用于探测电致发光的单光子计数器的设计

【作者】 何丽玲；

【导师】 周真；

【作者基本信息】 哈尔滨理工大学 ， 测试计量技术及仪器， 2002， 硕士

【摘要】 目前国内普遍采用的检测绝缘聚合物击穿性能的方法是测试其电性能，这种方法可靠性较低；本文提出了用探测电致发光来检测电介质老化、击穿性能的方法，重点研制了用于探测电致发光的单光子计数器，经测试计数器各部件性能良好，具有经济实用的特点。 绝缘聚合物的电致发光一般都非常微弱，功率都在10-16瓦以下，是典型的单光子，这给测试工作带来很大的困难，必须研制特殊的测试仪器。用光电倍增管（photomultiplier PMT）的光子计数模式将电致发光的光信号转换为电信号来进行测试。用幅度甄别器去掉大部分噪声，用脉冲计数器计数。一定时间内的计数值对应着相应的光功率。这就是用于检测微弱光的单光子计数器。经分析比较各种型号光电倍增管的性能及特点，本文采用EMI公司双碱阴极的9789QB管型光电倍增管。该管型的光谱范围在300～650nm，具有暗计数少，有单光子峰的特点，适于做单光子计数器；本文的光电倍增管分压器设计合理而冷却系统采用液氮，该系统体积小、结构简单、加工便利、成本低廉且性能良好。用Max4416放大器件作为前置放大器，用Max900系列比较器件作成窗口比较器，用高速器件74LS393两片作成16位的计数器，用单片机89C51读取数据，并处理后显示在液晶显示模块上。实验证明本文设计的单光子计数器的噪声、量子效率、总灵敏度等主要指标完全符合设计要求；其最小探测功率比近期国内报道的光子计数器最小探测功率小。本文设计的单光子计数器可应用于聚合物性能的检测及新型绝缘材料的开发利用，也可推广到其他微弱光检测系统。更多还原

【Abstract】 The present method for testing aging and breaking-down property of polymer is usually carried out by testing its electrical property. This conventional is of low reliability. This paper has established a new method for testing the aging and breaking-down property of polymer to develop new types of insulating materials by probing the electroluminescence of insulated polymers, which is in the highest flight at home. This paper mainly discusses the design of the single-photon-counter. Electroluminescence (EL) is a weak light with its power under 10-16W, which can,t be detected with conventional method. We consider testing it using photon counting mode of photomultiplier PMT to transform light signals into electric signals. Much of the noise can be eliminated with an amplitude discriminator. The light can be counted with a pulse counter. The value counted in a certain length of time is in accordance with that of light power. This system used for testing weak light is called single-photon counter. The most important parameter in the single-photon counter is the total sensitivity. Noise level should be decreased and quantum efficiency should be raised in order to improve the total sensitivity, which needs a better cooling system. The multiplication system of the electron-multiplier phototube is based on electronic voltage. So, it is especially important to choose a suitable PMT and reasonably design PMT disparted-voltage-device. We adopt double alkali cathodal tube 9789QB, which was made by EMI corporation in England , as our photomultiplier, whose spectrum ranges between 300nm to 650nm, with less noise counters and single-photon apices, which make it suitable as a single-photon-counter. The disparted-voltage device is designed in a reasonable way and the cooling system of iquefied nitrogen which makes it small in size, simple in structure, easy in processing, cheap in cost and good in performance. We also magnify the signal with new IC amplifier, deduct yawp counters, design system to desl with data,total system is control by singlechip and can count in fastness time range and deal with data. This paper is of great importance in the testing of property of the polymer and in the development new type of insulating materials. And it can also be extended to other weak light testing system.更多还原