Optical fibres - Part 1-34: Measurement methods and test procedures - Fibre curl
- method A: side view microscopy;
- method B: laser beam scattering.
Both methods measure the radius of curvature of an uncoated fibre by determining the amount of deflection that occurs as an unsupported fibre end is rotated about the fibre's axis. Method A uses visual or digital video methods to determine the deflection of the fibre while method B uses a line sensor to measure the maximum deflection of one laser beam relative to a reference laser beam. By measuring the deflection behaviour of the fibre as it is rotated about its axis and understanding the geometry of the measuring device, the fibre's radius of curvature can be calculated from simple circular models, the derivation of which are given in Annex C. Both methods are applicable to type B optical fibres as described in IEC 60793 (all parts). Method A is the reference test method, used to resolve disputes. This third edition cancels and replaces the second edition published in 2006. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
- modification of several derivation equations for laser scattering;
- change of angular increment from 10° to 30° to 10° to 45°;
- change of Annex B from informative to normative.