Polarized Light Microscopy

Section Overview:

The polarized light microscope is designed to observe and photograph specimens that are visible primarily due to their optically anisotropic character. In order to accomplish this task, the microscope must be equipped with both a polarizer, positioned in the light path somewhere before the specimen, and an analyzer (a second polarizer), placed in the optical pathway between the objective rear aperture and the observation tubes or camera port. Image contrast arises from the interaction of plane-polarized light with a birefringent (or doubly-refracting) specimen to produce two individual wave components that are each polarized in mutually perpendicular planes. The velocities of these components are different and vary with the propagation direction through the specimen. After exiting the specimen, the light components become out of phase, but are recombined with constructive and destructive interference when they pass through the analyzer. Polarized light is a contrast-enhancing technique that improves the quality of the image obtained with birefringent materials when compared to other techniques such as darkfield and brightfield illumination, differential interference contrast, phase contrast, Hoffman modulation contrast, and fluorescence.

Review Articles

Interactive Java Tutorials

Polarized Light Virtual Microscopy Java Tutorials

Polarized Light Virtual Microscopes

When a birefringent material is placed between crossed polarizers in an optical microscope, light incident upon the material is split into two component beams whose amplitude and intensity vary depending upon the orientation angle between the polarizer and permitted vibration directions of the material. Use this link to explore our tutorials on polarized light microscopy.

Digital Image Gallery

Polarized Light Image Gallery

As a contrast-enhancing optical technique, polarized light is unsurpassed in the magnificent array of colors generated by interference of orthogonal light waves at the analyzer. Useful for observation of mineral thin sections, hairs, fibers, particles, bones, chemical crystals, polymers, and a wide variety of other specimens, polarized light can be employed both quantitatively as well as qualitatively. Visit this gallery to observe how polarized light can be employed to observe specimens that would otherwise be difficult to distinguish from the background.

Selected Literature and Web Resources

Contributing Authors

Douglas B. Murphy - Department of Cell Biology and Anatomy and Microscope Facility, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, 107 WBSB, Baltimore, Maryland 21205.

Edward D. Salmon - Department of Cell Biology, The University of North Carolina, Chapel Hill, North Carolina 27599.

Kenneth R. Spring - Scientific Consultant, Lusby, Maryland, 20657.

Mortimer Abramowitz - Olympus America, Inc., Two Corporate Center Drive., Melville, New York, 11747.

Maksymilian Pluta - Physical Optics Department, Institute of Applied Optics, 18 Kamionkowska Street, Warsaw, Poland, 03-805.

Matthew Parry-Hill, Robert T. Sutter and Michael W. Davidson - National High Magnetic Field Laboratory, 1800 East Paul Dirac Dr., The Florida State University, Tallahassee, Florida, 32310.