Application of terahertz transmission wave in measuring the thickness of insulating medium

The nondestructive testing of insulation equipment is of great significance for detecting the hidden danger of insulation as soon as possible. Terahertz wave, which is located between microwave and infrared waves, has good penetrability in insulating materials, and there will be reflected waves in different media due to the change of refractive index of medium. Therefore, it has been widely studied in material performance analysis and nondestructive testing. In this paper, the time domain transmission and reflection waves of silicone rubber and epoxy glass fiber plates are measured. The amplitude of THz wave in medium propagation attenuation characteristics were discussed. According to the relationship between time delay and the thickness in both transmission and reflection mode, two methods of thickness measurement were analyzed.