Lasers (Forensic Science)
In forensic investigations, the presence of such evidentiary materials as fingerprints, skin, hair, body fluids, and bone fragments is more easily detected with laser light than with other optical devices. When suspected matter in an investigation is coated or injected with fluorescent dyes and then illuminated with the spectral brightness of laser light, atoms in the dyes absorb photons and become excited. Upon de-excitation, the material fluoresces, and photons of a lower frequency are emitted. The fluorescence produces a sharp image of hidden evidence that can be captured on film.
The technique of combining laser technology with mass spectrometry, known as laser ablation-inductively coupled plasma-mass spectrometry, is an accurate, rapid method for identifying evidential substances. An extremely fine laser beam is used to vaporize small amounts of the suspect material inside of a mass spectrometer. By analyzing the mass spectral fragmentation patterns of the components of this vapor, scientists can identify the constituent compounds. This method can be used to differentiate trace amounts of dirt, paint chips, clothing fibers, strands of hair, and pieces of glass. Forensic scientists can use this method to analyze rates of growth in a shaft of hair, which can indicate drug usage or exposure of the subject to materials used to manufacture chemical and biological weapons.
During forensic anthropology studies, when it is difficult to...
(The entire section is 444 words.)
Further Reading (Forensic Science)
Conn, Michael P., ed. Laser Capture Microscopy and Microdissection. Boston: Academic Press, 2002.
James, Stuart H., and Jon J. Nordby, eds. Forensic Science: An Introduction to Scientific and Investigative Techniques. 2d ed. Boca Raton, Fla.: CRC Press, 2005.
Murray, Graeme I., and Stephanie Curran, eds. Laser Capture Microdissection: Methods and Protocols. Totowa, N.J.: Humana Press, 2005.
(The entire section is 54 words.)