Visualization and enhancement of latent fingerprints using low pressure dye vapor deposition
View Patent ↗Methods and apparatus for the recovery, visualization and enhancement of latent fingerprints using Low Pressure Dye Vapor Deposition (LPDVD) are described. The LPDVD methods of the present invention provide for fine control over the deposition of a precursor in combination with a fluorescent dye, combination of dyes or a premixed dry solid compound of the precursor and dyestuffs, to make the latent fingerprints visible. The LPDVD process makes use of a heated carrier gas to dilute and carry the vapors into a vacuum chamber where they condense onto the exposed surfaces of the article being developed. The LPDVD process can be used to develop latent fingerprints on a wide variety of substrates, including metal, plastic, glass and thermal paper and has been shown to perform as well or better than conventional fingerprint development techniques on these surfaces.
1. An apparatus for developing latent fingerprints comprising:
a vapor delivery chamber for containing source materials to be vaporized;
a vacuum deposition chamber for containing an article having latent fingerprints to develop communicating with the vapor delivery chamber;
a vacuum pump communicating with the vapor delivery chamber and with the vacuum deposition chamber for evacuating the vapor delivery chamber and the vacuum deposition chamber;
heating means communicating with the vapor delivery chamber for heating the source materials within the vapor delivery chamber;
a carrier gas source in communication with the vapor delivery chamber for providing a metered flow of carrier gas to the vapor delivery chamber, the carrier gas for transporting vaporized source materials from the vapor delivery chamber to the vacuum deposition chamber.
2. An apparatus according to claim 1 further includes a viewing window associated with the vacuum deposition chamber for viewing progress of development of latent fingerprints on the article.
3. An apparatus according to claim 1 further including an excitation light source associated with the vacuum deposition chamber for aiding the view of progress of development of latent fingerprints on the article.
4. An apparatus according to claim 1 further including a system controller for controlling flow rates, pressures and temperatures within the apparatus.
5. An apparatus according to claim 4 wherein the system controller is a PC or a PLC controller.