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20 September 1977 The Use Of Optical Techniques In Tagging Explosives
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Proceedings Volume 0108, Optics in Security and Law Enforcement I; (1977)
Event: 1977 SPIE/SPSE Technical Symposium East, 1977, Reston, United States
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.
© (1977) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
F. M. Ryan, F. M. Vodoklys, and R. W. Watson "The Use Of Optical Techniques In Tagging Explosives", Proc. SPIE 0108, Optics in Security and Law Enforcement I, (20 September 1977);


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