Chromatic dispersion and thermal coefficients of hygroscopic liquids: 5 glycols and glycerol

TL;DR

This study measures the chromatic dispersion and thermal coefficients of six hygroscopic liquids across a broad wavelength and temperature range, providing detailed data and fitting models for their optical properties.

Contribution

It offers new experimental data and analysis on the optical and thermal properties of six hygroscopic liquids, including fitting Sellmeier equations for each temperature.

Findings

Refractive index dependence on wavelength and temperature can be considered independent.

Thermal coefficients show weak wavelength dependence.

Sellmeier equations fitted for each temperature.

Abstract

Chromatic dispersion and thermal coefficients of 6 hygroscopic liquids: ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol (propane-1,2-diol), and glycerol were measured in the range from 390 to 1070 nm for temperatures from 1 to 45degC. A modified Abbe refractometer was utilised. Special care was taken to avoid contamination of the liquids under the test with water and solid particles. The measurement uncertainties were analysed. It was noticed that (in the given range and within the available measurement accuracy) the dependence of the refractive indices on the wavelength and temperature could be considered independently. Thus, thermal coefficients were found for each wavelength used, and their weak dependence on the wavelength was recognised. Then the Sellmeier equation was fitted to the experimental results for each temperature.