Using a New Laser Process to Custom Shape Optical Fibers

Thanks to a new laser process, optical fibers can now be inserted into even smaller vein branches. In this prototype, the tip is inside the fiber probe. (Source: Fraunhofer IZM)

Thanks to a new laser process, optical fibers can now be inserted into even smaller vein branches. In this prototype, the tip is inside the fiber probe. (Source: Fraunhofer IZM)

According to the German Venous League, one in five women and one in six men suffer from varicose veins, thrombosis or other vein problems. Endovenous laser vein therapy is one remedy. For this procedure, a plastic-coated optical fiber 0.5 millimeters in diameter is inserted into the affected blood vessel. Laser light is conducted through the middle of the fiber to the fiber tip. At a temperature of several hundred degrees, the emitted light cauterizes the tissue and causes the veins to collapse. To ensure that the light strikes the side walls of the vein directly, the fiber tip is tapered with a cone-shaped indentation that forms a reflective surface for the laser light. A protective glass cap ensures that no blood deposits directly on the tip could change the optical characteristics of the laser light.
In the LaserDELight project, researchers at the Fraunhofer Institute for Reliability and Microintegration IZM in Berlin, Germany, have developed a new, laser-based process for precisely shaping this sort of optical fiber. They use the FiberTurningLaser, which is otherwise a laser for glass processing. “The method enables the first automated series production,” explains Henning Schröder from Fraunhofer IZM. Until now, producing the fibers required complicated mechanical and manual processes that not only took significantly longer, but cost more too. Automation ensures consistent high quality. The project is being funded by the German Federal Ministry of Education and Research BMBF, a fiber probe prototype manufactured using the new technique was presented at the Sensor+Test 2015 in Nuremberg.
Using a laser beam, the researchers can shape the optical fiber tip. In a later production step, the protective cap is fused onto the fiber so that no additional fixture is needed. The new process has demonstrated that it is more practical to fashion a cone-shaped indentation in the fiber than have a tapered shape like the tip of a pencil. This offers yet another advantage: the cap on the fiber end is smaller making the fiber probe head in general more compact and versatile. (Source: Fraunhofer IZM)
Links: Fraunhofer Institute for Reliability and Microintegration IZM

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