Forensic analysis of glass consists of the examination of two or more fragments to determine whether they have a common origin. Identifying broken glass fragments having a common source to the exclusion of all other sources may only be done if they can be physically matched together.
Submitted samples from a crime scene must first be confirmed as glass. Differentiating glass from plastic is done by examining relative hardness, solubility, and observation with a polarized light microscope. Once confirmed as glass, the examiner will perform an analysis of physical properties (color, fluorescence, thickness, curvature, density), optical properties (Refractive Index) and chemical composition. If a difference between questioned and known samples is found at any point in this process no further comparison is needed.
Reference: Scientific Working Group on Materials Analysis, “Initial Examinations of Glass”, http://media.wix.com/ugd/4344b0_292c63e8448a46eb84252b6e62603680.pdf, July 2004, accessed March 10, 2016.
1.Characterization of float glass by laser-induced breakdown spectroscopy (LIBS)
2.Forensic comparison of glass by laser-induced breakdown spectroscopy (LIBS)
3.Comparison of float glass by application of chemometrics to LIBS data.
For more information contact Dr. Michael Sigman and Dr. Matthieu Baudelet.