Procedure of calculation of a dynamic focusing systems for technological electron beam  and ion beam devices.

L.B. Rozenfeld

Research Institute for Electron & Ion Optics, Moscow, Russia

The problems of construction of dynamic focusing system for electron beam (or ion beam) technological devices, providing constant value of  beam diameter on all scanning field on the object, are discussed. Analytical expressions for calculation such systems are proposed. It is shown, that for providing constant value of magnification at big angles of  beam deflection it is necessary to use (as a minimum) three dynamic lenses.

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