Parallel Slit Torch for Uniform Optical Fiber Preform Deposition
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Solution Overview
Problem
Existing torches used in optical fiber manufacturing, such as those with multiple orifices, face challenges in achieving uniform soot deposition during the outside vapor deposition (OVD) and vapor axial deposition (VAD) processes, leading to non-uniformities and difficulties in controlling the soot growth surface, especially in VAD due to its tapering diameter.
Innovation Solution
A torch with an array of slit-shaped orifices oriented parallel to each other, coupled with manifolds for gas distribution, is used to emit different gases in a controlled manner, ensuring uniform soot deposition by adjusting the gas flow and orifice configuration to match the preform substrate's geometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a linear torch with multiple orifices is used in OVD, then soot deposition coverage is improved, but uniformity of soot deposition deteriorates due to thicker deposition near the torch and thinner deposition farther away
Solution Approach 1:
The torch is divided into multiple independent orifices (e.g., central orifice and concentric orifices) that can emit gases separately. This segmentation allows different regions of the torch to deposit soot on different areas of the seed rod, improving overall coverage while maintaining control over deposition uniformity through individual orifice adjustment.
Solution Approach 2:
Different orifices are configured with different properties (central orifice vs. concentric orifices) to address different deposition needs. The central orifice targets the center region while concentric orifices target outer regions, with each orifice optimized for its specific deposition zone to achieve uniform overall deposition.
2Productivity
If the traverse speed is increased, then productivity is improved, but uniformity of soot deposition deteriorates due to helical bubbles or non-uniformities on the surface
Solution Approach 1:
Multiple orifices distributed along the torch length allow simultaneous deposition across different seed rod regions. This parallel deposition approach maintains uniformity even at higher traverse speeds by preventing the formation of helical bubbles that occur with single-point deposition.
Solution Approach 2:
Multiple orifices emit gases continuously along the torch length, ensuring continuous soot deposition across the entire seed rod surface. This continuous action prevents gaps or non-uniformities that would occur with intermittent or single-point deposition, maintaining uniformity at higher traverse speeds.
3Manufacturing precision
If the traverse speed is decreased, then uniformity of soot deposition is improved, but productivity deteriorates due to undesirably thick and non-uniform soot buildup
Solution Approach 1:
The torch is segmented into multiple orifices that deposit soot simultaneously on different seed rod regions. This parallel deposition increases the overall soot deposition rate (productivity) while maintaining uniformity, as each orifice contributes to the overall uniform coating rather than creating localized thick buildup.
Solution Approach 2:
Different orifices are optimized for different deposition rates and patterns. By coordinating the gas flow and deposition characteristics of each orifice, the system achieves both high productivity and uniform deposition, preventing the thick non-uniform buildup that occurs with slow single-point deposition.
4Device complexity
If a linear torch is used in VAD, then simplicity of device is improved, but uniformity of soot deposition deteriorates due to the tapering diameter of the soot growth surface
Solution Approach 1:
The linear torch is segmented into multiple orifices positioned at different locations along its length. This segmentation allows each orifice to target specific regions of the tapering seed rod surface, compensating for the diameter variation and achieving uniform soot deposition while maintaining the simplicity of the linear torch structure.
Solution Approach 2:
Different orifices are configured with different properties (position, size, gas flow) to match the local characteristics of the tapering seed rod surface. This local optimization allows uniform deposition across the varying diameter while keeping the overall torch structure simple and linear.
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
The solution enables uniform soot deposition along the length of the preform substrate, improving the precision and consistency of the optical fiber preform fabrication process, particularly addressing the challenges faced in VAD's tapering diameter scenarios.
Implementation Method 1
gases such as silicon tetrachloride, oxygen, and hydrogen, are reacted in a torch flame, and the resulting particles, known as soot, are deposited on the seed rod
Implementation Method 2
gases such as silicon tetrachloride, oxygen, and hydrogen, are reacted in a torch flame
Data Source
AI summary
A torch for fabricating optical fiber preforms may include a body having a surface and two or more slit-shaped orifices oriented parallel or substantially parallel to each other along the surface. The torch body may further include two or more conduits connected to corresponding orifices. The torch may be used by orienting it relative to a preform substrate, and simultaneously emitting two or more gases from corresponding orifices toward the surface of the preform substrate, such that the gases are involved in a reaction to form a soot.