Abstract: A gas burner for externally heating a glass tube which is positioned to be rotated on a rotational axis characterized by at least two multi-jet gas port blocks having a block axis with an arrangement of jets therearound being arranged with the block axes being on a radii extending from the rotational axis. Preferably only two port blocks are utilized and they are each separately displaceable relative to one another along the rotational axis and can be simultaneously displaced together along the axis during a heating operation. The arrangement of the plurality of jets on each of the front surfaces of the multi-jet gas port blocks is such that the jets are directed to a focal line which is at a distance beyond the rotational axis and a definite distance in front of the front surface.

Abstract: Technique for making glass having a predetermined refractive index profile using fluorine doping and fluorine etching. A substrate glass body is coated with a plurality of successively applied vapor deposited glass layers wherein each succeeding layer is built with a larger quantity of fluorine than the adjacent preceding layer. The amount of the doping in each layer is such as to achieve the desired refractive index profile. Fluorine etching is employed to provide a uniform core before the glass body is heat fused into a rod-like structure suitable for the preparation of light waveguides for use in optical communications technology.

Abstract: Glass preforms useful for producing optical fibers therefrom are produced by forming at least one layer of glass on an inner surface of a hollow glass tube by introducing a reactive gas mixture suitable for glass synthesis (ie., SiCl.sub.4, GeCl.sub.4, etc., and O.sub.2) and a combustible heating gas mixture (ie., CO, C.sub.2 N.sub.2, CS.sub.2, C.sub.4 N.sub.2, COS, C.sub.3 O.sub.2, etc., and O.sub.2) into a hot region within the hollow tube which is generated by exterior heating of such tube. The reactive gas undergoes a chemical reaction at such hot region whereby a material having the composition of glass is deposited on the hot inner surface of the tube as a layer and melts into a clear glass film while the heating gas combusts at the hot region and aids the rate of glass formation on the inner surface of the tube.

Abstract: In a process for producing a glass blank or workpiece from which a glass fiber light conductor of a low attenuation is drawn, said workpiece being formed by providing a body on which amorphous glass powder is precipitated from a reaction gas after a chemical reaction and then transformed into a clear glass characterized by the reaction gas being passed over or through a powder composed of amorphous glass of the same type which is being precipitated from the reaction gas onto the body to filter impurities therefrom. Preferably, the amorphous powders of the filter are contained in a precipitator and are produced by also reacting the gas and collecting the powder in the precipitator.

Abstract: A process for producing a glass fiber light conductor which has increased tensile strength characterized by forming a protective layer at an elevated temperature either on a preform of the fiber and cladding or on the cladding of a drawn fiber with the material of the protective layer having a coefficient of thermal expansion, which is lower than the adjoining glass material of the fiber so that on cooling from the elevated temperature, the layer is subjected to compressive stresses to increase the tensile strength of the fiber.