An optical microscope can do more than magnify small objects. It can examine a subject's interaction with light, which can provide information about structure and characteristics of the sample. A polarizing light microscope is equipped with a polarizing light filter so that the light striking the sample is linearly polarized—that is, the light waves vibrate in one specific direction. Under polarized light, it is possible to investigate crystal structure.

Polarized light microscopy is often the first technique used to analyze the structure of objects. It is an important instrument in authentication of paintings. GCI scientists have used it to examine pigments from a painting by Mantegna, illuminated manuscripts, and corrosion on a prototype display case.

Applications:

Polarized light microscopy is frequently used to identify paints and pigments in old master paintings and in murals. It is also used to examine ancient metallic samples and cross-sections of paint.

Further reading:

Scott, David A. "The Verisimilitude of Verdigris." Reviews in Conservation (Sept. 2001).