SEMs produce images of surfaces that are high resolution and surpass the images that common microscopes provide. There is an electron beam which comes from a heated source inside the microscope, and it has lenses that are electrostatic meant for focusing the beam. The beam is steered by scanning coils so that the sample being examined is scanned in a pattern that moves line by line. The electron beam runs in a systematic fashion until it hits an atom in the sample being looked at, and this will make a signal. Some frequently measured signals include secondary electrons, which are emitted by a particle that the electron from the microscope agitated.
Just a couple of these types of electrons are cathodoluminescence, which is known to be light that comes from particles that are impacted by electron beams, and backscattered electrons that reflect from the surface of whatever materials are being looked at through the microscope. The signals then produce an array of information regarding the sample itself. The signal provides information that is used along with the specific scanning pattern so that it produces an image of the scanned sample.
The use of electrons allows for a greater depth of field - as much as 100 times that offered by traditional light microscopes, which means more of the image can be rendered clearly. Often, a scanning electron microscope can reveal features that are smaller than one nanometer. SEM analysis has numerous purposes in materials analysis as well as in other areas. You can use it for dimensional analysis, or to measure and produce a picture of microscopic features, structure, size, and spacing. When failure analysis is needed for a particular sample, electron microscopes are able to see the fracture surface of a sample.
In addition, analysis can reveal particle identity - which is helpful in investigating contaminants or checking for their presence in a sample - and it can yield information needed for reverse engineering. An electron microscope could also be used to examine biological samples, including bacteria, parasites, cells, insects, and a lot of other things. The application of electron microscopes has increased in many industries in recent years; SEM technology can be utilized in fields as diverse as metallurgy, forensics, microbiology, and engineering.
Scanning electron microscopes can still be very costly to own, and it requires some expertise to properly operate one and prepare the sample, so companies that offer these services are very important in making it possible for researchers and industrial concerns to increase their knowledge. SEM analysis already has proven to have a number of useful applications, and will certainly continue to lead researchers to new insights and technological advances.