Home  |  Contact Us  |  Links
HOME
  ABOUT  
  NATIONAL MEASUREMENTS STANDARDS  
  CALIBRATION SERVICES  
  TRAINING  
  PUBLICATIONS  
  NEWS  
ABOUT METROLOGY
   

YOU ARE AT: ABOUT > ABOUT METROLOGY > ABOUT METROLOGY

ABOUT METROLOGY

Metrology covers three main tasks:

  1. The definition of internationally accepted units of measurement, e.g. the metre.
  2. The realisation of units of measurement by scientific methods, e.g. the realisation of a metre through the use of laser beams.
  3. The establishment of traceability chains in documenting the accuracy of a measurement, e.g. the documented relationship between the micrometer screw in a precision engineering workshop and a primary laboratory for optical length metrology.

Metrology develops ...

Metrology is essential in scientific research, and scientific research forms the basis of the development of metrology itself. Science pushes out the frontiers of the possible all the time and fundamental metrology follows the metrological aspects of these new discoveries. This means still better metrological tools to enable researchers to continue their discoveries.

Correspondingly, legal and industrial metrology must also develop in order to keep pace with the needs of society and industry - and remain relevant and useful.

Categories of metrology

In the EU, metrology is separated into three catagories with different levels of complexity and accuracy.
  1. Scientific metrology deals with the organisation and development of measurement standards and with their maintenance (highest level).
  2. Industrial metrology has to ensure the adequate functioning of measurement instruments used in industry as well as in production and testing processes.
  3. Legal metrology is concerned with the accuracy of measurements where these have influence on the transparency of economic transactions, health and safety.
Fundamental metrology has no international definition, but it signifies the highest level of accuracy within a given field. Fundamental metrology may therefore be described as scientific metrology, supplemented by those parts of legal and industrial metrology that require scientific competence.

Traceability

A traceability chain is an unbroken chain of comparisons which shall make if certain that a measurement result or the value is related to references at a higher level, ending at the final level with a primary standard.

Industry in Europe ensures traceability to the highest international level by using accredited European laboratories.

In the USA, industry ensures traceability to the highest level direct from NIST.

Calibration

A basic tool in ensuring the traceability of a measurement is measuring instrument calibration. This calibration involves determining the metrological characteristics of an instrument. It is achieved by means of a direct comparison against standards. A calibration certificate is issued and (in most cases) a sticker is attached. Based on this information a user can decide whether the instrument is fit for the application in question.

There are three main reasons for having instruments calibrated:
  1. To ensure readings from an instrument are consistant with other measurements.
  2. To determine the accuracy of the instrument readings.
  3. To establish the reliability of the instrument i.e. that it can be trusted.
By calibrating an instrument it is possible to obtain the following:
  • The result of a calibration permits either the assignment of values of measurands to the indications or the determination of corrections with respect to indications.
  • A calibration may also determine other metrological properties such as the effect of influence quantities.
  • The result of a calibration may be recorded in a document, sometimes called the calibration certificate or a calibration report.

Measurement standards

A measurement standard or etalon, is a material measure, measuring instrument, reference material or measuring system intended to define, realise, conserve or reproduce a unit or one or more values of a quantity to serve as a reference.

Site Map vx