OPTICAL FIBRES

摘要

A method of drawing an optical fibre (310') or the like from an elongate pre-form (310), the fibre (310') and the pre-form (310) having at least one hole (311,312) running along their lengths, includes the steps of heating the pre-form (310) and drawing the fibre (310') from the pre-form (310) while controlling the ambient pressure around the pre-form (310) to be significantly higher or significantly lower than it would be under standard fibre drawing conditions.