PROCESS FOR MANUFACTURING A MICROSTRUCTURED OPTICAL FIBRE AND METHOD AND SYSTEM FOR ON-LINE CONTROL OF A MICROSTRUCTURED OPTICAL FIBRE

摘要

The present invention relates to a manufacturing process of a microstructured optical fibre comprising a void-containing region, the process comprising the steps of: drawing a microstructured optical fibre along a longitudinal direction from a heated preform, wherein the optical fibre is continuously advanced along the longitudinal direction; directing a radiation beam at a longitudinal position in the longitudinal direction of the optical fibre so as to produce an interference pattern; detecting the interference pattern and producing at least one electrical detection signal corresponding to the interference pattern and comprising a plurality of signal fringe cycles; feeding the first detection signal into a first counter circuit; determining a first number of interference fringe increments NA in the plurality of signal wave fringe cycles of the at least one detection signal by using the first counter circuit; determining the outer diameter d of the optical fibre, and controlling the microstructure of the optical fibre during advancement of the optical fibre, wherein the step of controlling comprises at least one step selected from: (a) controlling that the first number of interference fringe increments NA is comprised within a reference number range of reference numbers of interference fringe increments NA t, the reference numbers NA t being smaller than a second number of interference fringe increments ND related to the outer diameter d of the microstructured optical fibre by a conversion factor K, and (b) calculating a microstructure length value dA by multiplying the first number of interference fringe increments NA by a conversion factor K and controlling that the value of the microstructure length value dA is comprised within a reference length range of reference microstructure length values dA t, the reference microstructure length values being smaller than the outer diameter d of the microstructured optical fibre.