Patent ID: 7595866
Filing Date: 2009-09-29
Classification: G01B,G02B

Abstract:
1. A method for measuring non-circularity of a core portion of an optical fiber base material, comprising: a distribution measuring step of(i) moving the optical fiber base material in a direction parallel to a central axis of the core portion while light is irradiated, in a direction perpendicular to the central axis, to the optical fiber base material which is immersed in an oil, and (ii) measuring a variation in a width of a portion of the irradiated light which transmits through the core portion, for a predetermined length of the optical fiber base material in a serial manner in a longitudinal direction of the optical fiber base material and recording the variation in a width of a portion of the irradiated light in association with a moved distance of the optical fiber base material, thereby measuring a distribution of relative values of an outer diameter of the core portion in terms of the longitudinal direction of the optical fiber base material; a distribution storing step of performing the distribution measuring step each time the optical fiber base material is rotated about the central axis by a predetermined angle, thereby recording a plurality of distributions of the relative values of the outer diameter of the core portion each of which is associated with the predetermined angle; and a non-circularity calculating step of calculating a plurality of values, in terms of the longitudinal direction of the optical fiber base material, each indicating non-circularity of the core portion, based on the plurality of distributions of the relative values of the outer diameter stored in the distribution storing step.