定在乙炔的一个吸收峰上,稳定度达到10-8量级。     

Simultaneous measurement on gas concentration and particle mass concentration by tunable diode laser

The method of simultaneous measurement on gas concentration and particle mass concentration by tunable diode laser absorption spectroscopy is developed. The method is validated using a 1.58 μm diode laser with wavelength modulation spectroscopy. The experimental environment of particulated gas flow is imitated by adding uniform-sized quart sands into CO₂ gas. Calibrated second harmonic signals are proved to be independent of particle effects but only depend on gas concentration, and particle mass concentration can be calculated from the attenuation of laser power. This technique would be helpful to improve the quality and applicability of tunable diode laser absorption spectroscopy in emission monitoring.     

High-limit detection and accurate analysis of acetylene in transformer oil gases with a tunable laser-based photoacoustic spectrometer

Acetylene in transformer oil is an important feature gas, which can reflect early discharge faults. A tunable fiber laser photoacoustic (PA) spectrometer based on second harmonic modulation, with its fast response and good noise immunity, can be well applied to detect trace gases. In this work, the second harmonic PA measurement of the acetylene gas at the 1530.3709 nm transition line is demonstrated. An accurate analysis of acetylene in transformer oil gases is ensured by using an overcomplete-independent-component-analysis(ICA)-basis BSS model and a five-point-sampling method to improve the detection limit from 1.12 to 0.71 ppb. The experiment for detecting and analyzing acetylene in transformer oil gases shows that the discharge acetylene productivity can reach 303.72 ppb/s with a dynamic response time of less than 10 s, relative error of about 1.40%, and relevance coefficient up to 0.99946. At room temperature and atmospheric pressure, this can meet the demands of acetylene detection and analysis in early or ultra-early predictions of transformer discharge faults.     

Characterization of a derivative photoacoustic spectrometer

A design of derivative photoacoustic spectrometer is presented in this article. It mainly includes a wavelength-intensity splitter and a complementary chopper. In our design, a dual wavelength derivative method is introduced to implement a derivative operation. Through the wavelength-intensity splitter, two beams are obtained and then complementarily modulated by the complementary chopper to satisfy the first derivative requirements as well as to achieve the differential of photoacoustic signals. As examples, the first derivative photoacoustic spectra of He-Ne laser and xenon lamp are also presented in this article. The results show that the first derivative photoacoustic spectrum can provide a superior fine spectral structure and spectral resolution compared to the photoacoustic absorption spectrum.     

基于TDLAS技术的在线气体检测系统评介

基于可调谐激光二极管吸收光谱技术的在线气体检测系统可用于分析工业过程气体浓度,具有无需采样预处理、响应速度快、不受背景气体和粉尘影响以及适应恶劣工业环境能力强等突出优势。本文在介绍运用波长调制技术的吸收光谱原理的基础上详细介绍该仪器的性能特点和组成结构。     

Repetitive vacuum ultraviolet xenon excimer laser

A repetitive, tunable, high-power vacuum ultraviolet laser operating on the 172-nm bound-free transition in xenon has been developed for use in photochemistry, selective excitation spectroscopy, and in the generation of coherent radiation in the XUV spectral region. A compact high-voltage generator is employed in conjunction with a coaxial cold-cathode diode to pump high-pressure xenon at a repetition rate of up to 10 Hz, though at present gas heating limits the operation of the laser to 0.5 Hz. The apparatus has been designed for compatibility with fluorine, and is consequently a suitable pumping source for the rare gas halide exciplex lasers. The gas handling techniques which enabled reliable, reproducible laser action to be achieved in xenon for several hundred pulses are described.     

Mobile spectroscopic system for trace gas detection using a tunable mid-IR laser

We describe a mobile spectroscopic system for trace gas analysis based on the open path differential absorption spectrometer and the photoacoustic spectrometer. The first method allows long distance measurements (up to a few kilometers) while the second one provides local in situ detection of pollutants. The open path system is based on the nanosecond (f = 10 Hz, tau = 5 ns) lamp pumped Nd:YAG laser and a tunable two cascade optical parametric generator operating in the 5-12 microm spectral region. This source was mounted into the lidar setup based on the coaxial transmitter/receiver. The photoacoustic system was constructed using the same laser as well as a nonresonant photoacoustic cell.     

Er3+/Yb3+共掺双包层光纤的高功率L-band 光纤激光器的实验研究

采用端面泵浦的方式,用尾纤输出波长为976 nm的高亮度多模半导体激光器, 包层泵浦的铒镱共掺双包层大模面积光纤,非球面镜组耦合系统,进行了共掺双包层光纤的高功率L-band光纤激光器的研究,泵浦耦合效率达到了62%以上,并在F-P激光振荡腔中实现了高效的连续激光输出。在光纤长度为30 m、入纤功率为 13.41 W时,首次报道输出连续功率达到了4.3 W。激光器的斜率效率为44％, 激光输出中心波长1 603 nm。     

一种新型在线分析仪器——可调谐二极管激光光谱分析器

介绍了可调谐激光二极管激光光谱分析器的工作原理、性能特点和结构形式,说明了该仪器在在线过程分析中的优势,对其发展远景作了讨论.