APPARATUS FOR PRODUCING MULTIPLE OVERCLAD OPTICAL FIBER PRECURSOR AND PRODUCING OPTICAL FIBER THEREFROM AND METHOD THEREFOR

摘要

PROBLEM TO BE SOLVED: To provide a method and an apparatus usable for the production of a larger overclad precursor without using an additional overclad step of RIT(rod-in-tube) method to improve the efficiency of the conventional RIT and ODD (overclad during drawing) method for the production of an MCVD optical fiber saving the processing time (and money). SOLUTION: The method for the production of the precursor comprises the positioning of the 1st overclad tube around a precursor core rod, the positioning of at least one 2nd overclad tube around the 1st overclad tube and the heating of the precursor core rod together with the overclad tubes under pressure to form the objective multiple overclad optical fiber precursor. The heating is carried out e.g. as a part of an overclad (ODD) treatment during the pulling action in a drawing tower furnace or in an independent heat-source before introducing the precursor into the drawing tower in a manner similar to the conventional rod-in-tube(RIT) treatment. The method includes the pulling of the optical fiber as a part of the precursor during the heating in the drawing tower furnace or with a heat-source separated from the drawing tower and the transfer to the drawing tower.