Calibration
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Calibration Simone Carmignato* University of Padua, Vicenza, Italy
Definition Operation that, under specified conditions, in a first step, establishes a relation between the quantity values with measurement uncertainties provided by measurement standards and corresponding indications with associated measurement uncertainties and, in a second step, uses this information to establish a relation for obtaining a measurement result from an indication. Note 1: A calibration may be expressed by a statement, calibration function, calibration diagram, calibration curve, or calibration table. In some cases, it may consist of an additive or multiplicative correction of the indication with associated measurement uncertainty. Note 2: Calibration should not be confused with adjustment of a measuring system, often mistakenly called “self-calibration,” nor with verification of calibration. Note 3: Often, the first step alone in the above definition is perceived as being calibration (JCGM 200:2012, Definition 2.39).
Theory and Application Basic Concepts
According to the definition given in the International Vocabulary of Metrology (JCGM 200:2012, Definition 2.39), calibration establishes a relation between the quantity value provided by a measurement standard and the corresponding indication provided by a measuring instrument or system. Calibration also requires determination of the uncertainties associated with the measurements performed. A calibration can be executed either on a measuring instrument (or system) or on a measurement standard. The calibration of a measuring instrument allows determining the deviation of the indication of the measuring instrument from a known value of the measurand provided by the measurement standard, with associated measurement uncertainty. In other words, the deviation of the indication of an instrument from the conventional “true value” of the measurand is established and documented. For example, this is the case of calibrating micrometers or other dimensional measuring instruments using gauge blocks. The calibration of a measurement standard can be performed by comparing its quantity value and associated measurement uncertainty to a reference indication (with associated measurement uncertainty) obtained by a calibrated measuring system. For instance, a measuring system calibrated by a primary reference standard can be used to calibrate a secondary measurement standard. Also a comparison between two measurement standards can be viewed as a calibration if the comparison is used to check (and, if necessary, to correct) the quantity value and measurement uncertainty attributed to one of the two measurement standards. This is, for example, the case of the calibration of gauge blocks through comparison with other previously calibrated gauge blocks.
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CIRP Encyclopedia of Production Engineering DOI 10.1007/978-3-642-35950-7_16754-1 # CIRP 2014
In certain fields, such as measurement of quantities in biological samples and medical applications, a measurement sta
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