Abstract: A filament cooler suitable for cooling freshly drawn optical fibre preparatory for being coated with a protective plastics coating has a water-cooled body member provided with a through hole opening out abruptly into a succession of spherical chambers in which a cyclonic gas flow is induced by the tangential injection of helium.

Abstract: A non-contacting method of measuring the electrical resistance per unit length of a filament, such as a carbon-coated optical fibre, makes the filament the inner conductor of a co-axial transmission line and measures a propagation characteristic of that line. The transmission line may be divided into seven sections, with a signal injected on the second section, and a comparison of the resulting signals appearing on the fourth and sixth sections being used in a feedback loop to control the injected signal frequency in such a way as to hold constant either the relative amplitudes or the relative phases of the signals appearing at the fourth and sixth sections.

Abstract: An optical fiber is provided with a vitreous carbon coating by the pyrolysis of propadiene promoted by the retained heat of the fiber immediately after it has been drawn from preform.

Abstract: A process for the continuous preparation of an oriented film of a polymer material comprising shearing at least one film of a solution and/or gel of the polymer material between at least one set of two solid surfaces which are in motion relative to one another. At least one of which surfaces is endless, so as to cause by the shearing, solidification of the polymer material from the solution or gel to a degree sufficient that a coherent, oriented film of the polymer material is formed on one of the surfaces. The film is sufficiently coherent so as to be capable of being removed from the surface on which it is formed in a continuous manner.