Optical Fiber Preform Sealing for Extended Drawing Length
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Solution Overview
Problem
The existing methods for producing optical fiber preforms face challenges in securing a sufficient effective drawing region and reducing residual preform length, leading to limitations in the length of optical fibers that can be drawn, due to issues with dummy tube deformation and sealing during the heating process.
Innovation Solution
The method involves inserting glass rods into through-holes of a cladding glass body, integrating a dummy silica rod to seal one end, and sealing the other end by heating and deforming the cladding glass body, creating inner holes with both ends sealed to maintain vacuum pressure and prevent dummy tube deformation, allowing for continuous drawing of optical fibers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dummy tube is welded to the preform base end for vacuum suctioning, then vacuum pressure can be applied to draw the optical fiber, but the total length of the preform with attached dummy tube is restricted due to installation limits in the drawing device
Solution Approach 1:
The patent extracts the vacuum suctioning function from a separate dummy tube component and integrates it directly into the preform base end through a sealing structure. This eliminates the need for a separate welded dummy tube, reducing the total length while maintaining the vacuum suctioning capability for fiber drawing
Solution Approach 2:
The patent merges the dummy tube function with the preform base end by forming a sealing structure that integrates both components. The sealing structure at the base end directly provides the vacuum seal, combining what were previously separate elements into one unified structure, thereby reducing overall length
2Object-affected harmful factors
If a large distance is secured between the connector and the preform to prevent sealing components from being heated, then heat conduction is reduced, but it becomes difficult to secure sufficient effective drawing region length
Solution Approach 1:
The patent introduces a sealing structure that acts as an intermediary between the connector and the preform hot zone. This sealing structure is positioned to prevent direct heat conduction paths while still allowing the vacuum function to work, enabling the connector to remain cooler without requiring excessive distance from the preform
Solution Approach 2:
The sealing structure is formed in advance during preform fabrication, creating a pre-positioned thermal barrier. This preliminary action establishes heat protection before the drawing process begins, allowing optimal positioning of the connector relative to the preform without worrying about heat damage during operation
3Strength
If the dummy tube is welded to abut the outer peripheral portion of the preform base end, then connection is secure, but the dummy tube may be destroyed due to heat conducted from the preform before completing the drawing
Solution Approach 1:
The patent removes the separate dummy tube component that was susceptible to heat damage, and instead integrates the vacuum sealing function directly into the preform base end. This eliminates the heat-resistant requirements for a separate dummy tube while maintaining secure connection through the integrated sealing structure
Solution Approach 2:
The patent replaces the heat-vulnerable dummy tube with a sealing structure that is formed as part of the preform itself. This sealing structure is designed to withstand the thermal environment from the beginning, effectively making the system more robust by eliminating the weak dummy tube component that would otherwise be destroyed by heat
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces residual preform length and increases the effective drawing region, enabling longer optical fiber production while maintaining negative pressure within the preform, thus enhancing the drawing process efficiency and fiber length.
Implementation Method 1
sealing the other end by heating and deforming the cladding glass body
Implementation Method 2
heating and deforming the cladding glass body
Implementation Method 3
vacuum suctioning the inside of the preform
Implementation Method 4
vacuum suctioning the inside of the preform from one of the end
Data Source
AI summary
An optical fiber preform production method includes: inserting at least one glass rod into at least one through-hole that penetrates a cladding glass body that is a cladding of an optical fiber; integrating a dummy rod by either integrating a solid dummy silica rod with a first end of the cladding glass body by heating the first end to close a first opening of the through-hole that opens in the first end, or forming a base end seal that closes the first opening in the first end and integrating the solid dummy silica rod with the base end; and closing a second opening of the through-hole that opens in a second end of the cladding glass body by heating and deforming the second end.