Non-destructive terahertz imaging of alkali products in coated steels with cathodic disbanding

Fuse, Norikazu; Sugae, Kiyonobu

doi:10.1016/j.porgcoat.2019.105334

Cited by 13 publications

(5 citation statements)

References 31 publications

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“…Kurabayash T verified the feasibility of detecting metal rust beneath paint layers [10]. Norikazu F performed terahertz tomography observations on coated steels to visualize the distribution of alkali products deposited on the coating/substrate interface [11]. Staats N and Koch M et al detected air voids underneath paint layers while monitoring the consolidation of paint layers [12].…”

Section: Introductionmentioning

confidence: 97%

Non-Destructive Evaluation of Hidden Defects Beneath the Multilayer Organic Protective Coatings Based on Terahertz Technology

Zhong

Luo

et al. 2021

Front. Phys.

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An organic protective coating system plays an important role for the corrosion protection of offshore metallic structures. It is of practical importance to detect possible coating defects and evaluate coating performance for corrosion degradation monitoring. Reliable defect identification can provide timely and effective maintenance to avoid serious consequences. This work investigated various multilayer organic coating systems by terahertz pulse imaging technology and aimed to explore the inspection ability of terahertz non-destructive testing (THz NDT) of protective coatings. Several types of defective coating samples were measured. The comparison of measurements obtained for sites with and without defects was provided. The changes in the signals caused by the presence of defects were explained. Structural analysis, quantitative evaluation, and defect identification were carried out in detail. The results of measurements showed that corrosion defects, paint bulge defects, and paint detachment defects can be distinguished and identified in combination with the causes of defects. It can provide effective technical guidance for terahertz technology to be gradually extended to engineering applications.

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Section: Introductionmentioning

confidence: 97%

Non-Destructive Evaluation of Hidden Defects Beneath the Multilayer Organic Protective Coatings Based on Terahertz Technology

Zhong

Luo

et al. 2021

Front. Phys.

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“…In particular, the THz technique is desirable for the nondestructive testing (NDT) of the internal structures of objects. This is possible because THz waves are frequently transparent to the enclosures when they are made of nonconductive materials [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ]. The recent technological advances in novel THz sources and detectors have increased the feasibility of effective THz imaging systems for practical application—for example, to identify ithe size, shape, and location of conductive objects and defects in insulating materials [ 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ].…”

Section: Introductionmentioning

confidence: 99%

High-Speed THz Time-of-Flight Imaging with Reflective Optics

Yoo

Kim²,

Ahn

2023

Sensors

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In this study, we develop a 3D THz time-of-flight (TOF) imaging technique by using reflective optics to preserve the high-frequency components from a THz antenna. We use an Fe:InGaAs/InAlAs emitter containing relatively high-frequency components. THz-TOF imaging with asynchronous optical sampling (ASOPS) enables the rapid scanning of 100 Hz/scan with a time delay span of 100 ps. We characterize the transverse resolution using knife edge tests for a focal length of 5; the Rayleigh resolution has been measured at 1.0 mm at the focal plane. Conversely, the longitudinal resolution is determined by the temporal pulse width, confirmed with various gap structures enclosed by a quartz substrate. The phase analysis reveals that reflected waves from the top interface exhibit a phase shift when the gap is filled by high-indexed materials such as water but shows in-phase behavior when it is filled with air and low-indexed material. Our imaging tool was effective for inspecting the packaged chip with high lateral and longitudinal resolution. Importantly, the phase information in 2D and 3D images is shown to be a powerful tool in identifying the defect—in particular, delamination in the chip—which tends to be detrimental to the packaged chip’s stability.

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“…In recent decades, the first pilot applications appeared in different scientific and industrial areas. Nowadays, many different applications in the field of THz devices can be found for material scanning and food inspection [2,3], imaging [4], tissue analysis [5], security scanning [6], etc. Unlike the other inspection techniques based on X-rays and infrared radiation, the THz represent non-ionizing waves with low quantum energy, which cannot damage the inspected material permanently, and has good penetration ability.…”

Section: Introductionmentioning

confidence: 99%

A Novel System for Quasi-Continuous THz Signal Transmission and Reception

Sarjaš

Pongrac

Gleich

2022

Sensors

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This paper presents a novel system for generating and receiving quasi-continuous (QC) TeraHertz (THz) waves. A system design and theoretical foundation for QC-THz signal generation are presented. The proposed QC-THz system consists of commercially available photo-conductive antennas used for transmission and reception of THz waves and a custom-designed QC optical signal generator, which is based on a fast optical frequency sweep of a single telecom distributed-feedback laser diode and unbalanced optical fiber Michelson interferometer used for a high-frequency modulation. The theoretical model for the proposed system is presented and experimentally evaluated. The experimental results were compared to the state-of-the-art continuous-wave THz system. The comparison between the continuous-wave THz system and the proposed QC-THz system showed the ability to transmit and receive QC-THz waves up to 300 GHz. The upper-frequency limit is bounded by the length of the used Michelson interferometer. The presented design of THz signal generation has a potential for industrial application because it is cost-efficient and can be built using commercially available components.

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Non-destructive terahertz imaging of alkali products in coated steels with cathodic disbanding

Cited by 13 publications

References 31 publications

Non-Destructive Evaluation of Hidden Defects Beneath the Multilayer Organic Protective Coatings Based on Terahertz Technology

Non-Destructive Evaluation of Hidden Defects Beneath the Multilayer Organic Protective Coatings Based on Terahertz Technology

High-Speed THz Time-of-Flight Imaging with Reflective Optics

A Novel System for Quasi-Continuous THz Signal Transmission and Reception

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