Novel Method to Monitor Quartz Tube Darkening upon Optical Fiber Drawing

摘要

Length of optical fiber produced from one preform is getting longer owing to fatter preforms. The longer the fiber drawing lasts, the darker the quartz tube in the UV lamp chamber becomes. In extreme case, at the end of the drawing, UV curable coatings may not receive enough energy from the UV lamp to be cured properly because of darkened tube. We found that the surface temperature of the quartz tube has a certain relationship with the darkness of the tube. Based on this relationship, a new on-line monitoring method to keep track of the darkness during drawing was developed. Using this new method, a new shape of quartz tube, which darkens much less than conventional tubular one, was suggested.