NCJ Number
136517
Journal
FBI Law Enforcement Bulletin Volume: 61 Issue: 5 Dated: (May 1992) Pages: 14-16
Date Published
1992
Length
3 pages
Annotation
Ultraviolet (UV) light allows investigators and forensic researchers to examine clues and recover evidence that could not have been previously detected.
Abstract
UV light provides more detail and contrast to an injured area, including bite marks, than standard lighting techniques. There are two techniques for UV photography. In one method, known as reflective UV imaging, the wound is flooded with UV light, and the reflected UV image is photographed. An UV bandpass filter mounted on the camera lens blocks all light returning to the film except UV. In the second method, called fluorescent UV imaging, the wound is flooded with only UV light; however, a different filter is used to block all UV rays returning to the camera, so that only the visible light colors fluorescing from the wound will be captured on the film. Photographs done with these techniques show wounds in greater detail than would be possible with conventional photographic equipment; they reveal images of wounds that could not be seen by the naked eye. UV technology can also be used to scan a body or a crime scene for evidence not detectable by the naked eye. A video intensifier tube, which is sensitive to light waves from the UV spectrum through the infrared, can be modified to detect only UV light waves. The resulting images are displayed on a video screen within the device which can be linked to other video equipment, such as a standard video cassette recorder, a graphics computer, or a conventional camera for still photographs. Use of the intensifier and VCR allows investigators and forensic researchers to visualize an ultraviolet image immediately without waiting for film to be developed.