TR 62469 @ IEC:2007(E) - 11 0,8 0,6 0,4 Phase rect. 0,2 0,0 0 30 60 60 40 20 90 Projection angle 120 -20 -40 Radius [um] 150 -60 180 IEC1695/07 Figure 6 - Measured projected phases S(y,α) of a PM fibre for various projected angles as a function of fibre radius 200 100 0 Ozz [Mpa] -100 -200 60 -300 40 20 -400 0 -60 -40 -20 Y [μm] -20 0 -40 20 X [μm] -60 40 60 IEC1696/07 Figure 7 - Calculated 2-D stress profile of a PM fibre TR 62469 @ IEC:2007(E) Measurement procedure 5 5.1 Alignment of polarizer and analyzer Without a fibre sample in the setup, rotate the axis of the analyzer in such a way that minimum light can pass through the analyzer. This makes the angle between the polarizer and the analyzer 9o°. Place a Babinet compensator between the polarizer and the analyzer Calibrate the compensating angle of the Babinet compensator by making the transmitted light a minimum when θ = 0. 5.2 Fibre mounting Prepare a fibre sample with a minimum length of 1o mm. Strip the plastic coating with a solvent, note that mechanical stripping or thermal stripping is not recommended because of the stress changes they may cause. Mount the bare fibre in the holding fixture and straighten it without applying any force. Sandwich the fibre between two thin glass plates with an index matching fluid or gel between them, note that the plates must be parallel. Place the sample between the Babinet compensator and the polarizer. DTOME 5.3 Taking transmitted intensity data I(y, O) For a given external phase retardation angle from the Babinet compensator, obtain a transmitted optical intensity I(y,O) as a function of the transverse distance of a fibre y, which corresponds to I(y,)= I。 sin?(S(y)+)/2}. Repeat this transmitted optical intensity measurement while scanning the external phase retardation angles such that sine square intensity function I(y,) can be obtained as a function of for a given radius position y. The external phase retardation angle θ needs to be scanned at least for 30° with a step size of 1° NGALO to reduce errors during the curve fitting process. The scanning range of the external phase retardation needs to be carefully chosen so that the transmitted intensity data I(y,O) has at least one maximum or minimum point of a sine square function. Calculation of 1-D stress profile for a fibre with a cylindrically symmetric 5.4 structure For each transverse position y, calculate the phase retardation S(y) by fitting the I(y,)= I。 sin²[(S(y)+)/2l curve with a sine square function by using a least square curve fitting method. The stress profile of a fibre O,(r) can be calculated from S(y) using equation (3). Calculation of 2-D stress profile for a fibre with a cylindrically non-symmetric 5.5 structure For a fibre with a non-axially symmetric stress distribution, measure a series of phase retardations S(y,α) in equation (4) for many different projection angles α between O° and 180°. At least 20 different projected phase retardation measurements S(y,α) with regularly spaced projection angle α need to be measured. A sample fibre should be rotated along the fibre axis with a computer controlled motorized rotating stage. Using equation (5), obtain the 2-D stress profile of the fibre Oz (x, y) . 6 Documentation 6.1 Information to be reported for each measurement 1) Identification of each test specimen 2) Date of the measurement - 13 - TR 62469 @ IEC:2007(E) 3) Wavelength of the light source 4) 1-D fibre stress profile ,(r) 5)( Optional 2-D fibre stress profile O zz (x, y) Information that should be available upon request 6.2 1)[ Description of the measurement method used Description of the measurement equipment, including: light source, polarizer and analyzer, 2) Babinet compensator, imaging lens, detection device 3）： Spatial resolution and stress resolution of the measurement equipment 4) Date and results for the most recent instrument calibration (S Data on measurement reproducibility OME ANCHN/BAN SLUP