Editing Scanning electron microscope (section)

===Magnification===
Magnification in an SEM can be controlled over a range of about 6 [[order of magnitude|orders of magnitude]] from about 10 to 3,000,000 times.<ref>{{cite web| url = https://www.hitachi-hightech.com/eu/product_detail/?pn=em-su9000&version=#productSub-1| title = Ultra-high Resolution Scanning Electron Microscope SU9000}}</ref> Unlike optical and transmission electron microscopes, image magnification in an SEM is not a function of the power of the [[objective (optics)|objective lens]]. SEMs may have [[condenser (microscope)|condenser]] and objective lenses, but their function is to focus the beam to a spot, and not to image the specimen. Provided the electron gun can generate a beam with a sufficiently small diameter, an SEM could in principle work entirely without condenser or objective lenses. However, it might not be very versatile or achieve very high resolution. In an SEM, as in [[scanning probe microscopy]], magnification results from the ratio of the raster on the display device and dimensions of the raster on the specimen. Assuming that the display screen has a fixed size, higher magnification results from reducing the size of the raster on the specimen, and vice versa. Magnification is therefore controlled by the current supplied to the x, y scanning coils, or the voltage supplied to the x, y deflector plates, and not by objective lens power.