Scanning Electron Microscope

921 Words4 Pages
In the forensic science field there are various machines used to examine physical evidence. One of those instruments is the scanning electron microscope (SEM). This instrument can be used in examining physical evidence found at crime scenes. There have been a number of scientists that have developed and improved the SEM. SEM is very significant in forensics because it can narrow down size, shape, and chemical composition. The scanning electron microscope is always growing and becoming a great impact on forensic science.
We will start of learning where the scanning electron microscope (SEM) began. Knoll built the first scanning microscope in 1935; he was not using demagnifying lenses. Von Ardenne expressed the theoretical philosophy underlying the scanning electron microscope. Developing the first scanning electron microscope in 1942 was Zworykin. This microscope was more improved due to using an electron multiplier tube as a preamplifier off the secondary electrons emission current. The resolution on the SEM was 50 nm (Physics Emory). Improving the SEM that Zworykin had developed, Oatley used nonlinear signal amplification. He was also the first to place in a stigmator in the SEM, which was used to correct lens cylindrical imperfections. In 1960, Everhart and Thornley improved the secondary electron detection. Three years following that Pease and Nixon, combined all the improvements in one microscope. The first commercial scanning electron microscope was developed in 1965 by the Cambridge Scientific Instruments Mark I (Physics Emory).
The scanning electron microscope has 10 parts to it which are the secondary detector, x-ray detector, backscatter detector, sample chamber, objective lens, electron beam, condenser lens, anode, ...

... middle of paper ...

...nated is very significant in criminal cases. We have reviewed the history and parts of the SEM, how it works, how it can aid in solving cases, and an actual case it was used to find the murderer. Scanning electron microscope is very significant and it will continue to be in the future.

Works Cited

Atteberry, J. (n.d.). How stuff works:How scanning Electron Microscopes Work. Retrieved from how stuff works: http://science.howstuffworks.com/scanning-electron-microscope2.htm
Khursheed, A. (2011). Scanning Electron Microscope Optics and Spectrometers. Danvers: World Scientific Publisher.
Physics Emory. (n.d.). Retrieved from Physics Emory: http://www.physics.emory.edu/~weeks/lab/papers/bogner-micron07.pdf
Swapp, S. (n.d.). Geochemical Instrumentation and Analysis. Retrieved from Carleton: http://serc.carleton.edu/research_education/geochemsheets/techniques/SEM.html
Open Document