Difference between optical microscope and electron microscope
First, the light source is different
Optical microscope uses visible light as light source, and electron microscope uses electron beam as light source.
Second, the imaging principle is different.
Optical microscope uses geometrical optics imaging principle to image. Electron microscope bombards the sample surface with high-energy electron beam, which excites various physical signals on the sample surface, and then uses different signal detectors to receive the physical signals and convert them into image information.
Third, the resolution is different
Because of the interference and diffraction of light, the resolution of optical microscope can only be limited to 0.2-0.5um. Because electron microscope uses electron beam as light source, its resolution can reach 1-3nm, so the tissue observation of optical microscope belongs to micron analysis, and the tissue observation of electron microscope belongs to nano analysis.
Fourth, the depth of field is different
Generally, the depth of field of an optical microscope is between 2-3um, so the surface smoothness of the sample is highly required, so the sample preparation process is relatively complicated. The depth of field of electron microscope can be as high as several millimeters, so there is no requirement for the smoothness of the sample surface geometry, and the sample preparation is relatively simple. Some samples almost need no sample preparation, although the stereomicroscope also has a relatively large depth of field.
What can an optical microscope see?
1. The organelles that can be seen under the optical microscope include mitochondria, chloroplasts, vacuoles, nucleoli and other structures with the size exceeding 0.2 micron.
2. The organelles that can be seen under the electron microscope are: mitochondria, chloroplasts, Golgi bodies, endoplasmic reticulum, centrosomes, lysosomes, vacuoles, ribosomes, peroxisomes, microbodies, bacterial plasmids, mitochondria, centrosomes, Golgi bodies, pits on cell walls, etc.
