In the field of forensic science, there is a need for a way to detect various evidence that may be used in a criminal prosecution, including blood, saliva, other body fluids, hair, flesh, bone fragments, teeth, human skin damage such as bruises, bite marks or cuts, shoe prints, fingerprints, footprints, tire prints, gunpowder residue, bullets and portions thereof, explosive devices, explosive materials, parts of explosives, chemical weapons, chemical agents, biological weapons, paint, grease or oil, glass fragments, metal rubbings, fibers, dust patterns, various trace evidence, alteration of documents (forgery, different inks), narcotics, herbal evidence, and components, residues and traces thereof.
In the past, forensic personnel used high intensity conventional light sources, such as halogen bulbs, or ion gas laser light sources in order to illuminate areas of a crime scene and attempt to detect evidence since some evidence such as fingerprints do not fluorescence brightly alone. Contrast between such evidence being sought and the background against which it was found was sometimes achieved by using fluorescent dusting powder, dye, or other marker material, and light having a wavelength that substantially coincides with a known excitation wavelength of the marker. The characteristic of the marker is that, upon illumination with light at one of its excitation wavelengths, it will fluoresce, or emit light. Such fluorescence is typically at a longer wavelength as compared to the excitation wavelength. Examination of evidence was also enhanced through the use of color filtering glasses or barrier filters, whose color filtering characteristics are tuned to maximize the image to be detected. The forensic lights in the past had numerous drawbacks including bulky size, need for access to an AC power supply, and high cost.