Patent ID: 7804066

Claim:
A charged-particle beam apparatus comprising: a chamber having an interior evacuated by an intra-chamber evacuating means; and a lens-barrel emitting a charged-particle beam onto a sample placed in the chamber, wherein the lens-barrel comprises: a cylindrical body having a distal end at which an emission outlet is formed for communication with the chamber and from which the charged-particle beam is released; a charged-particle supplier housed at a side of a proximal end in an interior of the cylindrical body to release the charged-particle beam; and an objective lens housed at a side of a distal end in the interior of the cylindrical body and having an electrostatic lens generating an electric field by voltage application and converging the charged-particle beam released from the charged-particle supplier, and a gas supplying means in the cylindrical body of the lens-barrel for supplying an inert gas into the cylindrical body at a side of a proximal end of the objective lens and configured to provide an inert gas pressure in the chamber sufficient to substantially prevent dust present in the chamber from contact with the objective lens.