原理 of スキャン 電子 顕微鏡
Scanning Electron Microscope (SEM), abbreviated as SEM, is a complex system; it condenses electron optical technology, vacuum technology, fine mechanical structure and modern computer control technology. The scanning electron microscope collects the electrons emitted by the electron gun into a fine electron beam through a multi-stage electromagnetic lens under the action of accelerated high voltage. Scan the surface of the sample to stimulate various information, and analyze the surface of the sample by receiving, amplifying and displaying the information. The interaction of the incident electrons with the sample produces the types of information shown in Figure 1. The two-dimensional intensity distribution of these information changes with the characteristics of the sample surface (these characteristics include surface morphology, composition, crystal orientation, electromagnetic properties, etc.), and the information collected by various detectors is sequentially and proportionally converted A video signal is sent to a synchronously scanned picture tube and its brightness is modulated to obtain a scan image reflecting the surface condition of the sample. If the signal received by the detector is digitized and converted into a digital signal, it can be further processed and stored by a computer. The scanning electron microscope is mainly used to observe thick samples with large height difference and roughness, so the depth of field effect is highlighted in the design, and it is generally used to analyze fractures and natural surfaces that have not been artificially processed.
電子 顕微鏡 および 金属組織 顕微鏡
1. Different light sources: metallographic microscopes use visible light as the light source, and scanning electron microscopes use electron beams as the light source for imaging.
2. The 原理 is 異なる: the 金属組織 顕微鏡 用途 the 原理 of 幾何学的 光学 イメージング for イメージング, および the スキャン 電子 顕微鏡 使用 高エネルギー 電子 ビーム to bombard the sample 表面 to 刺激 さまざまな 物理的 信号 on the sample surface, および then use different signal detectors to receive physical signal and convert them into images information。
3. The resolution is different: due to the interference and diffraction of light, the resolution of the metallographic microscope can only be limited to 0.2-0.5um. Because the scanning electron microscope uses electron beams as the light source, its resolution can reach between 1-3nm. Therefore, the tissue observation of the metallographic microscope belongs to micron-scale analysis, and the tissue observation of scanning electron microscope belongs to nano-scale analysis.
4. The depth of field is different: the depth of field of a general metallogramic microscope is between 2-3um, so it has extremly high requirements on the smoothness of the surface of the sample, so the sample preparation process is 比較的 複雑です. The scaning 電子 顕微鏡 has a large depth of field, a large field of view, and a 3次元 イメージング, which can 直接 観察 the 細かい 構造 の の 不均一 表面 の さまざまな サンプル。
