A new high accuracy real-time processing system for the measurement of core-axis misalignment error of single-mode fibres

A high-accuracy real-time processing system is proposed for the measurement of core-axis misalignment error between single-mode fibres which are to be spliced. By using a high-frequency pulse insertion method, the image detection resolution for the edge characteristic points of the fibre core has been improved by a few times compared with the conventional method using a CCD (charge-coupled device) image sensor connected to a microprocessor through an analogue-digital converter (ADC). After analysing the principle of the measurement method, the authors describe the design and implementation of this real-time system. The experimental results show that a measurement accuracy of +or-0.1 mu m with a reliability of 86% and a measurement speed of half a second for the fibre core-axis misalignment error have been achieved.