Abstract: An apparatus is proposed for controlling the coating thickness of an optical fiber (2) passing sequentially, in that order, from a unit (1) for fabricating the fiber (2) through a cooling unit (3), a coating unit (4) and along a device (5) which determines the diameter of the fiber. The apparatus includes a control element (14) for controlling a control device (15, 16) as a function of the measured diameter in such a way that the thickness of the coating corresponds to a target value, wherein the control device (15, 16) is placed before the coating unit (4) when viewed in the transport direction of the fiber (2), and the control device (15,16) adjusts the temperature of the fiber (2). Also described is a method for controlling the coating thickness.

Abstract: A device for applying a coating material to an optical fiber (1) has a coating nozzle (7) arranged in a nozzle holder (3) and a coating chamber (17) located before the coating nozzle (7) in the direction of travel of the optical fiber (1). Beyond that the device has at least one inlet channel (19) which is connected to the coating chamber (17), as well as a number of feed lines (23) for different coating materials. A connection can be established between one of the feed lines (23) and the at least one inlet channel (19), so that a change of coating material can be made in a simple manner, particularly a color change, without costly conversion and cleaning operations.

Abstract: In an optical fiber (1) with a coating (8) for the cladding of one or more plastic layers containing the fiber core and a color marking (3) on or in the outer plastic layer, the color marking (3) is covered by a further transparent or translucent layer (4).

Abstract: To increase the identification characteristics of optical fibers (9) with one or more protective covers (10, 11) and an external color coating (12) of UV-hardened varnish, additional different color identification markings (13) are integrated into the external color coating (12).