共轴双光束LIBS检测土壤中Pb的参数优化  

Parameter optimization for detecting Pb in soil by coaxial DBLIBS

作　　者：林永增[1] 姚明印[1] 陈添兵[1] 黎文兵[1] 郑美兰[1] 刘木华[1] 

机构地区：[1]江西农业大学生物光电技术及应用重点实验室,江西南昌330045

出　　处：《光电子．激光》2014年第3期540-544,共5页Journal of Optoelectronics·Laser

基　　金：国家自然科学基金(31271612);江西省教育厅科技计划(CJJ12294);江西省学术带头人计划项目(09004005)资助项目

摘　　要：为了提高共轴双光束激光诱导击率光谱（DB—LIBS）检测土壤中重金属元素的检测精度，对试验装置进行了参数优化。试验时，以土壤中重金属Pb为例，首先对双光束与单光束作用效果进行对比，单束激光脉冲工作能量均为120mJ，得到双光束作用下土壤中Pb的特征光谱强度明显比单光束作用下增强了2～3倍。然后，分别设置两束激光之间的脉冲延迟时间为0、50和100ns，在每个激光脉冲延迟时间下，设置光谱采集延迟时间从2．6～5．2μs以步长为0．2ps递增，分别对样品的光谱进行采集，获取Pb元素在405．78nm处的特征光谱信息。通过对特征光谱强度和信背比的综合比较，得到最佳的激光脉冲延迟时间为50ns、光谱采集延迟时间为4．6μs，在此条件下，光谱强度的相对标准偏差为0．10。由此表明，参数优化有利于提高共轴DB-LIBS装置的检测精度。In order to improve the detection accuracy of coaxial optical path double-beam laser-induced breakdown spectroscope （DB-LIBS） in detecting heavy metal of soil, parameter optimization of testing setup has been done. The heavy metal Pb in soil is set as the detection target in the experiment. Fii＇st, the characteristic spectral intensity of Pb in soil under double beam is enhanced by 2-3 times than the single one which is gained from the comparative test with 120 nJ working energy of a single pulse. Then,delay time between two laser pulses is set as 0 ns,50 ns and 100 ns,the spectrum acquisition delay time is in- creased from 2.6 μs to 5.2 μs by increment of 0.2μs,and experiment is done in 14 spectrum acquisition time delays under each laser pulse delay time to obtain the spectrum information of Pb element at 405.78 nm. And the best laser pulse delay time and spectrum acquisition delay time are 50 ns and 4. 6 μs, re- spectively, which are obtained from consideration of both characteristic spectral intensity and signal to background ratio in the results of the experiment,and the relative standard deviation reaches 0.10. So,it is demonstrated that the parameter optimization is good for improving the detection accuracy of coaxial optical path DB-LIBS system.

关 键 词：激光诱导击率光谱(LIBS) 参数优化 土壤 重金属 

分 类 号：TN249[电子电信—物理电子学]