| 摘要 |
PURPOSE:To improve working accuracy by measuring the element characteristic of an optical fiber in the longitudinal direction of the core glass rod or preform glass rod for an optical fiber and nonuniformly etching the glass surface in accordance with the variation. CONSTITUTION:A core glass rod for an optical fiber or its surface is coated with a clad layer to produce an optical fiber preform glass rod. The element characteristics such as the refractive index difference between respective positions in its longitudinal direction, profile index and clad thickness are then measured and calculated to prepare the variation graph in the longitudinal direction. The etching amt. at the terminal part is calculated to correct the thickness, the concn. and temp. of a liq. etchant such as aq. hydrofluoric acid soln. and gaseous hydrofluoric acid are determined from the thickness of the clad layer to be removed, the end requiring a long etching time is firstly dipped, the rod is taken out after a specified time, and the etchant is neutralized with an etching terminator such as cold water, hot water and aq. NH3. The operation is automated with a computer to improve accuracy, and an optical fiber glass preform is obtained. |
