ASTM E 1967 : 2011 : REV A

1.1 This test method covers a procedure for measuring the refractive index (η_λ^t) 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 (η_λ^t) at any other wavelength other than the Sodium D line (η_D^t). This method employs a narrow band pass filter at 589 nm, but other filters could be employed using the described method and allowing the η_λ^t to be determined at other wavelengths, therefore, also allowing for the dispersion value to be calculated.

1.3 Alternative methods for the determination of η_λ^t are listed in Refs (1-5).

1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.5 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.