部分相干条件下的弱散射样品ptychography iterative engine成像  

Ptychographic iterative engine with partially coherent illumination for weakly scattering samples

作　　者：余伟[1] 田晓琳[1] 何小亮[2] 高淑梅[1] 刘诚[1,2] 朱健强[2] 

机构地区：[1]江南大学理学院,无锡214122 [2]中国科学院上海光学精密机械研究所,上海201800

出　　处：《物理学报》2016年第18期258-265,共8页Acta Physica Sinica

基　　金：江苏省自然科学基金(批准号:BK2012548)资助的课题~~

摘　　要：分析了照明相干性对ptychography iterative engine(PIE)成像技术的影响机理,指出利用零级衍射光范围内的衍射斑进行图像重建,可以避免由于部分相干性所引入的矛盾因素,并大幅度提高再现像质量,但再现像的对比度会明显降低.而采用散射斑强度的高次方进行图像重建时,相位的倍增作用可使相干性不足所引起的对比度降低大部分得以弥补,从而大大降低PIE技术对光源相干性的依赖并拓展其可应用范围.As an expansion of coherent diffraction imaging,ptychographic iterative engine（PIE） not only inherits advantages such as ultra-high resolution and compact optical system,but also expands the field of view in quantitative imaging,thus PIE is widely used in short wavelength imaging such as X-ray and electron beam imaging,and then extended to visible light field.However,PIE requires coherent illumination for both phase and amplitude retrieval,while traditional X-ray or electron beam sources often cannot satisfy this strict coherent condition,which leads to poor-quality information retrieval with low signal-to-noise ratio.Though several proposed methods such as multiple wavelength and multi-mode algorithms can eliminate incoherency influence to some extent,various details such as quantitative spectrum of illuminating source should be obtained before information retrieval,which complicates computing procedures.In addition,it is hard to acquire the spectrum of the illuminating source in most cases.In order to acquire high-quality information based on PIE with partially coherent illumination,a newly designed enhanced phase retrieval method for weakly scattering samples in PIE with partially coherent illumination is presented in this paper,in which only the bright field of the diffraction patterns is used in the iterative procedures mimicking the coherent cases especially for weakly scattering samples without any prior illuminating details.The bright field area can be regarded as purely coherent diffraction patterns composed of a strengthened zeroth order beam and a weakened diffracted beam.While the dark-field area generated by interference of diffracted beams cannot satisfy the requirement for coherence,therefore,dark-field diffraction patterns should be excluded in sample information extraction and only the bright field is used for phase retrieval via iterative process.Compared with the proposed multiple wavelength and multi-mode algorithms,the proposed method can simplify sample reconstructing procedures due to n

关 键 词：PTYCHOGRAPHY ITERATIVE engine技术 部分相干照明 弱散射样品 

分 类 号：O436.1[机械工程—光学工程]