National standards of optical density units: principles of optical scheme design, constructive and metrological characteristics

The current state of metrological support for precision optical density measurements is described. In order to analyze the principles of building optical schemes, structural, constructive and functional features of the blocks included in the standards, and metrological characteristics of national standards of optical density units, high-precision optical density measuring instruments developed by national metrological institutes of Russia, Germany, China, and the USA are considered. The equations of optical density measurements are presented, which are a mathematical model of the process of measuring the optical transmittance density of materials. The principles of operation of optical transmittance density unit standards based on light fl fi ration are described. The data of studies of geometric and spectral characteristics of fi national standards of optical density units of four countries are presented, as well as optical schemes and characteristics of standards in the following areas are analyzed: compliance with international standards; features of optical schemes; methods of fi the luminous fl and creating scattered radiation; features of object positioning; type of radiation receiver; metrological characteristics. Information is provided on the participation of national standards in international comparisons. The metrological characteristics of these national standards are summarized in a table. Taking into account and using the considered features of optical schemes, design solutions in conjunction with the metrological characteristics of the described devices contributes to an increase in the level of development while improving the State primary standard of the unit of optical density GET 206-2016.