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 FIBER OPTIC INSPECTION
UNDERSTANDING FIBER OPTIC INSPECTION
Advancing the Standards to Best Practices Number 2 in a Series
Written by: Edward J. Forrest, Jr. © 2022 All Rights Reserved
Abstract: Within only about twenty years, the sciences of fiber optic inspection have evolved from a jeweler’s loupe, through handheld direct-view, to benchtop, portable, auto-detect, and recent patents for a digital photographic device. One inspection means is not better than the other: each has value, advantages, and disadvantages.
EARLY PIONEERS:
Jeweler’s loupes were the first means and are less common in these times. Still used, are ‘tube scopes’ and both ‘direct view instruments have inherent eye-safety issues. Along with others, Steve Lytle (Westover Scientific) and Glen Porter (MicroEnterprises) pioneered fiber optic video inspection. Lytle and Porter made important contribution to ‘see’ the surface by innovating benchtop ‘video inspection’. Innovations from Noyes Fiber Optic Systems’ co-founders John Noyes and Mike Schneider and lead to portable systems. EXFO developed inspection systems that would modularly integrate into an OTDR. Westover® became Viavi® and Schneider founded ODM/Ripley®.
A good jeweler’s loupe has a magnification between 5x and 60x and demands a steady hand to observe the connector. Handheld magnification evolved, early ‘tube’ scopes were 100x/200x: the design stabilized the connector. Early ‘bench top’ video scopes offered large screens. From this began “magnification wars”: 100x to 200x and 400x.
THE CONUNDRUM WAS “FIELD OF VIEW”: the greater the magnification the less of the “end face” will be seen. Porter and Lytle addressed this by innovating ‘scrollers’ which enabled views of the ‘total horizontal end face’ by physically moving the end face in a ‘east/west and north/south’ perspective past the camera. Standards limited the surface as described to the right.
The ‘mother standard’, IEC 61300-3-
5, characterized the horizontal end face
UNDERSTANDING CONNECTORS IN THREE-DIMENSIONS
Existing fiber optic microscopy (except for digital photography) views the area superimposed on Image-2. With advanced understanding, this becomes the ‘primary surface’ and the remainder of the horizontal surface as well as vertical surfaces, alignment sleeves, adapters and intersurfaces
are secondary surfaces. Both are critical to all future-proof best- practice deployment procedures.
THE NEW CHARACTERIZATION: ‘Primary surfaces’ are Zones- 1-2-3; ‘secondary surfaces’ are re-designated as Zone- 4 and Zone-5. Debris may be present in any connector sector. While cleaning the “primary surface” is essential, awareness of debris in other sectors of the connector assures surfaces (such as an alignment sleeve) are not the problem leading to replacement or time-consuming multiple cleaning.
WHICH INSPECTION DEVICE IS BEST
There are four classifications of fiber optic inspection: 1.) direct view, 2.) portable/ benchtop video scopes, 3.) autodetect portable/benchtop video scopes, and 4.) digital photographic inspection. One is not ‘better’; each has a place in the FTTx, training, production-line toolbox.
There are two general types of 1.) DIRECT-VIEW MICROSCOPES. Both are never suitable to view an
active laser: in so doing there may be eye damage. The ‘jeweler’s loupe’ to the left is cumbersome to view fiber optic surfaces and best suited for adapters and alignment sleeves. The handheld device will have adapters for SC and LC. It’s best suited for QC of ‘dead’ jumpers. To be safe, ignore claims of ‘eye safety filters’ is my personal insight! The bodies on all of these look the same; differentializing is not easy!
2.) Some of the most cost-effective and practical instruments are the PORTABLE VIDEO SCOPES. Available in various configurations and price points, magnification
ranges from 100-200-400x. Always remember,
the higher the magnification the less of the
surface you will see. For this reason, explore
‘resolution’ and seek those with highest values.
                             3
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nto ‘zones’ (Fig-1). These consider a small
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egment of the two-dimensional ‘flatland’.
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 I
gnored are: vertical surfaces, alignment
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leeves, and the total horizontal end face. All
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  unseen connector sectors can lead to cross-
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  ontamination, misalignment, insertion loss, and reflectance.
The ‘IEC end face’ is characterized into four Zones: “A”, “B’, “C”, and “D”. This characterization encompasses about 250- 400 microns of the two-dimensional ‘horizontal end face’. Not included are vertical ferrule surfaces, alignment sleeves or “intersurfaces” © the spaces between fibers.
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