VERFAHREN ZUR HERSTELLUNG VON EINER MIKROSTRUKTURIERTEN OPTISCHEN FASER

The process includes calibrating an intermediate preform, wherein calibrating comprises: stretching the intermediate preform during a stretching period by heating it (51) at a predetermined stretching temperature above T g and applying a tensional load (F) to the intermediate preform (50) along its elongation axis, so as to cause its straining along the elongation axis, the stretching temperature, the tensional load and the stretching period being selected so as to impress a viscoelastic deformation to the intermediate preform; cooling the intermediate preform to a temperature below T g during a cooling period, while maintaining the stretched preform in tension, so as to avoid a substantial release of said viscoelastic deformation; inserting the intermediate preform in a calibration tube (53) having a cylindrical inner shape; and heating (52) the intermediate polymer preform to a calibration temperature above T g during a calibration period sufficient to achieve a substantial release of said viscoelastic deformation.