Optical Fiber Preform Dummy Rod Sealing for Extended Drawing Length
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Solution Overview
Problem
The existing methods for producing optical fiber preforms, particularly those using a dummy tube for vacuum suctioning, face challenges such as limited effective drawing region and risk of dummy tube destruction due to heat, leading to residual preform length issues.
Innovation Solution
The method involves inserting glass rods into a cladding glass body with through-holes, sealing both ends of the holes using a dummy silica rod and tip sealing, allowing for vacuum suctioning and heat resistance, thereby reducing residual preform length and increasing the effective drawing region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dummy tube is used for vacuum suctioning during optical fiber drawing, then vacuum pressure can be applied to the preform, but the dummy tube may be destroyed due to heat conducted from the preform
Solution Approach 1:
A heat-resistant tube made of heat-resistant glass is introduced as an intermediary component between the preform and the dummy tube. This heat-resistant tube is positioned closer to the preform and can withstand the heat conducted from the preform, while the dummy tube remains at a safer distance. The heat-resistant tube acts as a mediator that protects the dummy tube from thermal damage while still allowing vacuum pressure to be transmitted to the preform for optical fiber drawing.
2Temperature
If a large distance is secured between the connector and the preform to prevent sealing components from being heated, then heat resistance is improved, but the effective drawing region length is reduced
Solution Approach 1:
The system is segmented into distinct functional zones: a heat-resistant tube zone positioned close to the preform that can withstand heat, and a connector zone positioned at a distance that avoids heat exposure. The heat-resistant tube serves as an intermediate segment that allows the connector to be positioned away from the heat source while still maintaining vacuum connection to the preform, thereby preserving both heat resistance and effective drawing region length.
3Length of moving object
If the total length of the preform with attached dummy tube is increased to provide sufficient drawing region, then drawing length is improved, but the preform cannot be installed in the drawing device due to length limitations
Solution Approach 1:
The heat-resistant tube acts as an intermediary component that extends the functional drawing region without proportionally increasing the total preform length. By positioning the heat-resistant tube close to the preform and using it to transmit vacuum pressure, the system achieves a longer effective drawing region while keeping the overall assembly compact enough for installation in the drawing device.
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 enables a longer effective drawing region and reduced residual preform length, allowing for increased optical fiber drawing length while maintaining heat resistance and avoiding dummy tube deformation.
Implementation Method 1
integrating a solid dummy silica rod with a first end portion (first end) of the cladding glass body by heating the first end portion of the cladding glass body
Implementation Method 2
closing a second opening portion (second opening) of the through-hole, which opens in a second end portion (second end) of the cladding glass body, by heating and deforming the second end portion of the cladding glass body
Data Source
AI summary
An optical fiber preform includes: a cladding glass body that is a cladding of an optical fiber, is cylindrical, and comprises an inner hole along an axial direction; a glass rod accommodated in the inner hole; and a dummy silica rod selected from either one of a first solid dummy silica rod fixed to a first end of the cladding glass body that closes a first end of the inner hole positioned at the first end of the cladding glass body, or a second solid dummy silica rod accommodated and integrated in a connecting glass tube fixed to the first end to close a first tip opening end of the connecting glass tube. A tip seal that closes a second end of the inner hole at a second end of the cladding glass body is provided in the second end of the cladding glass body.