-
[show abstract]
[hide abstract]
ABSTRACT: In this article the Fourier transform method is applied to analyze multiple-beam interference Fizeau fringes. The real part of the inverse Fourier transform is used to estimate a theoretical pattern. This pattern coincides with the experimental one. A derivative-sign binary image of the interference pattern is also used in automated determination of the contour line of the fringe pattern, regardless of the quality of this pattern. A correlation between the pixel size and the accuracy of the measured fiber refractive index is presented. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 475–484, 2002
Journal of Applied Polymer Science 07/2002; 85(3):475 - 484. · 1.29 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A multiple-beam interference Fizeau fringes technique is used to measure the refractive index profile of drawn polyethylene fiber. The interference fringe shift in the fiber region has been analyzed automatically using an interactive algorithm. The method takes into consideration the refraction of the light beam when crossing the fiber. Plane polarized light vibrating parallel and perpendicular to the fiber axis are used to obtain the refractive index profiles of both cases. These profiles are used to determine some optical parameters such as the birefringence, the optical orientation function, the polarizability per unit volume, and the value Δα/3αo, which related to the material structure. The reliability of the method is tested considering the results of drawn polyethylene fiber samples using the manual technique. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 3099–3106, 2000
Journal of Applied Polymer Science 07/2000; 77(14):3099 - 3106. · 1.29 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A new model, using non-destructive two- and/or multiple-beam interferometric techniques, is suggested for measuring the refractive index profile of fibers having regular and/or irregular cross-sectional shape taking into consideration the refraction of the light rays by the fiber. The proposed model is applied for three different fibers having different cross-sectional shapes and different refractive index profiles. These fibers are PPT, homogeneous fiber, with circular cross-section, graded index optical fiber of circular cross-sectional shape and Dralon fiber of irregular cross-section. To validate the proposed model it is used, firstly, to calculate the index profile for a standard PPT fiber. Secondly, the calculated results for the irregular Dralon fiber and GR-IN optical fiber are compared with that calculated using other conventional method. From this comparison, we recommend that the refraction must be taken into account to obtain accurate results especially for birefringent fibers and graded index optical fibers.
Optics Communications 282(1):27-35. · 1.49 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A new method based on a mathematical model and a computer program is suggested to determine the refractive index profile of fibers having regular and/or irregular transverse sectional shape. Microinterferogram of both multiple-beam Fizeau fringes and the duplicated image from two-beam interference microscope are used for the determination of refractive index profile, cross-sectional area and shape of three different types of fibers. To confirm the suggested model, the calculated area and the shape of the transverse section of these fibers are compared with those results obtained using conventional methods.
Optics & Laser Technology 40(8):1082-1090. · 1.51 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Automatic fringe pattern analysis is a powerful and inexpensive digital image-processing technique. It is used to analyze the fringe pattern obtained by different optical techniques, such as multiple-beam Fizeau fringes. To perform accurate and fast automatic measurement of fiber refractive index profile, phase analysis method has been used with the Fourier transform technique. In this paper, the refractive index profiles of polyethylene fibers with different draw ratios are presented by two methods, fringe shift method and phase analysis method. A comparison between the results obtained is presented.
Optics and Lasers in Engineering.
-
[show abstract]
[hide abstract]
ABSTRACT: A new theoretical model considering the refraction of the incident light beam by the fibre is suggested to determine the refractive index profile of bent optical fibres. This new model (slabs model) considering the cross section of the bent optical fibre consists of large number of slabs. The slabs model bases on the refraction of the incident beam by the fibre. The refractive index profile of the optical fibre cladding before bending obtained using the automated Fizeau interferometer with the aid of suggested model is compared with other models such as, the homogenous model and the multilayer model to verify the ability of this slab model. The refractive index profile of the bent optical fibre cladding is investigated using this suggested model. In addition, the new model is used to obtain the induced birefringence and the guiding parameters. The bending radius is recommended to be greater than 7.1 mm for the used optical fibre. The consideration of the refraction increases the accuracy of the results.
Optics Communications.
