充气微喷粒子场全息诊断中激波引起的像差校正方法

Shock wave loaded ejecta and dynamic fragmentation are part of the most important content in the study of material science, inertial confinement fusion, national defense and aerospace. High speed particle field is the typical target. In recent years, the experiment of ejecta and dynamic fragmentation in the gas environment are gradually carried out at home and abroad. But the shock wave in the air will interfere the particle field holographic diagnosis, which will result in resolution reduction. This problem needs to be solved urgently. However, no effective solution has been found so far. .Holographic technology has played an irreplaceable role in the aspect of diagnosing three-dimensional distribution and size distribution of particle field since the last century. We think the solution of this problem is holographic aberration correction in the premise of without any damage of shock wave. In this study, firstly, we combine the 3D diagnosis of shock wave with the light diffraction model to give the background phase near the particle field in the shock wave. Secondly, the low order aberration correction is realized by using a mask based holographic aberration correction method. Thirdly, the high order aberration correction is further carried out by iteration method. This topic can widely promote and be applied to the complex shock loaded droplet breakup diagnosis, thick biological section samples holographic microscopy, plasma diagnosis, complicated airflow affected spray field diagnosis and land-based underwater target detection, etc.

冲击加载下的微喷与动态破碎是材料、惯性约束聚变、国防及航天中的重要研究内容，其典型目标为高速运动的粒子场。近年来，国内外逐渐展开充气环境下的微喷与动态破碎实验，但空气中的激波会干扰粒子场全息诊断并引起分辨率下降，截止目前尚无有效的解决方法。全息技术在诊断粒子场三维分布与颗粒度方面发挥着不可替代的作用，在不对激波造成破坏的前提下解决该问题的本质是全息像差校正。本课题从激波三维诊断入手，结合光衍射模型给出激波内的本底位相，应用全息像差校正中的一种掩膜方法实现低阶像差校正，并以迭代法进行高阶像差校正，最终消除激波对粒子场全息诊断的干扰。曲面位相目标对光的影响、激波三维重构算法及高阶像差校正方法是本课题的研究重点。本课题可广泛推动并应用于复杂激波加载下液滴破碎诊断、较厚生物切片样品全息显微、等离子体全息诊断、复杂气流下的喷雾场诊断以及陆基水下目标探测等领域。

充气条件下的材料动高压加载动态破碎精密实验中会产生高速运动的粒子场及气体激波，其中粒子尺寸是关心的主要内容之一，但是气体激波的存在会对粒子场全息诊断产生复杂的像差，进而影响粒子诊断效果。本课题组在国家自然科学基金委青年科学基金项目的资助下针对上述问题开展了相应研究。通过建立的激波模拟仿真程序可在计算机中产生激波的三维模型，将该模型与光学衍射算法进行耦合后便可研究激波对颗粒场诊断的影响。相关工作认识了光场在激波中的变化特征，也证实了激波中心区确实有位相提前的现象，而且粒子位于不同位置的变形特征也与静态近似验证实验相符合。在认识加深的基础上进行了诊断效果提升方法的探索，不诊断光场位相项时会导致粒子信息大幅丢失而难以重建，使用失真的光场位相项时重建效果依然会实现大幅提升，结合光场位相估计的方法进行光场位相项迭代优化后则会进一步提升，表现为背景噪声降低以及粒子整体性提升。这一方法已经在工程实验中进行了初步应用。