1、 IEC/TR 62469 Edition 1.0 2007-08 TECHNICAL REPORT Guidance for residual stress measurement of optical fibre IEC/TR 62469:2007(E) THIS PUBLICATION IS COPYRIGHT PROTECTED Copyright 2007 IEC, Geneva, Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reprod
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8、edback on this publication or need further assistance, please visit the Customer Service Centre FAQ or contact us: Email: csciec.ch Tel.: +41 22 919 02 11 Fax: +41 22 919 03 00 IEC/TR 62469 Edition 1.0 2007-08 TECHNICAL REPORT Guidance for residual stress measurement of optical fibre INTERNATIONAL E
9、LECTROTECHNICAL COMMISSION P ICS 33.180.10 PRICE CODE ISBN 2-8318-9301-1 2 TR 62469 IEC:2007(E) CONTENTS FOREWORD.3 1 Scope.5 2 Justification of measurement 5 3 Apparatus.6 3.1 General .6 3.2 Light source 6 3.3 Polarizer and analyzer.6 3.4 Sample fibre preparation .6 3.5 Variable phase compensator .
10、6 3.6 Optical intensity detection .7 3.7 Data acquisition 7 4 Data analysis and formula 7 4.1 General .7 4.2 1-D stress profile for a fibre with a cylindrically symmetric structure 8 4.3 2-D stress profile for a fibre with a cylindrically non-symmetric structure .9 5 Measurement procedure.12 5.1 Ali
11、gnment of polarizer and analyzer.12 5.2 Fibre mounting 12 5.3 Taking transmitted intensity data ) , ( y I .12 5.4 Calculation of 1-D stress profile for a fibre with a cylindrically symmetric structure12 5.5 Calculation of 2-D stress profile for a fibre with a cylindrically non-symmetric structure12
12、6 Documentation .12 6.1 Information to be reported for each measurement .12 6.2 Information that should be available upon request.13 Bibliography14 Figure 1 Polariscopic phase retardation measurement setup for an optical fibre 6 Figure 2 Measured transmission intensity as a function of fibre radius
13、and external phase .7 Figure 3 Propagation of laser light across the fibre cross-section.8 Figure 4 Stress profile for a fibre with depressed inner cladding and jacketed tube9 Figure 5 Examples of projected phase retardation measurement ) ( y for a PM fibre as a function of fibre radius y when the p
14、rojected angle is 0, 45, 90, and 13510 Figure 6 Measured projected phases ) , ( y of a PM fibre for various projected angles as a function of fibre radius .11 Figure 7 Calculated 2-D stress profile of a PM fibre .11 TR 62469 IEC:2007(E) 3 INTERNATIONAL ELECTROTECHNICAL COMMISSION _ GUIDANCE FOR RESI
15、DUAL STRESS MEASUREMENT OF OPTICAL FIBRE 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 all qu
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26、ifferent kind from that which is normally published as an International Standard, for example “state of the art“. IEC/TR 62469, which is a technical report, has been prepared by subcommittee 86A: Fibres and cables, of IEC technical committee 86: Fibre optics. The text of this technical report is bas
27、ed on the following documents: Enquiry draft Report on voting 86A/1143/DTR 86A/1148/RVC Full information on the voting for the approval of this technical report can be found in the report on voting indicated in the above table. This publication has been drafted in accordance with the ISO/IEC Directi
28、ves, Part 2. 4 TR 62469 IEC:2007(E) The committee has decided that the contents of this publication will remain unchanged until the maintenance result date indicated on the IEC web site under “http:/webstore.iec.ch“ in the data related to the specific publication. At this date, the publication will
29、be reconfirmed, withdrawn, replaced by a revised edition, or amended. A bilingual version of this publication may be issued at a later date. TR 62469 IEC:2007(E) 5 GUIDANCE FOR RESIDUAL STRESS MEASUREMENT OF OPTICAL FIBRE 1 Scope The measurement of residual stress distribution in an uncoated glass o
30、ptical fibre is considered to be important as it affects critical fibre parameters such as refractive index, intrinsic polarization mode dispersion, mode field diameter and dispersion. The optical polarimetric method is a well-established technique to measure the residual stress of an optical materi
31、al. This technical report describes a transverse polarimetric method to measure the residual stress profile of any type of optical fibre. The principle and detailed procedure for measuring the optical transverse stress profile of a fibre, which is cylindrically symmetric, is described in detail. It
32、is based on a polariscope, which is constructed with a fixed polarizer, a quarter-wave plate and an analyzer. An optical tomographic technique is also described for measuring the stress profile of a fibre with a cylindrically non-symmetric structure. 2 Justification of measurement Residual stress in
33、 an optical fibre is induced by the combination of the fibre construction and the drawing process. The stress information is important because it affects many important parameters of an optical fibre due to the following reasons. Temperature dependent changes of fibre parameters are larger for a fib
34、re with larger residual stress, and these are responsible for the statistical behaviour of polarization mode dispersion (PMD) changes in deployed fibre links. (See references 10-12.) 1) The variation of important fibre parameters such as chromatic dispersion, mode field diameter, PMD depends on the
35、intrinsic residual stress of an optical fibre. (See references 13-17.) The asymmetric residual stress profile of a fibre causes fibre curl, which affects cleaving quality for an optical fibre ribbon. The asymmetric residual stress of a fibre is a major cause of the intrinsic PMD of an optical fibre.
36、 (See references 18-20.) Excessive residual stress can lead to core cracking that might be seen in, for example, the preparation of the ends for connectors. The design of polarization retaining fibres normally involves inducing a non-symmetric stress field. This measurement can be used to confirm th
37、ese designs. Much progress has been made in measuring the residual stress profile of an optical fibre (see references 1-9) such that spatial resolution can be as small as 0,6 and accuracy in measuring stress can be as low as 0,4 MPa. Depending on the application, either one- or two-dimensional stres
38、s data may be needed. This document describes methods by measuring the polarization rotation of a transversely exposed laser light across a fibre cross-section using a polarimetric method. 1)Figures in square brackets refer to the Bibliography. 6 TR 62469 IEC:2007(E) 3 Apparatus 3.1 General An optic
39、al transverse phase retardation measurement method is used to determine the residual stresses in a fibre. Figure 1 shows a simple polariscopic phase retardation measurement setup consisting of a polarizer, fibre sample, Babinet variable phase compensator, and an analyzer. Stressed material shows str
40、ess-induced birefringence for light propagating through the medium. By measuring the polarization dependent phase retardation of light transmitted through a sample, the stress can be measured. 3.2 Light source The light source shall be a laser with a specified optical wavelength and narrow optical s
41、pectrum bandwidth (maximum 2 nm at FWHM full width at half maximum). A collimated laser light source is recommended. When a laser is used, a rotating diffuser is recommended in order to remove coherent interference effects. 3.3 Polarizer and analyzer The polarizer and the analyzer shall have a minim
42、um polarization dependent transmission contrast of 1:200. The transmission angles of the polarizer and the analyzer are set perpendicular with each other within 0,1-degree accuracy. 3.4 Sample fibre preparation The fibre sample shall be a few centimetres long. The jacket or plastic coating on the sa
43、mple shall be removed. The prepared sample is placed between the polarizer and the analyzer. Immerse the sample in an index matching gel or fluid. The refractive index difference between the cladding material of the fibre and the index matching material shall be less than 0,005. The angle between th
44、e fibre axis and the polarizer or the analyzer shall be 45 within 0,1- degree accuracy. Figure 1 Polariscopic phase retardation measurement setup for an optical fibre For measuring a two-dimensional stress profile, a fixture that holds the fibre on a constant axis at the holding position and allows
45、the fibre to be rotated through 180 is required. The fixture is required in order to be rotated with a motorized stage with an accuracy of 0,1. 3.5 Variable phase compensator A Babinet variable phase compensator is placed just after a fibre sample to add an external phase term, which is used for an
46、accurate phase retardation measurement. If the fibre sample has non-zero axial stress components, it acts as a phase retarder due to stress-induced X Analyzer 45 Babinet compensator Optical fibre Polarizer +45 Z Y Laser input IEC 1690/07 TR 62469 IEC:2007(E) 7 birefringence. Without a fibre sample a
47、nd the Babinet phase compensator, no light can pass through the analyzer. 3.6 Optical intensity detection An optical intensity detection system is needed to detect the transmitted light intensity after the optical analyzer shown in Figure 1. Such a device may consist of a single optical detector wit
48、h a small aperture size in the order of a few microns combined with a motorized linear scanning system. A detector array may be used to provide a more precise location of the deflections than might be obtained by a single detector. Such a system might include a detector array or a CCD with a frame g
49、rabber. 3.7 Data acquisition A computer is recommended to provide motion control, acquire data and perform computations. 4 Data analysis and formula 4.1 General The transmitted optical intensity ) ( y I as a function of the transverse distance of a fibre y, can be written as: () 2 ) ( sin ) , ( 2 + = y I y I o , (1) where o I is background intensity, is the external phase retardation term from the Babinet compensator and ) (y is the pha
