Non-Destructive Testing
Inspection of dielectric, layered, polymer, composite, and manufactured structures without destructive sampling.
Non-Destructive Testing: 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
- Theoretical and experimental studies of metallic grids absorption: Application to the design of a bolometer — DOI
The study delivers a comprehensive, validated framework for designing metallic grid absorbers with precisely tailored electrical resistivity, enabling the creation of efficient, room‑temperature bolometers and other thermal detectors. By treating structured metal layers as equivalent homogeneous films whose resistivity depends on geometry, the authors derived analytical expressions for transmission, reflection, and absorption that incorporate skin‑depth effects and diffraction when the grid period approaches the wavelength. Numerical simulations and experimental measurements at 0.3 THz and in the RF band confirm the model’s accuracy, demonstrating that…
- Aeronautics composite material inspection with a terahertz time-domain spectroscopy system — DOI
- A comprehensive study of the application of the EOP techniques on bipolar devices — DOI
The study demonstrates that Electro‑Optical Probing (EOP), a non‑invasive laser‑based diagnostic technique, can be reliably applied to bipolar semiconductor devices to uncover internal electrical activity and identify failure mechanisms that are otherwise invisible to conventional analysis. By measuring the modulation of a reflected 1350 nm laser beam on the backside of transistors, the researchers quantitatively correlated signal variations with the electric field, carrier distribution, and doping profiles within the base, emitter and collector regions. Experiments on both a reference NPN transistor array and a…
- 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…
- Terahertz Nondestructive Testing with Ultra-Wideband FMCW Radar — DOI
The 150 GHz continuous‑wave radar, based on a homodyne eight‑harmonic mixing architecture, delivers non‑contact, high‑dynamic‑range imaging of a broad class of materials at sub‑millimetre depth resolution and up to 7.6 kHz frame rates. Achieving a 100 dB measurement dynamic range for few‑second integrations and longitudinal precision better than 4 µm, the transceiver outperforms existing millimetre‑wave FMCW implementations by roughly 15 dB at comparable acquisition speeds. Its compactness and non‑ionising nature open new inspection routes in sectors where conventional X‑ray or ultrasonic methods are limited….