Terahertz reflection time-domain spectroscopy for measuring alcohol concentration

Alcohol is a kind of flammable substance. It is strictly forbidden in public places such as airports and high-speed railway stations. So the non-destructive testing of the alcohol is very crucial. In this paper, we used the reflective terahertz (THz) time-domain spectrometer to measure THz signals of alcohol aqueous solutions in different concentrations, the relationship between the pulse peak and concentration is obtained. And then reflectance spectra were obtained by using Fourier transform. Linear regression was employed to fit the relationship between the terahertz reflectance and the alcohol concentration at different frequencies. This pilot work has preliminarily formed a testing method for the detection of liquids concentration by using THz reflectance spectra. In the future, we can establish the THz spectral library for dangerous and inflammable liquids.