Test procedures of Measurement methods and test procedures Numerical aperture NAth is the maximum theoretical na. Report NAff at 850 nm as the fibre numerical aperture. This value may be obtained directly from a far- field measurement at 850 nm or using equation(11), indirectly from a profile measurement 6.2 Five per cent intensity angle, 0s Normalize the scanned pattern to the peak intensity Make note of the points on the pattern at which the intensity is 5 %of the maximum Record half the angle between these points as ee 6.3 Numerical aperture, NAff Calculate the far-field numerical aperture using the following formula NAf=sinθs (12) where NAff is the far-field numerical aperture; As is the 5 intensity angle Results 7. 1 Information to be provided with each measurement Report the following information with each measurement date and title of measurement identification of optical source wavelength, if other than 850 nm measurement results obtained from clause 8 7. 2 Information available upon request The following information shall be available upon request centre wavelength and spectral width of interference filters, if used detection system calibration and angular resolution erture of launch spot technique used to strip cladding modesTest procedures Page: 5 of 5 Subject: Originated by: Wu Jia Measurement methods and test procedures – Numerical aperture NAth is the maximum theoretical NA. Report NAff at 850 nm as the fibre numerical aperture. This value may be obtained directly from a far￾field measurement at 850 nm or using equation (11), indirectly from a profile measurement. 6.2 Five per cent intensity angle, θ5 Normalize the scanned pattern to the peak intensity. Make note of the points on the pattern at which the intensity is 5 % of the maximum. Record half the angle between these points as θ5. 6.3 Numerical aperture, NAff Calculate the far-field numerical aperture using the following formula: NAff = sin θ5 (12) where NAff is the far-field numerical aperture; θ5 is the 5 % intensity angle. 7 Results 7.1 Information to be provided with each measurement Report the following information with each measurement: – date and title of measurement; – identification of specimen; – optical source wavelength, if other than 850 nm; – measurement results obtained from clause 8. 7.2 Information available upon request The following information shall be available upon request: – centre wavelength and spectral width of interference filters, if used; – detection system technique used in 5.2; – detection system calibration and angular resolution; – size and numerical aperture of launch spot; – technique used to strip cladding modes. -END-