Device for measuring the refractive index of transparent liquids based on a sectoral diffractive sensor element

For Russian citation (Opticheskii Zhurnal):

Белоусов Д.А. Устройство для измерения показателя преломления прозрачных жидкостей на основе секторального дифракционного сенсорного элемента // Оптический журнал. 2025. Т. 92. № 5. С. 66–76. http://doi.org/10.17586/1023-5086-2025-92-05-66-76

Belousov D.A. Device for measuring the refractive index of transparent liquids based on a sectoral diffractive sensor element [in Russian] // Opticheskii Zhurnal. 2025. V. 92. № 5. P. 66–76. http://doi.org/10.17586/1023-5086-2025-92-05-66-76

For citation (Journal of Optical Technology):

Abstract:

Subject of study. A device for measuring the refractive index of transparent liquids, the operating principle of which is based on the use of a sectoral diffractive sensor element. Aim of study. Development of a diffractometric device for measuring the RI of transparent liquids, in a wide range of changes in measured values, using a statically installed diffractive sensor element and a diffraction pattern recording unit. Method. Illumination of a diffractive grating immersed in the liquid under study with laser radiation and measurement of the angular position of the diffraction orders allows one to determine the refractive index of the liquid under study. To expand the range of measurable values without loss of accuracy, instead of a single diffractive grating, a sectoral diffractive sensor element developed in this work can be used, consisting of a set of diffractive gratings with different periods and angular orientations. Main results. A diffractometric device for measuring the refractive index of transparent liquids has been developed. Its special feature is the use of a sectoral diffractive sensor element consisting of four diffractive gratings with different periods and angular orientations. An experimental sample has been created, which allows measuring the refractive index of transparent liquids in the range of 1.3200–1.7200 at a wavelength of 639 nm. Practical significance. The concept of a diffractometric device for measuring the refractive index of transparent liquids proposed allows simplifying the design of devices of this type, reducing their cost, and also improving the speed and the accuracy of the measurements performed.

Keywords:

diffraction optics, refractive index, liquids, diffractive sensor, measuring system, image processing

Acknowledgements:

the work was carried out with the support of the Foundation for Assistance to Small Innovative Enterprises within the framework of the «UMNIK» grant program, as well as using subsidies for financial support of the state task of the IA&E SB RAS (state registration № 124041700107-9) with application the equipment of the Central Research Center “Spectroscopy and Optics” of the IA&E SB RAS

OCIS codes: 120.4640, 050.1940, 050.1950

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