An aspect of the present disclosure enables prediction of a refractive index profile of a transparent glass preform obtained in a production stage of a glass particulate deposit by a VAD method. The glass preform production apparatus includes a gas supply system, a burner, and a signal processing device. The signal processing device includes an imaging device that images a particle flow of glass fine particles, and a calculation unit. The calculation unit extracts, at any one or more time points during a period from the start of production to the end of production of the glass particulate deposit, image data representing a state of at least the flame or the particle flow from an image obtained by the imaging device, and regressively predicts a refractive index profile of the transparent glass preform serving as an objective variable from an explanatory variable including the image data.

In a device for producing a large-sized porous base material by a VAD process, the cracking and variation of the outer diameter of the base material are suppressed by forming a smooth tapered part, without changing the length of a non-effective part. In producing the porous base material by a VAD process, the time for a gas to reach a flow amount of the gas in a steady state from starting of the deposition is extended more in a burner that deposits glass microparticles on a layer closer to the outside of the base material.

According to a fabrication method for fabricating a porous glass base material for optical fiber, the orientation of a clad forming burner used to form the outermost layer of a clad-corresponding portion is changed further upward while glass fine particles are deposited during the period between a first timing and a second timing. At the first timing, the outer diameter of the porous glass base material for optical fiber has not reached a target outer diameter. The second timing is later than the first timing, and either a timing at which the outer diameter of the porous glass base material for optical fiber reaches the target outer diameter for the first time, or a timing prior to this timing.

Provided is a manufacturing method for a porous glass deposit, comprising by depositing glass fine particle onto a starting material being pulled up in a rotating manner within a reaction chamber using a plurality of burners by which glass fine particles are deposited at positions that are different from each other, supplying humidified clean air to the reaction chamber through an air inlet provided on a wall surface of the reaction chamber in a manufacturing process of the porous glass deposit.

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 0.80 L and equal to or less than L is deposited, wherein L represents a final outer diameter of a part of the optical fiber glass preform manufactured, the part being formed by the deposition of the glass particles, the deposition is performed under a first condition where an angle formed by a first line extending from a center O of a cross section of the base material to a rotational position r0 at which one round trip of the relative reciprocation starts and a second line extending from the center O to a rotational position r1 at which the one round trip of the relative reciprocation ends is an angle excluding 0, 120, 240, 72, 144, 216, and 288; or the deposition is performed under a second condition where the angle is 120 or 240, thereby to deposit the glass particles to a thickness corresponding to a thickness equal to or less than 0.03 L; or the deposition is performed under a third condition where the angle is 72, 144, 216, or 288, thereby to deposit the glass particles to a thickness corresponding to a thickness equal to or less than 0.02 L; or the deposition is performed under a fourth condition where the angle is 0, thereby to deposit the glass particles to a thickness corresponding to a thickness equal to or less than 0.01 L.

This invention provides a manufacturing method for an optical fiber. In this invention, when the core layer loose body and the cladding layer loose body are deposited, the oxyhydrogen flame is used make a temperature of an interface between the core layer and the cladding layer rise, such that silicon dioxide at the interface appropriately contracts to form an isolation layer with a relatively high density. In addition, in this invention, a hollow glass tube is used as a target rod, and the hollow glass tube which is the target rod is directly connected with the core layer loose body. During the subsequent dehydration, not only a dehydration atmosphere penetrates from the outside to the inside of the cladding layer loose body, but also the dehydration atmosphere directly enters the core layer through the hollow glass tube.

This invention provides a manufacturing method for an optical fiber. In this invention, when the core layer loose body and the cladding layer loose body are deposited, the oxyhydrogen flame is used make a temperature of an interface between the core layer and the cladding layer rise, such that silicon dioxide at the interface appropriately contracts to form an isolation layer with a relatively high density. In addition, in this invention, a hollow glass tube is used as a target rod, and the hollow glass tube which is the target rod is directly connected with the core layer loose body. During the subsequent dehydration, not only a dehydration atmosphere penetrates from the outside to the inside of the cladding layer loose body, but also the dehydration atmosphere directly enters the core layer through the hollow glass tube.

According to a fabrication method for fabricating a porous glass base material for optical fiber, the orientation of a clad forming burner used to form the outermost layer of a clad-corresponding portion is changed further upward while glass fine particles are deposited during the period between a first timing and a second timing. At the first timing, the outer diameter of the porous glass base material for optical fiber has not reached a target outer diameter. The second timing is later than the first timing, and either a timing at which the outer diameter of the porous glass base material for optical fiber reaches the target outer diameter for the first time, or a timing prior to this timing.

Provided is a manufacturing apparatus for manufacturing a soot deposition body, including a main burner that deposits glass microparticles on a target rod while moving parallel to a longitudinal direction of the target rod; and a side burner that is positioned outside of a movement range of the main burner in a movement direction of the main burner, and fires an end portion of the soot deposition body formed on the target rod. The side burner includes a plurality of heating burners arranged distanced from each other in a circumferential direction of the target rod. In the manufacturing apparatus described above, the main burner may include a plurality of deposition burners that are arranged distanced from each other in the circumferential direction of the target rod.

A system and process for making a thin, soot particle or glass sheet is provided. The system includes a soot deposition plate having a deposition surface and a glass soot generating device spaced from the deposition surface along a first axis. The glass soot generating device is configured to generate glass soot particles and to deliver the glass soot particles through an outlet and on to the deposition surface in a layer having a thickness of less than 5 mm. At least one of the soot deposition plate and the glass soot generating device is movable to cause relative movement between the deposition surface of the soot deposition plate and the glass soot generating device. A thin soot or sintered soot sheet is also provided. The soot sheet has a variable surface topography that varies along at least two axes.