Deposition Tube Diameters Vary From Run To Run

by: FOC FAQ

Fiber Process Development and Manufacturing - Ask FOC Ask FOC

Published: November 22, 2017

, Last updated: September 18, 2025

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QUESTION: Our deposition tube diameter varies from run to run. Do you have information on how to control that?

ANSWER:

When you deposit barrier and core layers, your goal is consistent thickness every time. However, as you’re well aware, the burner flame pressure causes deposition tube shrinkage. Without diameter control, this shrinkage reduces the inside surface area. With constant vapor flows, the deposited layer thickness will decrease.

If the deposition tube diameter varies from run to run, or within a run, layer thickness will not reproduce. It’s absolutely critical to carefully control the diameter of the tube. When it comes to depositions, consistency is key.

We cover more in our blog, Critical Design Goals to Manufacture Optical Fiber Preforms: https://focenter.hwwserver.com/critical-design-goals-to-manufacture-optical-fiber-preforms/

Answered by AskFOC Technical Team: November 22, 2017

ADDITIONAL CONTENT & RESOURCES:

Category Resource: FOC Fiber Design and Manufacturing
Find More Information in this Blog: MCVD Tips: 14 ideas to enhance preform strength, yield, and reproducibility

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