On the Immersion Liquid Evaporation Method Based on the Dynamic Sweep of Magnitude of the Refractive Index of a Binary Liquid Mixture: A Case Study on Determining Mineral Particle Light Dispersion

Abstract

This is a feasibility study of a modified immersion liquid technique for determining the refractive index of micro-sized particles. The practical challenge of the traditional liquid immersion method is to find or produce a suitable host liquid whose refractive index equals that of a solid particle. Usually, the immersion liquid method uses a set of immersion liquids with different refractive indices or continuously mixes two liquids with different refractive indices, e.g., using a pumping system. Here, the phenomenon of liquid evaporation has been utilized in defining the time-dependent refractive index variation of the host liquid. From the spectral transmittance data measured during the evaporation process, the refractive index of a solid particle in the host liquid can be determined as a function of the wavelength. The method was tested using calcium fluoride (CaF) particles with an immersion liquid mixed from diethyl ether and diffusion pump fluid. The dispersion data obtained were consistent with the literature values thus indicating the proper functioning of the proposed procedure.

Image Information Obtained Using a Charge-Coupled Device (CCD) Camera During an Immersion Liquid Evaporation Process for Measuring the Refractive Index of Solid Particles

“…3 that the evaporation rate for immersion oil–diethyl ether mixture shows a nonlinear dependence on the time interval of the measurements range. This is different from the linear dependence obtained in Niskanen et al., 4 in which a different pair of immersion liquids was exploited. Nevertheless, since we measure the weight, and hence calculate the volume of the evaporated liquid using the density value, the linearity or nonlinearity of the liquid evaporation rate as a function of the time is not an issue.…”

“…Nevertheless, since we measure the weight, and hence calculate the volume of the evaporated liquid using the density value, the linearity or nonlinearity of the liquid evaporation rate as a function of the time is not an issue. Hence, we propose that the method using a balance to measure the weight loss of the immersion liquid is more general than the previous method, 4 because one can have different setups and even nonlinear evaporation rate. Yet, by detection of the volume loss we can get always an estimate for the refractive index of the evaporating immersion liquid at any time instant.…”

“…During the sweep of the refractive index, transmittance of light is detected with a spectrophotometer. 4 Here we suggest, in the frame of the immersion liquid evaporation, an alternative detection technique which is based on the use of image information detected using a charge-coupled device (CCD) camera. As far as we know, such a method has not been utilized with the aid of modern spectrophotometers and CCD camera techniques.…”

Measurement of Wavelength and Temperature-Dependent Optical Properties of Thermochromic Pigments

“…11,12 Recently, this approach has been receiving growing interests and widely used to determine optical constants of particles with the aid of multifunctional spectrophotometer. 13–17…”

“…11,12 Recently, this approach has been receiving growing interests and widely used to determine optical constants of particles with the aid of multifunctional spectrophotometer. [13][14][15][16][17] In the present study, the immersion liquid combining with a multifunction spectrophotometer was used to determine the unknown optical constants of thermochromic pigments. Three types of thermochromic pigments were embedded in water.…”