WCA November 2015

Technology news

Radiation-resistant multimode fibres for computer tomography

RADIATION-resistant multimode fibres by Leoni’s centre of expertise in fibre, Business Unit Fibre Optics, stand out with their mechanical stability and consistent functional integrity. Even when exposed to increased radiation in computer tomography (CT) scanners, the attenuation of the fibres remains virtually constant. Leoni supplies its radiation-resistant multimode fibres singly, but also in any desired cable variant such as hybrid cable, breakout versions and in assembled form. High data rates are generally no problem for glass fibres, but unwanted radiation-induced attenuation (RIA) occurs in the fibre core during transfer in a CT scanner due to the existing X-rays. Although the fibres recover after the CT scan has finished, their transfer performance is compromised during the process. Radiation-resistant multimode fibres by Leoni’s Business Unit Fibre Optics register lower radiation-induced attenuation readings than other multimode fibres. They boast not only a high bandwidth, easy handling and good spliceability, but also an exceptionally small increase in attenuation while exposed to radiation. The fibres 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 fibres. This test involves measuring the attenuation increase during pulsed and ❍ Radiation-resistant multimode fibres from Leoni

continuous radiation. The finding is that, during pulsed exposure to X-rays, Leoni’s glass fibres register radiation-induced attenuation of about 20 dB/km at 1,310nm after one second, while one minute after the impulse the induced attenuation increase is one of <0.5 dB/km. At continuous exposure with g_radiation (Co-60) to a total dose of up to 1·106 rad/1·104 Gy, the radiation-induced fibre attenuation of the tested multimode fibres comes to less than 40 dB/km at 1,310nm. In the fibre optics segment, Leoni has a portfolio ranging from fused quartz to preforms and the fibres drawn from this through to fibre optic cables and complete fibre optic systems, thus serving all value creation stages. The Business Unit Fibre Optics is able, at all production stages, to lay out its radiation-resistant glass fibres for their later use and to supply them in different configurations. The options include, for example, larger coatings of 500μm or various fibre core diameters of 50, 62.5 or 100μm. Integrated in every possible cable design 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-recognised types pursuant to UL 1651 OFNR (UL 1666) are also available, as are assembled solutions. Leoni Special Cables GmbH – Germany Website : www.leoni.com

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Wire & Cable ASIA – November/December 2015