Browsing by Author "Chao, Y. F."

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Artifactual circular dichroism effect in a photoelastic modulator
(2010-12-01)
Chao, Y. F.
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Lin, P. L.
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光電工程學系
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Department of Photonics
The three-Intensity technique is used to calibrate a photoelastic modulator by its temporal waveform. This method not only allows us to measure the intrinsic static phase retardation and modulation amplitude but also provides the evidence for the existence of circular dichroism (CD) in the photoelastic modulator. In this report, we will demonstrate the averaged intensity for normalization in this PEM modulated light not only depicts a periodic modulation, it also exhibits anti-symmetric distributions at P = 45 degrees and P = -45 degrees, which was considered as constant for conventional PEM ellipsometry Four models were examined to verify that only a circular dichroism medium coupled with the periodical induced birefringence modulator can explain the phenomena. This work can quantitatively measure the artifactual CD effect of PEM and reduce its system error in CD spectrometer which consists of a PEM (C) 2010 Elsevier B V All rights reserved
center dot-ray induced effects in Sm-doped strontium borate glasses
(2013)
Marinova, V.
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Tomov, V.
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Chuang, C. I.
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Lin, Y. C.
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Lin, S. H.
Strontium borate glasses SrB4O7 doped with Sm ions are prepared by conventional melting-quenching method. The effect of center dot-ray irradiation on the glass samples is studied by measuring the absorption spectra and the photoluminescence. It is found that the center dot -ray irradiation caused partial reduction of Sm3+ to Sm2+ at room temperature. Borate framework is supposed to be responsible for the Sm3+ to Sm2+ transition.
Three-intensity measurement technique and its measurement in elliptical retarder
(2008-07-01)
Lin, P. L.
;
Han, C. Y.
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Chao, Y. F.
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光電工程學系
;
Department of Photonics
A three-intensity technique is applied in polarimetry for measuring the physical parameters of an elliptical retarder. In this study, quartz and mica quarter wave plates are distinguished by two models: linear retarder and elliptical retarder. By considering the twist nematic liquid crystal cell as an elliptical retarder, we are able to relate the effective optic axis to its rubbing direction and twist angle. All its physical parameters can be deduced from the model. (C) 2008 Elsevier B.V. All rights reserved.