Get 130-2019: State Primary Special Standard of Unit of Length in Region of Measurements of Deviations from Straightness and Flatness

The composition, operating principle, and metrological characteristics of GET 130-2019, the State Primary Special Standard of the unit of length in the field of measurements of deviations from straightness and flatness, are described. Results of investigations of the metrological characteristics of the interference measurement system incorporated into GET 130-2019 by means of which reproduction of the unit is realized on the basis of the fundamental physical constants and the properties of matter (interference) are presented, thus eliminating any additional instrumental sources of errors (uncertainty). Transmission of the unit of length in the region of measurements of deviations from straightness and flatness in the range 0–50 μm with length of the measured surface up to 30 m is achieved with the highest accuracy attainable in Russia. Comparisons that were carried out demonstrate that the metrological characteristics of GET 130-2019 correspond to the level of precision of foreign standards in measurements of deviations from straightness on a length up to 30 m and to the measurement capabilities presented in the database of the International Bureau of Weights and Measures.