Polarized light microscopy , forensic

During an examination under the stereomicroscope, particles of particular interest are isolated and mounted for examination by polarized light microscopy, typically the next step in a forensic microscopical examination. By this point, the microscopist typically has a good idea of the material being observed, or at least the class of material, which aids in the choice of method for mounting the particle for additional analyses. 

The identification and comparison of fiber evidence in the forensic laboratory can encompass a number of different techniques. Nondestructive examination of fibers by polarized light microscopy, microspectrophotometry, and PT IR spectroscopy very often provide a sufficiently high discrimination in most casework comparisons that other analytical tests are not needed. When a sufficient amount of fiber evidence exists, a comparison of fiber dyes by thin-layer chromatography (TLC) or HPLC will often further the discrimination. Auxiliary techniques such as PGC, PGC/MS, pyrolysis mass spectrometry (PMS), and SEM-EDXS are only sporadically used when the evidence or situation is required. 

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