Prism refractive index measurement at INRiM

Abstract

A simple method to measure the refractive index of a glass prism with very low uncertainty was developed at INRiM. The method is a modification of the classical minimum deviation method. A brief description of the methods used to measure the vertex angles of the prism and the angle of minimum deviation is reported together with the uncertainty evaluation. The technique is going to be validated by a comparison between INRiM and two other laboratories. A relative standard uncertainty better than 1 ppm has been obtained.

Characterization of PbO-B2O3-GeO2-La2O3 and PbO-B2O3-SiO2-ZnO glasses: refractive, acoustic, photo-elastic and acousto-optic properties

“…Another technique applied to measure the refractive indices is a refractometric method, which is based on a Littrow prism arranged under condition of autocollimation [13][14][15][16]. The simplicity of optics inherent to this technique and the measurement accuracy achieved are comparable to those of a commonly known minimum-deviation method.…”

Refractive Index Determination for a Plane Dielectric Layer Using the Measurements of Transmitted Beam Intensity

“…However, using of data on measuring of such coefficients for two different polarizations, provides the opportunity to solve this problem independently on the layer thickness, like it made in [17,18] for determining of the absorption coefficient using the amplitude coefficients of reflection and refraction. Note that in the values |T H | 2 and |T E | 2 (3), one can construct the function, which is not dependent on the thickness: (4) where:…”

“…To improve its sensitivity and decrease calculation error at great values of the refractive index, one can increase the angle of incidence for radiation on the surface of the testing layer. Under increase of this angle, the difference between transmission coefficients for various polarizations (3) increases, what causes to increase of derivative value for the curve, representing the function (4). Up to here, we have considered the case of a perfectly transparent testing layer at the absence of absorption.…”

“…For its solving, one applies various techniques. There are refractometric ones (using also the phenomenon of total internal reflection) [1, [2][3][4], interferometric methods (utilizing the phase relationships between various coherent fields after transmission and reflection from the testing material) [1, 2, 5, 6] and others [7][8][9]. This topic acquires new importance last years due to development of study of heterogeneous disperse systems, i.e.…”

A multimode fiber refractive index sensor

“…The principal techniques employed for measuring RI, an optical phenomenon, consist of prisms [2][3], fiber-based surface plasmon resonance (SPR) [4], microstructured fiberbased SPR [5], Fresnel reflection at an optical fiber interface [6][7][8], fiber Bragg grating [9][10], fiber ring laser [11], nanometric plasmonic [12], multimode fiber [13][14][15], and tapered multimode optical fiber [16].…”