Simultaneous correction of spherical and chromatic aberrations by dynamic hollow-cone illumination

利用在透射电子显微镜上的一系列方位旋转图像，提出了一种新的动态空心锥体照明下的波场恢复方法。利用球面和色差无像差傅里叶分量恢复出射波场。对方位旋转图像的积分傅里叶谱进行逆傅立叶变换得到的图像清楚地表明，在轴向照明下，出射波的实部和虚部成功分离，分辨率提高超过了信息极限。此外，还提出了将三维傅立叶滤波方法应用于倾斜光照来实现更高空间分辨率的另一种方法。该方法减少了色差引起的图像对比度下降，纠正了球差、彗差和三重像散引起的图像失真，使轴向照明下的分辨率达到了信息极限的1.4倍以上。

A novel wave field restoration method under dynamic hollow-cone illumination is demonstrated using a series of 64 azimuthally rotated images in transmission electron microscopy(TEM). The restoration of the exit wave field was performed by utilizing spherical and chromatic aberration-free Fourier components. The images obtained by inverse Fourier transform of the integrated Fourier spectrum for the azimuthally rotated images clearly showed successful separation of real and imaginary components of the exit wave and resolution enhancement beyond the information limit under axial illumination. Another way to achieve higher spatial resolution was also proposed using the three-dimensional Fourier filtering method applied to tilted illumination. In the approach, the degradation of image contrast caused by chromatic aberration was reduced and the image distortion caused by spherical aberration, coma aberration and three-fold astigmatism was corrected, resulting in the achievement of 1. 4 times higher resolution beyond the information limit under axial illumination.