Scanning electron microscope (SEM) is a micro analysis instrument with a resolution between the optical microscope (OM) and transmission electron microscope (TEM). It uses a high-energy concentrated electron beam to scan the surface of the sample, excites various signals with sample information through the interaction between the electron beam and the sample, collects the signals, amplifies and images, and achieves the purpose of characterizing the micro morphology and elemental composition of the sample surface.

Back Scattered Electron (BSE): The incident electrons interact with the nucleus of the sample atoms and undergo a change in the incident path, and they are ejected at the surface of the sample. These electrons are called back scattered electrons. Back scattered electrons have high energy and are one of the main sources of electronic signals for the imaging of the scanning electron microscope.

· Secondary Electron (SE):Secondary electrons are electrons produced by the incident electrons that excite the extranuclear electrons of the surface atoms of the sample and cause them to escape. These electrons have very low energies and usually require a high voltage of 10 kV in front of the detector to detect them. The image formed by secondary electrons generated by direct excitation of the incident electron beam has a high resolution and is the most basic imaging signal of the scanning electron microscope.

· Characteristic X-rays and Auger Electrons: When the inner electrons of the sample atoms are excited, the outer electrons begin to transition to the inner shell, and the characteristic X-rays and Auger electrons are produced during the transition. The energies of these two signals are determined by the energy difference of the various electronic shells outside the nucleus, so both carry the characteristic information (i.e., chemical information) of the sample elements and are the main source of information for composition analysis by the scanning electron microscope. The energy of the Auger electron is low, and often only the Auger electrons produced by the atoms in a few layers on the surface of the sample can escape from the sample surface, which reflects the information of the shallow surface layer of the sample.

· Bremsstrahlung radiation X-rays: Unlike characteristic X-rays, the energy of bremsstrahlung radiation rays is continuously distributed, so it is also called continuous X-rays. It is an X-ray produced by the continuous loss of kinetic energy of the incident electrons during their travel. Bremsstrahlung radiation X-rays constitute the background signal of the X-ray energy spectrum signals.

· Cathodoluminescence: When the electron beam bombards an oxide or semiconductor material, it causes electrons in its band gap or defect location to transition, resulting in ultraviolet, visible, or infrared light (similar to the light-emitting principle of LED).

The scanning electron microscope has been widely used in basic scientific research, production process control, product quality identification, etc., and is mainly used in national defense, aerospace, life science, medicine, biology, geological exploration, pest control, disaster identification, criminal investigation, etc.

New energy and new materials：Battery cathode and anode materials, composite materials, polymer materials, nanomaterials, etc.;

Semiconductor：Device surface and section analysis, semiconductor materials, packaging solder joint analysis, silicon wafer inspection, circuit analysis, etc.

Biological field：Seaweed, diatoms and other animals, plants, and microorganisms;

Metallurgy and mining：Coal, oil, rare earths, metals, etc.；

Construction industry：Concrete, refractory bricks, cement powder, etc.；

Chemical industry：Dyes, ammonium tetramolybdate, manganese carbonate condensed particles, etc.；

Ceramic industry：Ceramic grain, zirconia, filtering ceramics, etc.；