Capillary tube and method of producing the same

A method of producing a capillary tube from glass, comprising:

• zonally softening a tubular preform having an outer diameter DOD, an inner diameter DID and a diameter ratio Drel—with Drel=DOD/DID—in a heating zone heated to a draw temperature Tdraw;
• drawning off continuously from the softened region a capillary strand having an outer diameter dOD, an inner diameter dID and a diameter ratio drel—with drel=dOD/dID—at a draw speed vdraw;
• and
• cutting the capillary tube to length therefrom;
• characterized in that a capillary bore is subjected in the heating zone to a shrinkage process based on the action of draw temperature Tdraw and surface tension in such a way that the diameter ratio drel of the capillary strand is adjusted to a value greater than the diameter ratio Drel of the preform by at least a factor of 5, and wherein a multimode optical fiber preform or a single-mode optical fiber preform with a preform core surrounding an inner bore and a preform cladding covering the preform core is employed as the preform, and a capillary strand is drawn therefrom having a capillary core surrounding a capillary bore and a capillary cladding covering the capillary core.