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Phase Function Effects on Identification of Terahertz Spectral Signatures Using the Discrete Wavelet Transform | IEEE Journals & Magazine | IEEE Xplore

Phase Function Effects on Identification of Terahertz Spectral Signatures Using the Discrete Wavelet Transform


Abstract:

We describe the application of the discrete wavelet transform (DWT) in extracting the characteristic absorption signatures of materials from terahertz reflection spectra....Show More

Abstract:

We describe the application of the discrete wavelet transform (DWT) in extracting the characteristic absorption signatures of materials from terahertz reflection spectra. We compare the performance of different mother wavelets, including Daubechies, least asymmetric (LA), and Coiflet, based on their phase and gain functions and filter lengths. We show that the phase functions of the wavelet and scaling filters result in spectral shifts to the absorption lines in the wavelet domain. We provide a solution by calculating advancement coefficients necessary to achieve effective zero-phase-function DWT. We demonstrate the utility of this signal processing technique using α-lactose monohydrate/polyethylene samples with different levels of rough surface scattering. In all cases, the DWT-based algorithm successfully extracts resonant signatures at 0.53 and 1.38 THz, even when they are obscured by the rough surface scattering effects. The DWT analysis with accompanying phase corrections can be utilized as a robust technique for material identification in nondestructive evaluation using terahertz spectroscopy.
Published in: IEEE Transactions on Terahertz Science and Technology ( Volume: 10, Issue: 6, November 2020)
Page(s): 656 - 666
Date of Publication: 25 May 2020

ISSN Information:

PubMed ID: 33738125

Funding Agency:


References

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