Irregular Transverse Sections Research Articles

Automatic determination of refractive index profile of fibers having regular and/or irregular transverse sections considering the refraction of light rays by the fiber

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.

Automatic determination of refractive index profile, sectional area, and shape of fibers having regular and/or irregular transverse sections

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.

Interferometric studies on fibres with irregular transverse sections

Multiple-beam Fizeau fringes in transmission and at reflection were applied to the study of the optical properties of fibres with irregular cross-section ( Orlon 42 and nylon fibres). The mathematical expressions used for the application of multiple-beam Fizeau fringes to determine the refractive indices and birefringence of fibres are given. The experimental techniques used for producing multiple-beam Fizeau fringes in transmission and at reflection are also given. Interferometric methods were applied to study the variation of refractive indices with wavelength of light and along the fibre axis. Values of refractive indices were used to calculate Cauchy's dispersion constants. The value of thermal coefficient of refractive index has been calculated. Illustrations are given using multiple-beam interferograms.

On the microinterferometric determination of refractive indices and birefringence of fibres

The paper deals with the determination of refractive indices and birefringence of polymer fibres using both two- and multiple-beam microinterferometry. Different techniques of interferometry are given together with their applications in investigating the optical properties of fibres. An analysis of the microinterferograms of fibres with irregular transverse sections is given. The optomechanical properties of polymer fibres, measured dynamically by interferometry, are dealt with. Lateral birefringence of fibres is also given. A mathematical expression is derived to determine the refractive indices, birefringence and the index profile of a cylindrical fibre taking into consideration the refraction of the incident beam by the fibre. This expression is applied with the two-beam microinterferograms produced for polypropylene fibres. A comparison between the two- and multiple-beam microinterferometric methods for the determination of refractive indices and birefringence of fibres is given. Both methods are evaluated. Microinterferograms are given for illustration.

Measurement of refractive indices of fibers with regular or irregular transverse sections and having a skin‐core structure

Multiple‐beam Fizeau fringes crossing fibers of different cross‐sectional shapes and having a skin‐core structure are studied to determine the refractive indices of the two layers. These fibers are of circular, rectangular, triangular, trilobal, elliptical, kidney, and dog‐bone cross‐sectional shapes. The area enclosed under the fringe shift is considered to represent the optical path difference integrated across the fiber. This method is suitable for the measurement of refractive indices of fibers of regular or irregular transverse sections. This method is applied to nylon 6 fibers.

Stress birefringence in compressible polymer fibres with irregular transverse sections

From an interferometric point of view a mathematical formula is developed for computing the exact optical path variations associated with a deformed cross-section of a fibre due to the drawing process. Fizeau fringes in transmission crossing Perlon fibres are obtained to illustrate the experimental applicability of the new corrected formula. The correction term is expressed as a function of the material compressibility, applied stress and the draw ratio. The birefringence of Perlon fibres is changed mechanically according to two different mechanisms in successive ranges of draw ratio. The mechanical response of Perlon fibres is found to be dependent on the direction with respect to the fibre axis. Another term is suggested to describe the mechanical anisotropy of a polymer. Microinterferograms are given for illustration.

Measurement of refractive indices of homogeneous fibers with regular or irregular transverse sections

Seven fibers of different cross-sectional shape are studied interferometrically using multiple-beam Fizeau fringes. These fibers are of circular, rectangular, triangular, trilobal, elliptical, kidney, and dog-bone cross-sectional shapes. The areas enclosed under the interference fringe shift is considered to represent the optical path difference integrated across the fiber. This principal is applied to nylon 6 fibers of trilobal cross-sectional shape. The described method is suitable for the measurement of refractive indices of any fiber with regular or irregular transverse sections. Microinterferograms are given for illustration.

Interferometric determination of optical properties of fibres with irregular transverse sections and having a skin-core structure

Multiple-beam Fizeau fringes in transmission and at reflection were used to investigate the optical properties of layers of fibres with irregular transverse sections having a skin-core structure. Mathematical expressions have been derived for the values of refractive indices and birefringence of these fibres. These expressions were applied to determine the optical properties of two samples of nylon-6 fibres.

Theory of the Interferometric Determination of the Refractive Indices of Multiple-Index Fibers Having Irregular Transverse Cross Sections

A formula is derived that relates interferometer and transverse area measurements to the indices of refraction of a multiple-index fiber having an irregular transverse cross section composed of irregularly shaped regions characterized by these refractive indices. From this formula, an equation is obtained for the average index of refraction of such a fiber. Two methods are suggested for recovering the separate indices of refraction from equations based on the general formula.

Multiple-beam interferometric studies on fibres with irregular transverse sections

An analysis of multiple-beam Fizeau fringes crossing fibres with irregular transverse sections is given. The area enclosed under the fringe shift is considered to represent the path difference integrated across the fibre. The method is applied to the determination of refractive indicies and birefringence of dralon fibres. Microinterferograms are given for illustration.

A Contribution to the Study of Optical Properties of Fibers with Irregular Transverse Sections

A new method is suggested by the complementary use of the interference and scanning electron microscopy to measure the mean refractive indices and birefringence of fibers having irregular trans verse section. '