Feature extraction and identification of explosive materials in reflective terahertz spectroscopic imaging system

We present a novel feature extraction technique for identification of explosive and biological materials using terahertz reflective time domain spectroscopy (THz-RTDS). The absorption signatures of the materials are extracted directly from the derivative of the amplitude reflectance without measuring the phase shift caused by the sample's height. This technique provides a straightforward and fast solution to solve the phase-retrieval problem in RTDS and will benefit the future development of standoff, large size focal-plane THz sensing and imaging system.