Wavelength Selective Terahertz Time-Domain Spectroscopy for Paper Thickness Measurement
CAO Bing-hua1, WANG Wei*, FAN Meng-bao2, WEI Zhong-liang3
1. School of Information and Control Engineering, China University of Mining and Technology, Xuzhou 221116, China
2. School of Mechatronic Engineering, China University of Mining and Technology, Xuzhou 221116, China
3. School of Computer Science and Engineering, Anhui University of Science and Technology, Huaian 230001, China
Abstract：Wavelength selection of spectra plays an important role in the quantitative analysis of terahertz spectroscopy. In this paper, a new method for quantitative measurement of paper sheet thickness is presented based on wavelength selection of terahertz phase spectra. Besides, binary particle swarm optimization (BPSO) algorithm is applied in wavelength selection of terahertz phase spectra and partial least square (PLS) algorithm is employed to establish the quantitative analysis model of paper sheet thickness. In addition, the root mean square error of prediction (RMSEP) is analyzed to show the performance of the method. Finally, the prediction error of the method is compared with both the methods using the raw spectra and the method using a single wavelength of the spectra. The results show that the method of this paper gives the most satisfactory quantitative accuracy.
Key words：Terahertz time-domain spectroscopy; Wavelength selection; Paper thickness; Binary particle swarm optimization; Partial least squares
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