Abstract-Composite multiscale entropy analysis of reflective terahertz signals for biological tissues

Rui Zhang, Yuezhi He, Kai Liu, Liangliang Zhang, Shijing Zhang, Emma Pickwell-MacPherson, Yuejin Zhao, and Cunlin Zhang

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-25-20-23669

We demonstrate a composite multiscale entropy (CMSE) method of terahertz (THz) signal complexity analysis to distinguish different biological tissues. The THz signals reflected from fresh porcine skin and muscle tissues were measured and analyzed. The statistically significant difference and separation of the two tissues based on several parameters were analyzed and compared for THz spectroscopy and imaging, which verified the better performance of the CMSE method and further enhancement of the contrast among THz signals that interact with different tissues. This process provides a better analysis and discrimination method for THz spectroscopy and imaging in biomedical applications.

© 2017 Optical Society of America

Abstract-Adaptive Sampling for Terahertz Time-Domain Spectroscopy and Imaging

Yuezhi He,  Edward P. J. Parrott ,  Emma Pickwell-MacPherson

http://ieeexplore.ieee.org/document/7815408/

We propose an adaptive sampling algorithm to improve the acquisition efficiency for terahertz time-domain spectroscopy (THz-TDS). Most THz-TDS measurements scan the delay line with constant speed and the data acquired have constant time steps. Our algorithm exploits the fact that the useful information within THz signals tends to cluster at certain positions: efficient sampling can be done by adaptively increasing the sample rate in regions containing more interesting features. The algorithm was implemented by programming a linear optical delay line. Depending on the experiment parameters, the sampling time of a pulse can be reduced by a factor of 2-3 with only slight degradation in accuracy, possible sources of error are discussed. We show how adaptive sampling algorithms can improve the acquisition time in applications where the main pulse is the primary concern.

Abstract-Freeze-thaw hysteresis effects in terahertz imaging of biomedical tissues

Yuezhi He, Benjamin S.-Y. Ung, Edward P. J. Parrott, Anil T. Ahuja, and Emma Pickwell-MacPherson

Freeze-thaw hysteresis effects in terahertz imaging of biomedical tissues

There have recently been several studies published involving terahertz (THz) imaging of frozen biomedical samples. In this paper, we investigate the effects of the freeze-thaw cycle on THz properties of porcine muscle and fat samples. For ordinary freezing, there was a significant change in the THz properties after thawing for muscle tissue but not for fat tissue. However, if snap-freezing was combined with fast-thawing instead of ordinary freezing and ordinary thawing, then the freeze-thaw hysteresis was removed.

© 2016 Optical Society of America

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