Polarized and Differential Interference Contrast (DIC) Microscopy
The term “polarized” light refers to the properties
of light waves in relation to the plane in which the
waves oscillate. A polarizer can be thought of as
an optical “screen” in which very fine slats are
made which only allows those waves whose
oscillations coincide with the orientation of the
slats to pass through and to exclude all waves that
oscillate in other planes.
Wavelengths of light
moving in the same
plane are said to be
“coherent”
By using polarizers arranged in orthogonal fashion
all light can be blocked. In such cases the filters are
said to be “cross-polar”
Thin slice of granite in polarized showing orientations
and positions of different grains.
Birefringence of microtubules
during cell division.
The silica spicule spines of pluteus
larvae of most echinoderms are
naturally birefringent and can be easily
seen in a polarized microscope.
Mitotic Spindles
Striated Muscle
(actin and myosin polymers)
Plant Cell Walls (cellulose and lignins)
Some protists with crystalline
Fat bodies in epithelial cells containing
structures in their cytoplasm
droplets of lipoproteins and proteins
which can be seen because of the birefringence
of the lipid, which produces maltese cross configurations.
The Wollaston prism splits the entering beam of polarized light into two beams
traveling in slightly different directions. The Wollaston prism is composed of two
quartz wedges cemented together, from which emerging light rays vibrate at 90
degrees relative to each other with a slight path difference. A different Wollaston
prism is needed for each objective of different magnification.
DIC (Nomarski) Image