SIST EN 3745-302:2004

• Abstract:

  This standard specifies a method of determining the effective numerical aperture of an optical cable or fibre used in aerospace applications.

• Status: Published
• Publication Date: 30-Apr-2004
• ICS: 49.060 - Aerospace electric equipment and systems
• Technical Committee: I08 - Imaginarni 08
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-May-2004
• Due Date: 01-May-2004
• Completion Date: 01-May-2004
• Ref Project: EN 3745-302:2002 - Aerospace series - Fibres and cables, optical, aircraft use - Test methods - Part 302: Numerical aperture

• Refers: SIST EN 2591-100:2024 - Aerospace series - Elements of electrical and optical connection - Test methods - Part 100: General
• Effective Date: 28-Jan-2026
• Refers: SIST EN 3745-100:2008 - Aerospace series - Fibres and cables, optical, aircraft use - Test methods - Part 100: General
• Effective Date: 28-Jan-2026
• Referred By: SIST EN 4641-200:2019 - Aerospace series - Cables, optical, 125 µm diameter cladding - Part 200: Semi-loose structure 9/125 µm GI fibre nominal 0,9 mm outside diameter - Product standard
• Effective Date: 28-Jan-2026
• Referred By: SIST EN 4641-102:2009 - Aerospace series - Cables, optical 125 μm outside diameter cladding - Part 102: Semi-loose 62,5/125 µm GI fibre nominal 1,8 mm outside diameter - Product standard
• Effective Date: 28-Jan-2026
• Referred By: SIST EN 4641-202:2019 - Aerospace series - Cables, optical, 125 µm diameter cladding - Part 202: Semi-loose, ruggedized simplex construction 9/125 µm SM fibre nominal 2,74 mm outside diameter - Product standard
• Effective Date: 28-Jan-2026
• Referred By: SIST EN 4641-401:2024 - Aerospace series - Cables, optical 125 μm diameter cladding - Part 401: Tight structure bend insensitive 50 µm/125 µm GI fibre nominal, 1,8 mm outside diameter - Product standard
• Effective Date: 28-Jan-2026
• Referred By: SIST EN 4641-301:2011 - Aerospace series - Cables, optical 125 μm diameter cladding - Part 301: Tight structure 50/125 µm GI fibre nominal 1,8 mm outside diameter - Product standard
• Effective Date: 28-Jan-2026
• Referred By: SIST EN 4641-100:2015 - erospace series - Cables, optical 125 μm diameter cladding - Part 100: Tight structure 62,5/125 µm core GI fibre 1,8 mm outside diameter - Product standard
• Effective Date: 28-Jan-2026
• Referred By: SIST EN 4641-201:2019 - Aerospace series - Cables, optical, 125 µm diameter cladding - Part 201: Semi-loose structure 9/125 µm SM fibre nominal 1,8 mm outside diameter - Product standard
• Effective Date: 28-Jan-2026
• Referred By: SIST EN 4641-301:2022 - Aerospace series - Cables, optical 125 μm diameter cladding - Part 301: Tight structure 50/125 μm GI, fibre nominal 1,8 mm, outside diameter - Product standard
• Effective Date: 28-Jan-2026
• Referred By: SIST EN 4641-301:2024 - Aerospace series - Cables, optical 125 μm diameter cladding - Part 301: Tight structure 50/125 μm GI, fibre nominal 1,8 mm, outside diameter - Product standard
• Effective Date: 28-Jan-2026
• Referred By: SIST EN 4641-101:2015 - Aerospace series - Cables, optical 125 μm diameter cladding - Part 101: Tight structure 62,5 μm core GI fibre 0,9 mm outside diameter - Product standard
• Effective Date: 28-Jan-2026
• Referred By: SIST EN 4641-102:2025 - Aerospace series - Cables, optical 125 μm outside diameter cladding - Part 102: Semi-loose 62,5/125 µm GI fibre nominal 1,8 mm outside diameter - Product standard
• Effective Date: 28-Jan-2026
• Referred By: SIST EN 4641-106:2019 - Aerospace series - Cables, optical, 125 µm diameter cladding - Part 106: Semi-loose structure 62,5/125 µm GI fibre nominal 0,9 mm outside diameter - Product standard
• Effective Date: 28-Jan-2026
• Revised: kSIST FprEN 3745-100:2026 - Aerospace series - Fibres and cables, optical, aircraft use - Test methods - Part 100: General
• Effective Date: 15-Oct-2025

SIST EN 3745-302:2004 is a SIST adoption of the European aerospace standard for optical fibres and cables used in aircraft applications. It specifies a test method for determining the effective numerical aperture of an optical cable or fibre, so laboratories, manufacturers and quality teams can measure how the fibre emits light in a controlled way.

What does SIST EN 3745-302:2004 specify?

SIST EN 3745-302:2004 covers one test method for determining the effective numerical aperture of an optical cable or fibre used in aerospace applications. The document is organized as a short test standard: scope, normative references, specimen preparation, apparatus, the measurement method, the final reading of numerical aperture, and special precautions.

• Clause 1 states the scope: the method is for optical cable or fibre in aerospace use.
• Clause 2 lists the normative references that support specimen preparation and test setup.
• Clause 3 covers how to prepare and condition specimens before measurement.
• Clause 4 describes the apparatus and gives two measurement arrangements.
• Clause 5 explains the two measurement methods, how to derive the result, and what to watch during testing.

What are the key requirements of SIST EN 3745-302:2004?

SIST EN 3745-302:2004 is built around controlled specimen preparation, defined launch conditions, and a radiation diagram from which numerical aperture is read. In practice, the standard asks the tester to control the fibre state, choose one of two apparatus arrangements, and keep the bend condition stable throughout the measurement.

Specimen preparation and conditioning

Clause 3.1 requires specimens to be prepared in accordance with EN 2591-100 unless the product standard says otherwise. If the specimen is not already at standard test conditions, it is brought to those conditions and stabilized for 24 h as defined in EN 3745-100. For a laboratory, this means the sample must be conditioned before any optical reading is taken.

Clause 3.2 says the technical specification shall state the cable or fibre type, the length when it differs from 2 m, and the acceptable bending radius during measurement. That matters because geometry affects the measured emission pattern.

Apparatus and test arrangement

Clause 4 requires a Light Launch System (LLS) as defined in EN 2591-100, a mechanical chopper H, and detection equipment suited to the selected method. Method A uses a fixed specimen with the detector on a rotating arm and a goniometer, while Method B uses a fixed specimen and a Charge Coupled Device (CCD) camera. This choice affects how the output light is collected and processed.

Launch conditions and measurement

Clause 5.1 sets the launch condition parameters before the test begins. The tester connects the specimen to the LLS and the chosen detector arrangement, then records the emitted light under the specified launch settings. This is what makes results comparable from one test to another.

Method A in Clause 5.2 measures radiant intensity as the detector angle changes. The result is an intensity-versus-angle diagram, which the user processes, averages and plots.

Method B in Clause 5.3 uses a CCD camera to analyse the output light pixel by pixel. The signal is corrected for the viewing angle, then stored and plotted as a radiation diagram. The method also calls for three curves for each determination so that an average value and a related standard deviation can be obtained.

Clause 5.4 states that the numerical aperture is taken from the radiation diagram at the point where intensity has dropped to 5% of the maximum. In practice, the reader uses the plotted diagram rather than a direct measurement on the fibre end face.

Clause 5.5 warns not to change the specimen bend radius during the different measurement steps. That is important because a changed bend can alter the light distribution and distort the result.

What terms does SIST EN 3745-302:2004 define?

• Effective numerical aperture - the optical output quantity the standard measures for an aircraft-use fibre or cable.
• Light Launch System (LLS) - the apparatus that injects light into the specimen under controlled launch conditions.
• Charge Coupled Device (CCD) camera - the fixed detector used in Method B to capture the output light image.
• Numerical aperture (NA) - the measured optical quantity derived from the emitted radiation diagram.
• NA nom - the nominal numerical aperture value used when setting the launch condition.
• Imax - the maximum intensity on the radiation diagram used as the reference level for reading the result.
• q - the detector angle relative to the normal to the source in the radiation pattern.
• fCR - a launch-condition parameter set before the measurement.

Who uses SIST EN 3745-302:2004?

SIST EN 3745-302:2004 is used by aerospace fibre and cable manufacturers, test laboratories, and quality teams that need a repeatable way to measure optical emission behaviour. It is also relevant to engineers writing product specifications or technical specifications for aircraft-use optical fibres and cables. Buyers and approvers use it to check that a proposed test method matches the aerospace product they are sourcing or qualifying.

Which standards are used with SIST EN 3745-302:2004?

• EN 2591-100 - provides the general test-method framework and defines the Light Launch System used in this test.
• EN 3745-100 - provides the general aerospace fibre-and-cable test conditions, including stabilization at standard test conditions.

What does the SIST EN 3745-302:2004 document contain?

SIST EN 3745-302:2004 contains two alternative measurement setups, shown as Method A and Method B, plus a final reading method based on a radiation diagram. Figures 1 and 2 show the apparatus layouts for the rotating-arm detector and the CCD camera arrangement, and Figure 3 shows how the numerical aperture is read from the intensity curve.

The body of the standard also gives specimen preparation rules, required apparatus, launch-condition settings, signal processing steps, and the caution about keeping the bend radius unchanged. In practice, the document is a test procedure for design verification, laboratory testing, and product qualification of optical fibres and cables for aerospace use.

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Aerospace series - Fibres and cables, optical, aircraft use - Test methods - Part 302: Numerical apertureLuft- und Raumfahrt - Faseroptische Leitungen für Luftfahrzeuge - Prüfverfahren - Teil 302: Numerische AperturSérie aérospatiale - Fibres et câbles optiques a usage aéronautique - Méthodes d'essais - Partie 302: Ouverture numériqueAerospace series - Fibres and cables, optical, aircraft use - Test methods - Part 302: Numerical aperture49.060Aerospace electric equipment and systemsICS:Ta slovenski standard je istoveten z:EN 3745-302:2002SIST EN 3745-302:2004en01-maj-2004SIST EN 3745-302:2004SLOVENSKI
STANDARD
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 3745-302June 2002ICS 49.060English versionAerospace series - Fibres and cables, optical, aircraft use - Testmethods - Part 302: Numerical apertureSérie aérospatiale - Fibres et câbles optiques à usageaéronautique - Méthodes d'essais - Partie 302: OuverturenumériqueLuft- und Raumfahrt - Faseroptische Leitungen fürLuftfahrzeuge - Prüfverfahren - Teil 302: NumerischeAperturThis European Standard was approved by CEN on 1 March 2002.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Management Centre or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2002 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 3745-302:2002 ESIST EN 3745-302:2004
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