Prediction of Thickness for Plastic Products Based on Terahertz Frequency-Domain Spectroscopy

A novel method for predicting the thicknesses of plastics based on continuous-wave terahertz (THz) sented in this study. Initially, the target material's THz refractive index is determined from the phase information provided by the coherent nature of THz-FDS. For thickness prediction, the optimal frequency band with a high signal-to-noise ratio and minor water vapor absorption is chosen first. The optical path along which the THz wave passes through a sample with unknown thickness is extracted from the phase delay information. The physical thickness of the sample is then determined using the calibrated refractive index obtained in the first step. Teflon, a classical plastic material, is utilized to illustrate the proposed process. A remarkable consistency with an overall relative differpredicted and caliper measured thicknesses. The procapabilities of THz spectroscopy.