T Suganuma 1987 J. Phys. E: Sci. Instrum. 20 67 doi:10.1088/0022-3735/20/1/012
T Suganuma
Show affiliationsA method has been developed for automatic measurements and correction of astigmatism and defocusing in a SEM. The method is based on a theoretical analysis of the three-dimensional structure of the focused electron beam. In this method, auto-focusing is carried out for three different scanning directions to find three focus lens currents, from which the magnitude and orientation of the astigmatism are then computed, and also the defocus from the Gaussian plane. The experimental system is equipped with an eight-bit microcomputer and electronic analogue circuits and has demonstrated that it can focus and anastigmatise the beam on general SEM specimens with an execution time varying from 14-30 s depending on the characteristics of the specimen.
41.85.Lc Particle beam focusing and bending magnets, wiggler magnets, and quadrupoles
42.79.Bh Lenses, prisms and mirrors
07.78.+s Electron, positron, and ion microscopes; electron diffractometers
Accelerators, beams and electromagnetism
Issue 1 (January 1987)
T Suganuma 1987 J. Phys. E: Sci. Instrum. 20 67
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