Patent ID: 7923686
Filing Date: 2011-04-12
Classification: H01J

Abstract:
1. A transmission electron microscope comprising: means for producing an electron beam; a specimen chamber in which a specimen may be positioned; gas supply means for supplying gas at a controlled flow rate at least around a surface of the specimen; evacuation means for evacuating the inside of the specimen chamber; an objective lens having an upper polepiece and a lower polepiece, the upper polepiece being disposed at a higher position in the specimen chamber, the lower polepiece being disposed at a lower position in the specimen chamber; detection means for detecting electrons transmitted through the specimen; display means for displaying a transmission image of the specimen based on an output signal from the detection means; and beam-blocking plates disposed on upper and lower surfaces of the upper and lower polepieces, respectively, of the objective lens, all the beam-blocking plates being capable of blocking off the electron beam or passing the electron beam by being moved in a direction crossing the optical axis of the beam, wherein each of said plates is provided with plural holes which are different from each other in diameter and can be brought onto the optical axis.