Aeronautics
Terahertz inspection of aeronautical composites and layered structures, building on research into contactless non-destructive testing.
Aeronautics: measurement approach and use cases
Work begins with the material and the decision that the measurement must support. Feasibility depends on dielectric properties, water content, thickness, roughness, geometry, access, and the scale of the feature being sought. The same nominal frequency range may therefore be useful in one polymer stack and strongly attenuated in another sample.
An application study normally combines representative specimens, a controlled acquisition protocol, and a reference description obtained through another measurement or expert assessment. The objective is not merely to produce a visually convincing image, but to determine which feature of the signal is stable, specific enough for the question, and compatible with the practical constraints of the domain.
Validation requirements and practical limits
Terahertz results should be compared with reference measurements and interpreted within the limits of the sample set. Laboratory feasibility does not by itself establish operational readiness. Transfer may require larger cohorts, blind testing, calibration standards, faster acquisition, robust positioning, environmental control, uncertainty budgets, and integration with an existing decision process.
Related publications
- Propagation beam consideration for 3D THz computed tomography — DOI
The study introduces a new physical model that captures the real behaviour of terahertz (THz) radiation when used for three-dimensional tomographic imaging. Unlike conventional X‑ray methods that treat the beam as a straight, uniform ray, the authors model the THz pulse as a Gaussian beam whose intensity spreads during propagation. This model is incorporated into a realistic acquisition simulator, allowing researchers to predict how the beam will illuminate an object from different angles and to produce more accurate projection data—sinograms—than those obtained with the…
- Aeronautics composite material inspection with a terahertz time-domain spectroscopy system — DOI
- Ordered subsets convex algorithm for 3D terahertz transmission tomography — DOI
This research introduces a practical, high‑performance technique for three‑dimensional terahertz (THz) tomography that is designed to meet the stringent demands of non‑destructive inspection in industrial and cultural heritage contexts. The method refines the maximum‑likelihood reconstruction framework originally developed for X‑ray computed tomography, integrating a realistic Gaussian beam propagation model that captures THz diffraction and intensity variation across the sample. By incorporating direct measurements of the system’s blank‑scan background and dark‑field signals into the algorithm, the approach delivers robust estimates of material attenuation without the…
- Advanced Processing Sequence for 3-D THz Imaging — DOI
The authors present a comprehensive, automated image‑processing pipeline that transforms raw terahertz (THz) radiographs into detailed three‑dimensional reconstructions of an object’s internal structure. The sequence combines a regularized tomographic reconstruction algorithm with K‑means segmentation, connected‑component labelling, skeletonisation and calibre tracking. This workflow produces accurate surface, volume, wall‑thickness and lumen‑diameter measurements from purely transmitted THz data, enabling fully non‑destructive inspection of composites, plastics, paper, and other low‑attenuation materials that are difficult to image with conventional X‑ray or optical methods. The practical applications demonstrated include the…
- Terahertz imaging and tomography as efficient instruments for testing polymer additive manufacturing objects — DOI
Terahertz (THz) imaging and tomography have been shown to provide a rapid, non‑destructive and radiation‑free method for inspecting polymer parts produced by additive manufacturing. Unlike conventional X‑ray tomography, THz techniques offer the possibility of routine quality assurance for complex medical implants and aerospace components, detecting internal voids, pores or misalignments that would otherwise compromise mechanical performance or patient safety. The study demonstrates that polyether‑ether‑ketone (PEEK) and polyamide‑12 structures, typical of spinal fusion cages and aircraft pneumatic valves, can be fully visualised and measured in…