Author : AHMED MOHAMED ALI ASHOUR AHMED
CoAuthors : Fouad El-Diasty, Mona A Soliman and Abdel Fatah T. Elgendy
Source : Journal of Optics A: Pure and Applied Optics
Date of Publication : 01/2007
Abstract :
Cellulose triacetate, CTA, as a uniaxial material, has many diverse scientific
and technological applications. These applications depend basically on the
optical properties of the material. In this paper, a simple two-beam
interferometric technique is used to measure the absolute (built-in)
birefringence in cellulose triacetate film plates. By a least squares fitting to
the Cauchy dispersion formula, the quantum parameters of CTA are deduced.
The dispersion of the induced-birefringence due to gamma irradiation, at the
visible region of the spectrum, is determined. The relative error in
birefringence is 5 × 10−3. It is found that the birefringence is inversely
proportional to the wavelength and its rate of increase is greater at shorter
wavelengths. As the gamma irradiation dose increases, the birefringence
increases, which in turn enhances the anisotropic character of the CTA films.
The variation in birefringence dispersion (as the retardance or relative
retardation) versus the irradiation dose is investigated. We conclude that
measuring the birefringence is essential in order to provide correct
refractometric data to study the structure of irradiated materials.
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