IEC 61300-3-35:2009

IEC 61300-3-35
®

Edition 1.0 2009-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside


Fibre optic interconnecting devices and passive components – Basic test and
measurement procedures –
Part 3-35: Examinations and measurements – Fibre optic connector endface
visual and automated inspection

Dispositifs d’interconnexion et composants passifs à fibres optiques –
Méthodes fondamentales d’essais et de mesures –
Partie 3-35: Examens et mesures – Inspection automatique et visuelle de
l'extrémité des connecteurs à fibres optiques

IEC 61300-3-35:2009

---------------------- Page: 1 ----------------------
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IEC 61300-3-35
®

Edition 1.0 2009-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside


Fibre optic interconnecting devices and passive components – Basic test and
measurement procedures –
Part 3-35: Examinations and measurements – Fibre optic connector endface
visual and automated inspection

Dispositifs d’interconnexion et composants passifs à fibres optiques –
Méthodes fondamentales d’essais et de mesures –
Partie 3-35: Examens et mesures – Inspection automatique et visuelle de
l'extrémité des connecteurs à fibres optiques

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX S
ICS 33.180.20 ISBN 978-2-88912-749-8

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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– 2 – 61300-3-35  IEC:2009
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references. 5
3 Measurement . 5
3.1 General . 5
3.2 Measurement conditions . 6
3.3 Pre-conditioning . 6
3.4 Recovery . 6
4 Apparatus . 6
4.1 Method A: direct view optical microscopy . 6
4.2 Method B: video microscopy . 6
4.3 Method C: automated analysis microscopy . 7
4.4 Calibration requirements for low and high resolution systems . 7
5 Procedure . 8
5.1 Measurement regions . 8
5.2 Calibration procedure . 8
5.3 Inspection procedure . 9
5.4 Visual requirements . 10
Annex A (informative) Examples of inspected end-faces with defects . 12
Annex B (normative) Diagram of calibration artefact and method of manufacture . 18
Bibliography . 21

Figure 1 – Inspection procedure flow . 9

Table 1 – Measurement regions for single fibre connectors . 8
Table 2 – Measurement regions for multiple fibre rectangular ferruled connectors . 8
Table 3 – Visual requirements for PC polished connectors, single mode fibre, RL ≥ 45 dB . 10
Table 4 – Visual requirements for angle polished connectors (APC), single mode fibre . 10
Table 5 – Visual requirements for PC polished connectors, single mode fibre, RL ≥ 26 dB . 11
Table 6 – Visual requirements for PC polished connectors, multimode fibres . 11

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61300-3-35  IEC:2009 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

FIBRE OPTIC INTERCONNECTING
DEVICES AND PASSIVE COMPONENTS –
BASIC TEST AND MEASUREMENT PROCEDURES –

Part 3-35: Examinations and measurements –
Fibre optic connector endface visual and automated inspection


FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61300-3-35 has been prepared by subcommittee 86B: Fibre optic
interconnecting devices and passive components, of IEC technical committee 86: Fibre optics.
This standard replaces IEC/PAS 61300-3-35 which was published in 2002.
This bilingual version corresponds to the monolingual English version published in 2009-11.

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– 4 – 61300-3-35  IEC:2009
The text of this standard is based on the following documents:
FDIS Report on voting
86B/2909/FDIS 86B/2947/RVD

Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
The French version of this standard has not been voted upon.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of IEC 61300 series, published under the general title, Fibre optic
interconnecting devices and passive components – Basic test and measurement procedures
can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until the
maintenance result date indicated on the IEC web site under “http://webstore.iec.ch” in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
The contents of the corrigendum of June 2010 have been included in this copy.

IMPORTANT – The “colour inside” logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this publication using a colour printer.

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61300-3-35  IEC:2009 – 5 –
FIBRE OPTIC INTERCONNECTING
DEVICES AND PASSIVE COMPONENTS –
BASIC TEST AND MEASUREMENT PROCEDURES –

Part 3-35: Examinations and measurements –
Fibre optic connector endface visual and automated inspection



1 Scope
This part of IEC 61300 describes methods for quantitatively assessing the endface quality of a
polished fibre optic connector. The information is intended for use with other standards which
set requirements for allowable surface defects such as scratches, pits and debris which may
affect optical performance. In general, the methods described in this standard apply to 125 µm
cladding fibres contained within a ferrule and intended for use with sources of ≤2 W of input
power. However, portions are applicable to non-ferruled connectors and other fibre types.
Those portions are identified where appropriate.
2 Normative references
The following referenced documents are indispensable for the application of this document. For
dated references, only the edition cited applies. For undated references, the latest edition of
the referenced document (including any amendments) applies.
None.
3 Measurement
3.1 General
The objective of this standard is to prescribe methods for quantitatively inspecting fibre optic
endfaces to determine if they are suitable for use. Three methods are described: A: direct view
optical microscopy, B: video microscopy, C: automated analysis microscopy. Within each
method, there are hardware requirements and procedures for both low resolution and high
resolution systems. High resolution systems are to be utilized for critical examination of the
glass fibre after polishing and upon incoming quality assurance. High resolution systems are
typically not used during field polishing or in conjunction with multimode connectors. Low
resolution systems are to be utilized prior to mating connectors for any purpose. All methods
require a means for measuring and quantifying defects.
There are many types of defects. Commonly used terminology would include: particles, pits,
chips, scratches, embedded debris, loose debris, cracks, etc. For practical purposes, all
defects will be categorized in one of two groups. They are defined as follows:
scratches: permanent linear surface features;
defects: all non-linear features detectable on the fibre. This includes particulates, other debris,
pits, chips, edge chipping, etc.
All defects and scratches are surface anomalies. Sub-surface cracks and fractures are not
reliably detectable with a light microscope in all situations and are therefore not covered within
this standard. Cracks and fractures to the fibre may be detected with a light microscope and
are generally considered a catastrophic failure.

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– 6 – 61300-3-35  IEC:2009
Differentiating between a scratch and all other defects is generally intuitive to a human being.
However, to provide clarity, and for automated systems, scratches are defined as being less
than 4 µm wide, linear in nature, and with a length that is at least 30 times their width. As the
width dimension is not practical to visually measure below 3 µm, these figures can be grossly
estimated.
Defects size is defined for methods A and B as the diameter of the smallest circle that can
encompass the entire defect. Defect size for method C can be either the actual measured
surface area or the diameter of the smallest circle than can encompass the entire defect.
Some fibre types have structural features potentially visible on the fibre endface. Fibres that
use microstructures to contain the light signal, such as photonic band-gap and hole-assisted
fibres, can have an engineered or random pattern of structures surrounding the core. These
features are not defects.
For methods A and B below, it is recommended that visual gauge tools be developed to
facilitate the measurement procedure. For method A, an eyepiece reticule is recommended.
For method B, an overlay is recommended.
3.2 Measurement conditions
No restrictions are placed on the range of atmospheric conditions under which the test can be
conducted. It may be performed in controlled or uncontrolled environments
3.3 Pre-conditioning
No minimum pre-conditioning time is required.
3.4 Recovery
Since measurements are to be made at standard test conditions, no minimum recovery time is
required.
4 Apparatus
4.1 Method A: direct view optical microscopy
This method utilizes a light microscope in which a primary objective lens forms a first image
that is then magnified by an eyepiece that projects the image directly to the user’s eye. It shall
have the following features and capabilities:
• a suitable ferrule or connector adapter;
• a light source and focusing mechanism;
• a means to measure defects observed in the image.
4.2 Method B: video microscopy
This method utilizes a light microscope in which a lens system forms an image on a sensor that,
in turn, transfers the image to a display. The user views the image on the display. It shall have
the following features and capabilities:
• a suitable ferrule or connector adapter;
• a light source and focusing mechanism;
• a means to measure defects observed in the image.

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61300-3-35  IEC:2009 – 7 –
4.3 Method C: automated analysis microscopy
This method utilizes a light microscope in which a digital image is acquired or created and
subsequently analyzed via an algorithmic process. The purpose of such a system is to reduce
the effects of human subjectivity in the analysis process and, in some cases, to improve cycle
times. It shall have the following features and capabilities:
• a suitable ferrule or connector adapter;
• a means for acquiring or creating a digital image;
• algorithmic analysis of the digital image.
A means to compare the analyzed image to programmable acceptance criteria in such a
manner that a result of “pass” or “fail” is provided.
4.4 Calibration requirements for low and high resolution systems
4.4.1 General
Microscope systems for any of the methods above shall be calibrated for use in either low or
high resolution applications. It is suggested that this calibration be conducted with a purpose-
built calibration artefact that can serve to validate a system’s ability to detect defects of
relevant size. Such an artefact shall be provided with instructions on its use and shall be
manufactured in a method such that it can be measured in a traceable manner. Details on the
manufacture of such artefacts can be found in Annex B.
For reference, a system’s optical resolution may be calculated using the formula below. Optical
resolution is not equivalent to the system’s detection capability. In most cases, the system will
be able to detect defects smaller than its optical resolution.
Optical resolution = (0,61 × wavelength of illumination source) / system’s numerical aperture
4.4.2 Requirements for low resolution microscope systems
Minimum total magnification offering a field of view of at least 250 µm (for methods B and C,
this dimension is to be measured in the vertical, or most constrained, axis) capable of detecting
low-contrast defects of 2 µm in diameter or width.
4.4.3 Requirements for high resolution microscope systems
Minimum total magnification offering a field of view of at least 120 µm (for methods B and C,
this dimension shall be measured in the vertical, or most constrained, axis) capable of
detecting low contrast scratches of 0,2 µm in width and 0,003 µm in depth.

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– 8 – 61300-3-35  IEC:2009
5 Procedure
5.1 Measurement regions
For the purposes of setting requirements on endface quality, the polished endface of a
connector is divided into measurement regions defined as follows (see Table 1 and Table 2).
Table 1 – Measurement regions for single fibre connectors
Zone Diameter for single mode Diameter for multimode
A: core
0 µm to 25 µm 0 µm to 65 µm
B: cladding
25 µm to 120 µm 65 µm to 120 µm
C: adhesive 120 µm to 130 µm 120 µm to 130 µm
D: contact 130 µm to 250 µm 130 µm to 250 µm
NOTE 1 All data above assumes a 125 µm cladding diameter.
NOTE 2 Multimode core zone diameter is set at 65 µm to accommodate all
common core sizes in a practical manner.
NOTE 3 A defect is defined as existing entirely within the inner-most zone which
it touches.

Table 2 – Measurement regions for multiple fibre rectangular ferruled connectors
Zone Diameter for single mode Diameter for multimode
A: Core
0 µm to 25 µm 0 µm to 65 µm
B: Cladding
25 µm to 115 µm 65 µm to 115 µm
NOTE 1 All data above assumes a 125 µm cladding diameter.
NOTE 2 Multimode core zone diameter is set at 65 µm to accommodate all
common core sizes in a practical manner.
NOTE 3 A defect is defined as existing entirely within the inner-most zone which
it touches.
NOTE 4 Criteria should be applied to all fibres in the array for functionality of
any fibres in the array.

5.2 Calibration procedure
On commissioning, and periodically during its life, the microscope system shall be calibrated.
Fix the artefact(s) on the microscope system, focus the image.
Follow manufacturer’s instructions on how to calibrate the system using the artefact. Generally,
this should entail viewing the artefact and verifying that the small features and contrast targets
are “reliably detectable”; and that the region of interest can be fully viewed or scanned. Reliably
detectable is defined as sufficient clear and visible so that a typical technician of average
training would recognize the feature at least 98 % of the time.
For automated systems, software utilities to perform this calibration shall be provided. In any
event, those systems shall be able to perform the same calibration to validate that they can
reliably detect the features of the artefact.

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61300-3-35  IEC:2009 – 9 –
5.3 Inspection procedure
Focus the microscope so that a crisp image can be seen.
Locate all defects and scratches within the zones prescribed in the acceptance criteria. Count
and measure defects and count scratches within each zone. Scratches that are extremely wide
may be judged to be too large, per the acceptance criteria and result in immediate failure of the
DUT.
Once all defects and scratches have been quantified, the results should be totalled by zone
and compared to the appropriate acceptance criteria. Such criteria can be found in 5.4.
Any endface with quantified defects or scratches in excess of the values shown in any given
zone on the table are determined to have failed.
If the fibre fails inspection for defects, the user shall clean the fibre and repeat the inspection
process. In this way, loose debris can be removed and the fibre may be able to pass a
subsequent inspection without rework or scrap. Cleaning shall be repeated a number of times
consistent with the cleaning procedure being used.

Begin

Quantify
scratches and

defects


Meets

No
Acceptance

Criteria?

Fail for
No
Fail for
Scratches?
defects

Yes
Clean fibre
Yes

endface

Quantify
scratches and
defects


No Decrease Yes

defects?


DUT passes DUT fails

End

IEC  2214/09
Figure 1 – Inspection procedure flow

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– 10 – 61300-3-35  IEC:2009
5.4 Visual requirements
Visual requirements for each connector are shown in Table 3, Table 4, Table 5 and Table 6.
Table 3 – Visual requirements for PC polished connectors,
single mode fibre, RL ≥ 45 dB
Zone name Scratches Defects
A: core None None
No limit <2 µm
No limit ≤3 µm
B: cladding
5 from 2 µm to 5 µm
None >3 µm
None >5 µm
C: adhesive No limit No limit
D: contact No limit
None =>10 µm
NOTE 1 For scratches, the requirement refers to width.
NOTE 2 No visible subsurface cracks are allowed in the core or cladding
zones.
NOTE 3 All loose particles should be removed. If defect(s) are non-
removable, it should be within the criteria above to be acceptable for use.
NOTE 4 There are no requirements for the area outside the contact zone
since defects in this area have no influence on the performance. Cleaning
loose debris beyond this region is recommended good practice.
NOTE 5 Structural features that are part of the functional design of the
optical fibre, such as microstructures, are not considered defects.

Table 4 – Visual requirements for angle polished connectors (APC), single mode fibre
Zone name Scratches Defects
A: core None
≤4
No limit <2 µm
B: cladding No limit 5 from 2 µm to 5 µm
None >5 µm
C: adhesive No limit No limit
D: contact No limit
None ≥10 µm
NOTE 1 For scratches, the requirement refers to width.
NOTE 2 No visible subsurface cracks are allowed in the core or cladding
zones.
NOTE 3 All loose particles should be removed. If defect(s) are non-
removable, it should be within the criteria above to be acceptable for use.
NOTE 4 There are no requirements for the area outside the contact zone
since defects in this area have no influence on the performance. Cleaning
loose debris beyond this region is recommended good practice.
NOTE 5 Structural features that are part of the functional design of the
optical fibre, such as microstructures, are not considered defects.

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61300-3-35  IEC:2009 – 11 –
Table 5 – Visual requirements for PC polished connectors, single mode fibre, RL ≥ 26 dB
Zone name Scratches Defects
2 ≤ 3 µm 2 ≤ 3 µm
A: core
None >3 µm None >3 µm
No limit <2 µm
No limit ≤3 µm
B: cladding 5 from 2 µm to 5 µm
3 > 3 µm
None >5 µm
C: adhesive No limit No limit
D: contact No limit No ≥10 µm
NOTE 1 For scratches, the requirement refers to width.
NOTE 2 No visible subsurface cracks are allowed in the core or cladding
zones.
NOTE 3 All loose particles should be removed. If defect(s) are non-
removable, it should be within the criteria above to be acceptable for use.
NOTE 4 There are no requirements for the area outside the contact zone
since defects in this area have no influence on the performance. Cleaning
loose debris beyond this region is recommended good practice.
NOTE 5 Criteria should be applied to all fibre pairs in the array for
functionality of any fibre pairs in the array.
NOTE 6 Structural features that are part of the functional design of the
optical fibre, such as microstructures, are not considered defects.

Table 6 – Visual requirements for PC polished connectors, multimode fibres
Zone name Scratches Defects
No limit ≤ 3 µm
4 ≤ 5 µm
A: core
None > 5 µm
0 > 3 µm
No limit < 2 µm
No limit ≤ 5 µm
B: cladding
5 from 2 µm to 5 µm
0 > 5 µm
None > 5 µm
C: adhesive No limit No limit
D: contact No limit
None ≥ 10 µm
NOTE 1 For scratches, the requirement refers to width.
NOTE 2 No visible subsurface cracks are allowed in the core or cladding
zones.
NOT
...