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。     

实用化CuBr激光泵浦混合染料激光器

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,设计了一种象散补偿的三镜折叠腔,染料溶液采用高速喷流循环方式,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,转换效率高达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。     

四程抽运Yb:YAG盘式激光器

报道了激光二极管阵列(LDA)抽运Yb:YAG盘式激光器。Yb:YAG晶体掺杂浓度10-at.%,几何尺寸为Φ10mm×300μm,采用铟焊工艺将其焊接到水冷系统上,用可调式恒温水箱对其进行温度控制。利用蒙特卡罗方法对抽运光斑的大小进行了计算,将反射镜轴向与光纤头轴向夹角控制在120以内,以使抽运光斑半径与基模光斑半径比符合模式匹配原则。使用两个Φ=30mm,R=50mm的球面反射镜,完成了四程抽运。在LDA抽运功率为4.13W时,获得了最高功率为670mW的1030nm连续激光输出,光-光转换效率为16.2% 。     

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.     

可调谐环形染料激光器的微机控制

本文论述了可调谐单模环形染料激光器微型计算机控制系统的设计与实现, 包括硬件设计与软件设计.文章最后给出了可能达到的实验结果.     

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。     

混合单频激励下连续扫描激光多普勒振动测试

提出了一种混合单频激励下激光连续扫描振动测试方法,提高了连续扫描激光多普勒振动测试效率。首先,基于单频激励下连续扫描激光多普勒振动测试的原理,研究了混合单频激励下连续扫描激光多普勒振动测试技术,提出了适合混合单频激励的结构工作变形提取方法;其次,通过仿真测试,从理论上验证了方法的有效性;最后,以悬臂梁结构为例,进行了连续扫描和离散点扫描测试的试验验证。结果表明,混合单频激励下的连续扫描激光振动测试及分析方法可准确获得结构工作变形,具有效率高、空间分辨率高等优点,对进一步的工程应用具有实用价值。     

闪光灯泵浦长脉冲染料激光器的实验研究

从实验的角度出发,研究了分别添加氧气和环辛四烯两种染料三重态猝灭剂后,闪光灯泵浦长脉冲染料激光器的脉冲宽度和输出能量特性,讨论了影响脉宽和输出能量的两个主要因素。     

基于激光激励技术的结构损伤成像

采用了一种新型的损伤检测技术,利用激光脉冲在板类结构中产生热弹效应,激发出板中的导波（Lamb波）。通过分析Lamb波的传播状态与损伤之间的关系,并利用Morlet复数小波变换和频散补偿能量聚焦的方法,从两个不同的角度分析信号并提取信号特征,实现了对平板结构的快速、大面积检测。实验结果表明,该系统具有较高的测量精度,能较好地检测结构缺陷。     

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。     

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。     

超短脉冲染料激光倍频的实验研究

本文阐述了激光倍频的几个问题,实验中利用一块5.5×6×7mm³的BBO晶体对超短脉冲染料激光进行了腔外倍频实验。为了提高倍频转换效率,实验中利用了柱面镜及不同焦长的球面镜进行聚焦。最后,在基波平均功率120mV的情况下,得到了平均功率为0.54mV的紫外谐波辐射。考虑到基波及谐波的各种损失后,最大倍频转换效率η0.5%。     

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.     

新型固态染料激光材料光谱特性的研究

实验制备了改性聚甲基丙烯酸甲酯(MPMMA)和低温无机光学玻璃,并在两种光学基质材料中掺杂了大致相同浓度的激光染料罗丹明B.研究了两类染料掺杂材料的吸收光谱、发光光谱。