Goniometric methods of measuring the refractive index of optically transparent materials based on the refraction of light by a triangular prism are studied. A modified minimum deviation method and 3 ...modified constant deviation methods are examined which make it possible to determine the refractive indices of triangular prisms with unknown refracting angles. According to the modified prism methods the deflection angles of the light by the prism are measured with a goniometer, while the refractive index of the material and the refraction angles of the prism are determined by solving systems of equations. Thus, there is no need for preliminary measurement of the prism angles, which would require special autocollimation goniometers. In addition, in the modified prism methods, light reflected from the faces of the prism is not used, which makes it possible to extend the spectral range of a measurement of the refractive index to the infrared and ultraviolet ranges. The errors in measurements of the refractive index by these methods are compared for the example of a prism with a refractive index of 1.5 and a refraction angle of 60°. It is shown that the modified minimum deviation method has the smallest error among all the prism methods, so it can be recommended for high-precision measurements of the refractive index in those cases where the refractive angles of the prism are unknown or it is technically difficult to measure them. The modified methods examined here can be used for measuring the refractive index of triangular prisms made of optically transparent materials, as well as of liquids poured into hollow prisms with plane-parallel transparent windows. Practical implementation of methods of this type should be useful in the optical, chemical, and food industries for monitoring the composition and properties of optically transparent materials.
In this article, goniometric methods for measuring the refractive index of optically transparent materials are discussed, and a modified method for measuring the refractive index of triangular prisms ...is proposed. A modified constant deviation method for measuring the refractive index was proposed in the previous study 1 that did not require refractive angle measurement of the prism and simplified the measurement process; however, its implementation required low-intensity radiation reflected from the input face of the prism, which created difficulties in processing signals from a photoelectric receiver and can increase measurement error. In this study, this problem was eliminated with the usage of two fixed mirrors to obtain the reflection of the refracted beam and determine the initial position of the prism, and the refractive index of the prism material was calculated from the solution of a system of equations. This approach avoids the use of radiation reflected from the prism faces, which helped in increasing the accuracy by automating the measurement process. Herein, the results of an experimental study of a triangular prism made of optical glass using the proposed modified prism method are compared with the values obtained using the least deviation method, which has the highest accuracy in determining the refractive index. The proposed method can be used to study triangular prisms made of optically transparent materials as well as optically transparent liquids poured in a hollow triangular prism.
Goniometric methods for measurement of the refractive index of optically transparent materials are considered. A modified constant deviation method is proposed for measurement of the refractive index ...of a trihedral prism. The proposed modified method does not require measurement of the refractive angle of the prism, which simplifies the measurement process compared to the widely used methods of minimum deviation (the Fraunhofer method) and autocollimation (the Littrow–Abbe method). To implement the method, a goniometric system was used, designed to measure angles formed by flat surfaces of objects. In order to obtain a reflection of the refracted ray, a fixed mirror was placed in its path, and the refractive index of the prism material was calculated from the solution of a system of equations. Results are presented for an experimental study of a triangular prism made of optical glass using the proposed method, and they are compared with results obtained using the method of minimum deviation. The proposed method of constant deviation can be used to study trihedral prisms made of optically transparent materials, as well as liquid optically transparent substances placed in a hollow trihedral prism.
The issues of metrological support of the instruments for measuring a two-dimensional spatial distribution (profile) of a unit of refractive index for solids are considered. A reference system has ...been developed, which is included into the State Primary Refractive Index Standard (GET 138-2021). The composition, principle of operation, and main metrological characteristics of the reference system, based on a digital interferometer for measuring a two-dimensional spatial distribution (profile) of the refractive index for thin sections of the preforms of graded-index glass fibers, are presented. The reference system according to GET 138-2021 provides the uniformity of measurements for the instruments used to measure the refractive index profile—so-called optical analyzers of preforms of the graded-index and optical glass fibers. The results of experimental studies of GET 138-2021 in terms of reproducing a two-dimensional spatial distribution of the refractive index unit are presented.
The composition, operating principle, and main metrological characteristics of GET 138-2021 State Primary Refractive Index Standard are presented. This standard provides uniform measurements of the ...spectral dependence and spatial distribution of the refractive index in solid and liquid substances within the extended wavelength range of 0.4–1.55 μm by means of using 12 replaceable light sources, a dynamic gonio-spectrometer equipped with a ring laser and an autocollimator-based null-indicator. Performance of highly accurate and reliable refractometric measurements constitutes an important scientific field that is crucial in improving the resolution of lenses and other optical instruments used in the optical industry, as well as in controlling quality and determining the composition of substances in the food, chemical, and pharmacological industries.
Based on the Jones matrix formalism, the paper describes the optical scheme of a single-pass homodyne displacement measuring interferometer with a quadrature principle of phase detection. The ...interferometer is based on the Michelson scheme, and quadrature signals are obtain using polarization optical elements. The interferometer is supposed to be used as part of a new domestic kilogram standard based on watt-balance for precision measurements of the vertical displacements and speed of the coil. The results of modeling the optical scheme of the interferometer in order to assess the influence of the imperfection of polarization elements on the accuracy of measurements and the quality of their alignment are considered. An algorithm for compensating for nonlinear effects arising from quadratic detection of interference signals is also implemented.
A system of four magnets which is a part of the SPASCHARM experimental setup at the U-70 accelerator facility for the study of spin effects in hadronic interactions is described. An unique magnet ...with the field of 2.4 T and a field uniformity at the level of 10
–4
in a working volume of 60 cm
3
is used to pump up and hold polarization in a polarized proton frozen target. A special wide-aperture magnet is the central part of the spectrometer of the setup based on the drift tubes. For precision steering the beam to the center of the target, two small magnets correctors developed by the Efremov Research Institute of Electrophysical Equipment have been manufactured and introduced into the setup.
In the previous work 1, the results of mathematical modeling of the optical scheme of a single-pass homodyne displacement interferometer with the quadrature principle of phase recording have been ...presented. The interferometer has been built according to the Michelson scheme and polarization optical elements have been used to obtain quadrature signals. The interferometer has been supposed to be used as part of a new national standard of the kilogram based on watt balance method for precision measurements of the displacement and speed of the coil in the vertical direction. This paper presents experimental studies of the operation of a homodyne quadrature displacement interferometer model. In this work, a conventional (non-polarization) beam splitter and two polarizers have been used in the optical scheme of a homodyne interferometer in the recording unit instead of a polarization beam splitter. This added additional degrees of freedom when aligning the optical channels for recording interference channels and has made it possible to achieve the required signal shift of 90° with an accuracy of 0.1°. As a result, a displacement measurement error of 0.2 nm has been experimentally achieved. Generalized expressions have been obtained for quadrature signals for arbitrary azimuths of polarizers in three channels of recording of interference signals. An assessment of the accuracy of displacement measurements using a quadrature homodyne interferometer has been carried out and it has been found that the extended uncertainty of such measurements does not exceed 0.3 nm.
Methods for measuring the salinity of sea water are considered. The results of an experimental study of samples of common and sea salt solutions with different salinity poured into a hollow trihedral ...optical glass prism are presented. The light refraction angles are measured with a goniometric system by use of which the minimum deviation method possessing a high accuracy of determining the refractive index is implemented. Using dispersion analysis of experimental results, it is proved that the refractive index of water does not depend on its salt composition. An equation describing the dependence of the refractive index on salinity and temperature for a fixed wavelength is proposed.
First results on
-dependence measurements in inclusive
meson production in
interactions (
, Al, Cu, Sn, and W) are presented at
GeV/
c
. The ratios of the differential cross sections of four of these ...nuclei to the differential cross section on aluminum were measured and the dependence of these cross sections on the atomic of the nucleus was studied. The measurements were carried out in the kinematic region of the Feynman variable
and transverse momentum
GeV/
c
.
mesons were detected in the decay mode
at the SPASCHARM experimental setup using negative charged beams at beamline 14 of the U-70 accelerator complex.
