The compound light microscope focuses visible light through a specimen. Different regions of the object scatter the light differently, producing an image. The use of light microscope is limited. A limit of a light microscope is that the user can view only two dimensional plane of the specimen at a time.
Electron microscope is a device for forming greatly magnified images of objects by means of electrons. Electron microscope serves primary two purposes:
i) the visual examination of structures too fine to be resolved with ordinary, or light microscopes, and ii) the study of surfaces that emit electrons. The first function made transmission electron microscopes essential research tools in biology.
Electron Microscope vs Light Microscope