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。     

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...     

注入锁定腔增强拉曼光谱微量气体检测技术

为了提高微量气体的拉曼散射强度,本文设计并搭建了注入锁定腔增强拉曼光谱微量气体检测平台。半导体激光器(波长为638nm,功率为15mW)输出到由三块高反镜组成的V型增强腔中,结合注入锁定技术,腔内激光强度达到7.5 W,实现了500倍的增强效果。利用该实验平台对微量单一气体及其混合气体进行了拉曼检测,并根据拉曼特征谱峰选取原则及信噪比大于3的原则,确定了H2、CO、CO2、CH4、C2H6、C2H4、C2H2的特征拉曼谱峰分别为4 156,2 143,1 388,2 918,2 955,1 344,1 975cm-1,最小检测极限分别为10.2,21.7,9.4,2.1,8.9,4.9,3.3Pa。腔增强拉曼光谱法可以实现微量同核双原子气体检测及利用单一波长激光的混合气体同时检测,具有替代气体检测传统光谱方法的潜力。     

浅析波长扫描光腔衰荡光谱技术

波长扫描腔衰荡光谱技术是一种新型的光谱检测方法,由于该技术具有吸收光程长,不受光源强度起伏影响的特点,因而受到国内外的广泛重视,已被应用于监测分子及原子体系。波长扫描光腔衰荡光谱技术在痕量元素监测分析中的应用,证明它完全可以在通用的原子吸收分光光度计上实现。它的主要用途是进行多元素分析。能够带来一些其它的扩展功能,是一种很有发展前途的新技术。     

变压器油中气体拉曼光谱检测及信号处理方法

准确检测变压器油中溶解故障特征气体是诊断变压器运行状态的重要技术手段之一。论文基于拉曼光谱和腔长调制频率锁定原理,搭建了变压器故障特征气体频率锁定腔增强拉曼光检测平台,实现了H_2、CH_4、C_2H_2、C_2H_4、C_2H_6、CO、CO_2等七种故障特征气体的同时检测;1atm时,H_2、CH_4、C_2H_2、C_2H_4、C_2H_6、CO、CO_2的最小检测浓度实验值分别达到106、25、45、73、41、170、126(ppm)。频率锁定增强腔技术使最小检测浓度提高了约68倍。运用小波模极大值法对H_2的拉曼光谱检测信号进行了去噪处理,提出了基于包络线迭代法的光谱基线校正方法,校正后的光谱荧光背景残留减少,使气体拉曼光谱检测准确度提高了约2.95%,为变压器油中溶解故障气体同时准确检测提出了一种新方法。     

一种新型单腔双振子压电泵的结构设计和性能试验

为优化单腔双振子压电泵的结构,提高输出性能,设计了一种新型结构的单腔双振子压电泵。将新设计结构同前期设计结构进行了比较,并对两种结构的试验样机进行了输出流量测试。试验显示,新结构的输出流量是前期结构输出流量的2倍,最大流量可达800mL/min。将新结构加工了不同腔体初始容积样机,得到了压缩比对泵输出性能的影响。试验发现,当腔体高度为1.2mm,工作时的压缩比为1/46,此时单腔双振子压电泵整体输出效果最好。分析了单腔双振子压电输送液体和气体时工作特点,得到泵输送液体介质时最佳工作频率点远远低于输送气体介质。     

外腔调谐的全固态Cr∶LiSAF激光器

由于调谐元件置于主腔外时,插入损耗影响小,可以扩展调谐范围,本文采用外腔棱镜和光栅调谐结构研制了全固态Cr∶LiSAF激光器。分析了外腔调谐结构的基本原理,分别选用棱镜和光栅作为调谐元件,研制了棱镜外腔调谐Cr∶LiSAF激光器和光栅外腔调谐Cr∶LiSAF激光器。分析对比了棱镜和光栅调谐的输出功率、光谱、调谐范围等特性以及镜片镀膜对输出特性的影响。进行了调谐实验,结果显示:选用棱镜作为外腔调谐元件时,在325mW的吸收泵浦功率下实现了785~985nm的调谐,输出功率最高达21mW。选用光栅作为调谐元件时,亦可实现785~985nm的调谐,最大输出功率为20mW,光谱的半峰全宽(FWHM)为0.12nm。得到的结果表明外腔全固态Cr∶LiSAF激光器可以实现窄线宽、宽谱调谐输出。     

可调谐皮秒染料激光器的腔倒空器驱动器

介绍了皮秒染料激光器输出的腔倒空器工作原理,研制腔倒空器驱动器的电路技术,并列出所制成仪器的实测结果.     

不同容积比的双腔串联压电泵测试分析

为提高双腔串联压电泵的输出性能,对泵的进口腔与出口腔的容积比进行了优化设计。分别设计了容积比为1.9、1.5、1.3三种串联压电泵样机,并对样机进行了试验测试。试验结果显示,采用增加容积比的方式可以提高双腔串联压电泵的输出流量,但不能提高其输出压力;对每个不同腔体容积比的双腔串联压电泵在异步驱动和同步驱动下进行了输出性能测试,测试结果显示,当输送气体时,两种驱动方式均有很好的流量输出,且输出结果比较接近,但仅有异相驱动时才能输出液体。分析结果为提高双腔串联压电泵的输出性能提供了很好的依据。     

防止污氮电加热器接线腔过热和潮湿的技术探讨

污氮气体是一种氮气占绝对比重,氧气、氩气、氦气、氖气等气体占比极小的空气分离工艺所需气体。污氮电加热器是一种常见的加热污氮气体的空分设备,在进口处污氮气体温度很高的工况下,接线腔内温度更高,对电缆等零部件的寿命影响较大;在潮湿恶劣环境下,接线腔内铜排、电加热管等导电零部件易凝结露水,影响绝缘性能。鉴于此,创新设计了一种能够防止过热和潮湿的污氮电加热器接线腔,并对其技术方案进行了简要介绍。     

Measurement technology for material emissivity under high temperature dynamic heating conditions

The thermal dissipation of radiation is main heat shield mechanism for non-ablative thermal protection materials on hypersonic vehicles withstanding high temperature dynamic heating cycle during endo-atmospheric ascent, cruise and reentry. Therefore, it is necessary to know the thermal radiative properties of the material under the simulated high temperature dynamic heating conditions on the ground. The emissivity depends on the surface state and its temperature. A new simultaneous measurement technology of emissivity and varying surface temperature is proposed under high temperature dynamic heating conditions. This new technology solved synchronous measurement problems by utilizing spectral signal of Fourier transform infrared (FTIR) spectroscopy. The calibration of different temperature ranges, the background disturbances, the influences on temperature measurement by wavelength range and its corresponding fluctuations of measurement signal, were thoroughly investigated. The measured results of steel and graphite as reference materials proved the effectiveness of this simultaneous measurement technology and showed great potential in engineering applications under high temperature dynamic heating conditions.     

同位素比值质谱与激光吸收光谱分析水中氢氧同位素方法的比较

氢氧稳定同位素在研究地球水循环过程中发挥着重要作用。本研究采用激光光谱法和高温热转换元素-同位素比值质谱法测定水样中氢同位素,采用激光光谱法和CO₂-H₂O平衡-同位素比值质谱法测定水样中氧同位素。结果表明：使用原理不同的两种方法测定地下水、海水和大气降水样品,测定的δ²H和δ¹⁸O值的精密度与准确度相当,激光光谱法以其快速高效、低成本、样品用量少占有优势;但使用这两种方法测定土壤抽提水样品时,激光光谱法测定δ¹⁸O值与真值的偏差为0.34‰,而质谱法测定的偏差小于0.10‰;激光光谱法测定δ2H值与真值的偏差为2.3‰,而质谱法测定的偏差小于0.6‰,说明质谱法的结果明显优于激光光谱法。     

太赫兹双梳光谱中重复频率差影响的研究

太赫兹双梳光谱技术因其高频率分辨率和高灵敏度等优点，近年来成为一种有力的光谱测量技术。为了提高光谱系统的探测性能，本文分析了双梳光谱技术在时域和频域中的采样原理及方法，基于两台飞秒激光器搭建了一套重复频率可调的太赫兹双梳光谱系统。通过改变一台光频梳的重复频率，系统地研究了不同重复频率差对太赫兹双梳光谱系统性能的影响。结果表明有效范围内的重复频率差越小，探测到光谱质量越高。当重复频率差为10 Hz时，太赫兹双梳光谱系统的探测性能最佳。此研究为太赫兹双梳光谱技术选择最合适的重复频率差提供了方法。     

Application of fluorescence emission ratio technique for transformer oil monitoring

In this work a new fluorescence emission measurement technology was introduced and experimentally compared with other measurement methods, such as the titration method and IR spectroscopy, to validate it for the oil oxidation measurement of electrical insulating oil. The oxidation characteristics of insulating oil were found to be fairly represented by the titration method and IR spectroscopy, and the results are comparable to a change in the fluorescence emission ratio that is defined as the shift in fluorescence intensity in the measured wavelength range. The result also shows that by the measurement of fluorescence emission ratio, it is possible to detect the oxidation of oil relatively earlier than by other methods. This study suggests that the developed technology can provide sufficient information for evaluating the insulating oil quality, and that the developed FER sensor can be used as an effective condition monitoring device of electrical insulating oil oxidation.     

Spectral contaminant identifier for off-axis integrated cavity output spectroscopy measurements of liquid water isotopes

Developments in cavity-enhanced absorption spectrometry have made it possible to measure water isotopes using faster, more cost-effective field-deployable instrumentation. Several groups have attempted to extend this technology to measure water extracted from plants and found that other extracted organics absorb light at frequencies similar to that absorbed by the water isotopomers, leading to δ(2)H and δ(18)O measurement errors (Δδ(2)H and Δδ(18)O). In this note, the off-axis integrated cavity output spectroscopy (ICOS) spectra of stable isotopes in liquid water is analyzed to determine the presence of interfering absorbers that lead to erroneous isotope measurements. The baseline offset of the spectra is used to calculate a broadband spectral metric, m(BB), and the mean subtracted fit residuals in two regions of interest are used to determine a narrowband metric, m(NB). These metrics are used to correct for Δδ(2)H and Δδ(18)O. The method was tested on 14 instruments and Δδ(18)O was found to scale linearly with contaminant concentration for both narrowband (e.g., methanol) and broadband (e.g., ethanol) absorbers, while Δδ(2)H scaled linearly with narrowband and as a polynomial with broadband absorbers. Additionally, the isotope errors scaled logarithmically with m(NB). Using the isotope error versus m(NB) and m(BB) curves, Δδ(2)H and Δδ(18)O resulting from methanol contamination were corrected to a maximum mean absolute error of 0.93 [per thousand] and 0.25 [per thousand] respectively, while Δδ(2)H and Δδ(18)O from ethanol contamination were corrected to a maximum mean absolute error of 1.22 [per thousand] and 0.22 [per thousand]. Large variation between instruments indicates that the sensitivities must be calibrated for each individual isotope analyzer. These results suggest that the properly calibrated interference metrics can be used to correct for polluted samples and extend off-axis ICOS measurements of liquid water to include plant waters, soil extracts, wastewater, and alcoholic beverages. The general technique may also be extended to other laser-based analyzers including methane and carbon dioxide isotope sensors.     

基于光腔衰荡的反射率测量技术的研究

根据光腔衰荡原理开展了高反射率镜片反射率测量技术的研究。理论上给出了直型腔和折叠腔的反射率计算方法,构建了测量高反镜反射率的实验系统。实验结果表明系统结构简单,易调节,可以测量任意角度的反射率,测量结果精确,可满足高反镜片的各种测量要求。     

Improving the performance of an RF resonant cavity water-cut meter using an impedance matching network

In multiphase flow measurement, one of the most challenging issues is to define an adequate technology for a specific scenario, taking into account the measurement accuracy, implementation feasibility and costs. The electromagnetic technology based on resonant cavities is often employed in water-cut meters to measure two-phase flows such as water/oil and water/gas mixtures. The main disadvantage of this technology is the electromagnetic signal attenuation that occurs as the water content decreases. This undesirable behavior is amplified due to the impedance mismatch between the sensor ports and the transmitter/receiver modules. This paper presents a study to implement an impedance matching network in order to improve the instrument performance. Impedance matching networks were built, taking into account the matching for a 100%, 50% and, also, for the worst case of 0% of water fraction where there is a significant signal attenuation. The implemented networks improved the signal amplitude ratio between the first resonant mode and the other modes, increasing the identification accuracy of the first resonance peak.     

一种皮鞋内腔尺寸CT测量仪

针对目前皮鞋内腔尺寸测量尚无有效的测量方法，致使制鞋业的产品设计生产落后、皮鞋的档次低及品种少的实际情况，本文研究开发了一种基于CT技术的皮鞋内腔尺寸自动测量仪。皮鞋内腔尺寸CT测量仪由6个部分组成，即X射线源与前准直器、探测系统、机械扫描及控制系统、主计算机系统、图像重建与处理系统及尺寸测量分析系统。研究结果表明，重建出的皮鞋内腔CT图像清晰，尺寸误差〈0．4mm，达到了设计使用的要求，为皮鞋内腔尺寸的无损测量提供了一种新的检测手段。     

ESPCP系统推力球在原油态下摩擦磨损性能研究

利用SRV摩擦磨损试验机模拟了潜油螺杆泵采油系统（ESPCP系统）推力球在原油为润滑介质时的摩擦磨损性能，通过不同热处理的GCr15钢球与GCr15钢盘的摩擦磨损性能研究，考察了等离子渗氮GCr15钢代替淬火GCr15钢的可行性；利用X射线散射（XRD）对等离子渗氮GCr15钢表面进行成分分析，考察了以原油为润滑介质时，钢盘的摩擦磨损性能。结果表明，GCr15钢等离子渗氮后在提高表面硬度的同时，其抗磨性能大幅度提高。通过扫描电子显微镜（SEM）和X光电子能谱仪（XPS）对磨斑表面形貌和表面成分进行了分析，表明等离子渗氮层具有更好的抗磨、减摩性能和更高的承载能力。