METHODS OF AND APPARATUS FOR VAPOR DELIVERY CONTROL IN OPTICAL PREFORM MANUFACTURE

摘要

METHODS OF AND APPARATUS FOR VAPOR DELIVERY CONTROL IN OPTICAL PREFORM MANUFACTURE A vapor delivery system for the manufacture of an optical preform includes a deposition bubbler and another bubbler referred to as a supply bubbler which is interposed between a reservoir of a liquid and the deposition bubbler. Heat energy is applied to the supply bubbler and to the deposition bubbler to vaporize liquid therein. A carrier gas is introduced into the liquid in the supply bubbler at a location below the free surface and into the deposition bubbler to cause vapor to the liquid to become entrained in the carrier gas and to flow from the supply bubbler into the deposition bubbler and from the deposition bubbler to a substrate tube from which an optical preform is made. Facilities are provided for maintaining sufficient liquid in the supply bubbler and suitable temperatures of the liquid in the supply and deposition bubblers to control the vapor flow into and out of the deposition bubbler to prevent unintended perturbations in the deposition bubbler. As a result, the concentration level of the vapor which is entrained in the carrier gas and delivered to the substrate tube is maintained at a substantially constant value.