Influence of anti-symmetric wave aberrations and the simple correction filter in the Fourier space

In imaging systems, especially in a high-resolution transmission electron microscope, residual aberrations of objective lenses, such as a spherical aberration or coma aberration, degrade the quality of observed images. Recently practical solutions by the use of an aberration-corrected lens or real-time image processing based on active defocus modulation have been reported with respect to the spherical aberration. Therefore, the future should be aimed at correcting other aberrations such as coma or higher-order astigmatisms. This paper describes the influence of such higher-order aberrations, and a preliminary attempt to correct the coma aberration for observed images under the coherent vertical illumination using an optical microscope. In addition, an estimation technique for the amplitude and the direction of the coma aberration using an image as is observed, is also discussed.