THz wave imaging through layered dielectric using correlating synthesis method

Abstract

Abstract We have introduced a correlating synthesis (CS) method for high-resolution terahertz (THz) imaging. The efficiency of the CS method was verified by imaging experiment of metal cylinders using a pulse reflection mode terahertz time-domain-spectrometry system. In this paper, we study the influence of layered dielectric in the propagation path of THz wave. A method of propagation time correction by ray tracing in the dielectric layer is proposed. The efficiency on decreasing the distortion and artifact images is verified by imaging experiment with a dielectric substrate board. Moreover, it is noticed that the appropriate correlation interval used in CS processing depends on the shape of the target. We propose a method of synthesizing the images derived from a series of different correlation intervals, which ensures the robustness of parameter independent with the target. The efficiency of the proposed method is verified by comparison imaging experiments using samples of different targets on a substrate board.