Output characteristics of two-circle coaxial optical fiber bundle with regard to three-dimensional tip clearance

A two-circle coaxial optical fiber bundle is a type of optical sensor which has been widely used in non-contact radial displacement measurement applications. This paper has focused on output characteristics of a two-circle coaxial optical fiber bundle used as a measurement unit in a probe designed to measure a three-dimensional tip clearance. First, a model that could calculate intensity point-by-point on each receiving fiber with a simplified algorithm of overlap area was established, an aperture angle compensation algorithm was then proposed to improve the performance of the model. In order to test the reliability of the model, an experiment was done with different three-dimensional displacement of the reflector. Comparison between experimental and simulation results indicates the model built in this article could better describe how three-dimensional displacement of reflector affects the output of the bundle than previous studies.