IED Logistics report, December 2011. Status Report Demonstrator
Publish date: 2011-12-13
Report number: FOI-R--3346--SE
Written in: English
- multispectral imaging
Improvised explosive devices, IEDs, are a common threat to the civilian society and military operations, therefore there is a need to detect and identify such explosive charges in real environments. One way is to find and attack the network behind the production, handling and placement of the charges. The handling of explosive material often leaves trace particles behind and the aim in this project is to further develop a sensor system for finding these trace particles. The system will be based on multispectral imaging Raman spectroscopy, utilising a UV laser; it will be mobile and suitable for field applications. This report shows the ongoing work on developing an imaging UV-Raman system. Parts of the work have been made hand in hand with another project called the CEREX project (Collaborative Effort for Raman Explosive detection). The project, in which the imaging Raman system has been developed, is funded by the Swedish Civil Contingencies Agency. A graphical user interface (GUI) is under development to give a user friendly control system. The GUI will show a near- and a far-field view of the target together with some control buttons. In order to identify the targets, three different types of methods for spectra classification is been investigated; a) direct fitting, b) classification methods and c) subspace methods. A first step has been, to reduce the number of Raman shifts to measure at by feature selection. Preliminary results shows that for sulfur (S), ammonium nitrate (AN), 2,4-dinitrotouluene (DNT) and 2,4,6-trinitrotouluene (TNT) 8-10 shifts are enough when using least square fitting. Good Raman spectra from polytetrafluoroethylene (PTFE), potassium chlorate (PC), AN, urea nitrate (UN) and cyclotrimethylenetrinitramine (RDX) have been recorded at 355 nm laser wavelengths. Also by using a tunable OPO-laser and a tunable notch filter, Raman spectra of the same substances have been recorded in the 320-360 nm laser wavelength range. For most targets the measured Raman signal decreases considerably towards shorter wavelengths.