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Studies of a magnetically focused electrostatic mirror. II. Aberration corrections
Author(s) -
Tsai
Publication year - 2000
Publication title -
journal of microscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0022-2720
DOI - 10.1046/j.1365-2818.2000.00646.x
Subject(s) - chromatic aberration , spherical aberration , electrostatic lens , optics , physics , chromatic scale , lens (geology) , solenoid , curved mirror , electric field , electron optics , magnetic field , magnetic lens , optical aberration , asymmetry , deformable mirror , beam (structure) , electron , wavefront , quantum mechanics
A magnetically focused electrostatic mirror is shown to be able to correct the spherical and chromatic aberrations of a probe forming system simultaneously. The probe forming system comprises a uniform magnetic lens and a uniform electrostatic mirror. Previous theoretical investigations showed that the spherical and chromatic aberration coefficients of these two components are the same values but with opposite sign, whose combination will therefore be free from aberrations. The experimental arrangement used a solenoid to produce a uniform magnetic field, and a series of plate electrodes to produce a uniform electrostatic field. These fields are shown to satisfy the experimental requirements. By deliberately changing the extraction voltage to defocus the electron beam, the author is able to observe correction of chromatic aberration by one order of magnitude. By deliberately changing the lens field and the mirror field, the author is able to observe the reduction of the asymmetry caused by the spherical aberration, which the author believes also indicates correction by one order of magnitude.