IEC 60793-1-54-2018 pdf free

IEC 60793-1-54-2018 pdf free.Optical fibres – Part 1-54: Measurement methods and test procedures – Gamma irradiation.
4 Apparatus
4.1 General
Attention is drawn to the fact that strict regulations and suitable protective facilities are to be adopted in the laboratory for this test. Carefully selected trained personnel shall be used to perform this test. It can be extremely hazardous to test personnel if it is improperly performed or without qualified conditions.
4.2 Radiation source
4.2.1 Testing of environmental background radiation
A 60Co or equivalent ionising source shall be used to deliver gamma radiation. This
environment is characterised by relatively low total dose and dose rate.
4.2.2 Testing of adverse nuclear environments
A 60Co or equivalent ionizing source(s) shall be used to deliver gamma radiation. This
environment is characterised by higher total dose and dose rate.
4.3 Optical source
An optical source such as a white light source, laser or light emitting diode emitting at wavelengths compatible with the optical fibres under test shall be used. The wavelength of the source shall be according to the detailed specification.
The optical source shall be stable in intensity over a time period sufficient to perform the measurement. The power coupled from the source into the test sample shall be —30 dBm (1.0 pW) with a tolerance of ± 2 dBm or as specified in the detail specification. The optical source may be modulated with a pulsed signal at a 50 % duty cycle, if a lock-in amplifier is used.
4.4 Optical filtersimonochromators
Unless otherwise specified, wavelength tolerances of ± 20 nm shall be obtained by filtering the optical source with a set of optical filters or a monochromator. The 3 dB optical bandwidth of the filters shall be less than or equal to 25 nm
4.5 Cladding mode stripper
When necessary, a device that extracts cladding modes shall be employed at the input end and output end of the test sample. If the fibre coating materials are designed to strip cladding modes, a cladding mode stripper is not required.
4.6 Fibre support and positioning apparatus
A means of stable support for the input end of the test sample, such as a vacuum chuck, shall be arranged. This support shall be mounted on a positioning device so that the end of the test sample can be repeatedly positioned in the input beam.
4.7 Optical splitter
An optical splitter shall divert a small portion of the input light to a reference detector. The reference path shall be used to monitor system fluctuations for the duration of the test.
4.8 Input launch conditions
4.8.1 Class A, Category Al fibres (graded index multimode fibres)
An equilibrium mode simulator shall be used to attenuate higher order propagation modes and to establish a steady-state mode condition near the inout end of the fibre. The reauirements for the launch conditions for sub-category Ala graded index multimode fibre measurements are defined in IEC 61280-4-1.
4.8.2 Class A, Category A2 fibres (quasi-step and step index fibres) Launch conditions shall be created as specified in the detail specification.
4.8.3 Class B fibres (single-mode fibres)
An optical lens system or fibre pigtail may be employed to excite the test fibre. The power coupled into the test sample shall be stable for the duration of the test. If an optical lens system is used, a method of making the positioning of the fibre less sensitive is to overfill the fibre end spatially and angularly. If a pigtail is used, it may be necessary to use index matching material to eliminate interference effects. A high order mode filter shall be employed to remove high order propagating modes in the wavelength range greater than or equal to the cut-off wavelength of the test fibre. The test condition specified in IEC 60793-1-44. method C. satisfies this requirement.
4.9 Detector — Signal detection electronics
An optical detector that is linear and stable over the range of intensities that are encountered shall be used. A typical system might include a photovoltaic mode photodiode amplified by a current input preamplifier, with synchronous detection by a lock-up amplifier.
4.10 Optical power meter
A suitable optical power meter shall be used to determine that the power coupled from the optical source into the test sample is equal to 1.0 pW or the level specified in the detail specification.
4.11 Radiation dosimeter
Thermo luminescent LiF or CaF crystal detectors (TLDs) or an ion chamber detector shall be
used to measure the total radiation dose received by the specimen fibre.
4.12 Temperature-controlled container
Unless otherwise specified. the temperature-controlled container shall have the capability of
maintaining the specified temperatures to within ± 2 C.
4.13 Test reel
The test reel shall not act as a shield or sink for the radiation used in this test. Reels of wood, plastic or similar non-conducting materials would, in principle, act as transparent to the radiation. The additional absorption shall be taken into account for exact measurements.
An appropriate dose build-up layer of similar material shall be used.IEC 60793-1-54 pdf download.