Identification of chemical materials using reference-free terahertz transmission spectroscopy and artificial neural networks

Weiwei Li; Hua Zhong; Liangliang Zhang; Chao Deng; Cunlin Zhang

doi:10.1117/12.805705

9 February 2009 Identification of chemical materials using reference-free terahertz transmission spectroscopy and artificial neural networks

Weiwei Li, Hua Zhong, Liangliang Zhang, Chao Deng, Cunlin Zhang

Author Affiliations +

Proceedings Volume 7158, 2008 International Conference on Optical Instruments and Technology: Microelectronic and Optoelectronic Devices and Integration; 71581M (2009) https://doi.org/10.1117/12.805705
Event: International Conference of Optical Instrument and Technology, 2008, Beijing, China

Abstract

In this paper, the THz spectra of several weakly absorptive chemical materials are measured by a novel technology: reference-free THz transmission spectroscopy. We then introduce a new THz spectral feature recognition method by applying pattern recognition method in explosive spectra classification and identification. Two types of artificial neural networks (ANNs): self organized mapping (SOM) and multilayer perceptron (MLP) and are used through repetitive modeling and adequate training with high accuracy rate and low alarm rate. The results indicate that the reference-free technique is a viable and valid spectroscopic modality by replacing the conventional absorbance curves with phase curves as features for identification and classification. The phase spectroscopy method is especially favorable for long distance and large size THz sensing and imaging systems by ignoring the imperfect beam amplitude profile. We also show that it is feasible to apply these two ANNS on the identification of different types of explosives, amino acid and many other chemicals. It provides an effective method in material inspection and identification using THz-TDS.

Citation Download Citation

Weiwei Li, Hua Zhong, Liangliang Zhang, Chao Deng, and Cunlin Zhang "Identification of chemical materials using reference-free terahertz transmission spectroscopy and artificial neural networks", Proc. SPIE 7158, 2008 International Conference on Optical Instruments and Technology: Microelectronic and Optoelectronic Devices and Integration, 71581M (9 February 2009); https://doi.org/10.1117/12.805705

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