1、BRITISH STANDARD AEROSPACE SERIES BS EN 3745-302:2002 Fibres and cables, optical, aircraft use Test methods Part 302: Numerical aperture The European Standard EN 3745-302:2002 has the status of a British Standard ICS 49.060 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBS EN
2、3745-302:2002 This British Standard, having been prepared under the direction of the Engineering Sector Policy and Strategy Committee, was published under the authority of the Standards Policy and Strategy Committee on 25 June 2002 BSI 25 June 2002 ISBN 0 580 39904 4 National foreword This British S
3、tandard is the official English language version of EN 3745-302:2002. The UK participation in its preparation was entrusted by Technical Committee ACE/6, Aerospace avionic electrical and fibre optic technology, to Subcommittee ACE/6/10, Aerospace fibre optic systems and equipment, which has the resp
4、onsibility to: A list of organizations represented on this subcommittee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the sectio
5、n entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. C
6、ompliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor rel
7、ated international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 5, and a back cover. The BSI copyright date displayed in this document indicates when the document was last issued.
8、 Amendments issued since publication Amd. No. Date CommentsEUROPEANSTANDARD NORMEEUROPENNE EUROPISCHENORM EN3745302 June2002 ICS49.060 Englishversion AerospaceseriesFibresandcables,optical,aircraftuseTest methodsPart302:Numericalaperture SriearospatialeFibresetcblesoptiquesusage aronautiqueMthodesde
9、ssaisPartie302:Ouverture numrique LuftundRaumfahrtFaseroptischeLeitungenfr LuftfahrzeugePrfverfahrenTeil302:Numerische Apertur ThisEuropeanStandardwasapprovedbyCENon1March2002. CENmembersareboundtocomplywiththeCEN/CENELECInternalRegulationswhichstipulatetheconditionsforgivingthisEurope an Standardth
10、estatusofanationalstandardwithoutanyalteration.Uptodatelistsandbibliographicalreferencesconcernings uchnational standardsmaybeobtainedonapplicationtotheManagementCentreortoanyCENmember. ThisEuropeanStandardexistsinthreeofficialversions(English,French,German).Aversioninanyotherlanguagemadebytra nslat
11、ion undertheresponsibilityofaCENmemberintoitsownlanguageandnotifiedtotheManagementCentrehasthesamestatusasthe official versions. CENmembersarethenationalstandardsbodiesofAustria,Belgium,CzechRepublic,Denmark,Finland,France,Germany,Greece, Iceland,Ireland,Italy,Luxembourg,Malta,Netherlands,Norway,Por
12、tugal,Spain,Sweden,SwitzerlandandUnitedKingdom. EUROPEANCOMMITTEEFORSTANDARDIZATION COMITEUROPENDENORMALISATION EUROPISCHESKOMITEEFRNORMUNG ManagementCentre:ruedeStassart,36B1050Brussels 2002CEN Allrightsofexploitationinanyformandbyanymeansreserved worldwideforCENnationalMembers. Ref.No.EN3745302:20
13、02EEN3745302:2002(E) 2 Foreword Thisdocument(EN3745302:2002)hasbeenpreparedbytheEuropeanAssociationofAerospace Manufacturers(AECMA). AfterenquiriesandvotescarriedoutinaccordancewiththerulesofthisAssociation,thisStandardhas receivedtheapprovaloftheNationalAssociationsandtheOfficialServicesofthemember
14、countriesof AECMA,priortoitspresentationtoCEN. ThisEuropeanStandardshallbegiventhestatusofanationalstandard,eitherbypublicationofanidentical textorbyendorsement,atthelatestbyDecember2002,andconflictingnationalstandardsshallbe withdrawnatthelatestbyDecember2002. AccordingtotheCEN/CENELECInternalRegul
15、ations,thenationalstandardsorganizationsofthefollowing countriesareboundtoimplementthisEuropeanStandard:Austria,Belgium,CzechRepublic,Denmark, Finland,France,Germany,Greece,Iceland,Ireland,Italy,Luxembourg,Malta,Netherlands,Norway, Portugal,Spain,Sweden,SwitzerlandandtheUnitedKingdom.EN3745302:2002(
16、E) 3 1 Scope Thisstandardspecifiesamethodofdeterminingtheeffectivenumericalapertureofanopticalcableorfibre usedinaerospaceapplications. 2 Normativereferences ThisEuropeanStandardincorporatesbydatedorundatedreferenceprovisionsfromotherpublications. Thesenormativereferencesarecitedattheappropriateplac
17、esinthetextandthepublicationsarelisted hereafter.Fordatedreferences,subsequentamendmentstoorrevisionsofanyofthesepublicationsapplyto thisEuropeanStandardonlywhenincorporatedinitbyamendmentorrevision.Forundatedreferencesthe latesteditionofthepublicationreferredtoapplies. EN2591100 AerospaceseriesElem
18、entsofelectricalandopticalconnectionTestmethods Part100:General 1) EN 3745100 AerospaceseriesFibresandcables,optical,aircraftuseTestmethods Part100:General 2) 3 Preparationofspecimens 3.1 ThespecimensshallbepreparedinaccordancewithEN2591100,unlessotherwisespecifiedin theproductstandard. Ifnotyetatst
19、andardtestconditions,thespecimensshallbesubjectedtostandardtestconditionsand stabilizedattheseconditionsfor24hasdefinedinEN3745100. 3.2 Unlessspecifiedinthetechnicalspecification,thefollowingdetailsshallbestated: typeofcableorfibreandlengthifdifferentfrom2m; acceptableradiusofcurvatureduringmeasurem
20、ent. 4 Apparatus Theapparatusshallcomprise: aLightLaunchSystem(LLS)asdefinedinEN2591100; amechanicalchopperH; detectionsystemsdependingontheselectedmethod. 1) PublishedasAECMAPrestandardatthedateofpublicationofthisstandard 2) InpreparationatthedateofpublicationofthisstandardEN3745302:2002(E) 4 4.1 A
21、pparatusformethodA (seefigure1): forthe“farfieldrotatingarmmethod“,thespecimenisfixed,thedetectorisattachedtoarotatingarm; distancebetweendetectorandfibre l f / CR 2 2 ; agoniometer; aclassicaldetectorwithasmallaperture. Figure1 4.2 ApparatusformethodB (seefigure2): forthe“ChargeCoupledDevice(CCD)ca
22、meramethod“,everythingisfixed(specimenanddetector), requiredapparatusisonlyaCCDcamera,placedatadistancefromtheopticalfibre l f / CR 2 2 . Figure2 5 Method 5.1 Methoddescription Adjustthelaunchconditionparameterstothefollowingvalues: N A =110%NA nom f CR =100% f CRnom ConnectthespecimentoLLSandtother
23、equireddetectorfollowingselectedmethod.EN3745302:2002(E) 5 5.2 MethodA (seefigure1) Theprincipleconsistsinmeasuringthevariationintheradiantintensityemittedbythefibreversusthe angularpositionofthedetectorthatis: i =f( q )( q beingtheemissionanglewithrespecttoalinenormalto thesource). Installthearmsup
24、portingthedetectoronagoniometerdrivenbyastepmotorconnectedtoacomputer. Rotatetherotatingarmatregularrotationangleintervalse.g. a 1.Iftheopticalaxisofthefibreistakenas beingtheorigin,thearmwilldescribesector:60,0,60. Processthemodulatedopticalsignalreceivedbythedetectorateachmeasurementstep(synchrono
25、us detectoramplifier). Averagethissignaloverthemeasurementintervals,storeitandthenplottheradiationintensitydiagram. NOTE Theresolutiontgcorrespondstothefollowingratio: detectoraperturediameter tg = fibredetectordistance 5.3 MethodB (seefigure2) Theprincipleconsistsinanalysingtheoutputlightofthefibre
26、bymeansofaCCDcamera.Theintensity profileisgivenbytheprocessingoftheintensitydeliveredbyeachpixeloftheCCDoutput. AdjusttheCCDcamerailluminationlevelandacquiretheoutputsignalemergingfromtheopticalfibre.A correctivefactor(cos q )shallbeappliedtothereceivedsignaltotakeintoaccounttheanglebetweenCCD plane
27、andunitoutputbeam. Storeitandthenplottheradiationintensitydiagram. Foreachnumericalaperturedetermination,threecurveswillbeplottedallowinganaverageofthecalculated valuetobedeterminedwitharelatedstandarddeviation. NOTE Ananglemeasurementdeterminedatq 0,5,correspondstypicallytoanumericalaperture accura
28、cyof 0,01. 5.4 Finalmeasurementsandrequirements Followingtheradiationdiagram i = f (q ),thenumericalaperturecorrespondsto: NA =sin q m at5%of I max. (seefigure3). Figure3 5.5 Specialprecautions Carewillbetakennottomodifycurvaturebendradiusofspecimenduringthevariousmeasurementsteps.BS EN 3745-302:200
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