Terahertz time-domain spectro-imaging and hyperspectral imagery to investigate a historical Longwy glazed ceramic

 Fauquet, Frédéric, Francesca Galluzzi, Philip F. Taday, Rémy Chapoulie, Aurélie Mounier, A. Ben Amara, and Patrick Mounaix. "Terahertz time-domain spectro-imaging and hyperspectral imagery to investigate a historical Longwy glazed ceramic." Scientific Reports 14, no. 1 (2024): 19248.

Abstract

In this paper, we present the potential of Terahertz Time-Domain Imaging (THz-TDI) as a tool to perform non-invasive 3D analysis of an ancient enamel plate manufactured by Longwy Company in France. The THz data collected in the reflection mode were processed using noise filtering procedures and an advanced imaging approach. The results validate the capability to identify glaze layers and the thickness of ceramic materials. To characterize the nature of the pigments, we also use with X-ray images, visible near-infrared hyperspectral imaging spectroscopy, and p-XRF (portable X-ray fluorescence) to qualitatively and quantitively identify the materials used. The obtained information enables a better understanding of the decoration chromogens nature and, thus, to determine the color palette of the artists who produced such decorative object. We also establish the efficiency of a focus, Z-tracker, which enables to perform THz imaging on non-flat samples and to attenuate artifacts obtained with a short focus lens. Then, 3D images are extracted and generated, providing a real vision. We also report the evaluation of the internal damage state through the detection of fractures.

see https://www.nature.com/articles/s41598-024-69697-6

Terahertz Assessment of the Battery Electrodes Save Production Costs of Electric Vehicles

Khat, F. Zarrin, A. Pentland, P. F. Taday, and D. D. Arnone. "Terahertz Assessment of the Battery Electrodes Save Production Costs of Electric Vehicles." Journal of Non Destructive Testing and Evaluation (JNDE) 21, no. 2 (2024): 33-40. 

Abstract

The electric vehicle market has experienced remarkable growth in recent years. A primary objective within this industry is to lower production costs. Notably, battery packs, which constitute up to 40% of the total production cost, allocate about 64% of this to the manufacturing of electrodes. It is vital to monitor key battery parameters such as thickness, loading, density, conductivity, and porosity to minimize waste during electrode production. Until recently, there was no technology capable of simultaneously tracking these parameters. However, terahertz technology has emerged as a powerful, non-destructive, and safe method for assessing battery electrodes.

Battery electrodes are coated on substrates made of materials like aluminium and copper. Since metals completely reflect terahertz waves, it's possible to measure the electrodes in reflection mode. This approach allows for the determination of the coating's thickness and its complex refractive index, which can be interpreted to deduce key electrode parameters.

In our study, we utilized TeraView's latest advancement, the TeraCota, a terahertz system designed for industrial applications, equipped with a self-referencing terahertz sensor. The sensor, mounted on a gantry, provided a terahertz image of the electrode loading and allowed for a direct comparison with an optical image, revealing defects on the cathode. We achieved an accuracy of 0.01 g/cm3 when comparing density measurements obtained through a terahertz sensor with those measured physically in the lab. Furthermore, the thickness measurements via the terahertz system agreed with those obtained using a micrometre to within less than 1 µm. Similarly, when comparing the conductivity measured by terahertz with DC conductivity measured via a four-point probe, the trends were consistent. Ongoing research into porosity has shown that the refractive index correlates with the porosity of specific electrode sets, indicating the potential for broader application. This comprehensive approach demonstrates the significant advantages of integrating terahertz technology into the battery electrode manufacturing process, potentially revolutionizing the industry by enhancing efficiency and reducing waste.

see https://jnde.isnt.in/index.php/JNDE/article/view/84

Exploring Porosity in Battery Electrodes: Terahertz Technology Unveiling Remote Sensing

 Zarrinkhat, Faezeh, Arturo I. Hernandez-Serrano, Alasdair Pentland, Philip F. Taday, Donald D. Arnone, and Michael Pepper. "Exploring porosity in battery electrodes: terahertz technology unveiling remote sensing." In 2024 49th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), pp. 1-2. IEEE, 2024.

Abstract:

Porosity significantly influences lithium-ion battery performance, impacting cell capacity, voltage, and specific power - critical to designers. Terahertz technology enables non-destructive, remote porosity assessment, addressing limitations in current measurement methods.

see https://ieeexplore.ieee.org/abstract/document/10697663

Optical and terahertz methods for studying easel oil paintings

 Bolshakov, Ivan S., Anastasiya A. Lykina, Olga V. Kravtsenyuk, Sergey V. Sirro, Vyacheslav Y. Toropov, Andrey R. Tsvetkov, Philip F. Taday, Donald D. Arnone, and Olga A. Smolyanskaya. "Optical and terahertz methods for studying easel oil paintings." Journal of Optical Technology 91, no. 5 (2024): 323-329.

Abstract

Subject of study. This study focuses on the application of terahertz tomography methods to easel oil paintings. Aim of study. The aim of this study is to assess the effectiveness of terahertz tomography in analyzing the layered structure of artworks and detecting hidden damage, elements, and annotations. Method. The study employed traditional analysis methods, such as infrared, ultraviolet fluorescence, and X-ray imaging. Special emphasis was placed on terahertz tomography, which enables non-invasive imaging of internal structures. Main results. The study showed that terahertz tomography allows for the differentiation of materials used in oil paintings. This method enables a detailed examination of the layered structure without damaging the object under investigation, revealing elements that cannot be detected using other methods. The novelty of this study lies in the proposed application of terahertz tomography for preliminary in situ examination of paintings to detect hidden defects and possible inscriptions on the reverse side of artworks. Practical significance. The results obtained from this study are valuable for researching, assessing the preservation status of, and restoring oil paintings. Specifically, the proposed method is suitable for detecting defects and hidden elements beneath paint layers without damaging the colorful surface. The terahertz tomography method proves particularly effective when applied in situ, as it does not require paintings to be dismantled.

see https://opg.optica.org/jot/abstract.cfm?uri=jot-91-5-323

The Measurement of the Coating Uniformity of Lithium Iron Phosphate Cathodes on Metal Substrates with Terahertz Time-domain Spectroscopy

 Zarrinkhat, Faezeh, Alasdair Pentland, Carl Reynolds, Emma Kendrick, and Philip F. Taday. "The Measurement of the Coating Uniformity of Lithium Iron Phosphate Cathodes on Metal Substrates with Terahertz Time-domain Spectroscopy." In 2023 48th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), pp. 1-2. IEEE, 2023.

Abstract:

For the first time, the thickness uniformity of lithium iron phosphate (LFP) cathodes are measured using terahertz time-domain spectroscopy. Cathodes are widely manufactured with cobalt, however providing cobalt material comes with supply and health issues. LFP cathodes are introduced as an alternative to tackle this challenge. The aim is to use terahertz pulses to generate an on-line tool to undertake manufacturing process control. Different thickness of cathodes compressed to different densities is measured and the uniformity of their coating is inspected.

see https://ieeexplore.ieee.org/abstract/document/10299358