Device for sustaining differential vacuum degrees for electron column

A device for sustaining different vacuum degrees to maintain an electron column and a sample under different vacuum degrees, the device comprising:

• a chamber comprising a first gasket accommodation part;
• a column housing coupling part coupled to a column housing contained in the chamber and for securing the electron column with vacuum sealing, wherein the column housing coupling part includes threads provided in an inner surface thereof and configured to be locked to a threaded part formed in the outer surface of the lower end portion of the column housing;
• a through-hole part defined by a wall surrounding a center portion of the device and surrounded by the column housing coupling part to allow an electron beam emitted from the electron column to pass therethrough;
• and a vacuum isolation part made of a metal, comprising a metal gasket for vacuum coupling extending perpendicularly from a lower portion of the column housing coupling part and being disposed around the through-hole part in order to allow the electron beam emitted from the electron column to pass through, wherein an upper portion of the metal gasket of the vacuum isolation part is configured to be coupled to the first gasket accommodation part at a lower portion of the chamber column housing and a lower portion of the metal gasket of the vacuum isolation part is configured to be coupled to a second gasket accommodation part at an upper portion of a sample chamber, wherein the column housing coupling part and the through-hole part and other portion out of the structure of the metal gasket of the vacuum isolation part are made as one body or integrally coupled each other, and wherein a difference of no less than 101 torr in a vacuum degree is maintained between both sides of the device by selecting an appropriate diameter of a lens electrode layer, which is finally positioned in a path along which the electron beam is emitted, or using the through-hole part, wherein the column housing coupling part, the through-hole part, and the vacuum isolation part are formed monolithically.