Method and apparatus for elongating optical fiber preform

摘要

In a elongating process, diameter gauges 20, 25 are provided at two locations of upstream measurement position P1 and downstream measurement position P2 which are in a taper portion 1b of an optical fiber preform 1, and fixed target diameters D10, D20 are set for the respective positions. Then a feed speed V1 of starting preform 1a is controlled based on a deviation (D1 - D10) of measured diameter D1 at the measurement position P1, while a take-up speed V2 of elongated preform 1c is controlled based on a deviation (D2 - D20) of measured diameter D2 at the measurement position P2. This decreases a time lag of control over the outside diameter of the elongated preform 1c and it thus becomes feasible to control the outside diameter in good response and with accuracy. Accordingly, an optical fiber preform elongating method and elongating apparatus are substantiated with improved elongating accuracy of the optical fiber preform and with improved productivity thereof.