Phosphorescent Fingerprint Imaging 

Fingerprint on a €5 banknote, dusted with rare earth powder

Phosphorescent fingerprint treatments may be used to develop high contrast fingerprints on surfaces that fluoresce at common examination wavelengths. Using the Crime-lite®Imager’s new Phosphorescent Imaging Mode it is possible to illuminate evidence using a multi-wavelength pulsed light source whilst imaging the resulting phosphorescence with a time-resolved camera.

Fluorescent powders, stains and dyes, excited by a powerful narrow band light source, are widely used for the detection and examination of (chemically) treated fingerprints. However, when searching for prints on a surface that fluoresces at similar wavelengths to the treatment being used, the fingerprint may be masked by background fluorescence. The use of a phosphorescent fingerprint treatment may resolve this problem.

Unlike fluorescence, where light is absorbed at one wavelength and instantaneously emitted at a higher wavelength, phosphorescence is a process in which light is absorbed at one wavelength and then emitted at a higher wavelength over an extended period of time.

Using the Crime-lite®Imager’s new Phosphorescent Imaging Mode it is possible to illuminate evidence using a multi-wavelength pulsed light source whilst imaging the resulting phosphorescence with a time-resolved camera.

Various phosphorescent fingermark enhancement processes are currently in use, including Theonyl Europium Chelate based cyanoacrylate dye stains and phosphorescent (rare earth) powders, as illustrated above.

Crime-lite Imager: A Semi-Automated Fingerprint Capture and Enhancement System

The Crime-lite Imager is designed to meet the varying demands of fingerprint photography by providing optimum illumination for a wide range of treatments and backgrounds. A semi-automated system, the Crime-lite Imager combines advanced imaging and multi-wavelength illumination with simple to use software and enables operatives to consistently produce high quality results.

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