Quartz glass preform production comprises preparing a quartz glass hollow cylinder collapsed on a quartz glass rod containing a dopant and collapsing the cylinder

摘要

Production of quartz glass preforms comprises preparing a quartz glass hollow cylinder (2) having an inner layer (4) with a dopant increasing the refractive index of the glass and an outer layer (5) with a lower refractive index surrounding the inner layer, and collapsing the cylinder. The cylinder is collapsed on a quartz glass rod (3) containing a dopant. Preferably the quartz glass rods and the inner layer (4) contain the dopant in the same concentration. The difference of the refractive index of the rod and the inner layer is maximum 0.001.