Patent ID: 7759652
Filing Date: 2010-07-20
Classification: H01J

Abstract:
1. An electron lens that focuses an electron beam on a sample, comprising: a permanent magnet being axially symmetrical and having a hole in the center thereof; and an upper magnetic pole and a sample-side magnetic pole which axially induces a magnetic field, wherein the upper magnetic pole and sample-side magnetic pole are made of a soft magnetic material and magnetically coupled to the permanent magnet, and the upper magnetic pole and sample-side magnetic pole axially forms one magnetic lens using a gap created between the upper magnetic pole and sample-side magnetic pole and located near the center of the electron lens; a magnetic path that is made of a soft magnetic material and movable in axial directions or rotatable with the axis as a center of rotation is disposed outside the permanent magnet; and the magnetic reluctance of the magnetic path outside the permanent magnet can be regulated.