Glass base material production apparatus, glass base material production method, and base material profile prediction method

A glass preform production method by producing a glass particulate deposit by a VAD method and dehydrating and sintering the glass particulate deposit in a heating furnace, the method comprising:

• a gas supply step of individually supplying a glass raw material gas and a fuel gas to a burner;
• a deposition step of generating glass fine particles from the glass raw material gas in a flame obtained by combustion of the fuel gas supplied to the burner, and blowing the glass fine particles in the flame onto the glass particulate deposit;
• and
• a prediction step of predicting, at any one or more time points during a period from a start to an end of the deposition step, a refractive index profile of a transparent glass preform obtained by dehydration and sintering of the glass particulate deposit, wherein
• the prediction step includes an imaging step of imaging the flame generated in the burner or a particle flow of glass fine particles generated in the flame, and
• a calculation step of extracting image data representing a state of at least the flame or the particle flow from an image obtained in the imaging step and regressively predicting the refractive index profile of the transparent glass preform serving as an objective variable from an explanatory variable including the image data.

A preform profile prediction method for predicting, at any one or more time points during a period from a start of production to an end of production of a glass particulate deposit, a refractive index profile of a transparent glass preform obtained by dehydration and sintering of the glass particulate deposit produced by a VAD method, the preform profile prediction method comprising:

• an imaging step of generating glass fine particles from a glass raw material gas supplied to a burner in a flame obtained by combustion of a fuel gas supplied to the burner and imaging, at any time points when the glass fine particles in the flame are blown onto the glass particulate deposit, the flame generated by the burner or a particle flow of the glass fine particles generated in the flame;
• an image processing step of extracting image data representing a state of the flame or the particle flow from an image obtained in the imaging step;
• and
• a calculation step of regressively predicting the refractive index profile of the transparent glass preform serving as an objective variable from an explanatory variable including at least the image data extracted in the image processing step.