Abstract: An improved method of forming porous glass preforms by generating glass particles from a vapor phase and applying the particles onto a substrate characterized by generating the glass particles from a vapor phase in a separate operation, collecting the particles and then subsequently applying the previously collected particles onto a deposition surface of the substrate by creating a hot zone adjacent the deposition surface and projecting the particles as a stream through the hot zone and onto the deposition surface.

Abstract: A method for the manufacture of starting materials for fiber optical waveguides and the like from gas phase, wherein glass compositions are produced in a reaction zone in the presence of condensation nuclei being additionally introduced into said reaction zone and being used to increase the rate of glassforming and the rate of deposition of said glass composition being deposited on a solid surface as a soot or a powder. The nuclei can be added as particles of micron size to a carrier or reaction gas that is to be introduced into the reaction zone. The particles can be themselves produced immediately before the deposition zone in a reaction gas mixture which is subsequently introduced into the reaction zone.

Abstract: A method and device for testing specimens, such as optical fibers or preforms from which optical fibers are produced, to discover defects in the specimen includes creating a spatial frequency spectrum of the specimen, filtering the spectrum by projecting it onto a spatial frequency filter and evaluating the portion or component of the spectrum passing through the filter.

Abstract: The invention relates to a method for manufacturing a hihg-tensile strength optical waveguide with a plastic layer of the epoxy-acrylate type located on the lightguide fiber, wherein a radiation-hardenable prepolymer is applied to the lightguide fiber immediately after the fiber-drawing process. The invention provides for the use in such a method of a preopolymer, which can be hardened by actinic radiation, of at least one acylated hydroxy ester of acrylic and/or methacrylic acid and an epoxide with n.ltoreq.3 epoxide groups per molecule. The optical waveguides manufactured by the method according the present invention are suitable particularly for purposes of optical information transmission.

Abstract: A light waveguide with a high tensile strength including a light conducting or optical fiber being coated with a plastic coating to improve the tensile strength characterized by the plastic coating being a plastic lacquer applied directly on the surface of the light conducting fiber, being a high temperature stable material selected from a group consisting of polyurethanes, epoxides, polyesters, polyesterimides, polyimides, and polyvinyl dimethoxymethane, which material has a softening temperature of at least 150.degree. C. The coating has a thickness of at least 2 .mu.m and is uniformly concentrically applied over the entire length of the light conducting fiber without any surface defects. The light waveguide may include an outer covering which is either tightly applied or loosely applied onto the light conducting fiber and its coating. To improve movement of the light conducting fiber and its coating in the covering, a slide layer may be interposed between the outer covering and the plastic lacquer coating.