Air Gap Effect on the Properties of Unsaturated Symmitrical Double Polepiece Lenses

Abstract

The  preferable  design  for  unsaturated  symmetrical  spherical

double-pole  piece electron  lens required good focal properties,  and in this  present  study  investigate  effect  of  air  gap  wide  (S)  on  the properties  of  the  projector  lens  specialized  the  minimum  projector

focal  length  1Fr) .     and  the  properties  of  the  axial  magnetic  field

\            lnlll

distribution:(the   maximum  value  of  magnetic  flux  density  Bm  and total half width  of magnetic field curve W)   , and at lowest values of

mm

 

(Fr) .          at low values of (S) will be obtained  high magnification  and

there  is an importance  indicator  for  preferable  lens design  which  is used in transmission electron microscope (TEM).