FIBRE-OPTIC METHOD FOR DETERMINING THE REFRACTIVE COEFFICIENT OF A TRANSPARENT SUBSTANCE AND A FIBRE-OPTICAL REFRACTOMETRIC MEASURING CONVERTER IMPLEMENTING IT Russian patent published in 2023 - IPC G01N21/43 G01B11/00 

FIELD: measuring technology.

SUBSTANCE: invention can be used to measure the change in the refractive index of transparent gases, liquids, gel-like substances, solid materials and ensure absolute spark-explosion-fire safety of an object. The claimed fibre-optic method for determining the refractive index of a transparent substance consists in the fact that at the output of the input optical fibre a light flux is formed in the form of a cone, directed to the transparent first side surface of the cylinder, where it is refracted at the interface "gas - material of the cylinder", falls on the second side surface of the cylinder, where it is refracted at the "cylinder material - gas" interface, after which it enters at angles to the ends of the outgoing optical fibres, and then to the first and second radiation receivers, which convert optical signals into electrical signals. The cylinder cavity is filled with a calibration substance with a known refractive index n ₀, the light flux refracted on the first side surface of the cylinder enters the first inner surface of the tube, where it is refracted at the “cylinder material - calibration substance” interface, passes through the calibration substance, enters the second internal the surface of the tube, where it is refracted at the interface between the media "calibration substance - material of the cylinder"; the input and output optical fibres are moved relative to the side surface of the cylinder in the vertical and longitudinal directions until the intensities of optical signals from the output of the upper and lower output optical fibres become maximum and equal to each other, after which the optical fibres are fixed in a fixed position. Instead of a cylinder with a calibration substance, a similar cylinder is placed in the form of a tube with a substance, the refractive index n_f of which must be determined, and the change in the signals from the output of the radiation receivers determines the refractive index of the substance n_f.

EFFECT: increase in the accuracy of measuring the refractive index, an increase in the manufacturability of the device, a decrease in the weight and size characteristics of the measuring transducer, and ensuring spark-explosion-fire safety.

9 cl, 4 dwg