electron photomicrography

Definition: Making photographs of images from electron microscope which produces magnified image of subject by focusing beam of electrons either to pass through subject or to reflect off subject. Two main methods: (1) Transmission electron microscope (TEM): a beam of electrons passing through subject is scattered and modulated by subject's structure: this beam thus carries image, much as light carries image, and is made to fall directly onto special film. (2) Scanning electron microscope (SEM): a beam of electrons is focused onto subject to be reflected off it: reflected electrons are focused onto sensor which scans image and rebuilds scans onto a monitor screen. * Image on screen is then photographed. Electron highs Magnifications possible with TEM can be 5,000,000X or more. With SEM, magnifications to 200,000X are possible with comparatively large depth of field. Results are always black and white though many photographs receive subsequent colouring.

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