Inspection of polyethylene gas pipe defect based on terahertz time domain spectroscopy

Polyethylene gas pipe sample with defects was detected by the transmission THz-TDS system. Firstly, the difference of the THz time-domain waveform and corresponding frequency spectra between the defect part and non-defect part was compared. Then, the PE pipe defects were imaged by the maximum value of THz time-domain data and the frequency-domain data. The results show that the existence of defects cause obvious reduction the maximum value of the THz time-domain spectrum. The PE defects can be clearly distinguished from the non-defect part by the transmission THz images. Imaged by the THz timed-domain and the frequency-domain parameter can reveal the defects in the polyethylene gas pipe.