Year
2014
Abstract
Reflective particle tags derive their unique identities through utilization of thousands of microscopic reflective elements randomly suspended in a clear adhesive matrix. For verification of a tag’s authenticity, a special illumination and imaging system is used to “read” information about the precise positions and orientations of the faceted particles. Sandia National Laboratories developed the original Reflective Particle Tag (RPT) system, comprising a tag and an imager, in the 1990’s to identify treaty-accountable items. Since that time, the RPT system has evolved with advances in computing, imaging, and material science, and is currently considered a robust, low-cost, hard-to-counterfeit passive tagging system for treaty verification and international safeguards applications. However, a limitation of the current RPT system is the need to mechanically dock the tag reader with the tag, which prevents its use in situations where contact with monitored items is not permitted or desired. This paper discusses efforts currently underway at Sandia National Laboratories to develop a non-contact handheld imaging system that incorporates a high-resolution, high frame-rate camera; a strobed, multidirectional illumination system; and a tablet computer. High speed image processing algorithms are used to facilitate alignment of the reader with the tag, as well as for focusing and rapid data acquisition.