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Proceedings Paper

Using a new liquid-crystal polarization modulator for a polarimetric glucose sensor
Author(s): Tsung-Chih Yu; Yu-Lung Lo
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Paper Abstract

This paper presents a new liquid-crystal polarization modulator comprising a nematic liquid-crystal variable retarder (LCVR) and two quarter-wave plates for the measurement of glucose concentrations. Rather than using a conventional Faraday modulator, this study firstly adopts a LCVR driven by sinusoidal signals to modulate the polarization angle of the light as a sinusoidal function. It is found that the variation frequency of the polarization angle doubles that of the driving signal, and the modulation depth is not proportional to the driving amplitude. These features are quite different from a Faraday modulator. Therefore, a signal demodulation algorithm which developed to adapt the particular features of the LC modulator enables the polarization rotation angle corresponding to the glucose concentration to be derived. The proposed measurement method has a minimum resolution of 0.05 degrees corresponding to a glucose concentration of 0.2 g/dl. Compared to its conventional counterparts, the developed polarimeter has a simpler structure, fewer optical elements, and a cheaper modulator component.

Paper Details

Date Published: 12 April 2005
PDF: 7 pages
Proc. SPIE 5852, Third International Conference on Experimental Mechanics and Third Conference of the Asian Committee on Experimental Mechanics, (12 April 2005); doi: 10.1117/12.621220
Show Author Affiliations
Tsung-Chih Yu, National Cheng Kung Univ. (Taiwan)
Yu-Lung Lo, National Cheng Kung Univ. (Taiwan)


Published in SPIE Proceedings Vol. 5852:
Third International Conference on Experimental Mechanics and Third Conference of the Asian Committee on Experimental Mechanics
Chenggen Quan; Fook Siong Chau; Anand Asundi; Brian Stephen Wong; Chwee Teck Lim, Editor(s)

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