自动聚焦激光诱导击穿光谱远程测量系统  

The Auto-Focusing Remote Laser-Induced Breakdown Spectroscopy System

作　　者：韩振宇[1] 潘从元[1] 安宁[1] 杜学维[1] 于云偲 杜亮亮[2] 王声波[3] 王秋平[1] 

机构地区：[1]中国科学技术大学国家同步辐射实验室,安徽合肥230029 [2]中国科学技术大学精密机械与精密仪器系,安徽合肥230027 [3]中国科学技术大学光学与光学工程系,安徽合肥230026

出　　处：《光谱学与光谱分析》2015年第2期304-308,共5页Spectroscopy and Spectral Analysis

基　　金：国家重大科学仪器设备开发专项(2011YQ120023)资助

摘　　要：激光诱导击穿光谱（LIBS）技术具有非接触测量、无需样品预处理以及快速多元素同时分析等特点,适合于高温、高压、真空、有毒以及敌对环境等仪器和操作人员无法靠近观测对象的应用中。LIBS技术结合望远镜系统可以实现物质成分的远距离检测与分析。搭建了一套可自动聚焦的LIBS远程测量系统。该系统中的望远镜采用Schwarzschild结构,由一块凹球面反射镜和一块凸球面反射镜组成。两块球面反射镜共轴安装。其中凸面反射镜安装在电控精密平移台上,电动平移台可带动凸面反射镜沿光轴移动。通过调整凸面反射镜的位置,改变凸面反射镜和凹面反射镜的间距,进而改变系统的焦距,实现对不同距离的样品进行光谱测量。该结构的优点在于：激光聚焦光路与信号光采集光路相同,便于安装和调试;望远镜系统采用全反射式光路,适用于紫外波段检测;只包括两个球面反射镜,结构紧凑,元件容易加工。望远镜系统调焦距离为1.5~3.6m,聚焦光斑直径约为0.5~1.0mm。使用该系统对铜样品进行了LIBS实验,确认了Cu元素的特征谱线。通过测量Cu元素的LIBS特征谱线（CuⅠ223.01nm,CuⅠ224.43nm）峰面积和反射镜间距之间关系,得到了激光的最优聚焦位置。实验结果表明,该系统能够完成样品的远程激发和LIBS光谱测量,并能够对不同距离的样品进行自动聚焦。The present paper presents an auto-focus laser-induced breakdown spectroscopy （LIBS）remote measuring system. This system contains a Schwarzschild telescope,which consists of a convex mirror and a concave mirror.The two spherical mir-rors are coaxially placed.The convex mirror is mounted on a motorized linear translation stage.With this motorized linear trans-lation stage,the convex mirror can move along the optical axis to change the spacing between the convex mirror and the concave mirror.Therefore the focal length can be adjusted to focus the laser on samples at different distances and collect the plasma spec-tra.The advantages of the telescope system include,firstly,the light path of laser focusing and spectra signal collection is the same,which make it easier for mounting and collimation;secondly,the light path of the telescope uses total reflection type, which is fit for the detection in ultra-violate region;finally,the telescope consists of only two spherical mirrors which are rela-tively easier to manufacture.Within the translation range of the motorized linear translation stage,the focal length of the tele-scope in this paper can be adjusted from 1. 5 to 3. 6 m.The diameter of the focusing spot varies from 0. 5 to 1. 0 mm.Utilizing this telescope system,LIBS experiments were conducted using copper sample.And the characteristic lines of Cu element （Cu Ⅰ223. 01 nm,Cu Ⅰ 224. 43 nm）obtained are used for the auto focusing.By investigating the relation of the area of spectral lines covered and the spacing between the mirrors,the optimal laser focusing location was obtained .The LIBS experiment results show that the system functions well,fulfilling the demand of remote ablation of sample and LIBS spectral measuring,and the telescope is able to auto-focus the laser on samples at different position to perform remote LIBS experiment.

关 键 词：激光诱导击穿光谱 远程 望远镜 自动聚焦 

分 类 号：O433.1[机械工程—光学工程] TF133[理学—光学]