Theory of temporal aberrations for electron optical imaging systems by direct integral method

Abstract

A new approach to calculate the temporal aberration coefficients of dynamic electron optical imaging systems is put forward in this paper. A new definition o f temporal aberration is given in which a certain initial energy of electron emi ssion along the axial direction εz1(0≤εz1≤ε0max) as a cr iterion is considered. The new method for calculating the temporal aberration c oefficients of dynamic electron optical imaging systems named “direct integral method" is presented which gives new expressions of the temporary aberration coe fficients expressed in integral form. The difference between “direct integral m ethod" and “τ-variation method" is that the “τ-variation method" n eeds to solve the differential equations for the three of temporal geometrical a berration coefficients of second order, while the “direct integral method" need s only to carry out the integral calculation of them, which is more convenient a nd suitable for computation in the practical design.