500fs紫外激光系统及其在闪烁体荧光特性测试中的应用  

500fs UV laser system and its application to fluorescence test of thin film scintillators

作　　者：张永生[1] 郑国鑫[1] 

机构地区：[1]西北核技术研究所,陕西西安710024

出　　处：《光学精密工程》2011年第2期475-481,共7页Optics and Precision Engineering

基　　金：国家自然科学基金资助项目(No.10474081)

摘　　要：介绍了用于高速时间记录设备以及多种闪烁体材料时间响应特性测试的500 fs,248 nm超短脉冲紫外激光系统的构成及其主要技术参数。系统的核心部分是一个分布反馈染料激光器,即一个稀疏刻线光栅的动态像。像的长度和染料溶液的折射率决定了脉冲的最短宽度,并且通过改变动态光栅的间距就可以改变输出光谱。在实验条件下,分布反馈染料激光器输出波长为496 nm,倍频后为248 nm,与KrF准分子激光放大器工作波长匹配。放大器介质的低饱和能量密度和三程离轴放大技术使得输出激光的强度分布非常均匀,这对于标定快速记录器件极其有利。利用该系统对ZnO∶Ga薄膜闪烁体在超短紫外激光激发下的荧光特性进行了测试,建立了荧光传输光路,解决了散射激光干扰和荧光高效率收集等问题。测量得到其荧光光谱为380410 nm,中心波长为392 nm,荧光响应时间约为80 ps。最后,讨论了在现有实验条件下影响测量结果的一些因素。A 500 fs,248 nm ultra-short UV laser system for high speed recording devices and scintillators＇ fluorescent excitation was introduced in the paper.The central part of the laser system is a Distributed Feedback Dye Laser（DFDL）,namely,a dynamic image of coarse grating.The image length and the index of dye solution give the shortest pulse duration and changing the pitch of the grating results in a tunable spectrum.In experiments the working wavelength of the DFDL was adjusted to 496 nm and frequency doubled to 248 nm,which was match to that of the KrF excimer amplifier.The off-axis three pass amplification schemes and low saturation energy density of the excimer laser media made the intensity profile of the laser beam faily uniform,which was very attractive for the calibration of a high-speed recording device.An experiment to measure the fluorescent characteristics of a thin film ZnO∶Ga scintillator under UV laser excitation was demonstrated with the laser system.The interference of the scattered laser and the weak fluorescent signal was solved by using a collective imaging lens and a monochrometer.Obtained results show that the fluoresce spectrum is in the 380 nm to 410 nm with the central peak at 392 nm,and the fluorescene time of the scintillator is about 80 ps.Finally,the factors which may affect the measuring results were also discussed.

关 键 词：紫外激光 闪烁体 荧光特性 时间响应特性 

分 类 号：TN248.2[电子电信—物理电子学]