Transmission electron microscope

A transmission electron microscope for observing a sample using an electron beam transmitted through the sample, the transmission electron microscope comprising:

• an electron beam source configured to emit the electron beam;
• a stage on which the sample is placed;
• a lens barrel configured to house the electron beam source and the stage;
• a diaphragm configured to airtightly seal a first space on an electron beam source side and a second space on a stage side inside the lens barrel;
• and
• a mechanism configured to move the diaphragm;
• and
• an irradiation lens configured to focus the electron beam between the electron beam source and the stage, wherein
• the diaphragm is disposed between the electron beam source and the irradiation lens,
• the diaphragm includes a transmission portion that transmits at least a part of the electron beam,
• the mechanism includes a movement mechanism different from a stage mechanism for moving or inclining the stage, and
• the mechanism is configured to switch between:
• a first mode in which the diaphragm is disposed at a first position at which the diaphragm airtightly seals the first space and the second space and transmits at least a part of the electron beam;
• and
• a second mode in which the diaphragm is disposed at a second position at which the diaphragm does not airtightly seal the first space and the second space and does not collide with the electron beam.