1、 IEC 60793-1-43 Edition 2.0 2015-03 INTERNATIONAL STANDARD Optical fibres Part 143: Measurement methods and test procedures Numerical aperture measurement IEC 60793-1-43:2015-03(en) colourinsideTHIS PUBLICATION IS COPYRIGHT PROTECTED Copyright 2015 IEC, Geneva, Switzerland All rights reserved. Unles
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11、cal aperture measurement INTERNATIONAL ELECTROTECHNICAL COMMISSION ICS 33.180.10 ISBN 978-2-8322-2545-5 Registered trademark of the International Electrotechnical Commission Warning! Make sure that you obtained this publication from an authorized distributor. colourinside 2 IEC 60793-1-43:2015 IEC 2
12、015 CONTENTS FOREWORD . 4 1 Scope 6 2 Normative references. 6 3 Overview of method . 6 4 Reference test method . 7 5 Apparatus 8 5.1 Input system . 8 5.1.1 Light source . 8 5.1.2 Input optics 8 5.1.3 Fibre input end support and alignment 8 5.1.4 Cladding mode stripper 8 5.2 Output system and detecti
13、on . 8 5.2.1 General . 8 5.2.2 Technique 1 Angular scan (see Figure 2) . 9 5.2.3 Technique 2 Angular scan (see Figure 3) . 10 5.2.4 Technique 3 Scan of the spatial field pattern (see Figure 4) . 10 5.2.5 Technique 4 Inverse far-field measurement (see Figure 5, applicable to subcategory A4d fibres) 1
14、2 6 Sampling and specimens . 13 6.1 Specimen length . 13 6.2 Specimen endface . 13 7 Procedure . 13 8 Calculations 13 8.1 Far-field versus maximum theoretical value . 13 8.2 Threshold intensity angle, k. 14 8.3 Numerical aperture, NAff. 14 8.4 Calculating far-field intensity pattern when using Techn
15、ique 3 15 8.5 Calculating NA when using Technique 4 15 9 Results 15 9.1 Information available with each measurement 15 9.2 Information available upon request 16 10 Specification information 16 Annex A (informative) Mapping NA measurement to alternative lengths 17 A.1 Introductory remark . 17 A.2 Map
16、ping long length NAffmeasurement to short length NAffmeasurement . 17 Annex B (normative) Product specific default values for NA measurement . 18 B.1 Introductory remark . 18 B.2 Table of default values used in NA measurement for multimode products . 18 Figure 1 Representative refractive index profi
17、le for a graded index multimode fibre 7 Figure 2 Technique 1 Angular scan . 9 Figure 3 Technique 2 Angular scan 10 Figure 4 Technique 3 Scan of the spatial field pattern 11 IEC 60793-1-43:2015 IEC 2015 3 Figure 5 Technique 4 Inverse far-field method . 13 Figure 6 Example of a far-field NA measuremen
18、t 14 Figure 7 Sample output of an A4d fibre measured using Technique 4 15 Table B.1 Default values for parameters used in the far-field NA measurement of multimode fibres . 18 4 IEC 60793-1-43:2015 IEC 2015 INTERNATIONAL ELECTROTECHNICAL COMMISSION _ OPTICAL FIBRES Part 143: Measurement methods and
19、test procedures Numerical aperture measurement 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 international co-operation on
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29、lication. 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 60793-1-43 has been prepared by subcommittee 86A: Fibr
30、es and cables, of IEC technical committee 86: Fibre optics. This second edition cancels and replaces the first edition published in 2001, and constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: expansion of the sco
31、pe to include A1, A2, A3 and A4 multimode fibre categories; addition of measurement parameters of sample length and threshold values, product specific to the variables that are now found in the product specifications; a new Annex B entitled “Product specific default values for NA measurement“; addit
32、ion of a new Technique 4 for measuring NA of A4d fibres; IEC 60793-1-43:2015 IEC 2015 5 a new Annex A entitled “Mapping NA measurement to alternative lengths“ that gives a mapping function to correlate shorter sample length measurements to the length suggested in the reference test method Naff. This
33、 International Standard is to be used in conjunction with IEC 60793-1-1, IEC 60793-1-21 and IEC 60793-1-22. The text of this standard is based on the following documents: CDV Report on voting 86A/1566/CDV 86A/1622/RVC Full information on the voting for the approval of this standard can be found in t
34、he report on voting indicated in the above table. This publication has been drafted in accordance with the ISO/IEC Directives, Part 2. A list of all parts in the IEC 60793 series, published under the general title Optical fibres, can be found on the IEC website. The committee has decided that the co
35、ntents of this publication will remain unchanged until the stability date indicated on the IEC website 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. A bilingual v
36、ersion of this publication may be issued at a later date. 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 document using a colo
37、ur printer. 6 IEC 60793-1-43:2015 IEC 2015 OPTICAL FIBRES Part 143: Measurement methods and test procedures Numerical aperture measurement 1 Scope This part of IEC 60793 establishes uniform requirements for measuring the numerical aperture of optical fibre, thereby assisting in the inspection of fib
38、res and cables for commercial purposes. The numerical aperture (NA) of categories A1, A2, A3 and A4 multimode fibre is an important parameter that describes a fibres light-gathering ability. It is used to predict launching efficiency, joint loss at splices, and micro/macrobending performance. The nu
39、merical aperture is defined by measuring the far-field pattern (NAff). In some cases the theoretical numerical aperture (NAth) is used in the literature, which can be determined from measuring the difference in refractive indexes between the core and cladding. Ideally these two methods should produc
40、e the same value. 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 references, the latest edition of the referenced document (i
41、ncluding any amendments) applies. IEC 60793-1-1, Optical fibres Part 1-1: Measurement methods and test procedures General and guidance IEC 60793-1-21, Optical fibres Part 1-21: Measurement methods and test procedures Coating geometry IEC 60793-1-22, Optical fibres Part 1-22: Measurement methods and
42、test procedures Length measurement IEC 60793-2-10, Optical fibres Part 2-10: Product specifications Sectional specification for category A1 multimode fibres IEC 60793-2-20, Optical fibres Part 2-20: Product specifications Sectional specification for category A2 multimode fibres IEC 60793-2-30, Optic
43、al fibres Part 2-30: Product specifications Sectional specification for category A3 multimode fibres IEC 60793-2-40, Optical fibres Part 2-40: Product specifications Sectional specification for category A4 multimode fibres 3 Overview of method This test procedure describes a method for measuring the
44、 angular radiant intensity (far-field) distribution from an optical fibre. The numerical aperture of multimode optical fibre can be IEC 60793-1-43:2015 IEC 2015 7 calculated from the results of this measurement using Equation (10) for NA in the far-field, NAff,as described in 8.3. As background the
45、maximum theoretical NA of a multimode fibre is defined as follows: NAth= sin m (1) where NAthis the maximum theoretical numerical aperture; mis the largest incident meridional ray angle that will be guided by the fibre. In terms of the fibre index profile: NAth= (2) where n1is the maximum refractive
46、 index of the core, and n2is the average refractive index of the cladding far from the core region. Figure 1 below shows a refractive index profile of a graded index multimode fibre and indicates n1and n2. Figure 1 Representative refractive index profile for a graded index multimode fibre NAffcan be
47、 determined from a far-field radiation pattern measurement on a short length of fibre or from a measurement of a fibres refractive index profile. Using the far-field method, the intensity pattern, I(), of a fibre is acquired, and the NAff(numerical aperture in the far-field) is defined as the sine o
48、f the half-angle where the intensity has decreased to a threshold percentage (kNA%) of its maximum value. The threshold used depends on the type of multimode fibre being measured and are given in the detailed product specification for the fibre being measured. 4 Reference test method The reference t
49、est method (RTM) for measuring numerical aperture is the far-field measurement defined in this standard. NOTE The core and cladding indexes can be empirically determined by Method A (refractive near-field measurement) of IEC 60793-1-20 to approximate the theoretical NA (NAth). n12n22IEC n1n2Light guiding core Cladding Cladding 8 IEC 60793-1-43:2015 IEC 2015 5 Apparatus 5.1 Input system 5.1.1 Light source Use an incoherent li
