Wide-spectral-range laser refractometer

We present refractometric measurements made in the 266-1064-nm spectral region with a pulsed Nd:YAG laser, and the second, third, and fourth harmonics of the laser's fundamental wavelength. The critical angle is determined by the disappearance of the diffraction orders from a metal grating, forming a microcuvette with the prism's reflecting wall. A fused-silica measuring prism is used in the experiments.     

Analysis of errors of a three-channel laser interferential fluid refractometer

Translated from Izmeritel'naya Tekhnika, No. 5, pp. 25–28, May, 1990.     

Multifunctional laser interference refractometer for gas analysis

We describe a multifunctional laser interference refractometer designed for certification of gas mixtures over a wide range of concentration measurements. We give an analysis of the components of the error in measuring the concentration and determine the error limits for the 14 most commonly used binary gas mixtures. We formulate the error requirements for verification of a laser refractometer. Translated from Izmeritel'naya Tekhnika, No. 10, p. 65–69, October, 1997.     

Measurement of the density of atmospheric air with a laser refractometer

The results are presented of air density measurements in the pressure range 410 to 820 mm Hg. The measurements were made with a differential laser refractometer. The error in the density measurements was about 1.10^–5. An evaluation of the errors is made, in comparison with those in weighing and calculation methods.Translated from Izmeritel'naya Tekhnika, No. 3, pp. 34–35, March, 1995.     

Simple autocollimation laser refractometer with highly sensitive, fiber-optic output

A simple autocollimation scheme for a laser refractometer with a highly sensitive, single-mode, fiber-optic output is described. It allows for the determination of the refractive index and dispersion of optical materials with an accuracy exceeding 10(-5), which is confirmed by both experimental and analytical investigations.     

A liquid laser interference refractometer for measuring the concentration of solutions

A liquid interference refractometer is described. The results of an investigation of the instrument and of its practical use to measure the concentration of aqueous solutions of caprolactam are presented.Translated from Izmeritelnaya Tekhnika, No. 12, pp. 58–61, December, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Effect of the finite dimensions of the probing beam on measurements using a laser scanning refractometer

Translated from Izmeritel'naya Tekhnika, No. 8, pp. 40–42, August, 1992.     

Capillary refractometer integrated in a microfluidic configuration

We propose a microfluidic method to measure the refractive index of liquids. This method is based on the dynamic focusing by a capillary when liquids with different refractive indexes are inserted into it. Fabrication of such a refractometer has been done by encapsulating two fibers and a capillary. A calibration method is proposed.     

Skin hydration state estimation using a fiber-optic refractometer

A U-shaped fiber-optic refractometer is used to estimate the hydration state of human skin. The validity of the sensor in this application has been investigated by comparing the sensor output with the conductance of the skin to a high-frequency electrical current of 3.5 MHz, which has been reported to be a good measure of the skin hydration state. Results indicate that there is a relatively close relationship between the optical sensor output and the electrical conductance. A water sorption-desorption test conducted to confirm the above relationship has revealed that the fiber-optic probe can provide a convenient means for estimating the skin hydration state in an easy manner.     

A liquid autocollimation refractometer

A liquid refractometer based on a digital autocollimator is described. The results of an investigation, estimates of the errors in measuring the refractive index of liquids, and an example of its use to determine the concentration of aqueous solutions of sodium chloride are presented. __________ Translated from Izmeritel’naya Tekhnika, No. 8, pp. 50–53, August, 2006.     

Polarimetric optical fiber refractometer

An optical fiber refractometer based on a photometric return-path birefringence sensor is proposed. For measuring the refractive index, the phase shift between polarization components on total internal reflection inside a refractometric prism is used. Several kinds of refractometric prism are described. It is shown that a refractive-index sensitivity of 0.0001 and higher for a wide range of index values is attainable.