ASD-STAN PREN 4533-001-2016 Aerospace series Fibre optic systems Handbook Part 001 Termination methods and tools (Edition P 2).pdf

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1、ASD-STAN STANDARD NORME ASD-STAN ASD-STAN NORM prEN 4533-001 Edition P 2 April 2016 PUBLISHED BY THE AEROSPACE AND DEFENCE INDUSTRIES ASSOCIATION OF EUROPE - STANDARDIZATION Rue Montoyer 10 - 1000 Brussels - Tel. 32 2 775 8126 - Fax. 32 2 775 8131 - www.asd-stan.org ICS: Supersedes edition P 1 of Ap

2、ril 2005 and will supersede EN 4533-001:2006 Descriptors: ENGLISH VERSION Aerospace series Fibre optic systems Handbook Part 001: Termination methods and tools Srie arospatiale Systmes des fibres optiques Manuel dutilisation Partie 001 : Mthodes des terminaisons et des outils Luft- und Raumfahrt Fas

3、eroptische Systemtechnik Handbuch Teil 001: Verarbeitungsmethoden und Werkzeuge This “Aerospace Series“ Prestandard has been drawn up under the responsibility of ASD-STAN (The AeroSpace and Defence Industries Association of Europe - Standardization). It is published for the needs of the European Aer

4、ospace Industry. It has been technically approved by the experts of the concerned Domain following member comments. Subsequent to the publication of this Prestandard, the technical content shall not be changed to an extent that interchangeability is affected, physically or functionally, without re-i

5、dentification of the standard. After examination and review by users and formal agreement of ASD-STAN, it will be submitted as a draft European Standard (prEN) to CEN (European Committee for Standardization) for formal vote and transformation to full European Standard (EN). The CEN national members

6、have then to implement the EN at national level by giving the EN the status of a national standard and by withdrawing any national standards conflicting with the EN. Edition approved for publication 1st April 2016 Comments should be sent within six months after the date of publication to ASD-STAN El

7、ectrical Domain Copyright 2016 by ASD-STAN prEN 4533-001:2016 (E) 2 Contents Page Foreword 4 Introduction .5 a) The Handbook 5 b) Background 5 1 Scope 6 1.1 General 6 1.2 Need to high integrity terminations .7 2 Normative references 7 3 Component Selection 7 3.1 Elements .7 3.2 Fibre optic cables 7

8、3.2.1 General 7 3.2.2 Cable construction 8 3.2.3 Fibre choice 9 3.2.4 Cladding materials 11 3.3 Primary buffer materials 11 3.3.1 Function . 11 3.3.2 Acrylate 12 3.3.3 Polyimide . 12 3.3.4 Silicone 12 3.3.5 Strength Members 12 3.4 Outer jacket . 13 3.5 Fibre optic interconnects (connectors) 13 3.5.1

9、 Introduction . 13 3.5.2 The Optical interface 13 3.5.3 Single-way Interconnects/Connectors . 20 3.5.4 Multi-way Interconnects/Connectors 20 3.5.5 Choice of tooling. 22 4 Health and safety aspects 22 4.1 General . 22 4.2 Chemicals 23 4.3 Sharps 23 5 Termination process 24 5.1 Objective 24 5.2 Cable

10、preparation . 24 5.2.1 General . 24 prEN 4533-001:2016 (E) 3 5.2.2 Cutting to length 24 5.2.3 Removal of outer jacket 25 5.2.4 Cable Handling tools (gripping the cable) 30 5.2.5 Strength member trimming/ removal 31 5.3 Removal of secondary coating(s) 32 5.4 Removal of primary coatings . 33 5.4.1 Gen

11、eral . 33 5.4.2 Mechanical techniques for primary coating removal 34 5.4.3 Alternative techniques 39 5.4.4 Troublesome coatings Polyimide and Silicone . 40 5.4.5 Evidence of strength reduction when stripping primary buffer coatings . 42 5.4.6 To clean or not to clean 43 5.5 Adhesives . 43 5.5.1 Gene

12、ral . 43 5.5.2 Adhesive types 44 5.5.3 The importance of glass transition temperature (Tg) 45 5.5.4 Epoxy cure schedule . 47 5.5.5 Usability 49 5.5.6 Qualification . 52 5.6 Connector preparation 53 5.6.1 Dry fitting (Dont do it!) . 53 5.7 Attachment of fibre to the terminus 54 5.7.1 Application of a

13、dhesive 54 5.7.2 Inserting Fibre Best-Practice 58 5.8 Adhesive cure 61 5.8.1 General . 61 5.8.2 Orientation 61 5.8.3 Curing equipment 62 5.9 Excess Fibre removal 65 5.9.1 General . 65 5.9.2 Post-cure rough cleaving . 65 5.9.3 Pre cleave . 67 5.9.4 Safety 67 5.9.5 Cleaving tools 67 5.9.6 Sprung blade

14、 hand tools 68 5.9.7 Cleaving fibres in Multi-fibre Ferrules . 68 5.10 Polishing . 68 5.10.1 Rationale . 68 5.10.2 Performance metrics . 68 5.10.3 End face geometries . 69 prEN 4533-001:2016 (E) 4 5.10.4 End-face geometry parameters . 70 5.10.5 Polishing stages . 79 5.10.6 Methods for controlling en

15、d-face geometry 91 6 Beginning of life Inspection . 97 6.1 Optical or Visual Inspection 97 6.2 Interferometric Inspection . 99 6.2.1 Inspection and Pass/Fail Criteria 100 Bibliography . 103 Foreword This standard was reviewed by the Domain Technical Coordinator of ASD-STANs Electrical Domain. After

16、inquiries and votes carried out in accordance with the rules of ASD-STAN defined in ASD-STANs General Process Manual, this standard has received approval for Publication. prEN 4533-001:2016 (E) 5 Introduction a) The Handbook The purpose of EN 4533 is to provide information on the use of fibre optic

17、components on aerospace platforms. The documents also include best practice methods for the through-life support of the installations. Where appropriate more detailed sources of information are referenced throughout the text. The handbook is arranged into 4 parts, which reflect key aspects of an opt

18、ical harness life cycle, namely: Part 001: Termination methods and tools. Part 002: Test and measurement. Part 003: Looming and installation practices Part 004: Repair, maintenance, cleaning and inspection. b) Background It is widely accepted in the aerospace industry that photonic technology offers

19、 significant advantages over conventional electrical hardware. These include massive signal bandwidth capacity, electrical safety, and immunity of passive fibre-optic components to the problems associated with electromagnetic interference (EMI). Significant weight savings can also be realized in com

20、parison to electrical harnesses which may require heavy screening. To date, the EMI issue has been the critical driver for airborne fibre-optic communications systems because of the growing use of non-metallic aero structures. However, future avionics requirements are driving bandwidth specification

21、s from 10s of Mbits/s into the multi-Gbits/s regime in some cases, i.e. beyond the limits of electrical interconnect technology. The properties of photonic technology can potentially be exploited to advantage in many avionic applications, such as video/sensor multiplexing, flight control signalling,

22、 electronic warfare, and entertainment systems, as well as in sensing many of the physical phenomena on-board aircraft. The basic optical interconnect fabric or optical harness is the key enabler for the successful introduction of optical technology onto commercial and military aircraft. Compared to

23、 the mature telecommunications applications, an aircraft fibre-optic system needs to operate in a hostile environment (e.g. temperature extremes, humidity, vibrations, and contamination) and accommodate additional physical restrictions imposed by the airframe (e.g. harness attachments, tight bend ra

24、dii requirements, and bulkhead connections). Until recently, optical harnessing technology and associated practices were insufficiently developed to be applied without large safety margins. In addition, the international standards did not adequately cover many aspects of the life cycle. The lack of

25、accepted standards thus leads to airframe specific hardware and support. These factors collectively carried a significant cost penalty (procurement and through-life costs) that often made an optical harness less competitive than an electrical equivalent. This situation is changing with the adoption

26、of more standardized (telecoms type) fibre types in aerospace cables and the availability of more ruggedized COTS components. These improved developments have been possible due to significant research collaboration between component and equipment manufacturers as well as the end users air framers. p

27、rEN 4533-001:2016 (E) 6 1 Scope 1.1 General Part 001 of EN 4533 examines the termination of optical fibre cables used in aerospace applications. Termination is the act of installing an optical terminus onto the end of a buffered fibre or fibre optic cable. It encompasses several sequential procedure

28、s or practices. Although termini will have specific termination procedures, many share common elements and these are discussed in this document. Termination is required to form an optical link between any two network or system components or to join fibre optic links together. The fibre optic terminu

29、s features a precision ferrule with a tight tolerance central bore hole to accommodate the optical fibre (suitably bonded in place and highly polished). Accurate alignment with another (mating) terminus will be provided within the interconnect (or connector) alignment mechanism. As well as single fi

30、bre ferrules, it is noted that multi-fibre ferrules exist (e.g. the MT ferrule) and these will also be discussed in this part of the handbook. Another technology used to connect 2 fibres is the expanded beam. 2 ball lenses are used to expand, collimate and then refocus the light from and to fibres.

31、Contacts are not mated together. It helps reducing the wear between 2 contacts and allows more mating cycles. This technology is less sensitive to misalignments and dust. Losses are remaining more stable than butt joint contact even if the nominal is higher. A Note on Terminology Current terminology

32、 in the aerospace fibre optics community refers to an optical terminus or termini. The term optical contact may be seen in some documents and has a similar meaning. However, the term contact is now generally reserved for electrical interconnection pins. The optical terminus (or termini) is housed wi

33、thin an interconnect (connector is an equivalent term). Interconnects can be single-way or multi-way. The interconnect or connector will generally house the alignment mechanism for the optical termini (usually a precision split-C sleeve made of ceramic or metal). The reader should be aware of these

34、different terms. An optical link can be classified as a length of fibre optic cable terminated at both ends with fibre optic termini. The optical link provides the transmission line between any two components via the optical termini which are typically housed within an interconnecting device (typica

35、lly a connector) with tight tolerancing within the alignment mechanisms to ensure a low loss light transmission. Part 001 will explain the need for high integrity terminations, provide an insight into component selection issues and suggests best practice when terminating fibres into termini for high

36、 integrity applications. A detailed review of the termination process can be found in section 4 of this part and is organised in line with the sequence of a typical termination procedure. The vast number of cable constructions and connectors available make defining a single termination instruction t

37、hat is applicable to all combinations very difficult. Therefore, this handbook concentrates on the common features of most termination practices and defining best practice for current to near future applications of fibre optics on aircraft. This has limited the studies within this part to currently

38、available avionic silica fibre cables and adhesive filled butt-coupled type connectors. Many of the principles described however would still be applicable for other termination techniques. Other types of termination are considered further in the repair part of this handbook. It is noted that the adh

39、esive based pot-and-polish process is applicable to the majority of single-way fibre optic interconnects connectors and termini for multi-way interconnects and connectors. They share this commonality. prEN 4533-001:2016 (E) 7 1.2 Need to high integrity terminations In order to implement a fibre opti

40、c based system on an aircraft it is vital to ensure that all the constituent elements of the system will continue to operate, to specification, over the life of the system. An important aspect of this requirement is the need for reliable interconnection components. Interconnects are a key component

41、in any fibre optic system or network. Digital communications links, sensor systems, entertainment systems etc. all require interconnects both at equipment interfaces and for linking cables and harness sections together over the airframe. Interconnects need to be robust to mating and demating operati

42、ons, environmental changes and also the effects of contamination. They need to be amenable to inspection and cleaning for through life support. The choice of technology used in optical links and connections is mainly dependant of the environment. In service performance is a pillar in the component s

43、election. Cable to connector interface needs to be assessed to prove the effectiveness of the solution. High integrity terminations are required to ensure reliable, low loss light transmission through the interconnection. High integrity terminations are produced by observing best practice and using

44、the correct materials, tools and procedures with appropriate controls. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated referen

45、ces, the latest edition of the referenced document (including any amendments) applies. All interconnection technologies are taken in account in the context of the EN 4533-001 EN 4533-002, Aerospace series Fibre optic systems Handbook Test and measurement EN 4533-003, Aerospace series Fibre optic sys

46、tems Handbook Looming and installation practices EN 4533-004, Aerospace series Fibre optic systems Handbook Repair, maintenance, cleaning and inspection 3 Component Selection 3.1 Elements It is important to recognise that a fibre optic termination, while appearing straightforward, is in fact a compl

47、ex interaction of the constituent elements such as: fibre, ferrule, fibre coatings, connector design, cable strength member anchorage method, adhesive type and cure regime (where used), material properties and so on. Each of these elements will have an impact on the termination, in terms of reliabil

48、ity, integrity and process complexity. The following sections discuss the key elements to the termination. 3.2 Fibre optic cables 3.2.1 General There are many types of fibre optic cable on the market today. Cables are essentially assemblies that contain and protect the optical light guide (used to c

49、arry the system light signal). The central light guide is usually made from silica glass although other materials can be used. Glass is inherently strong although it must be protected from external damage and other factors that could cause weakening (generally moisture and fluid contamination in the presence of any defects and stress). The cable provides the protective layers to the glass and generally also incorporates a strength member (this element is important in the te