A new method of measuring radius of an optical fiber and refractive index at the surface of a nonuniform fiber is proposed and is shown to be feasible also for a uniform fiber.
Jiang, J. A., Hsu, T. Y., Liao, W. B., & Ouyang, C. S. (2009). An Innovative Optical Fiber Flowmeter. 中國機械工程學刊, 30(2), 159-165. https://doi.org/10.29979/JCSME.200904.0010