Reel-less launch cable fibers without a mechanical spool

Tension-free storage of launch cable fibers to ensure high measurement accuracy even with temperature changes

Some kinds of demanding technical measurement tasks utilize lengths of fiber called ‘launch cables’. A typical application for these cables is OTDR measurement, which involves the excitation of a length of fiber with short optical pulses and the measurement of the light scattered back by the fiber. Integrity problems involving connectors or splices result in excessive reflectance (‘return loss’) and analyzing the pulse over time can help determine the exact location of the problem. With an OTDR instrument, the spatially-resolved attenuation can be obtained for a length of fiber to be tested.

To ensure high measurement accuracy, it is essential that the launch cable fiber does not have any tension to avoid the launch cable fiber affecting the measurement signal in any way. Launch cable fibers are connected in front of the actual fiber to be tested and so ‘bridge’ the fiber length that is undetectable by the OTDR device. This ensures you test only the actual length to be measured without any side effects that could introduce errors.

To meet this specific challenge, LEONI has now deployed a special fiber winding system that produces tension-free, reel-less launch cable fibers. No mechanical spool is used for the launch cable fibers, which means that they have no contact at all with a mechanical carrier system. Since the fibers are also not wound as cables, i.e. without an external jacket, this avoids the kinds of stresses that lead to measurement inaccuracies. By avoiding the use of a mechanical carrier as well as an external jacket, this achieves ideal, tension-free storage, even if ambient temperatures fluctuate.

LEONI produces bespoke reel-less launch cable fibers for customers:

Fiber typesSMF 9/125 µm, G50/125 µm (OM2, OM3), G62.5/125 µm – special fibers on request
Typical fiber lengths100–500 m
Winding diameter50–150 mm, depending on fiber type

For many applications, the special fiber windings are integrated into the instrument itself. LEONI offers customer-specific support for integration and can also supply the windings directly integrated into the customer’s own housing after production, potting the fibers tension-free as a second step. This solution from LEONI provides you with an ideal way to save valuable time during technical implementation.