Established in 1995, Guanghi Optical Instrument Co., Ltd. is a joint stock China electron microscope manufactuer and designer engaged in the manufacturing and marketing of a wide variety of Optical Instrument and products. Our products are widely applied in the education of students, research in lab, entertainment and science explore. During more than one decade's development, our products have awarded the CE certificate. We also have our own quality control system and customer' service system. So we can accept the order against customers' samples, specifying designs, specifications, and packaging requirements. We also prepared to accept the OEM and custom electron microscopes with customer's own trade marks or brand names.

This instrument employs a beam of electrons to image the specimen and no light is involved. An image of the specimen is viewed on a phosphor coated screen and the final pictures, called electron micrographs, are made on photographic plates or film. The source of the electrons is a heated tungsten filament, a single Lanthanum Hexaboride crystal, or a very sharp metal tip. The electron beam is accelerated down a vertical column (under vacuum) by high voltage and focused by electro-magnetic lenses. Electrons cannot be focused by glass lenses. In fact, even very thin glass will stop an electron beam. The voltages used to accelerate the beam can be from a few thousand up to a million volts in some research instruments. The usual potential is somewhere between 10 000V and 150 000V in routine instruments. Specimens for examination by TEM need to be very thin, of the order of 50 nanometers or less.

This instrument is quite different from a TEM because electrons are not used to directly image the specimen, but to excite it in such a way that it gives out secondary electrons. These secondary electrons are collected by detectors and used to form the image. Most of the SEM pictures seen in articles and books are secondary electron images. However, the beam not only causes the generation of secondary electrons, but scatters them as well. These backscattered electrons can also be used to form an image. In fact there are many different specimen beam interactions that produce useful information about the specimen. For example, the beam of electrons also causes the specimen to emit X-Rays. These can be collected by a separate detector and used to analyze the elemental components making up the specimen, or even to build up an elemental map of the specimen on a video screen.

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