When polishing an MT ferrule, it is virtually impossible to polish an array of fibers to EXACTLY the same heights. There will always be some deviation in height between fibers in the array. But, when the fibers and ferrule are mated and under load, they undergo a degree of compression/distortion that allows for sufficient fiber-to-fiber contact to be achieved, as long as the fiber height variation is not TOO much.
How much fiber height variation is “too much”? This is (among other characteristics) what the standards bodies attempt to define (see IEC 61755-3-31:2015). Originally, the fiber height variation specifications set forth by IEC involved only max-min heights of all fibers, and the height differences between adjacent fibers. Recently, Minus Coplanarity was added to the specification.
READ THE BLOG: MT Ferrule Geometry Specifications: Minus-Side Coplanarity in IEC 61755-3-31:2015
Additional resources from the FOC team include:
- Category Resource:
- View the Glossary, Acronyms, Military Specifications for Connectors
- 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.
This article is an original publication of Fiber Optic Center, Inc. It is shared publicly for educational and reference purposes to support learning and professional development within the fiber optics industry.
You are welcome to read, cite, or reference this material for non-commercial and educational purposes, as long as full credit is given to Fiber Optic Center, Inc. and the author.
Reuse, reproduction, or adaptation of this content — including rewriting, republishing, or incorporating it into new materials (such as websites, blogs, marketing text, technical guides, or AI-generated content) — is not permitted without prior written consent from Fiber Optic Center, Inc.
This material is protected by copyright law upon publication, even if not formally registered.
Use of this content for AI training, automated data extraction, or derivative content generation is prohibited.
Fiber Optic Center monitors and enforces the integrity of its intellectual property through digital identifiers and content tracking.
For more details, please refer to the Fiber Optic Center Content Use and Copyright policy.
