Wien filter for use in a scanning electron microscope or the like
AssigneeSchlumberger Technologies, Inc.
InventorsPaul J. Duval, Allan I. Rubin, Ira Rosenberg, Vladimir Vayner, Neal T. Sullivan
Life of this patent
Estimating the term…
Abstract
A charged particle filter such as a Wien filter in which components used as the pole pieces and electrodes are precisely and reliably secured to a supporting structure through which they extend and to which they are brazed. Electrical insulating gaps in the magnetic circuit are located very remotely from the pole faces of the pole pieces so as to minimize any adverse effect of the gaps on the produced magnetic field.
Claims21
An electromagnetic filter comprising a field-producing structure at least partly surrounding a passage, the improvement comprising:
- a supporting structure around said passage and having a plurality of inwardly extending openings therethrough;
- a plurality of magnetically permeable field-producing structures, each extending continuously through one of said openings, terminating at one end in a pole face located radially inwardly from said supporting structure and constituted at its other end by a portion extending radially outwardly from said supporting structure, each of said field-producing structures engaging said supporting structure;
- electromagnetic field-producing elements operatively connected to the radially outwardly extending portions of said field-producing structures and effective to act on said field-producing structures to produce magnetic and/or electric fields emanating therefrom and extending into said passage;
- said filter being adapted to function in combination with magnetic circuit means located outside said supporting structure operatively engaging and coupling the radially outwardly extending portions of said field-producing structures with a gap between said field-producing structures and said magnetic circuit means, said gap being located radially outside said supporting structure.
An electromagnetic filter for use with an electrical instrument emitting a beam of charged particles from a surface to be measured and having a passage through which pass the charged particles, the filter comprising:
- a supporting structure at least partly surrounding the passage and having a plurality of inwardly extending openings therethrough;
- a plurality of magnetically permeable field-producing structures, each extending continuously through one of said openings, terminating at one end in a pole face located radially inwardly from said supporting structure and constituted at its other end by a portion extending radially outwardly from said supporting structure, each of said field-producing structures engaging said supporting structure;
- electromagnetic field-producing means operatively connected to the radially outwardly extending portions of said field-producing structures and effective to act on said field-producing structures to produce magnetic and/or electric fields emanating therefrom and extending into said passage;
- said filter being adapted to function in combination with magnetic circuit means located outside said supporting structure operatively engaging and coupling the radially outwardly extending portions of said field-producing structures with a gap between said field-producing structures and said magnetic circuit means, said gap being located radially outside said supporting structure.
Dependencies are inferred from the claim text.