Abstract: A method of manufacturing an optical fiber glass preform, the method comprising depositing glass particles on a base material, the glass particles being generated by glass making feedstock gas being supplied while a burner and the base material that is rotating are reciprocated relatively to each other, wherein when a portion corresponding to an outer diameter equal to or more than 0.

Abstract: A method of manufacturing an optical fiber glass preform, the method comprising depositing glass particles on a base material, the glass particles being generated by glass making feedstock gas being supplied while a burner and the base material that is rotating are reciprocated relatively to each other, wherein when a portion corresponding to an outer diameter equal to or more than 0.

Abstract: A production method of an optical fiber preform includes forming a porous preform by depositing a silica particle on a circumference of a target rod; and dehydrating and sintering the porous preform by at least three thermal treatment steps. A first and a second thermal treatment steps of the three thermal treatment steps dehydrate the porous preform in an atmosphere including halogen gas or halogen-based compound gas, and a processing temperature at the second thermal treatment step is higher than a processing temperature at the first thermal treatment step.

Abstract: A porous layer is formed by depositing a silica glass particle around a core rod. The porous layer is dehydrated. The dehydrated porous layer is sintered under a decreased pressure until the dehydrated porous layer becomes a translucent glass layer containing a closed pore. The translucent glass layer is vitrified under an ambient atmosphere including an inert gas other than a helium gas.

Abstract: A porous layer is formed by depositing a silica glass particle around a core rod. The porous layer is dehydrated. The dehydrated porous layer is sintered under a decreased pressure until the dehydrated porous layer becomes a translucent glass layer containing a closed pore. The translucent glass layer is vitrified under an ambient atmosphere including an inert gas other than a helium gas.

Abstract: A porous layer is formed by depositing a silica glass particle around a core rod. The porous layer is dehydrated. The dehydrated porous layer is sintered under a decreased pressure until the dehydrated porous layer becomes a translucent glass layer containing a closed pore. The translucent glass layer is vitrified under an ambient atmosphere including an inert gas other than a helium gas.

Abstract: A porous layer is formed by depositing a silica glass particle around a core rod. The porous layer is dehydrated. The dehydrated porous layer is sintered under a decreased pressure until the dehydrated porous layer becomes a translucent glass layer containing a closed pore. The translucent glass layer is vitrified under an ambient atmosphere including an inert gas other than a helium gas.

Abstract: An apparatus for the production of a porous optical fiber preform preventing cracks in the preform and stabilizing quality over the longitudinal direction. The apparatus includes a reaction portion, a feed port for introducing a stream of gas, and a main exhaust port. A rotating mechanism is provided for mounting, rotating, and pulling up a seed rod for forming the porous optical fiber preform. A first burner emits a flame carrying fine particles of glass forming the core portion, and a second burner emits a flame carrying fine particles of glass forming the cladding portion. A portion adjusts the flow of the stream from the feed port to the main exhaust port so that the flames carrying the glass particles are not disturbed by the stream and so that the stream does not directly contact a fine glass particle deposit formed at a bottom end of the seed rod.

Abstract: A hooded glass particulate synthesizing torch, provided with at least a glass particulate synthesizing torch body having a feedstock gas injection passage formed at the center of its front end, a combustible gas injection passage formed concentrically at the outer circumference of the feedstock gas injection passage, and a plurality of small diameter combustion aid gas injection passages formed in the combustible gas injection passage along the outer circumference of the feedstock gas injection passage and a hood projecting out at the outer circumference of the front end of the torch body, the torch hood satisfying 0.5≦D/L≦2.0, where, L is the focal distance, that is, a distance from a point P, to which the small diameter combustion aid gas injection passages are directed and on an extension of the center line of the torch body in front of the torch body, to the front end of the torch body, and D is the hood length, that is, the distance from the front end of the hood to the front end of the torch body.

Abstract: An apparatus for manufacturing an optical fiber preform, comprising a reaction vessel housing a core, combustion burners each arranged such that a flame spurting port thereof is positioned within the reaction vessel so as to generate fine glass particles by a flame hydrolysis reaction, and a discharge unit including a discharge port arranged on a side of the reaction; vessel for discharging the excess fine glass particles which were not deposited on the core and the waste gas out of the reaction vessel, wherein an angle formed between an imaginary plane including the flame spurting port of one of the combustion burners and another imaginary plane including the discharge port of the discharge unit falls within a range of between 0.degree. and 40.degree..