Abstract

The fast identification of explosives, narcotics and other chemicals carried on board of ships or transported in containers to the harbors is an important problem of maritime security. Raman spectroscopy is widely used for fast identification of various chemicals. Continuous progress in the field of photonics has resulted in commercial availability of low-power compact Raman spectrometers which can be integrated into portable systems. Such systems can be used by law enforcement personnel or first responders to identify solid and liquid chemical substances of concern in the scene. Compared to other analytical techniques, these systems obviate the need for any sample preparation, perform measurement nondestructively, without physical contact with the substance (e.g. through the plastic or glass vials), providing result up to minutes. This paper present a portable Raman spectrometer designed and built as well as discusses its operation and performance. The device uses separate modules of 785 nm and 355 nm lasers of class IIIB that work independently to reduce disturbances at the field measurements and to increase amount of investigated chemicals. The spectrometer is controlled by an embedded PC. Measurements can be made in Raman shifts range even up to ~3500 cm-1 using thermoelectrically cooled CCD sensor and synchronous detection of modulated signal to increase signal-to-noise ratio. The example results of chemical identifications show efficiency of the developed system. The data analysis considers influence of glass/plastic vials on efficiency of detection of selected chemical mixtures. Finally, possible improvements in the quality of identification of chemicals that can be encountered by military and law enforcement personnel of maritime authorities will be discussed.

Authors (5)