Omega energy filter
AssigneeJEOL Ltd.
InventorKatsushige Tsuno
Life of this patent
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Abstract
There is disclosed an OMEGA energy filter comprising three magnetic field regions and producing small aberrations. The electron beam trajectory from the entrance window plane to the slit plane is continuously deflected into an omega-shaped form. Three magnetic field regions M1, M23, and M4 having deflection angles Φ, 2Φ, and Φ, respectively, are arranged in turn from the incident side. The deflection angle Φ is set such that 102°_. . . Φ_. . . 115°. The radius of curvature R3 of the beam in the magnetic field region having the deflection angle 2Φ is set less than the radius of curvature R4 of the beam in the magnetic field regions having the deflection angle Φ.
Claims2
An OMEGA energy filter comprising:
- electromagnets establishing three magnetic field regions to define a trajectory of an electron beam between an entrance window plane and a slit plate, said trajectory being continuously deflected into an omega-shaped form having a symmetrical plane perpendicular to a plane containing said trajectory of the electron beam;
- and
- said magnetic field regions arranged in turn from an incident side of the energy filter and having deflection angles of Φ, 2Φ, and Φ, respectively, said deflection angle Φ being set such that
- 102°<Φ<115°.
Dependencies are inferred from the claim text.