Optical fiber preform and method of measuring and measurement device for refractive index change position of optical fiber

Abstract

The method for measuring the refractive index variation position of an optical fiber preform comprises: rotating the optical fiber preform about the central axis such that a straight line which is orthogonal to the central axis and which passes through two more refractive index variation positions of choice that are subject to measurement is orthogonal to the observation axis; irradiating a side surface of the optical fiber preform with light emitted from the light source, via the polarizer; receiving, with the camera and via the analyzer, the light that has been transmitted by the optical fiber preform, and acquiring a light intensity image; detecting a refractive index variation position of the optical fiber preform on the basis of the light intensity image; and moving the optical fiber preform or the observation axis parallel to the central axis.