How is magnification in scanning electron microscope controlled?
Magnification in scanning electron microscope:
Magnification into a SEM (scanning electron microscope) can be controlled over a range of regarding 5 orders of magnitude start from x25 or less to x 250,000 or more. Not like optical and transmission electron microscopes, representation magnification into the SEM (scanning electron microscope) is not a function of the power of the purpose lens. SEMs (scanning electron microscopes) may have objective and condenser lenses, but their purpose is to focus the beam to a spot, and not to illustrate the specimen. Given the electron gun can produce a beam with sufficiently small diameter, a SEM (scanning electron microscope) could in principle work fully without condenser or objective lenses, although this might not be extremely versatile or attain very high resolution. In an SEM, as in scanning probe microscopy, magnification results through the ratio of the dimensions of the raster onto the specimen and the raster onto the display device. Assuming which the display screen has a fixed size, higher magnification results by reducing the size of the raster onto the specimen, and vice versa. Therefore Magnification is controlled through the current supplied to the x,y scanning coils, and not through objective lens power.