  Non-intrusive detection systems have the potential to characterise materials
through various transparent glass and plastic containers. Food and drink
adulteration is increasingly problematic, representing a serious health risk as
well as an economic issue. This is of particular concern for alcoholic spirits
such as Scotch whisky which are often targeted for fraudulent activity. We have
developed a Raman system with a novel geometry of excitation and collection,
exploiting the beam propagation from an axicon lens resulting in an annular
beam that transforms to a Bessel illumination within the sample. This
facilitates the efficient acquisition of Raman signals from the alcoholic
spirit contained inside the bottle, while avoiding the collection of
auto-fluorescence signals generated by the bottle wall. Therefore, this
technique provides a way of non-destructive and non-contact detection to
precisely analyse the contents without the requirement to open the bottle.
