How light microscopy differs from electron microscopy
The difference between electron microscope and optical microscope is mainly the following four points:
First, the light source is different
Optical microscopes use visible light as a light source, electron microscopes use an electron beam as a light source.
Second, the imaging principle is different
Optical microscope using geometric optics imaging principle for imaging, electron microscope using high-energy electron beam bombardment of the sample surface, excitation of a variety of physical signals on the surface of the sample, and then the use of different signal detectors to accept the physical signals converted into image information.
Third, the resolution is different
Optical microscope because of the interference and diffraction of light, the resolution can only be limited to 0.2-0.5 um. Electron microscope because of the use of electron beam as a light source, the resolution can reach between 1-3nm, so the tissue observation of the optical microscope belongs to the micron level analysis, the tissue observation of the electron microscope belongs to the nanometer level analysis.
Fourth, the depth of field is different
Generally, the depth of field of optical microscope is between 2-3um, so the surface smoothness of the sample has very high requirements, so the sample making process is relatively complex. Electron microscope electron microscope depth of field can be as high as a few millimetres, so there is no requirement for the geometry of the sample surface smoothness, sample preparation is relatively simple. Some samples require little or no sample preparation, although body microscopes also have a relatively large depth of field.
