Astigmatism(Axial): an electron-optical lens aberration that causes the defocus to be a function of azimuth, and the contrast transfer function to deviate from circular symmetry about the optical axis. As a consequence, the Thon rings deform into elliptic or hyperbolic patterns, depending on the size of defocus and the size of the astigmatic defocus difference. See astigmatism as defined by SPIDER commands.

 

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Astigmatism(Axial): an electron-optical lens aberration that causes the defocus to be a function of azimuth, and the contrast transfer function to deviate from circular symmetry about the optical axis. As a con . . . View Full Definition