Paul-Henri Guering

Optical measurement of the drawing tension of small glass fibres

This work introduces the principle of a simple interferometric method to measure the drawing tension (F ≈ 10−3–10−4 N) of a small glass fibre (D ≈ 7–30 µm) during its forming process. Because of the industrial process and the complexity of the light scattering properties of small glass fibres, mechanical methods or optical methods based on birefringence measurements are not suitable to measure this tension. The method we propose uses the principle of the phase Doppler technique to determine the fibre size and simultaneously, the fibre tension, with the vibrating string method. No calibration is required with the proposed technique, and it is thought to be applicable to other types of fibres (polymer, carbon, metallic, etc).