时间分辨光学涡旋日冕仪及其在空气等离子体诊断中的应用  

Time-resolved Optical Vortex Coronagraph and Its Application in Air Plasma Diagnostic

作　　者：黄霞 梁青青 牟彦霏 张文星 程庆庆 刘一 HUANG Xia;LIANG Qingqing;MOU Yanfei;ZHANG Wenxing;CHENG Qingqing;LIU Yi(School of Optical-electrical and Computer Engineering,University of Shanghai for Science and Technology,Shanghai 200093,China)

机构地区：[1]上海理工大学光电信息与计算机工程学院,上海200093

出　　处：《光子学报》2021年第8期222-228,共7页Acta Photonica Sinica

基　　金：国家自然科学基金(Nos.12034013,11904232);上海市教委创新计划项目(No.2017-01-07-00-07-E00007)。

摘　　要：将泵浦—探测技术的时间分辨能力引入到光学涡旋日冕仪成像系统中,从而在实现微弱相位型物体无背景成像的同时对其做时间分辨诊断。将该技术应用于飞秒激光激发的空气等离子体的诊断。实验结果表明,利用该技术可以清晰地观察到空气等离子体的生成过程,且实验结果与数值模拟结果符合较好。另外,还观测到空气等离子体的两个衰减过程,并对其进行了双指数拟合分析。其中,具有较快时间尺度(-65 ps)的过程主要由电子与正离子复合导致,具有较慢时间尺度(-810 ps)的衰减过程主要由自由电子在氧气分子上的附着所致。The ultrafast pump-probe method is introduced into the optical vortex coronagraph technique,which can realize time-resolved background free imaging of a weak phase object.Specifically,the proposed technique is applied to the diagnostic of air plasma pumped by femtosecond laser pulses.Experimental results show that the formation process of air plasma can be clearly measured.The numerical simulation results are consistent with the experimental results.In addition,two decay processes of the plasma are identified and fitted by double exponential decay.The fast process with a short time scale of 65 ps is attributed to the recombination of electrons and positive ions,while the other relatively slow process with a long time scale of 810 ps is due to the attachment of free electrons to oxygen molecules.

关 键 词：信息光学 灵敏相位探测 光学涡旋日冕仪 空气等离子体 泵浦探测 飞秒激光 

分 类 号：O437[机械工程—光学工程]