Classification of lactose and mandelic acid THz spectra using subspace and wavelet-packet algorithms

Xiaoxia Yin; Sillas Hadjiloucas; Bernd M. Fischer; Brian W.-H. Ng; Henrique M. Paiva; Roberto K. H. Galvão; Gillian C. Walker; John W. Bowen; Derek Abbott

doi:10.1117/12.755154

21 December 2007 Classification of lactose and mandelic acid THz spectra using subspace and wavelet-packet algorithms

Xiaoxia Yin, Sillas Hadjiloucas, Bernd M. Fischer, Brian W.-H. Ng, Henrique M. Paiva, Roberto K. H. Galvão, Gillian C. Walker, John W. Bowen, Derek Abbott

Author Affiliations +

Proceedings Volume 6798, Microelectronics: Design, Technology, and Packaging III; 679814 (2007) https://doi.org/10.1117/12.755154
Event: SPIE Microelectronics, MEMS, and Nanotechnology, 2007, Canberra, ACT, Australia

Abstract

This work compares classification results of lactose, mandelic acid and dl-mandelic acid, obtained on the basis of their respective THz transients. The performance of three different pre-processing algorithms applied to the time-domain signatures obtained using a THz-transient spectrometer are contrasted by evaluating the classifier performance. A range of amplitudes of zero-mean white Gaussian noise are used to artificially degrade the signal-to-noise ratio of the time-domain signatures to generate the data sets that are presented to the classifier for both learning and validation purposes. This gradual degradation of interferograms by increasing the noise level is equivalent to performing measurements assuming a reduced integration time. Three signal processing algorithms were adopted for the evaluation of the complex insertion loss function of the samples under study; a) standard evaluation by ratioing the sample with the background spectra, b) a subspace identification algorithm and c) a novel wavelet-packet identification procedure. Within class and between class dispersion metrics are adopted for the three data sets. A discrimination metric evaluates how well the three classes can be distinguished within the frequency range 0.1 - 1.0 THz using the above algorithms.

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Xiaoxia Yin, Sillas Hadjiloucas, Bernd M. Fischer, Brian W.-H. Ng, Henrique M. Paiva, Roberto K. H. Galvão, Gillian C. Walker, John W. Bowen, and Derek Abbott "Classification of lactose and mandelic acid THz spectra using subspace and wavelet-packet algorithms", Proc. SPIE 6798, Microelectronics: Design, Technology, and Packaging III, 679814 (21 December 2007); https://doi.org/10.1117/12.755154

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