Method and apparatus for drawing optical fibres by means of a double crucible

摘要

Method and apparatus for drawing optical glass fibres by means of a double crucible. The double crucible for producing a graded index optical fibre having a core and a cladding comprises inner and outer body portions (2) and (3) and a heated exit flow tube (4) which is elongate to allow thermal diffusion between the core and cladding to be prolonged.