Phase-contrast THz-CT for non-destructive testing

TL;DR

This paper introduces a novel phase-contrast THz-CT imaging method that utilizes a geometrical optics model and a new phase extraction algorithm, enabling rapid, non-destructive 3D imaging of plastic profiles.

Contribution

The paper presents a new algorithm for extracting phase information from THz signals and demonstrates its application in fast, non-destructive 3D imaging using THz-CT.

Findings

Successful experimental validation with a THz-TDS system

Reconstruction of 3D plastic profiles within minutes

Potential for non-destructive testing of plastics

Abstract

A new approach for image reconstruction in THz computed tomography (THz-CT) is presented. Based on a geometrical optics model containing the THz signal amplitude and phase, a novel algorithm for extracting an average phase from the measured THz signals is derived. Applying the algorithm results in a phase-contrast sinogram, which is further used for image reconstruction. For experimental validation, a fast THz time-domain spectrometer (THz-TDS) in transmission geometry is employed, enabling CT measurements within several minutes. Quantitative evaluation of reconstructed 3D printed plastic profiles reveals the potential of our approach in non-destructive testing of plastic profiles.