Section Overview:
Although much neglected and undervalued as an investigative tool, polarized light microscopy provides all the benefits of brightfield microscopy and yet offers a wealth of information, which is simply not available with any other optical microscopy technique. As well as providing information on absorption color and boundaries between minerals of differing refractive indices obtainable in brightfield microscopy, polarized light microscopy can distinguish between isotropic and anisotropic materials. The technique exploits optical properties of anisotropy to reveal detailed information about the structure and composition of materials, which are invaluable for identification and diagnostic purposes.
Web Articles
- Crystals and Light - Posted by Steven Dutch, of the Natural and Applied Sciences Department at the University of Wisconsin in Green Bay, this site contains a significant amount of useful material about polarized light and its interaction with various forms of matter.
- Exploratorium: Snacks about Polarization - Check out this site to view stress patterns in plastic, find why the sky is blue, learn how polarized sunglasses work, and why sugar dissolved in water rotates polarized light. Exploratorium snacks are miniature versions of some of the most popular exhibits at the Exploratorium web site.
- Introduction to the Petrographic Microscope - As reference material for a course on petrography taught at the University of British Columbia in Canada, this site offers a glimpse of several optical petrography techniques. Included are an introduction to Becke lines and oblique illumination in polarized light microscopy.
- Introduction to Polarizing Light Microscopy - Developed by Janel L. Schrenk and John L. Bordley for students in the course Chemistry and Art at the University of the South, this tutorial explores the basics of polarizing light microscopy, in particular as it pertains to identification of pigments.
- Light Microscopy Forum: Polarized Light Gallery - A nice feature of Canadian microscopist Ron Neumeyer's web site, this gallery contains digital images of birefringent crystals captured with a polarized light microscope. Also included is a brief introduction to the technique.
- Minerals Under the Microscope - Created and maintained by Charlotte Gladstone with the help of Paul Browning, this introduction to polarized light microscope also touches on various aspects of mineralogy and crystallography. The website is operated by the Earth Sciences Department at the University of Bristol in the United Kingdom.
- Optical Mineralogy - Designed and maintained by a collaboration of researchers in Spain, this site reviews the study of birefringent materials with a petrographic microscope. Included are an introduction to polarized light microscopy, a discussion on polarization of light, details about conoscopic and orthoscopic observations, and a reference listing.
- Polarization and Birefringence - Sponsored by Halbo Optics in the United Kingdom, this site contains useful information about birefringence, polarized light, and includes a discussion of materials that display double refraction (birefringence). Although only a few paragraphs in size, this discussion serves as good reference material on these subjects.
- Polarized Light Island - Describing an exhibition containing a multitude of props that can be used to explore various polarization effects, this website is sponsored by the Exploratorium in San Francisco. A large light-box provides adequate illumination for all experiments, and there are links to the individual concepts covered in the exhibit.
- Polarized Light Microscopy of Asbestos - Providing a comprehensive analysis of asbestos identification with a polarized light microscope, this site also reviews OSHA regulations on asbestos. Included are a detailed description of how a polarized light microscope works to identify asbestos fibers and specific instructions for preparing specimens.
- Polarized Light in Nature and Technology - Sponsored by Polarized.Com, this web site covers a broad spectrum of topics in polarized light, both in theory and application. Topics included are: Polarized Sunglasses, Are Rainbows Polarized?, the Incredible Edwin Land, the Viking Sunstone, and a Modern Light Compass.
- Polarized Light Microscopy - Published by the Heart Valve Laboratory in the Department of Biomedical Engineering at the Lerner Research Institute, this discussion covers basic aspects of polarized light microscope. Included are a brief description of the technique with emphasis on applications in biology and medicine.
- Potato Starch in Polarized Light - The regular birefringent molecular structure of starch grains enables these tiny globules to be imaged under crossed polarized illumination with an optical microscope. This site contains several digital images of these beautiful assemblies taken under different conditions of polarized illumination.
- Splendor in Stones - A virtual exhibit of the New York State Museum, this gallery features petrographic digital images of rock thin sections. The exhibit explores the microscopic world inside rocks -- a beautiful, fascinating place. It is a world inhabited by minerals with a wild spectrum of colors, textures and shapes; a world where science intersects art.