Although these gadgets were published in 1993, today they have become more useful than ever.
In 1993, Charles Smithart was convicted of the murder of an 11-year-old girl in the town of Glennallen, Alaska. Prosecutors suspected Smithart after he was spotted at the scene of the crime, but they had no evidence directly linking him to the murder. That's where a scanning electron microscope (SEM) came in.
Using the X-ray spectroscopy detector of an SEM, a forensic scientist analyzed bits of iron found at the scene of the crime. He found that they had a globular shape that only welding or grinding produces. As it turned out, Smithart had a welding rig in his shop and would sometimes repair bicycles for the local children. Thanks to the tremendous capabilities of scanning electron microscopes, prosecutors had the evidence they needed to link Smithart to the crime.
Why was an SEM, rather than a regular light, or optical, microscope from the local high school, necessary to examine the evidence for Smithart's trial? For one thing, SEMs can magnify objects at upward of 300,000 times the size of the object studied. Scientists refer to this number as the magnification power and denote it, for example, as 300,000x. In contrast, run-of-the-mill optical microscopes tend to have a magnification power of a few hundred times. SEMs also have tremendous depth of field compared to traditional microscopes, providing an almost 3-D image for researchers to analyze, as compared to the flatter image an optical microscope produces. Lastly, these advanced microscopes can look past the surface of an object, telling researchers information about its composition. All of these attributes proved essential in examining evidence from the Smithart case.
Of course, SEMs have their share of drawbacks as well, like cost. Even the cheapest among them cost tens of thousands of dollars. They're also bulky and complex instruments, requiring considerable expertise to operate. As a result, their use is typically limited to research and industrial applications, though recent breakthroughs have made SEMS more accessible in other applications.
To read more on Scanning Electron Microscopes and to view the whole article you can visit
http://science.howstuffworks.com/scanning-electron-microscope.htm
Great article to read, thank you. The Scanning Electron Microscopes remind me of some of the original computers, very large and expensive with limited uses but not in potential. It will be interesting to see what new applications they will be used for in the future. As components become cheaper and smaller we may see the day when children are using SEM in school instead of the current batch of optical microscopes. Once again society is pushing the development of technology, as the limits of the optical microscopes are reach new technology needs to be developed (or in this case technology that has been around for awhile). As more attention is focused on the SEMs more companies will see then as valuable to use and profitable to make continuing the cycle of increased manufacturing and lower costs leading to increase usage and addition evolution.
ReplyDelete