Length is the basis of the structure of space and objects.

The measurement of geometric quantities has accompanied mankind since its inception throughout history. We can say that in many respects the accuracy of geometric measurements characterizes the level of development of science and technology. Today, high-precision measurements of geometric quantities in a wide range are in demand: from the microworld (nanotechnology) to the size of the universe (space exploration and development technology).

The level of ensuring the unity of measurements of geometric quantities not only reflects the scientific and technical level of the economy, but also largely determines the quality of products, as well as environmental safety in the country.

Ensuring the unity of high-precision measurements of geometric quantities is especially necessary in such areas as defense technology (location and range), precision engineering, aviation and space technology (coordinate measurements, surface roughness measurements), environmental monitoring and safety (engineering measurements), geodesy and cartography (calibration of rangefinders, geodetic instruments, satellite navigation system receivers), modern nanotechnology (measurement of parameters of nanoobjects and ensuring the positioning of the probe of technological equipment), research (measurements during unique physical experiments).

Implementation of the system of unity of measurements of geometrical quantities at each level of transfer to unit of measurement provides maintenance of their traceability to unit of length - meter in accordance with the standards operating in modern international practice.

As you know, in 1983, the General Conference on Weights and Measures adopted the following definition of a meter: "A meter is a unit of length equal to the path of light in a vacuum in 1/299792458 fraction of a second." In this case, the speed of light is postulated equal to 299792458 m / s exactly, and the carrier of a unit of length is a source of light radiation - a laser. It is by this definition that the unit of length is reproduced in the state primary standard of Ukraine DETU 01-03-98.

At one time, the value of the speed of light, experimentally obtained at the NSC "Institute of Metrology", was recognized as one of the most accurate in the world, included in directories and tables of values ​​of physical constants and actually inscribed in the history of world science.