One of the steps in the production of INO's hair removal systems consists in polishing 1.5 mm diameter fused silica fiber. This polishing, which used to be done mechanically, presented a number of challenges. The mechanical footprint of a highly rigid fiber measuring several meters long prevents us from using standard automatic polishing devices. Polishing was therefore done manually, as is the standard practice for optical fibers. The fiber's footprint and the large surface to be polished made this a long and arduous process, to the point that it caused tendinitis in personnel responsible for the operation.
We developed a laser system specifically designed to polish fused silica, a material used in the majority of optical fibers. The system uses a laser to slightly melt the surface of the fiber. Once reduced to a liquid state, the fiber becomes very smooth and a very polished finish remains once the laser radiation stops and the surface solidifies once more. The end result is a mirror finish that rivals the best results by mechanical polishing in terms of roughness. The process can be fully automated and the polishing time is approximately one fiber per minute, which makes it a very appealing solution for cutting production costs.
Laser polishing removes only a few nanometers of the fused silica, which makes it possible to maintain the initial surface profiles. This level of precision is vital when polishing optical parts whose surface profile must be maintained to within a fraction of the wavelength of luminous radiation for which it is used. In addition, the method is not limited to polishing flat surfaces and can also be used for curved surfaces.