The Unification of Becke Line and Dispersion Staining Techniques for the Determination of Refractive Index of Non-Opaque Materials

Abstract

Becke line and dispersion staining are the two major techniques for measuring the refractive index of non-opaque materials by the immersion method via polarized light microscopy. The immersion method has wide applications in many scientific disciplines that require the refractive index measurement of natural or man-made materials, such as geology, material science, biology, pharmaceutical science, forensic science, etc., and especially in the environmental science to identify asbestos minerals in building and construction materials as well as in their natural occurrences. Based on the two techniques' inherent relationship, this paper presents a unified quantification diagram applicable to both Becke line and dispersion staining techniques for the measurement of the refractive index of non-opaque materials. Issues relevant to the application of Becke line and dispersion staining techniques are discussed in detail. Also presented is a suite of tables, charts, and illustrations to facilitate the refractive index measurement of asbestos minerals.