Scanning Electron Microscope

An (unsectioned) specimen is fixed and then coated having a thin layer of a heavy metal such as platinum in scanning electron microscopy.  Then   an electron beam scans   on    the   specimen, exciting molecules within it that release secondary electrons.  These all secondary electrons are focused on to a scintillation detector & the resulting image is displayed on a cathode-ray tube. The scanning electron microscope  generate a three-dimensional image because the number  of  secondary  electrons  generated  by  any  one  point  on  the  specimen based on the angle of the electron beam in relation to the surface of the specimen. Resolution of the scanning electron microscope is 10 nm, some 100- fold less than that of the transmission electron microscope.