Time-Correlated Single Photon Counting With Microchannel Plate Detectors

ABSTRACT

We describe the experimental techniques and methods of analysis used in our laboratory in the study of a wide range of chemical and biological systems. In addition to standard single exponential decay time measurements we discuss the resolution of multiexponential decays and the analysis of fluorescence anisotropy experiments.     

实用化CuBr激光泵浦混合染料激光器

本文介绍了一种ＣｕＢｒ激光纵向泵浦的混合染料激光器。针对ＣｕＢｒ激光的双谱线和时域特性,配制了一种二元混合激光染料,设计了一种像散补偿三镜折叠腔,染料溶液采用高速流循环方式,在平均功率为８．０Ｗ的ＣｕＢｒ激光泵浦下,获得平均功率为２．７Ｗ的宽带染料激光输出,转换效率这３３．６％,能持续长期稳定运行。     

Artefact and Distortion Sources in Time Correlated Single Photon Counting

ABSTRACT

Sources for artefacts and distortions in data from a time correlated single photon counting spectrometer are described and illustrated. Methods are provided to avoid these instumental problems and to correct for the residual distortions.     

Time Correlated Single-Photon Counting (Tcspc) Using Laser Excitation

Abstract

The basic methods of time-correlated single-photon counting are outlined briefly, and the advantages of rapid repetition-rate pulsed lasers as light sources in this experiment are outlined. Application of the method to time-resolved fluorescence anisotropy is described.

The basic principles of time-correlated single-photon counting have been the subjects of many reviews^1-6. The method relies on the basic concept that the probability distribution for emission of a single-photon following excitation gives the actual intensity against time distribution of all photons emitted, thus by sampling the time of single-photon emission following a large number of excitation pulses, the probability distribution is created.

The experiment is carried out as follows, with reference to Figure 1. A trigger T. which could be a photomultiplier, an antenna pick-up, or a logical synchronising pulse from the electronics pulsing the excitation source, generates an electrical pulse at a time exactly correlated with the time of generation of the optical pulse. The trigger pulse is routed, usually through a discriminator, to start input of the time-to-amplitude converter, (TAC) which initiates charging of a capacitor. In the meantime the optical pulse excites the sample, which subsequently fluoresces. An aperture is adjusted so that at most one photon is “detected” for each exciting event. The signal resulting from this photon stops the charging ramp in the TAC, which puts out a pulse, the amplitude of which is proportional to the charge in the capacitor, and hence to the time difference between START and STOP pulses. The TAC output pulse is given a numerical value in the analogue-to-digital converter and a count is stored in the data storage device in an address corresponding to that number. Excitation and data storage are repeated in this way until the histogram of number of counts against address number in the storage device has enough data so that it represents, to some required precision, the decay curve of the sample. If deconvolution is necessary, the time profile of the excitation pulse is collected in the same way by replacing the sample by a light scatterer.     

单光子荧光时间谱仪时间分辨率的设计和测定

探讨了影响时间分辨单元光子荧光谱仪时间分辨率的因素,组装和调试了三种类型的时间相关单光子荧光谱仪,测定了它们的激发光脉冲响应函数,提出了测定时间分辨率的方法,并测定了时间分辨率。     

光子计数分布式光纤动态检测技术的研究

提出将光子计数OTDR技术应用于施工设施的分布式动态测量,并对检测分辨率和灵敏度进行了理论分析.计算表明,在8km长度的光纤上实现10m空间分辨率,1kHz信号的检测是完全可行的.新型分布式动态监测技术有望成为检测对地下管线的侵扰和防范事故损害的有效方法.     

半导体泵浦激光器在选区激光熔化工艺中的应用研究

选区激光熔化是新出现的能直接成型致密性接近100%终端金属产品的快速成型技术,该技术对成型能量源的要求严格。半导体泵浦激光器具有电光转换效率高、性能可靠、体积小巧、使用寿命长、输出光束质量好等优点。本文分析了选区激光熔化工艺对能量源的选用要求,对将半导体侧向泵浦Nd押YAG激光器应用于选区激光熔化工艺的可行性进行了评估,并通过实验进一步验证了评估结果。     

基于微纳机械加工的THz单光子探测器及其应用

通过量子阱的子带跃迁光吸收改变自身带电状态来调控另一个量子阱中的二维电子横向输运特性,从而产生可探测的电导变化。这种双量子阱电容耦合的结构具有很高的非线性放大系数,从而具有很高的探测效率,响应波长可以从远红外设计至THz波段。针对器件特性设计增益可调读出电路,进一步研制成工业级微型光谱仪。     

LD泵浦Nd:YVO4激光器的测距应用

将ＬＤ泵浦的Ｎｄ：ＹＶＯ４激光与连续波频率调制技术相结合、提出一种绝对距离测量新方案。小尺寸的Ｒｄ：ＹＶＯ４晶体提高了光源的时间相干性,这一点对于长距离测量有重要意义。通过引入补偿通道,消除ＰＺＴ非线性调制的影响。实验结果证明了该方案的可行性。     

The Ring Dye Laser as a Source for Two-Photon Excited Fluorescence

ABSTRACT

The near-Gaussian beam profile, low pulse-to-pulse amplitude fluctuation and amenability to simple signal processing make synchronously-pumped dye lasers, both continuous and cavity-dumped, excellent sources for two-photon spectroscopy. In recent years attention has shifted from the more common standing wave configuration to a traveling wave ring laser of synchronous length. The continuous variant has proven to be a source with a detectivity for two-photon excited fluorescence equal to the cavity-dumped, standing wave laser but without the added optical and electronic complexity of the Bragg cell. However, cavity gain/loss, bandwidth and length changes influence pulse characteristics to a different extent than in standing wave lasers. These effects are discussed relative to both the two-color, two-photon experiment and overall instrumental design considerations.     

LD泵油Nd:YVO_4激光器的测距应用(英文)

将ＬＤ泵浦的Ｎｄ：ＹＶＯ４激光与连续波频率调制技术相结合,提出一种绝对距离测量新方案。小尺寸的Ｎｄ：ＹＶＯ４晶体提高了光源的时间相干性,这一点对于长距离测量有重要意义。通过引入补偿通道,消除ＰＺＴ非线性调制的影响。实验结果证明了该方案的可行性。     

大功率DPSSL的高性能驱动电源的设计

根据半导体激光二极管的工作特性,设计了基于全开关拓扑的大功率DPSSL驱动电源。为了提高开关电流源输入电压的波形质量和整个电源的供电可靠性,驱动电源的前级采用单相BOOST—PFC加ZVS移相全桥电路的拓扑结构组成精密电压源,并搭建了一台3kW的实验样机验证设计方案的可行性,实验证明该驱动电源具有比较高的综合性能,能够满足材料加工工业大功率DPSSL的需要。     

单激励力下多自由度机器人的控制与轨迹规划研究

多自由度机器人的研究在近年来被广泛开展,但是多激励下的控制难度较大,在此基础上,提出一种摩擦力控制的多自由度机器人控制策略,并对机器人的轨迹规划进行研究,首先建立单激励力下的压电驱动机器人动力学模型,然后针对离心激励机器人及运动副自由度电磁控制策略进行分析,最后对单一机器人精密轨迹规划算法展开研究。针对不平衡单一旋转周期内和旋转周期为10次进行运动轨迹与理想位移的实验对比,不平衡单一旋转周期内机器人的位移ΔSi=10~(-3)m,偏差ε=9.98×10~(-6)m,实验结果表明,摩擦控制角越大,能够实现的位移越大,但是沿着X轴的偏差也会随之增大。通过研究,为少驱动多自由度的机器人研究提供基础。     

线性扭矩激励下单跨转子的弯振特性

考虑非线性油膜力、以及弹性支承对转子系统的影响,建立了基于扭矩激励的转子系统数学模型并引入了扭矩对载荷的影响因数,采用四阶Rounge-kutta法对非线性方程进行求解,并分别对转子系统施加线性扭矩激励和无扭矩作用下进行仿真和试验研究。结果表明,在线性扭矩的作用下,轮盘处的振动位移发生了一定变化,轴心轨迹发生了明显偏移,受支承刚度的影响,在频谱分析中除了1倍频外,出现了及其丰富的低频成分。得出的结论对转子系统的故障诊断具有一定的意义。     

高分辨SPI/TOFMS的研制及VOCs分子式确定

单光子能量10.6eV的真空紫外灯可电离大部分的挥发性有机物,生成分子离子,几乎无碎片,谱图简单。本文介绍了实验室自制的真空紫外灯单光子电离反射式飞行时间质谱仪的原理、仪器结构及初步结果。测试仪器分辨率超过4000(FWHM),质量精度优于6ppm。苯的检出限可至52ppbv。将仪器用于香烟烟气和聚氯乙烯(PVC)热解产物的检测。结果表明,单光子软电离源与高分辨质谱的结合,可直接用于复杂挥发性有机物(VOCs)分子式的确定。     

A Computerized System for Controlling the Wavelength of a High-Power Dye Laser

A system for the rotation of a dispersive laser element with a stepper motor is described. The motor is controlled by a personal computer that can be located at a distance of more than 20 m from the motor. The stepper control unit is connected to the computer interface board by a twin line. The system ensures highly reliable operation under conditions of intense electromagnetic noises from the laser power supply system due to the use of noise-suppressing differential transmission lines and optoelectronic isolators.     

半导体激光泵浦-固体激光诱导荧光检测装置的研制

以半导体激光泵浦-固体激光器为激发光源,采用共聚焦光学结构,研制了一种小型化激光诱导荧光检测器。整机采用模块化设计,配置了两种发射波长的激发光源(532nm、473nm),可以柱上检测或配流通池,能应用于几乎所有的液流分析系统。实验结果表明该检测器的最小检出浓度分别210-11mol/L,最小检出量10-19mol,响应线性2个数量级,可满足日常生化痕量分析的要求。     

基于单片机的同步发电机励磁调节器的设计

励磁调节器是水电站同步发电机的重要组成部分。以单片机作为微控制器,采用交流采样、数字脉冲和数字PID算法等先进技术,对励磁调节器进行了详细的硬件和软件设计。现已成功运用于某水电站,运行效果良好。     

CO2气体激光器的激励技术及其发展趋势

本文主要介绍了CO2气体激光器的各种激励方式及其特点,分析了各自的优缺点,对其各种性能做出了对比,并指出从直流到交流、从低频到高频是CO2激光电源发展的总体过程和趋势.