metrologie

Metrology, in French metrologie, is the science of measurement. It covers the theory, science, and technology of measurement, including the realization of measurement standards and the application of measurement to science, industry, and everyday life. Metrology aims to ensure that measurements are accurate, reliable, and comparable across times and places. The field is commonly divided into scientific metrology, industrial metrology, and legal metrology.

Scientific metrology deals with developing measurement methods, realizing and maintaining standards, and assessing measurement quality, including uncertainty. It provides reference standards for the SI and supports research across disciplines.

Industrial metrology focuses on calibration, testing, and use of measurement equipment in manufacturing and services. It ensures traceability to SI units through calibration laboratories and quality systems, enabling consistent product quality and process control.

Legal metrology covers regulatory aspects of measurements used in commerce and public safety. It governs operation and verification of measuring instruments such as scales, gas meters, taximeters, and medical devices, and enforces standards to protect consumers and ensure fair trade.

Internationally, metrology is coordinated by the Bureau International des Poids et Mesures (BIPM), the Comité International des Poids et Mesures (CIPM), and the General Conference on Weights and Measures (CGPM). The SI base units are defined by fixed constants: the second by cesium-133; the meter by the speed of light in vacuum; the kilogram by the Planck constant, with definitions for the ampere, kelvin, mole and candela. This framework provides traceability and quantified uncertainty, supporting science and industry.

Historically, metrology emerged from standardization efforts in the 19th century, culminating in the Metre Convention of 1875 and the founding of BIPM. Today, metrology underpins science, industry, commerce, safety, and environmental monitoring.