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Proceedings Paper

The Use Of Optical Techniques In Tagging Explosives
Author(s): F. M. Ryan; F. M. Vodoklys; R. W. Watson
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Paper Abstract

A system of tagging explosives with inorganic phosphors to yield post detonation information is described with particular emphasis given to the optical instrumentation involved. The taggant consists of small cemented aggregates containing a "spotting" phosphor plus magnetic material for recovering the taggant, and various combinations of rare-earth "coding" phosphors which contain coded source information which, because of record keeping, can identify in many cases the last legal purchaser of the explosives. By employing various fluorescent colors for the "spotting" phosphor the taggant may also be used to quickly identify the type of explosive used ("permissible" or non-permissible) during routine inspections by mine inspectors. The design of two portable high-powered 254 nm ultra-violet lamps used in locating the taggants by their "spotting" fluorescence is described, including a unit that has been certified as "permissible" for use in methane-air mixtures such as may be encountered in an underground mine. The information contained in the "coding" fluorescence is extracted by exciting the tags with the 325 nm output of a cadmium laser and measuring the resulting rare-earth fluorescence spectrum. This spectrum may be obtained in times ranging from a few milliseconds to a few minutes depending on the optical instrumentation chosen. The two methods that have been used to date for recording the fluorescent "coding" spectrum are by a scanning grating monochromator and by a multi-channel optical analyzer. These systems are descirbed as well as a proposed system using an acousto-optic filter to sample the spectrum at programmed wavelengths.

Paper Details

Date Published: 20 September 1977
PDF: 5 pages
Proc. SPIE 0108, Optics in Security and Law Enforcement I, (20 September 1977); doi: 10.1117/12.955475
Show Author Affiliations
F. M. Ryan, Westinghouse Research and Development Center (United States)
F. M. Vodoklys, Westinghouse Fluorescent and Vapor Lamp Division (United States)
R. W. Watson, U. S. Bureau of Mines (United States)

Published in SPIE Proceedings Vol. 0108:
Optics in Security and Law Enforcement I
Charles Freeman; Sol Nudelman; Joseph C. Richmond, Editor(s)

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