软X射线激光背光阴影成像技术的空间分辨研究  

Spatial resolution study of soft X-ray laser backlight shadow imaging technique

作　　者：王琛[1] 安红海[1] 方智恒[1] 熊俊[1] 王伟[1] 孙今人[1] 

机构地区：[1]上海激光等离子体研究所,上海201800

出　　处：《物理学报》2018年第1期202-208,共7页Acta Physica Sinica

基　　金：科学挑战专题(批准号:TZ2016005);国家自然科学基金(批准号:11075146;61475146)资助的课题~~

摘　　要：软X射线激光阴影成像技术是一种诊断高温稠密等离子体临界面附近阴影轮廓的诊断技术,具有测量视场大、空间分辨能力高的特点,具有重要的应用前景.对该技术的空间分辨具体能够达到什么程度则没有进行过系统研究.本文分别从光路几何、衍射极限、成像像差三个方面进行了仔细分析,结果表明目前采用该技术的诊断系统能够达到约2μm的空间分辨.主要受限是光路几何因素,通过增加放大倍数、选择单元尺寸更小的接收元器件等方式,有希望达到优于1μm的空间分辨.The soft X-ray laser shadow imaging technique is a good tool for diagnosing shadow profiles near the critical surface of high-temperature dense plasma. The short-pulse plasma X-ray laser, driven by high-power laser, is used as the backlight, which spreads freely approximately 500 mm far, passes through the plasma to be diagnosed, and changes its optical path by using a multi-layer spherical lens and multi-layer plane mirror, is attenuated by filters, and is recorded by a soft X-ray charge-coupled device（CCD）. The plasma to be diagnosed can be driven by one or multiple laser beams,according to the needs of the physical research being conducted, and is imaged onto the CCD surface through a multilayer spherical lens. The shadow profile image of the plasma to be diagnosed at a particular time is obtained by using the instantaneous photographic mode of short-pulse soft X-ray laser backlight imaging. Compared with the traditional ke V hard X-ray backlight technique, the soft X-ray laser shadow imaging technique has two distinct advantages. One is the appropriate wavelength of the probe light, which makes it possible to diagnose plasma near the critical surfac, and the other is a better spatial resolution because of the use of mature multilayer optical elements for near-normal incidence imaging. However, there has been no systematic study on the extent to which the spatial resolution of the imaging technology can be achieved. In this study, a careful analysis is carried out considering three aspects： the optical path geometry, the diffraction limit, and the imaging aberration. The results show that a spatial resolution of approximately2 μm can be achieved. An experiment is carried out to measure the Rayleigh-Taylor instability of plasma from the lateral direction, by using the soft X-ray laser shadow imaging technique. Some microfluids with a width of several microns can be clearly distinguished in the experimental shadow image, indicating that the diagnostic technique has a good spatial resolution. Further analy

关 键 词：等离子体诊断 空间分辨 软X射线激光 

分 类 号：O434.19[机械工程—光学工程]