IEC 60793-1-22:2001 pdf download

IEC 60793-1-22:2001 pdf download.optical fibres -Part 1-22: Measurement methods and test procedures-Length measurement.
Information common to all measurements is contained in clauses 2 to 8. Information on specific application appears in annexes A. B. C, D. and E for methods A. B. C, 0 and E. respectively.
3.1 Method A — Delay measuring
The delay measuring method applies to measurements of the fibre length by the measurement of the propagation time of an optical pulse or a pulse train on the basis of a known value of the group index of the fibre.
Alternatively, this method is suitable for measuring the group index of a fibre of known length. Therefore, in practice this fibre length measurement method is calibrated against a known length of fibre of the same type.
3.2 Method B — Backscattering
The backscattering method, which is a single-sided measurement, uses an optical time domain reflectometer (OTDR), and measures the optical power backscattered from different points in the fibre to the beginning of the fibre.
3.3 Method C — Fibre elongation
This measurement method describes a procedure for determining the fibre elongation. It does not measure absolute strain, but instead measures the changes in strain from one loading condition to another.
3.4 Method 0 — Mechanical length
This measurement method describes a procedure for determining the fibre length by winding a fibre around a fixed diameter calibrated wheel that rotates. The length Is determined by the number of revolutions of the wheel.
3.5 Method E — Phase shift
The phase shift method describes a procedure for determining the fibre length. The length is determined from the phase shift that occurs when a predetermined modulation frequency ‘m is applied,
3.6 Reference test method
The reference test method (RTM). which shall be the one used to settle disputes, varies depending on whether the fibre is cabled or not, such as
— uncabled fibre: method 0;
— length of fibre within cable: method B:
— elongation of fibre within cable: method C;
— elongation of uncabled fibre: method C.
4 Apparatus
Annexes A, B, C, D and E include layout drawings and other equipment requirements for each of the methods A, B. C, D and E, respectively.
5 Sampling and specimens
See the appropriate annex A, B. C. 0 oi E for specific requirements. General requirements follow.
Prepare a flat end face, perpendicular to the fibre axis, at the input and output ends of each specimen for measurements based on optical delay measurements.
6 Procedure
See the appropriate annex A, B, C, 0 or E far specific requirements.
7 Calculations
See the appropriate annex A. B, C, 0 or for specific requirements
8 Results
The following Information shall be provided with each measurement
— date and title of measurement:
— identification and description of specimen, including whether fibre or cable:
— specimen length, or elongation;
— measurement method used: A, B. C, 0 or E;
— other results, as required by the appropriate annex. A. B. C. 0 or E.
The following information shall be available upon request:
— description of measurement apparatus arrangement:
— type and wavelength of measurement source:
— launch conditions;
— details of computation technique:
— date of latest calibration of equipment.
See annexes A, B, C, 0 and E for any additional information that shall be available upon request.
9 Specification information
The detail specification shall specify the following information:
— type of fibre (or cable) to be measured;
— failure or acceptance criteria;
— Information to be reported;
— deviations to the procedure that apply.
lf N is known, the measurement of at gives L. On the other hand, the measurement of at givesthe value of N when L is known.
A.3 Apparatus
A.3.1 Two techniques
There are two techniques for measuring the propagation time of an optical pulse;-time measurement of the transmitted pulse (At measured);
– time measurement of the reflected pulse (2at measured).
See figures A.1 and A.2 for two different arrangements corresponding to the two techniquesapplying a sampling oscilloscope.
Instead of the sampling oscilloscope,backscattering equipment,or a counter with separatestart/stop gate and averaging capability (for example, at least 10 counts), can be used.