What is a Polarized Light Microscope?

Not a lot of people use polarized light microscopes. Some microscopists claim that this microscope is undervalued and neglected when compared to other investigative tools. Fact of the matter is that polarized light microscope offers just the same benefits as that of the brightfield microscope. It also gives researchers a wealth of information. The only problem is that it is not available with the other microscopy techniques.

A polarized light microscope distinguishes between anisotropic and the isotropic materials. This technique may exploit the optical properties in order to reveal the needed information regarding its composition and structure. If these aren’t obtained, it’s not possible to identify the element.

The application of polarized light microscopes often involves isotropic materials such as gases, unstressed glasses, liquids and cubic crystals. These elements show that the optical properties of the polarized light can flow in any direction – that they have a single refractive index, therefore no restriction whatsoever on the direction of the light and vibration passing through. On the other hand, anistotropic materials have 90 percent of solid substances that contain the optical properties that are very different from the isotropic materials. These demonstrate refractive indices dependent on the propagation and direction of the light on the specimen as well as the vibrating coordinates on the plane.

Above all, the anisotropic materials serve as the beam splitters which divide the rays into two. This technique is applied by the polarized light microscope. The interference of these light rays are re-united later on by going through the same path.

Polarized Light Microscope Applications
These microscopes are associated to geological applications – basically because they are needed in studying minerals, especially those that are in rock thin sections. On the other hand, it is also used in the study of other materials such as natural and industrial minerals, extracted or manufactured products, composites like ceramics, polymers, mineral fibers, cements and crystalline. It also observes the biological molecules like starch, urea, wood and even DNA. The technique in using polarized light microscope can either be quantitatively or qualitatively and it has been really helpful in geology, biology, medicine, chemistry and especially metallurgy.

Over time, the microscopist will understand the analytical techniques that are needed in polarized microscopy and this may then be more demanding than the other applications but look at the bright side – these are worth pursuing. This obtained information can be applied on the brightfield microscopy experiments and the awareness of these principles through the polarized light microscope is very essential to the effectiveness of the entire interpretation on the study of DIC or differential interference contrast (DIC) microscopy.

What is Polarized Light
Polarized light is best described as something similar to waves but they are made of light. These light waves vibrate at the right angles and toward the direction where light travels. This makes the whole traveling probable. It is coined as “Common” light. In a polarized plane, there is only one direction for the light and the vibration. In order to observe this, the polarized light microscope must be used because the human eye and the brain do not have the sensitivity to pinpoint where the vibration and the light goes. These can only be detected through a color effect. An example of which is the reduced glare that the polarized light microscope gives off.

A polarized light microscope has two filters – the polarizer and the analyzer. The polarizer can be located below the stage and it allows the vibration to go to a fixed direction which is left to right. This is also rotatable. On the other hand, the analyzer is aligned from up to down and is also rotatable. It can be moved depending on what the light path requires.

When both the polarizer and the analyzer are in the similar optical path, the vibration permitted by the polarized light microscope is set at the right angle. Therefore in this configuration, no light passes through the entire system and the dark field is visible on both eyepieces.

How to control the polarizer and analyzer?
These can be rotated in order to facilitate the centration of the stage. The optical axis of the polarized light microscope must be the center of the rotation and it should always coincide with the middle as well as the field that is being viewed.

The user must be stress-free whenever he produces the optical effects using the polarized light. If he is not focused enough, he would only strain the objectives and this can complicate the observations of the entire experiment.