Electron energy filter

An electron energy filter comprising:

• an outer upper plate, an outer lower plate and first and second inner plates assembled to form a sandwich-like assembly;
• a plurality of upper pole pieces mounted on said upper plate and a plurality of lower pole pieces mounted on said lower plate adjacent corresponding ones of said upper pole pieces so as to form respective pole piece pairs defining respective gaps between the pole pieces of each pair;
• a plurality of current coils disposed on respective ones of said pole pieces for coacting therewith to produce magnetic fields in corresponding ones of said gaps for deflecting an electron beam as the beam passes through the filter;
• said first inner plate having a plurality of cutouts formed therein for accommodating the pole pieces mounted on said upper plate and said second inner plate having a plurality of cutouts formed therein for accommodating the pole pieces mounted on said lower plate;
• said cutouts being so dimensioned that each pole piece and the inner plate corresponding thereto conjointly define a slot for receiving a corresponding one of said current coils therein;
• said first and second inner plates having respective surfaces which are mutually adjacent;
• first slot means formed in the surface of said first inner plate and second slot means formed in the surface of said second inner plate;
• and,
• said first and second slot means being mutually adjacent to conjointly define a channel interconnecting said gaps and providing a path through the filter for the electron beam.

A combination of an electron energy filter and an electron microscope defining an electron beam axis along which the electron beam of the electron microscope travels, the combination comprising:

• a microscope column surrounding said beam axis and defining the interior of the microscope;
• a vacuum flange extending laterally from said column;
• an electron energy filter;
• adjusting means arranged in said vacuum flange for adjusting the position of said filter with respect to said electron beam axis to permit the electron beam to pass therethrough;
• and,
• said electron energy filter including:
• two outer plates and an inner plate assembled to form a sandwich-like assembly;
• a plurality of upper pole pieces mounted on said upper plate and a plurality of lower pole pieces mounted on said lower plate adjacent corresponding ones of said upper pole pieces so as to form respective pole piece pairs defining respective gaps between the pole pieces of each pair;
• a plurality of current coils disposed on respective ones of said pole pieces for coacting therewith to produce magnetic fields in corresponding ones of said gaps for deflecting the electron beam as the beam passes through the filter;
• said inner plate having a plurality of cutouts formed therein for accommodating the pole pieces of each pole piece pair;
• said cutouts being so dimensioned that each pole piece and said inner plate conjointly define a slot for receiving a corresponding one of said current coils therein;
• and,
• channel means formed in said inner plate for interconnecting said gaps to define a path through the filter for the electron beam.