Details
Laser illumination is now widely accepted as the best approach for capturing fluorescent images of prints and other organic trace evidence—either treated with rhodamine or even from native (incipient) fluorescence. The object or surface under test is illuminated by light in particular wavelength band, usually green. The natural fluorescence or dye-aided fluorescence of trace organics occurs at a longer wavelength in the yellow and orange part of the visible spectrum. In order to preferentially image the weak fluorescence relative to the much brighter scatter from simple reflection of the light source, a blocking filter is placed between the object and the digital camera. This boosts the visibility of the fluorescence by many orders of magnitude. The laser gives superior results compared to a filtered lamp because it provides high spectral brightness (monochromaticity) with zero out-of-band light. Laser light at a single wavelength, and the coherent nature of a laser beam means that almost all the laser power can be directed to a particular area, usually by a handpiece coupled by a fiberoptic umbilical. Forensic light sources, including lasers, are used to excite fluorescence in trace evidence. Optimum images can be obtained by excitation with blue/green light with a wavelength in the 488-535 nm range. Emission is then observed through an orange filter somewhere around the 580 nm wavelength band, which blocks the intense scattered light in the illumination (green) band.
Customer Reviews
- Review by Austin Bills
-
No other light source compares to this wonderful piece of equipment! I highly recommend the Tracer. (Posted on 7/23/2015)Value Quality Price
