Liquid identifier based on Hilbert spectroscopy: Concept and proof of principle

Fast and reliable identification of bottled liquids is of great importance for security screening. An unambiguous identification of bottled liquids can be made by electromagnetic measurements of dielectric permittivity functions of the liquid in a frequency range, where bottles are transparent and liquids of concern have specific dispersions. However, this frequency range, from a few GHz to a few THz, cannot be covered by any single conventional spectroscopy. We have developed a concept of liquid identifier, which is based on our new broadband Hilbert spectroscopy and high-T_c Josephson detectors. The first proof-of-principle measurements of reflection spectra from various bottled liquids in the range 40-300 GHz with total scanning time of 1 second have been carried out.