METHOD FOR MANUFACTURING HIGH PURITY GLASS TUBES USEFUL FOR PRODUCING RELATIVELY LARGE SIZED OPTICAL FIBER

摘要

PURPOSE: Provided is a method for manufacturing high purity glass tubes useful for producing relatively large sized optical fiber preforms of high quality and at a low cost. CONSTITUTION: The method comprises the steps of: applying a first soot on an end of a starting member(12) to form an elongated cylindrical soot core(16) having a first density; applying a second soot including SiO2 on the circumference of the soot core(16) to form a soot cladding(20) having a second density greater than the first density of the soot core(16); heating the soot body at a temperature sufficient for sintering the soot core(16) and the soot cladding(20) into a core glass and a cladding glass, wherein the core glass collapses at a greater rate than the cladding glass and the core glass separates radially from the cladding glass; and then removing the core glass from inside the cladding glass to provide a high purity glass tube suitable for use in an optical fiber preform.