metrology

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metrology

[mə′träl·ə·jē]
(physics)
The science of measurement.

Metrology

 

the science of measurements and of methods of achieving the required uniformity and accuracy. Among the main problems of metrology are the general theory of measurement, the formation of units and systems of physical quantities, measurement methods and equipment, methods of determining the accuracy of measurements (the theory of measurement errors), the basic provisions for units of measurement and for uniformity of measurement equipment (legislative metrology), the development of standards and reference measurement equipment, and methods for transferring the dimensions of units from the standards to the reference measurement equipment and then to the operating equipment.

Metrology was originally concerned with the description of the various types of measures (linear measures; measurements of capacity, mass, and time), and also of the coins used in various countries and the interrelationships among them. The development of metrology reached a turning point in 1875, with the conclusion of the Metric Treaty and the founding of the International Bureau of Weights and Measures. Modern metrology rests on high-precision physical experimentation, and it uses the achievements of physics, chemistry, and other natural sciences, but it also establishes its own specific laws and rules that make it possible to find a quantitative expression for the properties of objects in the material world.

A general theory of measurements has not yet taken shape; such a theory includes information and generalizations that are obtained as a result of analysis and study of measurements and their elements: physical quantities and their units, measurement equipment and methods, and the results of measurement.

In metrology, as in physics, a physical quantity is treated as a property of physical objects (systems) that is qualitatively common to many objects but is quantitatively different for each object—that is, as a property that can be a certain number of times larger or smaller for one object than for another (for example, length, mass, density, temperature, power, or velocity). Every object has a definite length, mass, and so on; the concept of quantity thus becomes concrete for the object (the length of a table, the mass of a weight, and so on).

Only concrete quantities may be measured. For the objective evaluation of a quantity, a unit must be selected (for some quantities a scale). A unit is a specific physical quantity whose numerical value is arbitrarily taken as equal to 1. The sequence of values of different size adopted by agreement for like quantities is called the scale of a quantity (for example, a temperature scale or the Brinell hardness scale). With the development of science, units have changed from a random choice of individual quantities to the construction of systems of units. The theoretical aspects of the interrelationships among the physical quantities and the principles involved in constructing a system of units, as well as specific systems of units, are examined in metrology.

Proper calibration and periodic testing of all the measuring facilities in use are necessary to achieve uniformity of measurements (that is, to obtain results expressed in codified units that are not dependent on the time, place, and measurement equipment). To this end, standards of units and an assortment of reference measurement equipment are needed. Metrology studies methods of reproducing units by means of standards, ways of improving accuracy, and procedures for transferring the dimensions of the units (methods of testing).

A large section of metrology is devoted to methods of determining measurement errors by using the theories of probability and mathematical statistics, and sometimes of other branches of mathematics.

Legislative metrology treats questions associated with the achievement of uniformity of measurements and uniformity of measurement equipment that must be regulated and monitored by the government. Countries organize metrological services to take the required steps. In the USSR the State Metrological Service is under the control of the State Committee on Standards of the Council of Ministers of the USSR.

Because of the increasing role of metrology in the development of science, technology, and industry, special scientific research institutes of metrology were founded in a number of countries as early as the turn of the 20th century. Among them were the Main Bureau of Weights and Measures in Russia (1893; now the D. I. Mendeleev All-Union Scientific Research Institute of Metrology), the State Physicotechnical Institute in Germany (1887), the National Physical Laboratory in Great Britain (1899), and the National Bureau of Standards in the USA (1901). In the 20th century a number of international metrological organizations were founded and charged with the development and adoption of common recommendations and resolutions for all the participating countries on the metrological questions under consideration.

Metrological journals include IzmeriteVnaia tekhnika (Measurement Technology; 1940–41 and since 1955), which was preceded by Poverochnoe delo (Testing; 1916–29), IzmeriteVnaia tekhnika i poverochnoe delo (Measurement Technology and Testing; 1930–38), Metrologiia i poverochnoe delo (Metrology and Testing; 1938–39); Metrologia (Berlin, since 1965); Bulletin de l’Organisation Internationale de Metrologie Legale (Paris, since 1960); Journal of Research of the National Bureau of Standards (Washington, since 1928); Wissenschaftliche Abhandlungen der Physikalisch-technischen Bundesanstalt (Braunschweig, since 1949).

REFERENCES

Malikov, M. F. Osnovy metrologii, part 1. Moscow, 1949.
Malikov, S. F., and N. I. Tiurin. Vvedenie v metrologiiu, 2nd ed. Moscow, 1966.
Burdun, G. D., and B. N. Markov. Osnovy metrologii. Moscow, 1972.
Bassiere, M., and E. Gaignebet. Metrologie generate. Paris, 1966.
Arutiunov, V. O. “Soderzhanie i osnovnie zadachi sovremenoi metrologii.” IzmeriteVnaia tekhnika, 1967, no. 9.
Shirokov, K. P. “Ob osnovnykh poniatiiakh metrologii.” Tr. metrologicheskikh intov SSSR, 1972, fascs. 130–090).

K. P. SHIROKOV

metrology

The science of weights and measures. Metrology is an important part of semiconductor manufacturing where high-resolution tools are required to measure the tiny elements in a chip that continue to decrease year after year.