Polarizing microscopy

Polarizing Microscopy
Uses and Models in Light Microscopy

Brief Description
A polarizing microscope is a correct choice for birefringent materials, which have measurable refracting differences determined by observation direction. These anisotropic objects and substances can be studied under a polarizer. It increases the quality of image contrast more than other observation techniques like dark or brightfield illumination, fluorescence and phase contraste. Polarized light cannot be seen by human eyes in normal circumstances. But it can be be used in polarized light microscopy to highlight features of minerals and other materials.

What is a polarizing microscope?
A petrographic microscope is usually a modified compound microscope. However we also have the existence of such microscopes like a stereo microscopes which can also be altered to achieve polarization.

Differences between polarizing microscope and other microscopes
•	A polarizer and analyzer •	A circular rotating stage •	Special plates placed between the object and light path. •	Bertrand lens

A polarizer is an instrument that only allows specific light waves or vibrations to pass through it. An analyzer, often a second polarizer located above the sample, and determines the amount and direction of light that illuminates a sample.

Basically the polarizer focuses in the different wavelengths and vibrations of light in a single plane (polarized light flows in just one plane, In polarized light, the light waves vibrate in one direction; in normal light, the light waves vibrate in random directions.). The relationship of the polarizer and analyzer determines the amount of light absorbed, reflected, refracted and transmitted through the microscope. A polarizing microscope can employ transmitted (Transmitted light refers to the light diffused from below the specimen. This light is often passed through a condenser, which allows the viewer to see an enlarged contrasted image) and reflected light (sometimes referred to as incidental light, is best used for opaque samples, like metals, alloys, composites and mineral sulfides and oxides).

Important Applications
It is primarily used in the field of geology or petrography for the study of rocks and minerals, however it could eventually have many other applications like:

-Medicine -Chemistry -Biology -Metallurgy Materials under polarized light -minerals, ceramics, polymers, wood, urea and numerous opaque and thick sepecimens -Common substances/specimens, both of natural and synthetic fibers display birefringent properties and illumination between crossed polar filters. -Cellophane, crumpled up and stretched thin as well as sand are fascinating colorful subjects. -many botanical and insect specimens display beautifully in polarized light. -Fish scales

Objective of polarized Ligth
Polarization techniques give to the researchers the necessary information on color absorption, structure, composition, light refraction and other information (general) of isotropic and anisotropic substances. Anisotropic materials are solid substances that have several refractive indices; isotropic materials, which includes gases and liquids, have only one refractive index. Birefringence or double refraction occurs when a light wave passing through an anisotropic material is split into two rays of differing velocities.

Pathway of Light
1.	The light passes through a polarizing filter called the polarizer (the polarizer is fixed in an east to west vibrational way, but it can be rotated if necessary. There is one more polarizing filter called the analyzer. It is usually situated above the objectives and can be moved in and out of the optical path) 2.	 Passes through the birefringent specimen. The polarizer is usually fixed in an east to west vibrational direction, but it can be rotated as required. There is one more polarizing filter called the analyzer. It is usually situated above the objectives and can be moved in and out of the optical path.