Silica Glass Tube Doping Layout for Longer Optical Fiber Preforms
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Solution Overview
Problem
Existing methods for producing optical fiber preforms using the MCVD method face challenges in lengthening the glass rod due to deflection and distortion of the composite glass tube, making it difficult to produce long optical fibers.
Innovation Solution
An apparatus and method that utilize a first lathe grip part to grip the silica glass tube at a predetermined distance, a second lathe grip part, a first heating unit to heat the alkali compound to the melting point, a carrier gas introduction, and a second heating unit to move along the tube, allowing for efficient doping and suppression of deflection, enabling the production of longer glass rods for optical fiber preforms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the glass tube section is lengthened to produce longer optical fiber preforms, then the length of the optical fiber preform is improved, but deflection and distortion of the composite glass tube occur making production difficult
Solution Approach 1:
The apparatus divides the glass tube handling into two separate grip portions (first and second lathe grip parts) positioned at different locations along the tube. This segmentation allows each grip portion to independently support specific sections of the long glass tube, preventing deflection and distortion while enabling production of longer optical fiber preforms.
2Length of moving object
If the composite glass tube is made longer to increase glass rod length, then the length of the glass rod is improved, but the glass tube becomes more prone to deflection during rotation
Solution Approach 1:
The first and second lathe grip parts are positioned at specific locations along the glass tube to provide localized support where needed. This local quality approach ensures that critical sections of the long glass tube are stabilized during rotation, preventing deflection and maintaining structural integrity throughout the production process.
3Manufacturing precision
If alkali compound is disposed in the glass tube for doping, then the refractive index control is improved, but the glass tube structure becomes more complex
Solution Approach 1:
The alkali compound is disposed in the glass tube in advance before the doping process begins. This preliminary action allows the compound to be positioned and prepared within the tube structure, enabling precise refractive index control during subsequent heating and diffusion without requiring complex real-time adjustment mechanisms.
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 allows for the production of longer optical fiber preforms by suppressing deflection and distortion, facilitating the creation of longer optical fibers with reduced transmission loss.
Implementation Method 1
heating to a temperature equal to or higher than the melting point using a first oxyhydrogen burner, and the vaporized alkali compound is micronized
Implementation Method 2
the vaporized alkali compound is micronized by cooling with the carrier gas
Implementation Method 3
the alkali compound is heated at a temperature at which the alkali compound becomes an alkali oxide by thermal oxidation reaction
Implementation Method 4
the alkali oxide is deposited on the inner peripheral surface of the glass tube section
Implementation Method 5
the alkali oxide is deposited on the inner peripheral surface of the glass tube section and further allowed to diffuse into the silica glass constituting the glass tube section
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
An apparatus (30) for producing a glass rod for an optical fiber preform includes: a first lathe grip part (31) capable of gripping a silica glass tube (20) at a position partway therealong; a first heating part (33), on one side relative to the first lathe grip part (31), capable of heating the silica glass tube (20) such that an alkali compound (40) reaches the melting point or higher; a carrier gas introduction part (35) capable of introducing a carrier gas (CG) into a through hole (20H) of the silica glass tube (20) such that the alkali compound vaporized is allowed to flow through the through hole (20H); and a second heating part (34) capable of heating the silica glass tube (20) while moving along the lengthwise direction of the silica glass tube (20) on the other side of the silica glass tube (20) such that the alkali compound is heated and the silica glass tube (20) is doped with an alkali metal or an alkali earth metal.