The tube-cleaning process is a critical part of preparation. I find that using the first cleaning step to remove metallic impurities works well. If you were to HF etch first, you may etch the glass around the metallic impurity, but not necessarily remove it. If you only HF etch, some metallic impurities may remain. Here is my approach to the tube-cleaning process:
- For the first step, aqua regia can be used (an acid mix of hydrochloric acid nitric acid, and water). A typical acid cleaning cycle is 30-60 minutes with aqua regia to remove metallic impurities, followed by a DI water rinse. You may want to adjust the time depending on your process.
- The next step is to etch the glass surfaces, cleaning the inside and outside. Most MCVD operators use hydrofluoric acid. A 15% concentration for 30-60 minutes is a good starting point. You may want to adjust the time and concentration for your process.
- Follow that etch cycle with a final DI rinse and dry with nitrogen to prevent water spotting.
Additional resources from the FOC team include:
- Category Resource FOC Fiber Design and Manufacturing Page
- Glossary, Acronyms, Military Specifications for Connectors: http://bit.ly/2a2EFn8
- Q&A Resource: email technical questions to AskFOC@focenter.com
Have questions about this FOC Tip?
Contact FOC with questions at: (800) 473-4237 / 508-992-6464 or email: FiberOpticCenter@focenter.com and we will respond ASAP.
Additional articles from our preform fabrication consultant include:
- MCVD Tips: 14 ideas to enhance preform strength, yield, and reproducibility
- MCVD Options: These add-on features can enhance your optical fiber preform strength, yield, and reproducibility
- Controlling the optical fiber preform deposition process
- Preparing to Manufacture an Optical Fiber Preform
- Critical Design Goals to Manufacture Optical Fiber Preforms
- Comparing the 2 types of MCVD gas delivery systems to manufacture optical preforms: Stainless steel and Teflon/glass
- Attention specialty fiber manufacturers: Take advantage of FOC’s preform fabrication consulting to troubleshoot your system and achieve reproducibility and high yields
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