METHOD AND APPARATUS FOR DRAWING TRANSLUCENT MATERIAL

摘要

PROBLEM TO BE SOLVED: To provide a method and an apparatus for drawing a translucent material, capable of directly and readily measuring whether or not a drawn translucent material is provided with a twist in accordance with an object during the production of the drawn translucent material. SOLUTION: This method for drawing a translucent material comprises providing a void-containing optical fiber 7A provided with a twist round an axis in the drawing direction while producing the void-containing optical fiber 7A in which foams produced at its parts by drawing an optical fiber preform under heating in the longitudinal direction are drawn and exist as voids 6. The twist state of an optical fiber 5 is detected from the twist state of the voids 6 by detecting the change of diffuse light of light flux by rotation of the voids 6 with time by striking the light flux in the direction crossing the drawing direction on the void-containing optical fiber 7A.