Browsing by Author "Shih, Wen-Tse"

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A compact in-situ ellipsometer using the liquid crystal variable retarder
(2014-01-01)
Shih, Wen-Tse
;
Hsieh, Mei-Li
;
Chao, Yu Faye
;
光電工程學系
;
Department of Photonics
For monitoring the optical properties of material under a dynamical processing, we design a compact in-situ ellipsometry by using a liquid crystal (LC) phase retarder. Since the key issue of an accurate ellipsometer is the alignment of each optical component in the system, hence we not only proposed the alignment procedure, we also calibrated the phase retardation of LC retarder for this in-situ ellipsometry. The azimuths of polarizers and phase retarders can be aligned by the analytical solutions of the azimuthal deviations. The phase retardation can be directly determined by the intensity ratio technique.
Probing field-induced submolecular motions in a ferroelectric liquid crystal mixture with time-resolved two-dimensional infrared spectroscopy
(2006-08-16)
Huang, Jung Y.
;
Shih, Wen-Tse
;
光電工程學系
;
Department of Photonics
Time-resolved two-dimensional infrared (2D IR) spectroscopy has been applied to analyse an electro-optic switching ferroelectric liquid crystal (FLC) mixture. The 2D IR correlation technique clearly shows that the Goldstone mode in the SmC* phase is suppressed by an applied electric field. The field-induced reorientation process initiates from intramolecular motions in about 10 mu s. The intramolecular motions then propagate from the molecular segments attached to the same molecule to those fragments on other surrounding molecules. During the field-induced switching, the IR dipoles undergo a collective reorientation but with hindered rotation about the molecular long axis.