So-called stress testers are automated devices used to carry out the quality control of processed fibres. With linear tensile testers, a linear tensile stress is placed on the fibre to measure its tensile strength. Bend proof testers are used in the quality control of optical fibres by bending and twisting.

The quality control of fibres which are used in special environments or on which particularly high demands are placed is extremely important. This includes, for example, fibres that are used in medical applications or wind turbines. So-called high-strength splices are also used in submarine cables.

The linear tensile tester exposes optical fibres to longitudinal tension to test their strength. This is crucial for fibres used in medical applications and for optical fibres that are used under extreme conditions, both of which require a high resistance. This is the case, for example, in submarine cables.

The linear tensile tester can reliably identify weak spots that may not become apparent until the fibre is processed.

Linear tensile testers can be used on fibres with a diametre between 30 µm and >2 mm.

Bend proof testers are used to test the resistance of optical fibres. They apply specific tensile stress to the fibre “indirectly” by bending and then rotate it under this stress. To apply a linear tensile stress of equal force to the fibre, significantly higher grip pressure in the fibre mount would be necessary. Because of the risk of damage to the fibre, the linear method is less suited for applications in production.

Users who splice thicker fibres will appreciate the automated testing station: until recently, it was necessary for users who wanted to test the resistance of the fibre and splice to manually bend and rotate the fibres after each splice.

With the bend proof tester, an individualized programme can be set up and saved for each fibre diametre to carry out objective and reproducible tests. The bend proof tester works with fibre diametres between 250 µm and 1 mm.