prEN 3745

SLOVENSKI STANDARD
01-januar-2025
Aeronavtika - Optična vlakna in kabli za uporabo v zračnih plovilih - Preskusne
metode - 100. del: Splošno
Aerospace series - Fibres and cables, optical, aircraft use - Test methods - Part 100:
General
Luft- und Raumfahrt - Faseroptische Leitungen für Luftfahrzeuge - Prüfverfahren - Teil
100: Allgemeines
Série aérospatiale - Fibres et câbles optiques à usage aéronautique - Méthodes d’essais
- Partie 100 : Généralités
Ta slovenski standard je istoveten z: prEN 3745-100
ICS:
33.180.10 (Optična) vlakna in kabli Fibres and cables
49.060 Letalska in vesoljska Aerospace electric
električna oprema in sistemi equipment and systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
November 2024
ICS 49.060 Will supersede EN 3745-100:2008
English Version
Aerospace series - Fibres and cables, optical, aircraft use -
Test methods - Part 100: General
Série aérospatiale - Fibres et câbles optiques à usage Luft- und Raumfahrt - Faseroptische Leitungen für
aéronautique - Méthodes d'essais - Partie 100 : Luftfahrzeuge - Prüfverfahren - Teil 100: Allgemeines
Généralités
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee ASD-
STAN.
If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations
which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.

This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2024 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 3745-100:2024 E
worldwide for CEN national Members.

Contents Page
European foreword . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 6
4 Test conditions . 10
5 List of test methods . 10
6 Serie 2xx: General designation. 11
6.1 Test 201: Visual inspection of optical fibres and optical cables . 12
6.2 Test 202: Fibre dimensions . 13
6.3 Test 203: Cable dimensions . 23
6.4 Test 205: Cable longitudinal dimensional stability . 25
7 Serie 3xx: Optical tests . 26
7.1 Test 301: Attenuation . 26
7.2 Test 302: Numerical aperture . 27
7.3 Test 303: Bandwidth . 30
7.4 Test 305: Immunity to ambient light coupling . 30
7.5 Test 306: Variation of attenuation during temperature cycling . 33
8 Serie 4xx: Environmental tests . 34
8.1 Test 401: Accelerated ageing . 34
8.2 Test 402: Temperature cycling . 35
8.3 Test 404: Thermal shock . 36
8.4 Test 405: Low/High temperature bend test . 38
8.5 Test 406: Cold bend test . 40
8.6 Test 407: Flammability . 41
8.7 Test 410: Thermal life . 43
8.8 Test 411: Resistance to fluids . 49
8.9 Test 412: Humidity resistance . 56
9 Serie 5xx: Mechanical test . 57
9.1 Test 501: Optical fibre proof test . 58
9.2 Test 502: Tensile stength for short length of optical fibre . 58
9.3 Test 503: Scrape abrasion . 58
9.4 Test 504: Micro bending test . 60
9.5 Test 505: Cable tensile strength . 62
9.6 Test 506: Impact resistance . 64
9.7 Test 507: Cut-through. 68
9.8 Test 508: Torsion . 70
9.9 Test 509: Kink test . 72
9.10 Test 510: Bending test . 73
9.11 Test 511: Cable to cable abrasion . 77
9.12 Test 512: Flexure endurance . 79
9.13 Test 513: Crush resistance. 81
9.14 Test 514: Cable twist bend . 82
9.15 Test 515: Buffer insertion force . 84
9.16 Test 516: Severe cable bend test . 86
9.17 Test 517: Cable tie clamping test . 88
10 Serie 6xx: Sundry tests . 90
10.1 Test 601: Smoke density . 90
10.2 Test 602: Toxicity . 90
10.3 Test 603: Nuclear radiation . 91
11 Series 7xx and 8xx: Cable implementation tests . 93
11.1 Test 701: Strippability . 93
11.2 Test 703: Durability of manufacturer’s marking . 95
11.3 Test 705: Contrast measurement . 97
11.4 Test 801: Fibre movement under compression . 99
Bibliography . 103

European foreword
This document (prEN 3745-100:2024) has been prepared by ASD-STAN.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 3745-100:2008.
This document includes the following significant technical changes with respect to EN 3745-100:2008:
— integration of all the latest EN 3745 series documents, including their disposal of comments in the
— integration in the document of the revisions of current tests −306, −412, −510 et −801;
— integration of NWP proposal on tests −516 and −603.
1 Scope
This document defines terms, definition and all test methods for optical fibres and cable.
In this document test methods items have been kept according to the historical references.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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.
EN 2591-100:2024, Aerospace series - Elements of electrical and optical connection - Test methods - Part
100: General
EN 2591-601:2001, Aerospace series - Elements of electrical and optical connection - Test methods - Part
601: Optical elements - Insertion loss
EN 2591-602:2001, Aerospace series - Elements of electrical and optical connection - Test methods - Part
602: Optical elements - Variation of attenuation and optical discontinuity
EN 3475-601, Aerospace series - Cables, electrical, aircraft use - Test methods - Part 601: Smoke density
EN 3475-602, Aerospace series - Cables, electrical, aircraft use - Test methods - Part 602: Toxicity
EN 4056-003, Aerospace series - Cable ties for harnesses - Part 003: Plastic cable ties - Operating
temperatures - 65 °C to 105 °C and - 65 °C to 150 °C - Product standard
EN 4533-004, Aerospace series - Fibre optic systems - Handbook - Part 004: Repair, maintenance, cleaning
and inspection
EN IEC 60793-1-40:2019, Optical fibres - Part 1-40: Attenuation measurement methods (IEC 60793-1-40)
EN IEC 60793-1-41, Optical fibres - Part 1-41: Measurement methods and test procedures - Bandwidth
(IEC 60793-1-41)
EN IEC 60793-2, Optical fibres - Part 2: Product specifications – General (IEC 60793-2)
EN 60794 (all parts), Optical fibre cables
EN 61754-20, Fibre optic interconnecting devices and passive components - Fibre optic connector
interfaces - Part 20: Type LC connector family
IEC 61300-3-47, Fibre optic interconnecting devices and passive components — Basic test and
measurement procedures — Part 3-47: Examinations and measurements — End face geometry of PC/APC
spherically polished ferrules using interferometry
ISO 1817, Rubber, vulcanized or thermoplastic — Determination of the effect of liquids
ISO 4046, Paper, board, pulp and related terms — Vocabulary
ISO 7724-1, Paints and varnishes — Colorimetry — Part 1: Principles
AMS 1476C, Deodorant, Aircraft Toilet
ASTM-D740, Standard Specification for Methyl Ethyl Ketone
Error! Bookmark not defined.
Standard Test Methods for Hookup Wire Insulation
ASTM-D3032,
CIE 015, Colorimetry
MIL-PRF-87937, Performance specification: Cleaning compound, aerospace equipment
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at https://www.electropedia.org/
3.1
optical fibre
dielectric waveguide whose core consists of optically transparent material of low attenuation and
whose cladding consists of optical transparent material of lower refractive index than that of the core
(see Figure 1)
Note 1 to entry: In general the optical fibre is furnished with a primary coating (see Figure 1).
3.2
core
central region of an optical fibre through which most of the optical power is transmitted (see Figure 1)
3.3
cladding
dielectric material surrounding the core of the optical fibre (see Figure 1)
3.4
fibre coating
first protective coating directly applied to the fibre during its manufacture (see Figure 1)
Note 1 to entry: Its purpose is to maintain original optical performance of the fibre and to provide minimum
mechanical properties.
3.5
optical cable
assembly consisting of optical fibre, inner sheath and where applicable strength members and jacket
(see Figure 1)
3.6
multiple fibre cable
construction in which a number of fibres are placed together in a cable

Published by American Society for Testing and Materials (ASTM International), available at:
https://www.astm.org/.
Published by CIE Central Bureau - Kegelgasse 27 - A-1030 Wien - Austria.
Published by Department of Defense (DoD), available at: https://assist.dla.mil/online/start/.
3.7
buffer
material which surrounds and is immediately adjacent to a primary coating and provides mechanical
protection (see Figure 1)
3.8
strength members
protective envelope added to the inner sheath when necessary to improve the properties of mechanical
resistance (see Figure 1)
3.9
jacket
external protective covering (see Figure 1)
3.10
refractive index profile
distribution of the refractive index along the diameter of an optical fibre
Note 1 to entry: The refractive index profile for simple structures can be approximated by:
g
nr=n 12−<Δ(r/a)  forr a
( )
nr =  n= n 1−2∆ for r≥a
( )
2 1
22 2
with ∆ nn− /2n
( )
1 2 1
where
r is the radial distance from the centre of fibre;
n is the maximum refractive index value of the core material;
n is the refractive index value of the cladding material;
a is the core radius;
g is the profile parameter which defines the form of the profile:
10 ≤ g < ∝ ➜ step index profile
1 ≤ g < 3 ➜ graded index profile
3 ≤ g < 10 ➜ quasi step index profile.
3.11
core diameter
⌀ cr
diameter of the circle which best fits the core area
=
Note 1 to entry: For a cross section of an optical fibre, the core area is that within which the refractive index
everywhere (excluding any index dip) exceeds that of the innermost homogeneous cladding by a given fraction of
the difference between the maximum of the refractive index of the core (n ) and the refractive index of the
innermost homogeneous cladding (n ).
Note 2 to entry: It is contained within the focus of points where the refractive index n is given by:
n = n + k (n − n )
3 2 1 2
where
n = maximum refractive index value of core;
n = refractive index value of the innermost homogeneous cladding;
k = a constant (unless otherwise specified a k value of 0,05 is assumed).
3.12
cladding diameter
⌀ cd
physical diameter of the optical fibre
3.13
concentricity error core/cladding
distance between the centre point of the core and the centre point of the cladding divided by the core
diameter
3.14
non circularity of core
difference between the longest and the shortest chords passing through the core centre, divided by the
core diameter
3.15
non circularity of cladding
difference between the longest and the shortest chords passing through the cladding centre, divided by
the cladding diameter
3.16
attenuation
attenuation A at the wavelength lambda between two cross sections 1 (input) and 2 (output) separated
by the distance L of the fibre is defined by:
A = 10 log (P /P ) (dB)
10 1 2
P = optical power traversing the cross section 1
P = optical power traversing the cross section 2
Attenuation coefficient:
α (alpha) = A/L (dB/unit length)
Note 1 to entry: For practical use, generally, these parameters are given under modal equilibrium conditions (this
is not normally the case in avionic applications where lengths are short).
3.17
numerical aperture
NA
maximum theoretical numerical aperture defined by:
NA  nn−
where
n = maximum of the refractive index value of the core;
n = the refractive index value of the innermost homogeneous cladding
3.18
bandwidth
value numerically equal to the lowest frequency at which the magnitude of the baseband transfer
function of an optical fibre decreases to a specified fraction, generally to one half (3 dB), of the zero
frequency value
Key
1 cladding
2 buffer (if present)
3 jacket
4 core
} optical fibre
5 fibre coating
6 strength members (if present)
Figure 1 — Optical cable
3.19
contrast
ratio of reflecting light (here: reflecting light of cable identification marking and cable surface)
3.20
illuminance
reflection of visible light
3.21
measuring range
maximum effective range of measurement
=
4 Test conditions
Unless stated otherwise in the test methods, the technical specification or the product standard the test
conditions shall be:
— temperature: (20 ± 5) °C;
— atmospheric pressure: 86 KPa to 106 KPa;
— relative humidity: 45 % to 75 %.
The temperature and humidity shall remain constant during a series of measurement.
5 List of test methods
Table 1 — General designation
EN 3745 part Test designation
Subclause 6.1 Test 201: Visual examination
Subclause 6.2 Test 202: Fibre dimensions
Subclause 6.3 Test 203: Cable dimensions
Subclause 6.4 Test 205: Cable longitudinal dimensional stability
Table 2 — Optical tests
EN 3745 part Test designation
Subclause 7.1 Test 301: Attenuation
Subclause 7.2 Test 302: Numerical aperture
Subclause 7.3 Test 303: Bandwidth
Subclause 7.4 Test 305: Immunity to ambient light coupling
Subclause 7.5
Test 306: Variation of attenuation during
temperature cycling
Table 3 — Environmental tests
EN 3745 part Test designation
Subclause 8.1 Test 401: Accelerated ageing
Subclause 8.2 Test 402: Temperature cycling
Subclause 8.3 Test 404: Thermal shock
Subclause 8.4 Test 405: Low/High temperature bend test
Subclause 8.5 Test 406: Cold bend test
Subclause 8.6 Test 407: Flammability
Subclause 8.7 Test 410: Thermal life
Subclause 8.8 Test 411: Resistance to fluids
Subclause 8.9 Test 412: Humidity resistance
Table 4 — Mechanical tests
EN 3745 part Test designation
Subclause 9.1 Test 501: Optical fibre proof test
Subclause 9.2 Test 502: Tensile strength for short length of optical fibres
Subclause 9.3 Test 503: Scrape abrasion
Subclause 9.4 Test 504: Micro bending test
Subclause 9.5 Test 505: Cable tensile strength
Subclause 9.6 Test 506: Impact resistance
Subclause 9.7 Test 507: Cut-through
Subclause 9.8 Test 508: Torsion
Subclause 9.9 Test 509: Kink test
Subclause 9.10 Test 510: Bending test
Subclause 9.11 Test 511: Cable to cable abrasion
Subclause 9.12 Test 512: Flexure endurance
Subclause 9.13 Test 513: Crush resistance
Subclause 9.14 Test 514: Cable twist bend
Subclause 9.15 Test 515: Remove buffer
Subclause 9.16 Test 516: “Severe” cable bend test
Subclause 9.17 Test 517: Cable tie clamping test
Table 5 — Sundry tests
EN 3745 part Test designation
Subclause 10.1 Test 601: Smoke density
Subclause 10.2 Test 602: Toxicity
Subclause 10.3 Test 603: Nuclear radiation
Table 6 — Cable implementation tests
EN 3745 part Test designation
Subclause 11.1 Test 701: Strippability
Subclause 11.2 Test 703: Durability of manufacturer’s marking
Subclause 11.3 Test 705: Contrast measurement
Subclause 11.4 Test 801: Fibre movement under compression
6 Serie 2xx: General designation
6.1 General
Test series −20x corresponds to test methods allowing to measure general fibre and cable
characteristics.
6.2 Test 201: Visual inspection of optical fibres and optical cables
6.2.1 General
This clause a method for the visual inspection of optical fibres and optical cables.
6.2.2 Test 201: Characteristics to be examined
6.2.2.1 Test 201: General
The type and length of cable/fibre from which the specimen is taken shall be as specified in the product
specification.
6.2.2.2 Test 201: Optical fibre
6.1.1.2.1 The fibre shall have the correct identification colour coating if specified in the product
standard.
6.1.1.2.2 The coating shall be continuous and free of visible defects such as lumps, abrasions, cracks,
splits, or blisters.
6.2.2.3 Test 201: Optical cable
6.1.1.3.1 The cable shall have the correct identification colour if specified in the product standard.
6.1.1.3.2 The cable shall be marked in accordance with the product standard.
6.1.1.3.3 The cable shall be free from discoloration due to overheating or foreign materials such as
dust, grease, or oil.
6.1.1.3.4 The cable jacket (sheath) and/or coating shall not be scorched.
6.1.1.3.5 The cable jacket and/or coatings shall be free from delaminations and voids.
6.1.1.3.6 The cable shall be free from deformities in the jacket that increase, or decrease, the cable
diameter in excess of the specified maximum or minimum outside diameter.
6.1.1.3.7 The cable shall be free from metallic or gritty particles in the jacket and/or coating.
6.1.1.3.8 The cable shall show no cracking or crazing.
6.2.3 Test 201: Apparatus
A lamp which can provide an illumination of 500 lx to 700 lx on a flat workbench shall be used.
A 10x magnifying lens or microscope shall be used.
6.2.4 Test 201: Method A
Unless otherwise stated in the product standard, visual examination shall be made by the following
methods:
— by a 10x magnifying lens for the inspection of optical fibres;
— by a naked eye of normal vision, or normally corrected, for the inspection of optical cables.
The test specimen shall be placed flat on the workbench. The test specimen shall be visually examined
at a distance of not more than 0,3 m, if not using a magnifying device.
6.3 Test 202: Fibre dimensions
6.3.1 General
This clause specifies several methods for measuring the diameter of an optical fibre or cable, the non-
circularity and the concentricity of the fibre core/cladding on an optical fibre. If no method is
mentioned, method A applies.
6.3.2 Test 202: Preparation of specimens
6.3.2.1 The specimen shall comprise a length of the optical fibre or cable to be measured. The fibre
ends shall be prepared in accordance with EN 2591-100. The length of specimen shall be (3 ± 0,5) m
unless otherwise specified in the product standard.
lf not yet at standard test conditions, the specimens shall be subjected to standard test conditions and
stabilized at these conditions for 24 h as defined in Clause 4 (Test conditions).
6.3.2.2 The following detail shall be specified if not already included in the product standard:
— type of fibre/cable from which the specimen was taken.
6.3.3 Test 202: Apparatus
For method B, the Light Launch System used shall be as specified in EN 2591-100 with an angular
size > 110 % of the fibre numerical aperture and a spot size > 110 % of fibre core diameter.
6.3.4 Test 202: Method
6.3.4.1 Test 202: Method A: Refracted near field
6.3.4.1.1 Test 202 Method A: Object
— The refracted near-field measurement is straightforward, accurate and measures directly the
refractive index variation the fibre (core and cladding). The measurement is capable of good
resolution and can be calibrated to give absolute values of refractive indexes. It can be used to
obtain profiles of both single-mode and multimode fibre.
6.3.4.1.2 Test 202 Method A: Test apparatus
6.3.4.1.2.1 General
A schematic diagram of the test apparatus is shown in Figure 2 and Figure 3.
6.3.4.1.2.2 Test 202 Method A: Source
— A stable laser giving a few milliwatts of power in the TEM00 mode is required.
— A HeNe laser, which has a wavelength of 633 nm, may be used, but a correction factor shall be
applied to the results for extrapolation at different wavelengths. It shall be noted that measurement
at 633 nm shall not give complete information at longer wavelengths; in particular non-uniform
fibre doping can affect the correction.
— A quarter-wave plate is introduced to change the beam from linear to circular polarization because
the reflectivity of light at an air-glass interface is strongly angle and polarization dependent.
— A pinhole placed at the focus of lens 1 acts as a spatial filter.
6.3.4.1.2.3 Test 202 Method A: Launch optics
The launch optics, which are arranged to overfill the NA of the fibre, brings a beam of light to a focus on
the flat end of the fibre. The optical axis of the beam of light should be within 1° of the axis of the fibre.
The resolution of the equipment is determined by the size of the focused spot, which should be as small
as possible in order to maximize the resolution, for example less than 1,5 µm. The equipment enables to
focused spot to be scanned across the fibre diameter.
6.3.4.1.2.4 Test 202 Method A: Liquid cell
The liquid in the liquid cell shall have a refractive index slightly higher than that of the fibre cladding.
6.3.4.1.2.5 Test 202 Method A: Sensing
The refracted light is collected and brought to the detector in any convenient manner provided that all
the refracted light is collected. By calculation, the required size of disc and its position along the central
axis can be determined.
6.3.4.1.3 Test 202: Sample preparation
A length of fibre of about 1 m is required.
All fibre coating shall be removed from the clause of fibre immersed in the liquid cell.
The fibre ends shall be clean, smooth and perpendicular to the fibre axis.
6.3.4.1.4 Test 202 Method A: Procedure
6.3.4.1.4.1 General
Refer to the schematic diagram of the test apparatus (Figure 3).
6.3.4.1.4.2 Test 202 Method A: Fibre index profile plot
The launch end of the fibre to be measured is immersed in a liquid cell hose refractive index is slightly
higher than that of the fibre cladding. The fibre is back illuminated by light from a tungsten lamp.
Lenses 2 and 3 produce a focused image of the fibre.
The position of lens 3 is adjusted to centre and focus the fibre image, and the laser beam is
simultaneously centred and focused on the fibre.
The disc is centred on the output cone. For multimode fibre, the disc is positioned on the optical axis to
just block the leaky mode. For single-mode fibre, the disc is positioned to give optimum resolution.
Refracted modes passing the disc are collected and focused onto a photodiode. The focused laser spot is
traversed across the fibre end and a plot of fibre refractive index variation is directly obtained.
6.3.4.1.4.3 Test 202 Method A: Equipment calibration
The equipment is calibrated with the fibre removed from the liquid cell. During the measurement the
angle of the cone of light varies according to the refractive index seen at the entry point to the fibre
(hence the change of power passing the disc). With the fibre removed and the liquid index and cell
thickness known, this change in angle can be simulated by translating the disc along the optic axis. By
moving the disc to a number of predetermined positions the profile can be scaled is terms of relative
and n , can only be found in the cladding index or the liquid index, at the
index. Absolute indices, i.e. n
1 2
measurement wavelength and temperature is known accurately.
6.3.4.1.4.4 Test 202 Method A: Results
The following details shall be presented:
— test arrangement and wavelength correction procedure;
— relative humidity and ambient temperature;
— fibre identification. Depending on specification requirement:
— profile through core and cladding centres calibrated for a given wavelength;
— profile along the core major and minor axes calibrated for a given wavelength;
— profiles along the cladding major and minor axes calibrated for a given wavelength.
By the raster scan of the cross-section of the profile, the following quantities may be calculated:
— diameter of core;
— diameter of cladding;
— concentricity error core/cladding;
— non-circularity of core;
— non-circularity of cladding;
— maximum theoretical numerical aperture;
— index difference;
— relative index difference;
— indication of accuracy and reproducibility.
6.3.4.2 Test 202: Method B: Near field light distribution
6.3.4.2.1 Test 202: Method B: Object
The following test is for incoming and/or outgoing inspection. Imaging is made on a cross section at the
end of the fibre under test.
The image is magnified by an output optics, for example microscope and various kinds of sensors can be
used (direct examination, photographic camera, digital video analyser, scanning detector, etc.).
6.3.4.2.2 Test 202: Method B: Sample preparation
The sample shall be a short length of the optical fibre to be measured. This length shall be noted. The
fibre ends shall be clean, smooth and perpendicular to the fibre axis.
6.3.4.2.3 Test 202: Method B: Apparatus
6.3.4.2.3.1 Test 202: Method B: Light source
The core illumination source shall be incoherent, adjustable in intensity and the type shall be noted. A
second light source can be used to illuminate the fibre for cladding measurement purposes. The light
source selected shall be stable for the required period of measurement.
6.3.4.2.3.2 Test 202: Method B: Detection systems
Different detection systems can be used depending on the type of measurement to be done (visual
inspection, photography, calculation on the complete pattern).
6.3.4.2.3.3 Test 202: Method B: Microscope
An inverted metallurgical microscope or a biological microscope with a resolution near the diffraction
limit shall be used (for example it should have a calibrated magnification of up to 600x and be equipped
with the filar micrometre).
6.3.4.2.3.4 Test 202: Method B: Microscope with a photographic camera
The microscope described in 6.2.4.2.3.3 (Test 202: Method B: Microscope) may be equipped with a
camera for micro photography. A suitable scale shall be used to calibrate the dimensions in the
photograph.
6.3.4.2.3.5 Test 202: Method B: Video analyser
The microscope described in 6.2.4.2.3.3 (Test 202: Method B: Microscope) may be equipped with a TV
camera. The output signal of the camera can be sent to a TV monitor for visual inspection or to a video
analyser in order to record the complete output near of the fibre.
6.3.4.2.3.6 Test 202: Method B: Scanning detector
The TV camera described in 6.2.4.2.3.5 (Test 202: Method B: Video analyser) can be replaced by a
pinhole photodetector, to make one or several scans of the fibre output near field. The signal of the
detector is sent to a XY recorder.
6.3.4.2.4 Test 202: Method B: Procedure
6.3.4.2.4.1 General
a) The end of the sample from which the image will be produced shall be prepared and so set as to
make the end face perpendicular to the axis of the sample.
b) The numerical aperture and hence the resolving power of the objective lens shall be compatible
with the measuring accuracy required. The magnification shall be selected to be compatible with the
fibre size and the field of view.
c) The light source shall be attached to the other end of the sample, which may be prepared in the
same way as the first end, and adjusted so that the fibre end image will be substantially free of any
missing or unclear part. If necessary, index matching fluid shall be used couple the optical power
between source and sample.
6.3.4.2.4.2 Test 202: Method B: Microscope technique with visual inspection
a) The microscope shall be calibrated by measuring the length of an object of already known
dimensions.
b) The parameters of the sample to be measured may be determined by means of the filar micrometre
and the known calibration. The minimum and maximum diameter shall be measured by rotating the
image or the scale.
6.3.4.2.4.3 Test 202: Method B: Microscope technique with photography
a) The intensity of the front and back illumination, the shutter speed, f” stop and a film shall be
selected to obtain a clear photograph, for example clearly showing the boundary between core and
cladding.
b) The overall image magnification shall be determined by photographing a scale of known calibration
such as a stage micrometre.
c) The size of the photographic image shall be more than 30 mm xx30 mm the parameter to be
measured shall be determined from the size of the image and the magnification.
d) When using a scale as described in 6.2.4.2.3.4 (Test 202: Method B: Microscope with a photographic
camera), a transparent scale be placed upon the photographs and judged.
6.3.4.2.4.4 Test 202: Method B: Microscope technique with a video analyser
a) The output filed of the microscope is processed with a digital video analyser controlled by a
computer, such as a scanning vidicon, charge coupled device (CCD) or other pattern intensity
recognition device.
b) The complete image is monitored and the line being processed is indicated, for example by a cursor.
c) The boundaries are found by contrast level and referenced to a standard grating to give the
geometrical parameters to be measured.
6.3.4.2.4.5 Test 202: Method B: Microscope technique with a pinhole scanning detector
a) Focus a magnified image of the sample core onto a plane.
b) Determine the intensity of the magnified near filed patterns. As examples, any of the following
techniques may be used:
1) scanning detector with pinhole;
2) scanning mirror with fixed pinhole aperture detector.
c) Record the intensity as a function of detector position.
d) Use a phase-locked amplifier system (or equivalent apparatus) to amplify the low level signal.
e) Scan fibre core image or pinhole detector by mean of a stepping motor translation stage or a
scanning mirror.
f) Record intensity (signal) a signal a function of position of the core diameter.
g) The microscope shall be calibrated by measuring the length of an object of already known
dimensions.
6.3.4.2.5 Test 202: Method B: Documentation
The following data shall be presented:
— fibre identification;
— number of samples;
— relative humidity and ambient temperature;
— description of apparatus;
— magnification;
— parameters measured;
— photographic images or video analyser print out if applicable.
6.3.4.3 Test 202: Method C: Four concentric circles
6.3.4.3.1 Test 202: Method C: Object
The following is compliance test for optical fibre dimensional parameters and tolerance. It is not valid
for measuring the actual value of core and cladding diameter, non-circularity and concentricity errors.
This method gives evidence of compliance with the set of dimensional specification value. It should be
used as an incoming and/or outgoing inspection.
The four concentric circles form two rings with the diameters:
D + ΔD
CL CL
for the cladding
D + ΔD
CL CL
D + ΔD
CO CO
for the cladding
D + ΔD
CO CO
Which define the tolerance field.
A fibre will pass this test if a position of fibre and tolerance can be found where both the cladding
contour and the core contour lie completely inside the two rings. Values for D and ΔD , D and
CL CL CO
ΔD , should be taken from the detail specification.
CO
6.3.4.3.2 Test 202: Method C: Sample preparation/selection
The sample should be a short length of the optical fibre to be measured. This length should be noted.
6.3.4.3.3 Test 202: Method C: Apparatus
6.3.4.3.3.1 Test 202: Method C: Light source
The core illumination source shall be incoherent, adjustable in intensity and the type shall be noted. A
second light source can be used to illuminate the fibre for cladding measurement purposes. The light
source selected shall be stable for the required period of measurement.
6.3.4.3.3.2 Test 202: Method C: Microscope
An inverted metallurgical microscope or a biological microscope with a resolution near the diffraction
limit shall be used (for example it should have a calibrated magnification of up to 600x and be equipped
with the filar micrometre).
6.3.4.3.3.3 Test 202: Method C: Microscope with a photographic camera
The microscope described in 6.2.4.2.3.3 (Test 202: Method B: Microscope) may be equipped with a
camera for micro photography. A suitable scale shall be used to calibrate the dimensions in the
photograph.
6.3.4.3.3.4 Test 202: Method C: Video analyser
The microscope described in 6.2.4.2.3.3 (Test 202: Method B: Microscope) may be equipped with a TV
camera. The output signal of the camera can be sent to a TV monitor for visual inspection or to a video
analyser in order to record the complete output near of the fibre. The comparison between the given
four circles and core and cladding limits may be done by computation, visual or printed display.
6.3.4.3.3.5 Test 202: Method C: Scanning detector
The TV camera described in 6.2.4.2.3.4 (Test 202: Method B: Microscope with a photographic camera)
can be replaced by a pinhole photodetector, to make one or several scans of the fibre output near field.
The signal of the detector is sent to a XY recorder.
6.3.4.3.3.6 Test 202: Method C: Mask
A mask with four concentric circles should be provided and inserted in the optical measuring system.
The accuracy of the mark shall be such that the accuracy given in the detail specification can be
obtained on the sample.
One of the following methods can be applied:
— a mask in the ocular of the microscope;
— a transparent mark upon the photograph;
— two separate objectives in the microscope for mark and sample respectively.
NOTE For a video analyser hardware mark is not required.
6.3.4.3.4 Test 202: Method C: Procedure
The prepared sample is fixed in the sample holder and illuminated by the light source in such a way that
the core and cladding contours are as clear as possible. By manipulating the sample, the contours of
core and cladding are brought inside the two rings. If this possible the fibre has passed the test. If so
desired a photograph is taken to indicate the test results (passed/not passed).
6.3.4.3.5 Test 202: Method C: Documentation
The following data shall be presented:
— fibre identification;
— number of samples;
— relative humidity and ambient temperature;
— (photography);
— description of apparatus type of microscope and mask;
— test result: passed/not passed.
6.3.4.4 Test 202: Method D: Mechanical diameter measurement
6.3.4.4.1 Test 202: Method D: Object
The following method applies to the mechanical measurement of the cladding diameter of an optical
glass or silica fibre. In practice for smooth and substantially circular fibres, it gives a similar result to
that obtained by methods A and B, in which case non-circularity of fibre can also be determined. This
method can also be used for the measurement of the coating diameter of some types of coated or
buffered fibres. In this method both sides of the object are contacted with flat parallel surface, and the
separation of the surfaces is accurately measured.
6.3.4.4.2 Test 202: Method D: Scope
The diameter of a fibre and coated fibre are fundamental values and shall be known for subsequent
procedures such as handling, spicing, connectorization, cabling and measurements.
6.3.4.4.3 Test 202: Method D: Test apparatus
6.3.4.4.3.1 Test 202: Method D: General
The measurement used
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