IEC 61745:1998 pdf download – End-face image analysis procedure for the calibration of optical fibregeometry test sets

IEC 61745:1998 pdf download – End-face image analysis procedure for the calibration of optical fibregeometry test sets.
In the research and production environments there exists a range of test methods lot characterizing the geometry of optical fibres, Furthermore, each test method may determine one or more of the many parameters required for complete geometrical characterization. This International Standard describes the calibration of test sets which perform end-face image analysis, also known as near-field or grey-scale analysis. The principles, however. may be applied to test sets of a different type
This standard addresses the calibration of measurements made on single-mode fibres only; however, this type of test set may also be used to measure the geometrical parameters of the cores of multimode fibres, but the evaluation of uncertainties associated with these measurements is beyond the scope of this standard.
The procedures outlined are to be performed by calibration laboratories and by the manufacturers or users of geometry test sets, for the purpose of calibrating geometry test sets and for evaluating the uncertainties In measurements made on calibrated test sets. The calibration of fibre coahng or cable measurement test sets is not covered by this standard.
The object of this standard is to define a standard procedure for the calibration of test sets lot measuring the glass geometry of optical fibres
1.2 DefInitions
For the purpose of this International Standard, the following definitions apply.
1.2.1
accredited calibration laboratory
calibration laboratory authorised by the appropriate National Standards laboratory to issue calibration certificates with a specified uncertainty, which demonstrate traceability to national standards
1.2.2
artef act
any object that is measured on or used to calibrate a geometry test set. An artetact may be, for example, an optcal fibre or a chromlum.on.glass pattern
1.2.3
calibration
process by which the relationship between the values indicated by the geometry test set under calibration and the known values of the calibration standard is established. The purpose of calibration is to bring all geometry test sets into substantial agreement with a national standards laboratory. This may be performed either by adjustment of the geometry test set or by documentation of a calibration factor(s) in a calibration certificate. The pertaining environment and instrument conditions at the time of calibration are usually recorded Calibration includes estimation of all uncertainties
1.2.4
calibration chain
chain of transfers from a national standard to the geometry test set through intermediate or working standards see figure 1)
1.2.5
calibration checking
establishing that a geometry test set that has been previously calibrated but has reached its calibration due date remains within specified uncertainty limits. If the geometry test set has drifted outside these limits, then re-calibration as required. Otherwise, the re-checking period can be extended for a stated period. The test set may be checked using a working standard
1.2.6
calibration standard
artetact that is calibrated against a reference standard and is used to calibrate test sets. The artelact may be a fibre or a chromium-on-glass pattern. Proper use of a calibration standard ensures traceability. The term includes the reference standard, the transfer standard arid the working standard(s), in descending order of metrological uncertainty
1.2.7
combined standard uncertainty
combination of a number of individual standard uncertainties.
The term accuracy should be avoided in this context.
In calibration reports and technical data sheets, the combined standard uncertainty in the geometry test set measurement is reported as an overall expanded uncertainty with the applicable confidence level, br example 95,5% or 99,7%.
1.2.8
confidence level
estimation of the probability that the true value of a measured parameter lies within a given range expanded uncertainty)
1.2.9
correction offset
number that is added to or subtracted from the measurement result of a test set to correct for a known physical elf ect
1.2.10
coverage factor, k
lactor used to calculate the expanded uncertainty U from the standard uncertainty
1.2.11
expanded uncertainty, U
range of values within which the true value 01 the measured parameter, at the slated confidence level, can be expected to lie, It is also called the confidence interval and is equal to the coverage factor k times the standard uncertainty u.