Industry Update – Visual Inspection Standard

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A recent update to IEC 61300-3-35 (Fiber optic connector endface visual and automated inspection) is moving forward with the intention to modernize inspection practices and provide more uniform results industrywide.

The updates aim to accomplish three things:

  1. Link visual inspection results to optical performance
  2. Make results more uniform between manual (visual) and automated (software) platforms
  3. Make results more uniform between different automated platforms

The first goal aims to create more common-sense pass and fail criteria for visual inspection by tying the results to whether the defects impede function or if they are simply cosmetic. For example, scratches near the core that affect insertion loss should be deemed as failing while scratches far from the core that have no noticeable effect on performance may not need to fail visual inspection.

image of Fiber with scratches near the core
Fiber with scratches near the core
Fiber with scratches far from core

The other changes address the other two goals which can be neatly summed up by saying that they aim to make visual inspection tests more repeatable regardless of who performs them, when in the process it is performed, and what tools are used. This is achieved in two ways:

  1. The update to the standard intends to provide clear guidance on what should be considered a pass or a fail and establish a reliable agreement between visual inspection tests done at the time of production and tests performed in the field prior to installation.
  2. The update will try to provide clear guidance to inspection scope manufacturers regarding camera resolution and image analysis processes. This is aimed at increasing the accuracy and repeatability of this analysis across different models of inspection scopes and different automated analysis software applications.

There is still some work to be done regarding how to harmonize automatic inspection and analysis with manual “analog” analysis performed with an inspection scope that requires human interpretation.

These updates to the IEC’s visual inspection standard (61300-3-35) should provide functional improvements to the inspection processes by making the results agree across numerous platforms and reducing the amount of testing required to what is functionally necessary.

See Application Note AN-137 Preventing Damage to Optical Connectors and learn tips and tricks for preventing damage and maintaining the performance quality and longevity of optical connectors.


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OptoTest engineers and manufactures highly reliable fiber optic test equipment, including custom systems. We are a worldwide leader producing the fastest and most accurate Return Loss and Insertion Loss equipment for cable assembly production, R&D, Mil/Aero and Harsh Environments testing.
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