The image is seen in three dimensions. Electron microscopes have high magnification and high resolution. Electron microscopes were developed due to the limitations of light microscopes that are limited by the physics of light to 500x or 1000x magnification (Schalek & Drzal, 1997, 21).
A confocal microscope uses a laser light. This light is used because of its wavelength. Laser light scans across the specimen or target with the aid of scanning mirrors. The image is then placed on a digital computer screen for analysis.
One of the most important pieces of evidence at a crime scene is hair. Andrew Watson of Science explains that a single hair or specks of bodily fluids can provide enough DNA to help convict or clear a suspect. A hair shaft has three forensically relevant layers: the cuticle, cortex, and medulla.ß The cuticle has overlapping external scales, which helps in species identification.ß Within the cuticle is the cortex, made up of spindle-shaped cells that contain the color pigment. The way pigment is distributed helps to identify hairs from particular individuals.ß The center of the shaft is the medulla, which is also valuable for species differentiation.
Watson suggests that a criminologist will be taught that every person who is physically involved in a crime leaves some minute trace of his or her presence. Hair trace evidence is one example of trace evidence. Trace evidence, though often insufficient on its own to result in a conviction may corroborate other evidence or contradict a specific theory of the prosecution or the defense.
Hair specimens are understood in forensic research as "class characteristic."ß At best, a hair may have enough similar properties compared with a known sample to be "consistent with" the sample but it cannot be said definitively to be a perfect match.ß While hair samples can be used to exclude a suspect, they can only be considered as contributing evidence. Watson a