Terahertz single-scan extraction of the dynamic information in a layered deposition

Abstract

Current terahertz time-domain spectroscopy (THz-TDS) theory and techniques are limited with respect to adequately and directly characterizing the layered structure information in dynamic deposition. We exploited a THz single-scan measurement and extraction method for the dynamic information in a layered deposition. The layer numbers, thickness and the deposition velocity can be simultaneously characterized with a single THz scan in a one-by-one deposition. Based on that, the THz-TDS can reveal the thickness information of a polycarbonate sheet with a continuously changing thickness. To demonstrate this, multiple layers of slices were measured. The layers were determined to have a special THz waveform that did not possess complete signals, while the THz-TDS clearly reflected the velocity and thickness of each sample in the process of superposition. The THz-TDS of the layered structures had multiple peaks. Thus, the layered structure information such as the insertion velocity and layers could be obtained for any condition. Consequently, we believe that a precise measurement carried with a THz single scan can help in improving online detection for deposition in the material science and petroleum industry.