cross section of an electron microscope![click to hear](/images/speaker.jpg)
Electron microscope: it uses an electron beam (as opposed to light) to provide magnification that is markedly superior to that of an optical microscope.
stage ![click to hear](/images/speaker.jpg)
Adjustable metal plate (stage) on which the specimen is mounted in order to study it.
aperture diaphragm ![click to hear](/images/speaker.jpg)
Device with an opening whose diameter can be changed to narrow or widen the diameter of the electron beam.
aperture changer ![click to hear](/images/speaker.jpg)
Device that adjusts the diaphragm opening in order to change the diameter of the beam.
condenser ![click to hear](/images/speaker.jpg)
System of magnetic lenses (electromagnets producing a magnetic field when excited by an electric current) that concentrates the beam onto the specimen under study.
vacuum manifold ![click to hear](/images/speaker.jpg)
Conduit connected to a pump that creates enough of a vacuum in the microscope that it can function.
electron gun ![click to hear](/images/speaker.jpg)
Device that usually consists of a tungsten filament that is heated to produce an intense electron beam, which illuminates the specimen.
vacuum chamber ![click to hear](/images/speaker.jpg)
Part of the microscope in which pressure can be reduced so that the electrons can move.
visual transmission ![click to hear](/images/speaker.jpg)
The electron beam explores the surface of the specimen, which in turn emits electrons to form a point-by-point image on the screen.
focusing lenses ![click to hear](/images/speaker.jpg)
System of magnetic lenses (electromagnets) that concentrate the electron beam on one spot on the specimen.
beam diameter reduction ![click to hear](/images/speaker.jpg)
The two lenses of the condenser cause the divergent electron beam emitted by the gun to converge.
electron beam positioning ![click to hear](/images/speaker.jpg)
Control that positions the electron beam along the optical axis so that it reaches the specimen.
electron beam ![click to hear](/images/speaker.jpg)
Set of negatively charged particles that propagate toward the specimen.