Patent ID: 9343261
Filing Date: 2016-05-17
CPC Classification: H01J

Claim Text:
1. A desktop electron microscope, comprising: an electron gun, for providing an electron beam; and at least a combined round-multipole magnetic lens, comprising: a coil support, for winding merely one coil according to a central axis, the center of the coil support having a central opening portion for the electron beam passing through the central opening portion; a first pole piece, adjacently disposed at an upper-side of the coil support, having a first opening portion corresponding to the central opening portion of the coil support and a plurality of first pole shoes, the first pole shoes extending from an inner edge of the first opening portion to the central axis, wherein each of the plurality of first pole shoes has a first extending portion and a first ending portion, the first extending portion extends downward from the inner edge of the first opening portion, the first ending portion is connected with the inner edge of the first opening portion of the first pole piece through the first extending portion; and a second pole piece, adjacently disposed at an under-side of the coil support, having a second opening portion corresponding to the central opening portion of the coil support and a plurality of second pole shoes, the second pole shoes extending from an inner edge of the second opening portion to the central axis, each of the plurality of second pole shoes has a second extending portion and a second ending portion, the second extending portion extends upward from the inner edge of the second opening portion, the second ending portion is connected with the inner edge of the second opening portion of the second pole piece through the second extending portion, wherein the first ending portion and the second ending portion are located in the same horizontal plane, and the horizontal plane is perpendicular to the central axis; wherein the number of the first pole shoes and the number of the second pole shoes is N respectively, N is an integer larger than one, the plurality of first pole shoes are symmetrically arranged according to the central axis, the plurality of second pole shoes are symmetrically arranged according to the central axis, each first pole shoe and the adjacent second pole shoe differ from each other at an angle according to the central axis, and the angle is 360/2N degrees; wherein each first pole shoe and the adjacent second pole shoe form a magnetic-circuit gap, wherein when the coil is fed with an electric current, the first pole shoe, the corresponding magnetic-circuit gap and the second pole shoe form a first magnetic circuit.