Through-Bottle Whisky Sensing and Classification using Raman Spectroscopy in an Axicon-Based Backscattering Configuration

TL;DR

This paper presents a novel Raman spectroscopy method using an axicon-based backscattering setup to non-invasively detect and classify whisky inside bottles, effectively avoiding fluorescence from the bottle wall.

Contribution

The study introduces a new axicon-based geometry for Raman spectroscopy that enables non-contact, non-destructive analysis of liquids inside transparent containers, improving detection of adulteration.

Findings

Efficient Raman signal acquisition from whisky inside bottles.

Avoidance of auto-fluorescence signals from bottle walls.

Potential for non-intrusive quality control of alcoholic beverages.

Abstract

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.