Terahertz Time-Domain Spectroscopy for Multilayer Thickness Characterization: A Whale Optimization Algorithm-Enhanced Inversion Methodology

Chaoqi Wang; Longhai Jing; Lijia Wang; Ruilin Zhu; Yuao Xu

doi:10.54097/jntbbc07

Authors

Chaoqi Wang
Longhai Jing
Lijia Wang
Ruilin Zhu
Yuao Xu

DOI:

https://doi.org/10.54097/jntbbc07

Keywords:

Terahertz time-domain spectroscopy; layered thickness measurements; whale optimization algorithm; joint time-frequency domain inversion; nondestructive testing.

Abstract

Terahertz time-domain spectroscopy (THz-TDS) technology has received wide attention and rapid development in recent decades, and has been applied as an effective detection tool in various technical fields. Aiming at the problems of low algorithmic efficiency and easy to fall into local optimisation of THz-TDS technology in the thickness inversion of multilayered layered materials, a high-precision layer thickness measurement method based on the improved Whale Optimization Algorithm (WOA) is proposed. The efficiency of model parameter inversion is optimised by establishing a joint time-frequency domain objective function and combining a dynamic weight adjustment strategy with a physical constraint mechanism. The experimental results show that the absolute error of single-layer thickness measurement is ≤3.8 μm (relative error ≤6.5%), which is a significant improvement in accuracy over the traditional algorithm. This method provides an efficient solution for real-time non-destructive testing of composite coatings.

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References

[1] Zandonella, C. T-ray specs. Nature 424, 721–722 (2003).

[2] WATANABE M,KURODA S,YAMAWAKI H,et al.Terahertz dielectric properties of plasma-sprayed thermal-barrier coatings [J]. Surface and Coatings Technology, 2011, 205(19): 4620-4626.

[3] HUSSAIN B,NAWAZ M,AHMED M,et al.Measurement of thickness and refractive index using femtosecond and terahertz pulses[J].Laser Physics Letters,2013,10(5):055301.

[4] Krimi S ,Klier J ,Jonuscheit J , et al.Highly accurate thickness measurement of multi-layered automotive paints using terahertz technology[J]. Applied Physics Letters, 2016, 109(2): 021105.

[5] Xu, Yafei et al. “Terahertz nondestructive quantitative characterization for layer thickness based on sparse representation method.” NDT & E International (2021): n. pag.

[6] LIU Zenghua, WU Yuheng, WANG Kexin,et al. Research on Defect Detection Imaging of Ceramic Matrix Composites Based on Terahertz Time-domain Spectroscopy Technology[J]. Journal of Mechanical Engineering, 2023, 59(14): 33-42.

[7] Guo, S. J. Structural Design and Research of Terahertz Metamaterial Optical Sensors [D]. University of Jinan, 2024. p.18

[8] Mirjalili S ,Lewis A .The Whale Optimization Algorithm [J]. Advances in Engineering Software,2016,9551-67.

[9] CHEN H, XU Y, WANG M, et al. A balanced whale optimization algorithm for constrained engineering design problems [J]. Applied Mathematical Modelling, 2019, 71: 45-59.

[10] XIAO Zi-ya, LIU Sheng. Study on Elite Opposition-Based Golden-Sine Whale Optimization Algorithm and its Application of Project Optimization[J]. Acta Electronica Sinica, 2019, 47(10): 2177-2186.

[11] ZHANG Hong-zhen, HE Ming-xia, SHI Li-li, WANG Peng-fei. Terahertz Thickness Measurement Based on Stochastic Optimization Algorithm [J]. Spectroscopy and Spectral Analysis, 2020,40(10): 3066-3070.