Terahertz imaging super-resolution for documental heritage diagnostics

TL;DR

This paper introduces a super-resolution technique for terahertz imaging that enhances spatial resolution beyond traditional limits, enabling detailed analysis of cultural heritage artifacts and documents.

Contribution

The paper presents a novel super-resolution method using evanescent wave filtering and structured illumination in terahertz imaging, improving resolution for cultural heritage diagnostics.

Findings

Enhanced resolution in slit diffraction and edge imaging

Successful super-resolution imaging of ancient parchment documents

Effective spatial resolution improvement demonstrated on real samples

Abstract

Terahertz imaging provides valuable insights into the composition and structure of objects or materials, with applications spanning security screening, medical imaging, materials science, and cultural heritage preservation. Despite its widespread utility, traditional terahertz imaging is limited in spatial resolution to approximately 1 mm according to Abbe's formula. In this paper, we propose a novel super-resolution method for terahertz time-domain spectroscopy systems. Our approach involves spatial filtering through scattering in the far-field of high spatial frequency components of the imaged sample. This method leverages evanescent wave filtering using a knife edge, akin to a standard structured illumination scheme. We demonstrate improved spatial resolution in slit diffraction, edge imaging, and reflection imaging of structures fabricated on a paper substrate using commonly encountered materials in works of art and documents. Furthermore, we present super-resolved images of an ancient document on parchment, showcasing the effectiveness of our proposed method.