Method and deposition burner for manufacturing optical fibre preforms
AssigneePrysmian Cavi E Sistemi Energia S.R.L.
InventorsGiacomo Stefano Roba, Massimo Nutini
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Abstract
Method and burner for increasing the deposition rate of porous glass deposit in the manufacture of optical preforms, by modifying the cross-sectional shape of the flow of glass particles impacting onto a target preform. In particular, the cross-section of the flow of glass particles is modified by increasing the dimension of the flow from a circular cross-section to one having a major and minor axis in a direction substantially perpendicular to the longitudinal axis of the target preform.
Claims16
Method for increasing the deposition rate of a process for manufacturing an optical preform, which comprises the steps of:
- generating a flow of forming glass particles;
- directing said flow of particles towards a growing preform and causing said flow of particles to impact onto said preform;
- wherein said method further comprises the steps of:
- conferring to said flow of gas particles a cross-sectional shape having a major axis and a minor axis;
- causing said flow of particles to be directed towards said growing preform with the major axis of the cross-sectional shape having a direction substantially perpendicular to the longitudinal axis of said preform.
Method for producing an optical preform which comprises:
- feeding a flow of glass precursor material into a deposition burner and conferring to said flow a substantially circular cross-section;
- feeding a flow of combustible gas and a flow of combustion sustaining gas into said burner, in order to create a flame for uniformly heating said flow of glass precursor material and causing said glass precursor material to react, thereby forming a flow of fine glass particles;
- directing said flow of fine glass particles and said flame towards a target preform having an initial diameter;
- causing said flow of glass particles to impact onto said target preform, thus increasing the radial dimensions of said preform up to a final diameter;
- wherein the cross-section of at least the terminal portion of said flow impacting onto the target preform is modified into a cross-sectional shape having a major axis and a minor axis, said major axis being substantially orthogonal to the longitudinal axis of the target preform.
Deposition burner for manufacturing an optical preform, which comprises:
- a plurality of ducts through which at least a flow of a glass precursor material, of a combustible gas and of a combustion sustaining gas are passed, said flows of combustible gas and of combustion sustaining gas for generating a flame which surrounds said flow of glass precursor material;
- wherein an elongated hollow element is disposed to surround and confine said flame and said flow of glass precursor material, said elongated hollow element:
- having an initial portion adjacent to said plurality of ducts and an a terminal portion opposed to said initial portion;
- being formed into a substantially circular cross-section in at least said initial portion;
- and
- being formed into a cross-section having a major and a minor axis in its terminal portion.
13 Burner according to claim 11 wherein said elongated hollow element is formed into a substantially elliptical cross-section in its terminal portion.
Dependencies are inferred from the claim text.