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

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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.