JACIII Vol.27 No.4 pp. 726-731
doi: 10.20965/jaciii.2023.p0726

Research Paper:

Prediction of Thickness for Plastic Products Based on Terahertz Frequency-Domain Spectroscopy

Tianyao Zhang* ORCID Icon, Boyang Li*, Zhipeng Ye*, Jianfeng Yan**, Xiaoyan Zhao*, and Zhaohui Zhang*,†

*School of Automation and Electrical Engineering, University of Science and Technology Beijing
30 Xueyuan Road, Haidian District, Beijing 100083, China

Corresponding author

**China Ship Research and Development Academy
2 Dewai Shuangquanbao Road, Chaoyang District, Beijing 100192, China

February 15, 2023
May 8, 2023
July 20, 2023
terahertz waves, non-destructive inspection, plastic industry, thickness determination

A novel method for predicting the thicknesses of plastics based on continuous-wave terahertz (THz) frequency-domain spectroscopy (THz-FDS) is presented in this study. Initially, the target material’s THz refractive index is determined from the phase information provided by the coherent nature of THz-FDS. For thickness prediction, the optimal frequency band with a high signal-to-noise ratio and minor water vapor absorption is chosen first. The optical path along which the THz wave passes through a sample with unknown thickness is extracted from the phase delay information. The physical thickness of the sample is then determined using the calibrated refractive index obtained in the first step. Teflon, a classical plastic material, is utilized to illustrate the proposed process. A remarkable consistency with an overall relative difference of only 0.45% is revealed between the THz-FDS predicted and caliper measured thicknesses. The proposed method is expected to significantly expand the capabilities of THz spectroscopy.

Cite this article as:
T. Zhang, B. Li, Z. Ye, J. Yan, X. Zhao, and Z. Zhang, “Prediction of Thickness for Plastic Products Based on Terahertz Frequency-Domain Spectroscopy,” J. Adv. Comput. Intell. Intell. Inform., Vol.27 No.4, pp. 726-731, 2023.
Data files:
  1. [1] M. Naftaly, N. Vieweg, and A. Deninger, “Industrial applications of terahertz sensing: State of play,” Sensors, Vol.19, No.19, Article No.4203, 2019.
  2. [2] Y. Li, Z. Zhang, T. Zhang, X. Zhao, Y. Yu, X. Li, and X. Wu, “Quantitative Analysis of Iron Rust Using Terahertz Time-Domain Spectroscopy,” J. of Nondestructive Evaluation, Vol.42, Article No.7, 2023.
  3. [3] T. Zhang, Z. Zhang, and A. M. Arnold, “Dielectric analysis of polymeric materials and mixtures using terahertz time domain spectroscopy,” Spectroscopy and Spectral Analysis, Vol.39, No.6, pp. 1689-1694, 2019.
  4. [4] T. Zhang, Z. Zhang, X. Zhao, C. Cao, Y. Yu, X. Li, Y. Li, Y. Chen, and Q. Ren, “Molecular polarizability investigation of polar solvents: water, ethanol, and acetone at terahertz frequencies using terahertz time-domain spectroscopy,” Applied Optics, Vol.59, No.16, pp. 4775-4779, 2020.
  5. [5] N. Krumbholz, T. Hochrein, N. Vieweg, T. Hasek, K. Kretschmer, M. Bastian, M. Mikulics, and M. Koch, “Monitoring polymeric compounding processes inline with THz time-domain spectroscopy,” Polymer Testing, Vol.28, No.1, pp. 30-35, 2009.
  6. [6] X. Zhang, Q. Guo, T. Chang, and H.-L. Cui, “Broadband stepped-frequency modulated continuous terahertz wave tomography for non-destructive inspection of polymer materials,” Polymer Testing, Vol.76, pp. 455-463, 2019.
  7. [7] S. Wietzke, C. Jördens, N. Krumbholz, B. Baudrit, M. Bastian, and M. Koch, “Terahertz imaging: A new non-destructive technique for the quality control of plastic weld joints,” J. of the European Optical Society-Rapid Publications, Vol.2, 2007.
  8. [8] M. A. Alvi, Z. Zhang, X. Zhao, Y. Yu, T. Zhang, and J. Aslam, “Dissociation and Recombination Processes in Lactose Monohydrate Detected by THz Time-Domain Spectroscopy,” J. Adv. Comput. Intell. Intell. Inform., Vol.26, No.5, pp. 740-746, 2022.
  9. [9] A. Roggenbuck, H. Schmitz, A. Deninger, I. C. Mayorga, J. Hemberger, R. Güsten, and M. Grüninger, “Coherent broadband continuous-wave terahertz spectroscopy on solid-state samples,” New J. of Physics, Vol.12, No.4, Article No.043017, 2010.
  10. [10] B. Li, X. Li, Y. Li, X. Wu, Z. Zhang, X. Zhao, and T. Zhang, “A novel algorithm for refractive index determination using photomixing terahertz continuous-wave spectroscopy,” 2022 47th Int. Conf. on Infrared, Millimeter and Terahertz Waves (IRMMW-THz), 2022.
  11. [11] T. Zhang, Z. Zhang, and M. A. Arnold, “Polarizability of aspirin at terahertz frequencies using terahertz time domain spectroscopy (THz-TDS),” Applied Spectroscopy, Vol.73, No.3, pp. 253-260, 2019.

*This site is desgined based on HTML5 and CSS3 for modern browsers, e.g. Chrome, Firefox, Safari, Edge, Opera.

Last updated on Sep. 29, 2023