Abstract: A liquid replenishing apparatus for supplying liquid raw material replenishment for liquid raw material of an article to at least one raw material tank, including a replenishment tank for storing the liquid raw material replenishment, a first pipe extending between the replenishment tank and the raw material tank, a second pipe for introducing pressurized gas into a space of the replenishment tank, a branch pipe communicating with the first and second pipes, a pressure regulator provided in the second pipe, and a flow regulator provided in the branch pipe.

Abstract: A high frequency induction coupled plasma torch is disclosed. The torch is comprised of a multi-pipe structure and is used for forming a plasma flame by high frequency power induction. The torch is comprised of a plurality of pipes which are coaxially arranged within each other. Each of the pipes has one or more flanged openings positioned on its surface whereby it is interconnected to the adjacent pipe. By means of the flanged openings any given pipe may be interconnected with any number of outer pipes. The torch can be economically produced and maintained.

Abstract: A gas supply apparatus for supplying gaseous raw material of an article to a processing apparatus, including at least one main vessel for storing liquid raw material of the article and supplying the gaseous raw material to the processing apparatus, an auxiliary vessel for storing liquid raw material replenishment for the liquid raw material, a main pipe for delivering the liquid raw material replenishment to the main vessel, a return pipe branched form the main pipe, first and second control valves, and a feed device for feeding, through the main pipe, the liquid raw material replenishment to the main vessel.

Abstract: A device is disclosed for supplying a glass raw material gas in the form of the mixed gas consisting of the glass raw material gas and the carrier gas to a vapor deposition device for producing a preform of an optical fiber, the supply device including a secondary raw material container having a pressurizable interior and provided adjacent to a main raw material container. The bottoms, or areas near the bottoms, of the two containers are interconnected via a pipe including at a mid portion thereof a switching valve and a device for adjusting the flow rate of the raw material liquid between the two containers. Liquid level detectors are provided in one or both containers to maintain the constant volume of the liquid raw material so as to provide a constant state inside the main raw material container. The operation of this device can easily be entirely automated.

Abstract: A process for producing an optical fiber preform in a muffle furnace by hydrolyzing a gaseous glass forming material with a flame from an oxyhydrogen burner and depositing the resulting soot in a rod shape and an apparatus therefor are described, wherein a gas is supplied to the muffle furnace other than from said burner, and the volume supply of said gas is held constant by controlling the amount of a control gas supplied into an intermediate portion of an exhaust pipe through which the gases formed in the muffle furnace and the fine glass particles that do not deposit in a rod shape are discharged.

Abstract: A process and apparatus for producing an optical fiber preform by oxidizing a gaseous glass forming material with a flame from a burner and depositing the resulting soot in a rod form are described, wherein two signal beams, supplied by splitting a light beam, are projected in a direction normal to the direction in which the preform grows and are directed into the space between the burner and the deposition face of the preform, and they are positioned so that one beam partially contacts the deposition face of the preform, while the other beam is directed to pass between the burner and the deposition face, and the distance between the burner and the deposition face is controlled such that the ratio of the intensity of the two beams passing through the space between the burner and the deposition face is held constant.

Abstract: A process for producing a porous optical fiber preform by hydrolyzing a gaseous glass forming material with a flame from an oxyhydrogen burner and depositing the resulting soot in a rod form in a muffle furnace is described, wherein the muffle furnace is supplied with a gas other than that from the oxyhydrogen burner, and said gas is maintained at a constant temperature.