Terahertz Spectroscopy for Chemical Detection

Principal Investigator: Mohammad Arbab

Developments of methods for generating and detecting terahertz (THz) radiation have produced an interest in using THz data as a means to detect the presence of chemicals in an unobtrusive manner. Using Terahertz Time-Domain Spectroscopy (THz-TDS), certain chemicals can be identified by the absorption of their spectrum resonance. THz spectral information can be used to identify certain chemical compositions. For example, explosives have unique spectral characteristics in the THz region. However, surface roughness can cause electromagnetic scattering of THz waves, decreasing the signal to noise ratio. Little progress has been made in eliminating the negative consequences of scattering.

This invention includes a method and system for analyzing noisy terahertz spectroscopy data. It includes a method for detecting a chemical in a target using THz frequency spectrum of the target. This method and system for analyzing noisy THz spectroscopy data transforms the measured time-dependent data into frequency space using discrete Fourier transform and then transforms the frequency spectrum into wavelet frequency space. The twice-transformed data is analyzed to identify spectroscopic features of the signal such as resonance frequency.

Applications 

• The method and system described may be used to identify particular chemicals in a target. 

• The method and system described may be used in a stand-off detector for detecting chemicals in a target. Advantages 

• Terahertz radiation is non-ionizing. 

• Many materials such as clothing, paper, and the like are substantially transparent in THz frequency, while other materials, including plastics and ceramics, are readily visible. 

• Many chemicals of interest have a characteristic spectrum at THz frequencies that are amenable to detection by spectroscopic means.

For more info, contact: Lisa Norton