Abstract: Infiltrators into protected zones are identified by depositing a tacky narrow band fluorescent material, on a perimeter portion of the zone, by illuminating infiltrators of the perimeter with a beam of ultra-violet light and by spectroscopically analyzing a telescopic-received image of the illumination. Most suitably, the fluorescent material is a europium chelate composition, such as europium trifluoracetonate dissolved in acetonitrile and added to an uncatalyzed resin.