Focusless hand-held proximal Raman detection and two-dimensional mapping of explosives

Abstract

Raman sensing and mapping techniques traditionally use a tightly focused laser beam to incite and collect Raman scattered photons. A large amount of energy is typically focused in a very small (micron-sized) area potentially resulting in photo-induced damage and can be not eye-safe. In addition, when using a focused-based laser system, scanning a large area is time consuming due to the small area of interrogation and must be done at a specific distance. Therefore, either prior knowledge of the sample location (in three dimensions) is necessary, or a smaller area must be scanned. In this work, we demonstrate a hand-held proximal Raman detection instrument that uses a non-focused laser beam to interrogate a larger area. This reduces the time it takes to map a surface and provides greater flexibility in targeting the area to interrogate. Herein, we show detection and mapping of explosives in two dimensions with this hand-held proximal Raman instrument as well distance dependence of this non-focused instrument with explosive materials.