Optical fibre-coupled displacement and angle measurements using range-resolved interferometry

A novel approach to displacement and angle measurements that uses range-resolved interferometry to interrogate multiple interferometers is presented. Spatially offset beams are multiplexed onto the same delivery fibre using a very simple setup comprising of two stacked beamsplitters and the phase evaluation of these interferometers allows simultaneous measurement of both displacement and angular changes of a target surface. The operating principle of this technique and key design concepts are discussed. This approach, with its simple and compact fibre-coupled optical setup and ease of alignment, expands existing applications of laser interferometry, particularly for space-restricted environments, and its cost-effectiveness will be key to allowing widespread usage.