Leoni's Fiber Optics business unit (Jena, Germany) is supplying radiation-resistant multimode fibers that register lower radiation-induced attenuation readings than other multimode fibers. Leoni says these fibers boast not only a high bandwidth, easy handling, and good spliceability, but also have an exceptionally small increase in attenuation while exposed to radiation.
High data rates are generally no problem for glass fibers, but unwanted radiation-induced attenuation (RIA) occurs in the fiber core during transfer in a computed tomography (CT) scanner due to the existing x-rays. Although the fibers recover after the CT scan has finished, their transfer performance is compromised during the process.
The Leoni fibers conform to the standard IEC telecommunication specifications, and the Fraunhofer Institute INT in Euskirchen verified their radiation resistance pursuant to TIA/EIA 455-64, the common method to determine to RIA on optical fibers. This test involves measuring the attenuation increase during pulsed and continuous radiation. The finding is that, during pulsed exposure to x-rays, Leoni's glass fibers register radiation-induced attenuation of about 20 dB/km at 1310 nm after one second, while one minute after the impulse the induced attenuation increase is one of < 0.5 dB/km. At continuous exposure with gamma radiation (Co-60) to a total dose of up to 1·106 rad/1·104 Gy, the radiation-induced fiber attenuation of the tested multimode fibers comes to less than 40 dB/km at 1310 nm.
In the fiber optics segment, Leoni products range from fused quartz to preforms and the fibers drawn from this through to fiber optic cables and complete fiber optic systems. The Fiber Optics business unit is able, at all production stages, to lay out its radiation-resistant glass fibers for their later use and to supply them in different configurations. The options include, for example, larger coatings of 500 µm or various fiber core diameters of 50, 62.5 or 100 µm. Leoni can, by adjusting the structure and mix of materials, give the radiation-resistant cable tension or crush resistance up to 600 N or make it either extremely flexible or flame-retardant in compliance with IEC 60332-1-2 and IEC 60332-3-22 Cat.A. UL-recognized types pursuant to UL 1651 OFNR (UL 1666) are also available, as are assembled solutions.