Study on coma aberration correction technique for imaging systems of optical and electron microscope by the use of image processing

本研究是基于过去对“科学研究助学金”的研究结果。本研究的目的是建立透射式电子显微镜中彗差和高阶反对称波像差的像差校正理论。针对这一目标，将三维成像理论推广到反对称波像差的情况，得到了一种广义像差校正理论。在本研究的第一阶段(1999)，从像差校正理论出发，提出了一种简单的傅里叶空间校正滤光片。利用扩展的三维成像理论，还实现了对彗差校正的计算机模拟，以考察非线性成像项对当前的彗差校正…的影响更多是不适用的。在此模拟中，对于位相延迟大于1/20λ的位相物体，非线性成像项的影响开始显现。目前的彗差像差校正滤波器是基于傅里叶空间中简单的2D位相校正。在下一阶段(2000)，进行了实时在线像差矫正装置的系统设计和程序编写。由于编程困难，设计了一个局域网连接的独立的在线校正系统，用于视频图像采集和彗差校正，而不是最初期望的使用一台PC机的集成系统。所构建的在线像差矫正装置的处理速度约为30秒/帧。虽然与第一目标值(几帧/秒)相比，这种处理速度非常低，但其他特性，如在线彗差校正器，在本研究中得到了很好的证实。我们将重新规划系统设计，将其作为一个使用一台PC的集成系统。较少

The present study is based on results of past studies of 'Grant-in-aid for scientific research'. The aim of this study is the establishment of the aberration correction theory for coma and higher order anti-symmetric wave aberrations in transmission electron microscopes. And also, the construction of a real-time on-line coma aberration correction apparatus, based on the image processing, is the second aim of this study.According to these aims, a generalized aberration correction theory for coma aberration was obtained by extending the tree dimensional (3D) imaging theory to the case of the anti-symmetric wave aberration. And a simple correction filter in the Fourier space, derived from this aberration correction theory, is proposed in the first stage (1999) of this study. Using the extended 3D imaging theory, computer simulations of the coma aberration correction were also achieved to examine the influence of the non-linear imaging terms in which the present coma aberration correction … More is not applicable. In this simulation, the influence of non-linear imaging terms begun to exhibit obvious for phase objects of the phase delay greater than 1/20 λ.The present coma aberration correction filter is based on the simple 2D phase correction in the Fourier space. The system design and the program coding of the real-time on-line coma aberration correction apparatus were carried out in the next stage (2000). By the reason of difficulties on the program coding, a LAN connected separate on-line correction system was designed for the video image acquisition and the coma aberration correction, instead of the integrated system using one PC, originally expected. The processing rate of the constructed on-line coma aberration correction apparatus was about 30 sec/frame. Although this processing rate is very low compared with the first aimed value (several frames / second), other characteristics as the online coma aberration corrector were well confirmed in this study. We will be re-planning the system design as an integrated system using one PC. Less