Polarized light microscopy is a non-destructive technique which uses plane-polarized visible light to interrogate samples. The morphological character of a sample may be obtained by PLM as well as information about homogeneity, crystal structure, origin (natural versus synthetic). Additionally, with the addition of components such as hot stages and index matching oils, the refractive index of materials may also be determined by PLM.
While most broadly used in the fields of geology and materials science, PLM can also be applied to forensic, pharmaceutical, and biological samples as well. The combination of information obtained from PLM alone can often be used to identify unknown materials.