激光诱导荧光水质监测系统的研制

提出以Nd：YAG激光器的三倍频355nm波长激光为激发光源,以单个光电倍增管（PMT）为探测器,以水体污染监测为目的的激光诱导荧光系统的研制。采用光电倍增管高速双脉冲门控与单次脉冲触发数据采样相结合新技术,有效减少了户外环境下背景光的影响,提高了系统的测量精确度。试验结果表明,该系统能接收水体表面受激发射的荧光信号,探测到的荧光信号经信号处理后与水体受污染程度有良好的相关性。     

Single-photon counting system for measuring laser parameters

A single-photon counting system has been developed for measuring gas laser parameters. A linear accelerator provides nanosecond-wide pulses of heavy charged particles which are injected into a specially designed cell. The charged particles excite gas mixtures, and the temporal response of the emitted radiation is observed as a function of wavelength. The resulting data is analyzed to obtain pertinent parameters such as excited-state lifetimes, reaction rate constants, and quenching rate constants. At the present time nuclear pumper laser candidate gases are being examined.     

新型激光诱导荧光检测器的研制及评价

采用成本低、灵敏度高的反射式Z-型检测池,成功研制新型473nm固体激光诱导荧光检测器(LIFD)。用荧光物质异硫氰酸荧光素(FITC)标准品评价检测器性能,其灵敏度高,最低检测浓度为1×10-12mol/L(S/N=15),线性范围超过4个数量级。进一步使用FITC衍生化苯胺、对甲苯胺、对氯苯胺、联苯胺、对苯二胺等5种物质,评价该检测器,最小检测量达到pg级,重现性好,5种物质保留时间RSD值均小于1%(n=7)。说明该检测器具有灵敏度高、稳定性好、线性范围宽等特点,适用于环境与生物领域痕量物质检测。     

Air-borne laser induced fluorescence system for measuring OH and other trace gases in the parts-per-quadrillion to parts-per-trillion range

Described in detail is a laser induced fluorescence system which has been successfully interfaced with two aircraft sampling platforms (i.e., Sabreliner jet and an L-188C Electra). This system, which has been under development for four years, presently consists of the following major components: (1) a Nd-Yag laser driven oscillator-amplifier dye laser; (2) a sampling manifold with associated fluorescence detection optics; (3) an OH calibration chamber; (4) a laser beam steering assembly; and (5) sampling electronics and data processing hardware. During the last three years, this system has been flown some 50 000 air miles making tropospheric OH radical measurements over the latitude range of 70 degrees N to 57 degrees S. OH concentrations measured during these flights have ranged from 30 parts-per-quadrillion (3.7x10(5) molecules/cm(3)) at altitudes of 6 km to 0.8 parts-per-trillion (2.0x10(7) molecules/cm(3)) at 0.5 km. Computations have been completed which indicate that the existing aircraft system with modest modifications should also be capable of detecting natural tropospheric levels of NO, SO(2), CH(2)O, NO(2), HNO(2), NO(3), H(2)O(2), and CS(2) by using both conventional laser-induced fluorescence methodology and multiphoton techniques.     

用于激光频率参数测量的飞秒光学频率梳

近年来随着光纤制造技术和飞秒激光技术的成熟,以掺铒(Er)光纤光学频率梳为代表的频率梳技术,逐步突破了光学 频率测量领域,在长度测量、精密光谱分析、超低相位噪声微波频率产生、精密时间频率传递、温度测量等领域发挥出越来越重 要的作用,已成为许多高端科研领域的基础性工具。 但飞秒光学频率梳所解决的重要问题是对激光频率进行测量。 本文主要 面向激光频率参数测量的需求,研制基于掺 Er 光纤飞秒激光器的光学频率梳,在实现光学频率梳稳定运转的前提下,通过非线 性光学频率变换技术,实现光谱范围从掺 Er 光纤光学频率梳的中心波长向各个待测激光波长的转换,并完成与多个不同波长 激光的拍频信号探测。 目前已验证的飞秒光梳可测频率范围为 500 ~ 2 000 nm;频率稳定度和准确度为 10 -16 量级;线宽为 Hz 量级。 该指标满足了激光频率特性参数测量的需求,为激光绝对频率、频率漂移、线宽等参数的测量提供了基础性的测量工具。     

Time correlation method for measuring fluorescence decays with a cw laser

A simple experimental approach to measuring fluorescence decay by time correlation signal analysis is described. The approach allows the use of continuous wave excitation and inexpensive detection-signal processing apparatus. The technique is demonstrated using a cw He-Cd laser. The transient response of the instrument is 0.88 ns, limited by the photomultipliers. The fluorescence lifetime of rose bengal in ethanol is determined, in absence of reorientation relaxation, to be 0.66+/-0.04 ns.     

ir laser induced fluorescence cell for multiple photon processes

An efficient, easy to construct, long-path laser-induced fluorescence cell is described which is useful in studies of multiple ir photon induced phenomena.     

生物反应器系统参数虚拟测试仪的研制

文中简要介绍了生物工程的重要性和生物反应器监控发展概况,以及虚拟仪器在这方面的应用现状和优势。所研制的虚拟仪器可在线检测温度、罐压、溶解氧、pH值、尾气CO2含量等9个参数,充分发挥了虚拟仪器的优势,避免了传统硬件式仪器的不足。着重阐述了生物反应器参数虚拟测试仪的基本结构,在此基础上论述了该虚拟仪器的软件设计和硬件结构,并以温度、pH值为例介绍了它们的检测调理电路。     

纳秒激光等离子体光源的光谱测量技术

提出了一种新的探测和测量激光等离子体软X射线源光谱强度的方法。此方法使用通道电子倍增器和定标过的硅光电二极管为探测器,前者是非标准探测器,后者为标准探测器。应用电荷灵敏前置放大器和峰值探测器测量探测器产生的电量,并以高分辨率的光谱仪为分光元件,在已知光栅效率、通道电子倍增器增益、硅光电二极管能量响应的条件下,给出了计算激光等离子体软X射线源在某一波长光谱强度的公式。     

Experimental characterization of temperature sensitive dyes for laser induced fluorescence thermometry

Laser induced fluorescence (LIF) is a non-intrusive optical technique that uses fluorescent dyes to measure whole-field fluid scalars such as temperature, concentration, pH, etc. LIF measurements' accuracy is strongly influenced by the fluorescent dye's behavior under different experimental conditions. In particular, ratiometric LIF thermometry accuracy depends on the correct selection of fluorescent dyes mixtures. Therefore, a thorough characterizations of fluorescent dyes is needed to obtain optimal mixtures and suitable optical configurations for given experimental conditions. This work presents the experimental characterization of fluorescein-27 (FL27) and rhodamine-B (RhB) mixtures to determine suitable aqueous solutions for ratiometric LIF thermometry. The mixtures' fluorescence emission intensity was measured with a spectrofluorometer, and the influence of concentration ratio (C(RhB)/C(FL27)), temperature, excitation wavelength (λ(ext)), and pH were analyzed. The results show that the temperature dependence of FL27 emission intensity changed from a negative to a positive value as the excitation wavelength increased. The temperature sensitivity (4.0% per °C) of RhB and FL27 mixture under 532 nm excitation wavelength was found to be higher than that of the commonly used mixture of RhB and Rh110 (2.0% per °C) at the same excitation wavelength. While the emission intensities of the dyes are sensitive to pH value, the temperature dependence is unaffected. The influence of concentration ratio on temperature sensitivity depends on both the detected bands of the emitted spectrum and the temperature; the concentration ratio should be selected based on the measured temperature scope. A new multicolor method or advanced two color method with high temperature sensitivity (6.0% or 10.0% per °C) is presented. This technique was specially developed to improve whole-field temperature measurements.     

共聚焦激光扫描荧光显微镜扫描系统研制

为适应三维光学微细加工及三维光学信息存储研究的需要,研制了共聚焦激光扫描荧光显微镜的工作台式扫描系统,扫描范围138μm×138μm.工作台采用压电陶瓷驱动器( PZT actuator)驱动的方式来获得高分辨率的位移,采用带柔性铰链的杠杆放大装置来获得较大的位移范围.描述了工作台的工作原理,并对其静态和动态性能进行了测试,实验表明这一扫描系统能很好的应用于共聚焦激光扫描荧光显微镜系统.     

提高CCD激光自准直测角精度的硬件方法

设计了一个CCD激光自准直测角系统。为提高系统的测量精度和实时性,对系统中的硬件参数进行研究,有效改善了采集到图像的质量。降低数据处理难度的同时,缩短了图像处理时间和提高了系统的测量精度。对系统中小孔光阑的直径,CCD的积分时间,会聚镜头的焦距值,采集卡的亮度和对比度参数分别进行分析,寻找优化值对系统进行改进。对改进前后的系统进行对比实验,实验结果表明,改进后系统的测角精度由原来的5.0″提高到了1.0″,处理一帧图像的时间缩短到了0.417s。     

Qualification of a fluorescence spectrometer for measuring true fluorescence spectra

New analytical methods using fluorescence detection are becoming increasingly quantitative and require easy-to-use material standards for fluorometer qualification and method validation. NIST is responding to this need by developing and producing such standards. Reported here is the first step in this process, which is to qualify a research-grade fluorescence spectrometer for measuring true fluorescence spectra of reference material candidates. "True" spectra are defined here as those with fluorescence intensity, either relative or absolute as required, and wavelength both being reported with high accuracy and known precision, after wavelength has been calibrated and corrections for excitation intensity and detection system response have been applied. The uncertainties determined in relative and absolute intensity-corrected fluorescence spectra using both calibrated source (CS)- and calibrated detector (CD)-based methods were compared. The CS-based method gave uncertainties, typically about +/-5% for relative spectral correction, that were about half that of the CD-based method for determining both relative and absolute spectral correction factors. Absolute spectral correction factors can be determined using either method without knowing the optical geometry of the instrument. The absolute spectral correction factors were found to have much larger uncertainties than the corresponding relative correction factors with uncertainties for the CS-based method of +/-10% to +/-15% being typical and +/-20% or more not being uncommon, particularly for excitation and emission wavelengths below 400 nm. Uncertainties arising from detection system nonlinearity and instrument polarization ratios were also explored.     

纯净靶激光等离子体力学特性的理论模拟

基于磁流体力学模型,对Xe、He、C、N、O、Ne、Al、Ar等元素在激光辐照下的等离子体力学特性进行了研究,并且以Al元素为例,研究了不同波长情况下的靶材烧蚀速度以及烧蚀压力的变化趋势.结果表明:在相同入射条件下,除Xe外,He、C、N、O、Ne、Al、Ar这几种元素的烧蚀压力比较接近,并且各元素的烧蚀速度的情况也大体相同,这样从增加火箭的有效载荷的角度考虑,采用大气驱动模式将是非常有利的.另外数值模拟结果还表明,随着入射光波长的增加,靶材的烧蚀速度、烧蚀压力单调下降并逐渐趋于平缓,尤其是当入射光波长小于某一个值时,这个变化非常迅速.因此,如果单纯从入射光波长角度考虑,波长越短将越有利于产生更大的推力.但短波长激光被大气散射严重,造成极大的能量损耗.因而在实际应用时,应该根据飞行器所处的不同飞行位置合理选择驱动光波长.     

齿轮线激光三维测量仪的研制

快速获取齿轮全部齿面的三维误差信息,是表征复杂齿面质量的关键和前提。 本文基于激光三角测量原理,建立了齿 轮线激光三维测量模型,研制出齿轮线激光三维测量仪,可用于生产现场快速获取被测齿轮的三维齿面误差信息并进行质量评 定。 仪器采用立式结构,主要由基座、精密主轴、圆光栅传感器、控制系统、软件系统等部分组成。 精密主轴采用密珠轴系实现 高精度回转,保证了被测齿轮的高精度定位与回转。 在精密主轴周向布置两个高精度线激光传感器,并根据被测齿轮参数调整 其位姿状态;圆光栅实时获取精密主轴的回转角度,并触发采集器实时采集并记录被测齿轮左右齿面的几何信息。 开发了齿轮 线激光三维测量与评价软件,可实现齿轮齿廓偏差、齿距偏差、拓扑偏差等项目的测量与评定,能够满足 5 级精度齿轮的检测 要求。     

集成毛细管电泳芯片荧光检测的研究

集成毛细管电泳芯片由于其显著的优点而倍受人们的关注。介绍了这种芯片的特点和应用及检测方法 ,从光源、主物镜和共焦针孔等几个方面详细讨论了检测光路的特点 ,并给出了实验结果。     

激光诱导荧光光谱法检测高纯激光晶体中的痕量稀土杂质

以功率为40mW、波长为488nm的氩离子激光器作为激发光源,采用S2000光谱仪接收荧光。在高纯激光晶体Er:YAG中检测出痕量Nd3+离子4F3/2→4I9/2跃迁的946nm特征荧光峰和Yb3+离子2F5/2→2F7/2跃迁的1030nm特征荧光峰,钕和镱的痕量浓度低于2×10-6。同样方法在Pr:GdVO4单晶中检测到痕量Nd3+和Yb3+的荧光发射,特征峰分别在912nm和1031nm处,钕和镱的痕量浓度低于0.7×10-6。     

Turbidimetric method for measuring the parameters of submicron aerosols

A new turbidimetric method for determining the parameters of submicron aerosols was developed and implemented in hardware using a wide range of probe radiation wavelengths and high-speed video recording. The particle size distribution function is found using an original algorithm for solving the inverse problem of the optics of aerosols based on a direct search computational procedure..     

Calibration of a planar laser induced fluorescence technique for use in large scale water facilities

A calibration process for planar laser induced fluorescence (PLIF) is presented and employed to investigate the mixing field of a co-flowing jet in a water channel flow. The calibration technique uses individual calibration curves for each pixel in the image array that correct for the non-uniformities of the laser sheet, optics and digital sensor and account for parameters that affect fluorescence efficiency of the dye. A unique commercial optic is introduced into the optical train to generate a thin laser sheet with an approximately uniform laser intensity distribution. The performance of the calibration procedure is investigated by analysis of the calibration data and through the investigation of a co-flowing jet. The results compare well with the results documented in the literature for this flow field. The work shows that the simple approach designed specifically for application in large-scale facilities is suitable for calibration of PLIF style techniques.     

激光诱导等离子体光谱仪实验装置的构建

激光诱导等离子体光谱仪是一种具有实时在线、非接触、多元素同时探测等优点的分析仪器。它无需制备样品,是钢铁冶炼中在线元素快速检测的仪器之一。本文将线阵CCD放置于罗兰圆上,搭建了一台紫外波段的激光诱导等离子体光谱仪实验装置,光谱分辨率达0.1nm,覆盖的光谱波段为235～260nm,主要用于检测钢铁材料中的C元素。实验结果表明,该系统的搭建是成功的。