![]() The scanning electron microscope, designed within the framework of electrooptical principles, is one of the devices that serve this purpose. With the simultaneous development and use of electronics with optical systems, imaging at high magnifications has become possible. In the same period, transmissive electron microscopes (TEM) are being developed, but images with the desired resolution cannot be obtained. When Max Knoll manufactured the first Scanning Electron microscope in Berlin in 1935, he did not need a patent because he could not reach high magnifications. The first commercial scanning electron microscope was produced by Siemens in 1965. In 1935, Max Knoll became the name that produced the first SEM device. In 1926, Busch discovered that electrons are deflected in a magnetic field. In 1923, De Broglie showed that electrons have wave behavior. For this reason, optical devices have been developed that help to see smaller images and details by changing the light paths that provide the transmission of the image with the help of various lenses. The human eye’s ability to see very small and fine details is limited. In this part of our book, the historical development, general features and usage areas of SEM will be discussed. For this reason, electron microscopes were needed and developed to meet the need for higher magnification. While optical microscopes were sufficient up to a certain level, they were insufficient for high magnification needs. Optical microscopes use a radiation source, while electron microscopes use an electron source. Today, this instrument, which is the basis for scientific research, has two types as optical and electron. For this reason, SEM has become a basic need. It makes a great contribution to the examination of wet and dry structures in their natural state, especially in biological samples. Just as a kitchen cannot be thought of without a knife, it is unthinkable that we can understand micro and nano structures without enlarging them, especially in metallurgy and micro biology. ![]() The scanning electron microscope (SEM), which has made a great contribution to the development of the micro world view, has become a masterpiece in this regard. Technological developments and the advancement of the scientific world should shed light on these demands. From past to present, human beings need to see what is far from them closely. It arose from the need to see and interpret objects at the micro and later nano levels that humanity could not see with the naked eye. Microscope is derived from the Greek words mikros (small) and Skopeo (look at). In today’s technology, very modern and superior scanning electron microscopes are produced and used. For example, at 1000X magnification, the focal depth of the optical microscope is 0.1 μm, while the focal depth of the SEM is in the range of 30–40 μm. SEM has a much higher resolution and focusing depth compared to optical microscopes. Elemental analyzes of the surface can also be performed with the energy dispersive X-ray (EDX) feature. In addition, SEM have the ability to perform microchemical analysis. The image taken on the screen gives us information about the microstructure of our sample. These signals coming to the detector are converted into digital signals and given to the computer screen. Electrons and X-rays formed as a result of this interaction are collected by detectors. ![]() During the scanning of the surface of this focused electron beam, electrons and material atoms interact. In this method, electrons accelerated by high voltage (0-30 kV) are focused on the sample. Scanning electron microscopy (SEM) is the most preferred method in microstructural analysis today.
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