Sweep Distortion Removal from THz Images via Blind Demodulation

TL;DR

This paper introduces a novel algorithmic framework based on low-rank matrix recovery and alternating minimization to remove sweep distortions from THz images, enabling accurate reconstruction of signals despite complex temporal-spatial distortions.

Contribution

It presents a new blind demodulation method tailored for THz imaging that exploits the physics of acquisition for effective distortion removal.

Findings

Successful reconstruction on synthetic data

Effective distortion removal in experimental data

Applicable to other time-resolved sensing modalities

Abstract

Heavy sweep distortion induced by alignments and inter-reflections of layers of a sample is a major burden in recovering 2D and 3D information in time resolved spectral imaging. This problem cannot be addressed by conventional denoising and signal processing techniques as it heavily depends on the physics of the acquisition. Here we propose and implement an algorithmic framework based on low-rank matrix recovery and alternating minimization that exploits the forward model for THz acquisition. The method allows recovering the original signal in spite of the presence of temporal-spatial distortions. We address a blind-demodulation problem, where based on several observations of the sample texture modulated by an undesired sweep pattern, the two classes of signals are separated. The performance of the method is examined in both synthetic and experimental data, and the successful reconstructions are demonstrated. The proposed general scheme can be implemented to advance inspection and imaging applications in THz and other time-resolved sensing modalities.