Electron Microscope (EM) is an instrument that uses electron beams and electromagnetic lenses instead of light beams and optical lenses to magnify the microstructure of matter based on the principles of electron optics, with a resolution of up to 0.2 nanometers. Transmission Electron Microscope (TEM) is commonly used to observe microstructures that cannot be resolved by optical microscopes, while Scanning Electron Microscope (SEM) is mainly used to observe the surface morphology of solids.