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A standard
optical fibre usually has a cladding diameter of about
an eighth of a millimetre (or 125µm).
As you can imagine a strand of glass so thin is very
fragile so to make sure that the fibres do not get
damaged they need protecting.
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To protect
the fibre it is usually covered with one or two plastic
coatings. The primary coating is normally made of acrylate
and is usually about 0.25 mm in diameter. This allows the
fibre to bend without breaking. A secondary coating of about
1-2 mm diameter is sometimes used to provide additional
protection. This may be a tight-buffering or loose tubing
(where the fibre is not mechanically bonded to tube).
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| When many fibres are being
cabled up together to be installed in the ground then they are
usually "stranded" around a central strength member
and additional armouring is applied to the finished cable (to
protect it from the men who dig up the road!) |
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