Terahertz identification of inclusion defects in hot melt joint of polyethylene pipe

Abstract

The reflective pulsed terahertz time-domain spectroscopy system with a frequency range of 0.25 ~ 2.5 THz was used to detect the defects of polyethylene pipe hot-melt joints. Using white PE100 plate, normal and inclusion defect samples were made. Through the point-by-point scanning of the terahertz system, the waveform and kurtosis imaging are obtained. According to the difference between the waveform and the image, the presence or absence of defects and the size of defects can be distinguished. The sobel edge detection operator has a good recognition level for defects. The recognition error is below 6.47 %, and the error of metal recognition can reach 3.54 %.