Advantages of Polarized Light Microscopes

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The advent of microscopes made scientists realize that there are so many new worlds apart from our own, small worlds of microorganisms, viruses, atoms, protons and neutrons that go unnoticed by our eyes every day. However, these microorganisms and micro particles are the fundamental elements of everything that’s there in the world today including us. Understanding these tiny particles can shed more light on our origin, existence and life itself. And the role of microscopes in helping mankind to reach new technical and medical heights is immense. Optical microscope, X-ray microscope, Scanning Acoustic microscope, Electron microscope, Neutron microscope are a few of the most used microscopes today.

Polarized Light Microscopes – Overview

Polarized light microscopes are a type of optical microscopes that involve polarized light for better understanding and visualization of materials that are anisotropic and birefringent. Polarizing microscope has a wide range of applications in the field of visual mineralogy and geology to inspect, analyze and understand tiny particles like minerals and crystals. Considering their advantages in visualizing anisotropic and birefringent particles, these microscopes are also widely used in medical and biological fields today.

Working of Polarized Light Microscopes

What differentiates these polarized light microscopes from regular laboratory microscope is the fact that they use polarized light which cannot be seen by naked eyes and which has waves vibrating in a single direction. The normal light that we see has waves that vibrate in all random directions and for analysis of materials that are anisotropic i.e. ‘direction dependent’, using the regular light microscope is impossible. To analyze these direction dependent materials that exhibit different properties in different directions, a polarizing filter has to be used to configure the direction of light waves and force them to vibrate in a single direction. Any optical microscope that uses these polarizing filters is known to be a polarized light microscope (en.wikipedia.org/wiki/Polarized_light_microscopy). A fixed polarizer known as the ‘Polarizer’ is placed between the light source and the specimen and an adjustable polarizer known as the ‘Analyzer’ is placed between the objective and the eyepiece. Both polarizer and analyzer are placed 90 degrees apart and they together help in analyzing anisotropic and birefringent particles by suppressing vibrations of natural light in random directions and polarizing them into a single direction.

Advantages of Polarized Light Microscopes

• Polarized light microscopes are the default choices for study of tiny particles in the field of visual mineralogy. Materials like crystals and fibers are anisotropic and birefringent in nature and using other high-end techniques like X-ray diffraction and scanning electron microscopy to analyze these materials wouldn’t give promising results.

• Geology, Pathology and recently even Biology, Asbestos Testing and Forensic Sciences use polarized light microscopes. In fact, in routine asbestos pathology, these polarized microscopes are mainly preferred for their high-precision and cost-effective qualities.

• Fibers, crystals and minerals are the most commonly examined materials in visual mineralogy and medical specimens like bone, teeth, striated muscle, urine crystals, gout crystals and amyloids also need polarized light microscopes to be examined. Using any other microscopes for analyzing these specimens can produce varying results.

• These microscopes are especially known for their anti-reflective and anti-scratch properties. In earth and material science applications, analysis of birefringent and anisotropic particles requires high integrity of light transmission and involves critical aspects such as internal reflections that can be only addressed by polarized light microscopes.

• These microscopes provides crucial information regarding refractive index, birefringence, sign of elongation, pleochroism, and angle of extinction of the crystals under study. No other microscope can provide information on this depth and importance in the field of crystallography.

• They have an elegant external design and advanced internal applications that are well suited for the study of crystals and minerals. The polarizer filter can be rotated and is fixed in the light path beneath the specimen and usually below the stage. The analyzer is placed 90 degrees apart from the polarizer and can be pushed in or out of the light path according to the user needs.

• They have a large circular stage with two locking brakes to deliver a smooth 360 degrees of rotation. In addition, the circular stage is stain free to avoid any optical impurity come in the way of the polarized light. Two compensator plate slots and two centering tool slots are provided in addition to prevent unwanted loss of accessories.

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