However, since these methods do not intended to stabilize the shape of the whole deposit portion, the deposition shape of the glass fine particle deposit will change every manufacture of the glass preform. In the above mentioned method, the distal end part of the glass fine particle deposit or part of the deposition shape is monitored, and the pull-up rate and the charge quantities of the glass starting materials are controlled. There is also proposed, in manufacturing of the porous preform by a VAD process using three burners, to monitor the shape of a core portion with a CCD camera, and to control a pull-up rate, the flow rates of starting gases to be charged into the core portion, and the position of the core burner based on the change of the shape (refer to, for example, JP-H09-227147-A). In connection with that method, there is proposed to monitor the distal end part of the glass fine particle deposit with a CCD camera, and to control a pull-up rate, starting-gas charge quantities, or a burner position so as to make the distal end position of the deposit a predetermined position or in accordance with the change of the distal end position (refer to, for example, JP-2006-193360-A, JP-H08-198634-A, JP-2000-281378-A and JP-H08-034632-A).
In a VAD process for manufacturing a glass preform for an optical fiber, glass fine particles are deposited to form glass fine particle deposit. The present invention relates to a method of manufacturing a glass preform wherein a glass fine particle deposit is manufactured by depositing glass fine particles in accordance with a VAD process. This application claims priority from Japanese Patent Application No.Ģ010-240901 filed on October 27, 2010, the entire, contents of which are incorporated herein by reference. pdfģ66-Information under section 8(2) (MANDATORY). According to one embodiment, there is provided a method of manufacturing a glass preform, including: obtaining a glass-fine-particle deposit by a VAD process and heating the obtained glass-fine-particle deposit at a high temperature, thereby manufacturing a transparent glass preform, wherein, while depositing glass fine particles, in addition to monitoring a deposition shape of the glass-fine-particle deposit and controlling a pull-up rate of the glass-fine-particle deposit, there is controlled at least any of: flow rates of glass starting gases to be charged into glass-fine-particle producing burners flow rates of flame forming gases to be charged into the glass-fine-particle producing burners and positions of the glass-fine-particle producing burners relative to the glass-fine-particle deposit, so that the deposition shape may become a target shape, and wherein the deposition of the glass fine particles is stopped in a case where the deposition shape deviates from the target shape.ģ66 DECSRIPTION (COMPLETE) 25-10-2011.pdfģ66-PETITION UNDER RULE 137.
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