亚米尺度空间云粒子关键参数数字全息照相探测机理与模型

In present cloud process models,assuming cloud particles satisfy with Poisson distribution in all scales.However it has been observed that cloud particles are spatially correlated in submeter length scales.On this scales lacking of key parameter especially spatial distribution of cloud particles,it can not explain the important cloud processes occur,e.g., collision-coalescence, turbulence-induced particle clustering etc.With airborne in-line holographic imaging method,this project proposes a method of measuring parameter of cloud particles with digital holography,research about rules of detection with digital hologram for cloud particles,opening out relation of cloud particles,hologram, digital reconstruction, building set-up of airborne digitial holographic imaging system,illuminating digital holograhic method for detection of spatial distribution of cloud particles in submeter scale.Compared with the others, this method takes advatange of decreasing ice crystal shattering,obtaining three spatial distribution of cloud particles as welll as shape,size, concentration of cloud particles. This project provides a new method for cloud particles's parameter in submeter length scales,and also offering a new method of airborne detecton of cloud particles, also providing cloud particles's parameter,which is needed by explaining micro-mechansim of formation and development for cloud particles,e.g.,the collision of cloud particles.it also validates the result from satellite remote sensing for cloud process and cloud parameter.it also provide a visible method and instrument for formation and governance of fog-haze.

现有云过程模型假设云粒子在空间上随机分布，但研究表明云粒子在亚米尺度空间存在相关性。亚米空间云粒子关键参数尤其是空间分布信息的缺失，成为解释云粒子碰撞、聚集、以及湍流引起的粒子团簇等云粒子形成和发展过程的瓶颈。本项目采用数字全息照相术，提出云粒子关键参数空基数字全息照相探测方法，探求云粒子全息照相规律，揭示云粒子参数、全息图、数字重构之间的内在关系，构建基于数字全息照相的云粒子关键参数探测方法，阐明亚米尺度空间上云粒子三维空间分布、尺寸、形状、浓度等关键参数空基探测规律。与现有的方法相比，本项目方法具有测量空间较大，避免冰晶破碎影响，能够获得亚米尺度空间云粒子三维空间分布、尺寸、形状、浓度等关键参数的优点，唯一不足是重构算法较复杂。本项目为解释亚米空间云粒子碰撞等云粒子形成和发展微观机理提供关键参数获得方法，为云卫星遥感真实性检验提供空基观测方法，为雾霾形成和治理提供可视化监测方法及手段。

本项目研究数字全息技术。通过对数字全息技术记录和再现过程的深入研究，建立了同轴数字全息系统和离轴数字全息系统。并在实验室条件下，对粒子进行记录，经过对图像数据的预处理，达到降低图像噪声的目的。研究多种粒子判焦方法，其中运用灰度合成法对灰度进行提取，来实现粒子三维坐标的测量；运用灰度梯度法对梯度进行提取，获取粒子的边缘来测量粒子三维坐标。在测量过程中，均需要使用阈值对判焦方法中的粒子进行提取。最终对所提取到的粒子的粒径进行估算，从而验证了同轴数字全息系统应用于云粒子探测的可行性。通过设计空基检测平台，为进一步实现机载全息检测云粒子提供基础。利用离轴全息技术，设计了改进的Jamin干涉仪离轴全息光路。激光通过光路分为参考光和物光干涉后通过CCD记录离轴全息图。分析并研究了离轴全息图像的重构算法，用实验验证了本套光学系统的可行性。对于发展离轴全息探测云粒子系统，相比于同轴全息来说提高分辨率提供了理论依据和实验数据。