ASTM International Standard Test Method for the Automated Determinaton of Refractive Index of Glass Samples Using the Oil Immersion Method and a Phase Contrast Microscope ASTM E1967-98(2003)

1.1 This test method covers a procedure for measuring the refractive index (ηλt) of glass samples, irregularly shaped and as small as 300 μg, for the comparison of fragments of a known source to recovered fragments from a questioned source. 1.2 This test method does not include the measurement of optical dispersion or the measurement of refractive index (ηλt) at any other wavelength other than the Sodium D line (ηDt). This method employs a narrow band pass filter at 589 nm, but other filters could be employed using the described method and allowing the ηλt to be determined at other wavelengths, therefore, also allowing for the dispersion value to be calculated. 1.3 Alternative methods for the determination of ηλt are listed in Refs (1-5). 1.4 This standard test method does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.