In-depth analysis of optical fiber displacement sensor design process

Distance measurement is an essential issue in modern industry. Differential intensity sensors based on optical fibers have been very successful. Nevertheless, their ultimate range and sensitivity are limited by an inefficient fiber bundle design. This paper presents a method and a framework that allows researchers to find the best design for a sensor operating point. A database has been created that provides the responses of all bundles that can be configured with the major commercial fibers. Results show that the design of a fiber bundle for an operating point or range is not as critical as one might think. In fact, several fiber configurations allow working over the same distance range with the same responsivity. As we have shown, this result is maintained even when we impose stringent manufacturing tolerances (0.1%) on the positioning of the fibers. For this reason, the tool makes it possible to optimize the sensor response by selecting, among all possible solutions, those that maximize other parameters such as sensitivity, responsivity, operating range, or linearity. In addition, the tool is general purpose and facilitates the design of bundles tailored for precise distance measurement. The results obtained with the model and the tool have been validated with our experimental results and those obtained by other authors.