Patent ID: 7197898

Claim:
A drawing process for producing an optical fiber comprising the steps of: measuring either the outer diameter or shape of a preform; feeding said preform at a feeding speed into a furnace to heat and melt said preform; heating and melting said preform; while heating and melting, drawing said optical fiber from said preform at a drawing speed to form said optical fiber; measuring the outer diameter of said optical fiber at a position below the furnace; providing a control system with the measured outer diameter or shape of said preform, the measured outer diameter of said optical fiber, a predetermined preform value and a predetermined fiber value for controlling said drawing process; calculating a preform deviation of the measured preform diameter or shape from the predetermined preform value, and a fiber diameter deviation of the measured fiber diameter from the predetermined fiber value; generating control signals based on the combination of the preform deviation, the fiber diameter deviation, the measured preform diameter or shape, and the predetermined preform value for said optical fiber drawing process control; and adjusting the feeding speed of said preform and the drawing speed of said fiber according to said control signals; whereby said optical fiber drawing process is robustly controlled against deviations of the preform outer diameter or shape at different locations and against deviations of various preforms.