Long-distance fiberoptic white-light displacement sensing system using a source-synthesizing technique

A long-distance fibre-optic white-light displacement sensing system, using a synthesised source generated by combining the outputs from two low coherence sources, is demonstrated. As the wavelengths of both sources are compatible with standard 1.3 mu m singlemode telecommunication fibre, allowing the peak of the central fringe in interferogram to be determined precisely, a measurement range to resolution of better than 10(4):1 over a remote distance of 3.3 km has been achieved. It can be expected that this system could find important applications in long-distance, remote, and absolute measurements for quasistatic parameters.