Comparison of Signal Processing Algorithms for High-Resolution FMCW Terahertz Thickness Measurements

Schreiner, Nina S.; Keil, Andreas; Sauer-Greff, W.; Urbansky, R.; Friederich, Fabian

doi:10.1088/1742-6596/1537/1/012018

Cited by 2 publications

(2 citation statements)

References 4 publications

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“…The main weakness of the THz image compared to the Xray and optical ones is the lower resolution. Nevertheless, due to the great advances of THz technology, recently the enhancement of the THz image resolution has been given a great focus by researchers either by improving the THz imaging techniques [12]- [15] or developing super resolution algorithms [16]- [20].…”

Section: Introductionmentioning

confidence: 99%

Defect Detection in Bidirectional Glass Fabric Reinforced Thermoplastics Based on 3-D-THz Imaging

Souliman

Kahl

Stock

et al. 2023

IEEE Trans. THz Sci. Technol.

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Non-homogeneous, bi-directional glass fabric reinforced thermoplastic (GFRT) composites are used in the automobile industry to produce economic and environmentally friendly vehicles. Despite the fact that GFRT materials have superior mechanical characteristics and lower manufacturing cost compared with traditional materials, they are prone to significant deformation and defect emergence during the forming/manufacturing of parts from prefabricated laminates. Some defects, especially hidden ones like delamination and consolidation defects, can significantly reduce the mechanical properties of the final parts. It is essential to use 3D non-destructive testing (NDT) technology to detect and identify such hidden defects. This research investigates the ability of 3D THz imaging to detect hidden defects (i.e., delamination and consolidation) in GFRT composite materials. Frequency modulated continuous wave (FMCW) technique is used to generate 3D-THz cross-sectional images. Non-defective and defective samples with a thickness of 1.5 mm have been measured with two 3D THz imaging systems operating in the frequency range from 238 to 316 GHz and from 499 to 733 GHz. In addition, a simulation of the reflected FMCW spectrum is presented to analyze the measurements and intercompare the performance of the two imaging systems. A systematic analysis in a large sample set demonstrates that a delamination defect with a thickness of 125 µm as well as a consolidation defect with a difference in thickness less than 0.4 mm can be successfully detected by the 700-GHz imaging system.

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Section: Introductionmentioning

confidence: 99%

Defect Detection in Bidirectional Glass Fabric Reinforced Thermoplastics Based on 3-D-THz Imaging

Souliman

Kahl

Stock

et al. 2023

IEEE Trans. THz Sci. Technol.

View full text Add to dashboard Cite

show abstract

“…The main weakness of the THz image compared to the X-ray and optical ones is the lower resolution. Nevertheless, due to the great advances of THz technology, recently the enhancement of the THz image resolution has been given a great focus by researchers either by improving the THz imaging techniques [16]- [19] or developing super resolution algorithms [20]- [24].…”

Section: Introductionmentioning

confidence: 99%

Defect Detection in Bi-directional Glass Fabric Reinforced Thermoplastics Based on 3D THz Imaging

Souliman¹

2022

Preprint

View full text Add to dashboard Cite

Non-homogeneous, bi-directional glass fabric reinforced thermoplastic (GFRT) composites are used in the automobile industry to produce economic, environmentally friendly and recyclable vehicles. Despite the fact that GFRT materials have superior mechanical characteristics and lower manufacturing cost compared with traditional materials, they are prone to significant deformation and defect emergence during the forming/manufacturing of parts from prefabricated laminates. Some defects, especially hidden ones like delamination and consolidation defects, can significantly reduce the mechanical properties of the final parts. It is essential to use 3D non-destructive testing (NDT) technology to detect and identify such hidden defects. This research investigates the ability of 3D THz imaging to detect hidden defects (i.e., delamination and consolidation) in GFRT composite materials. Frequency modulated continuous wave (FMCW) technique is used to generate 3D-THz cross-sectional images. Non-defective and defective samples with a thickness of 1.5 mm have been measured with two 3D THz imaging systems operating in the frequency range from 238 to 316 GHz and from 499 to 733 GHz. In addition, a simulation of the reflected FMCW spectrum is presented to analyze the measurements and intercompare the performance of the two imaging systems. A systematic analysis in a large sample set demonstrates that a delamination defect with a thickness of 125 µm as well as a consolidation defect with a difference in thickness less than 0.4 mm can be successfully detected by the 700-GHz imaging system.

show abstract

Comparison of Signal Processing Algorithms for High-Resolution FMCW Terahertz Thickness Measurements

Cited by 2 publications

References 4 publications

Defect Detection in Bidirectional Glass Fabric Reinforced Thermoplastics Based on 3-D-THz Imaging

Defect Detection in Bidirectional Glass Fabric Reinforced Thermoplastics Based on 3-D-THz Imaging

Defect Detection in Bi-directional Glass Fabric Reinforced Thermoplastics Based on 3D THz Imaging

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