What Is A Polarizing Light Microscope: Peering And Understanding
You are inside the school’s laboratory and your science teacher asked you to identify microscopes. What is a polarizing light microscope, she said to the class. She asked what difference does it has over other microscopes and why it was called such. Will you know the answer to what a polarizing microscope is?
All you have to remember is that a polarizing light microscope is an optical device which applies two polarizers. These polarizers help in polarizing light in one surface while light surpasses the first filter as it approaches the specimen.
The crystalline parts of the specimen then revolve around the light. You will notice upon peering through the eyepiece that some of the light travels through the next polarizing filter making the crystalline parts brightly contrasted against the dim background. This makes polarizing light microscope different from other types of microscopes—different lens system and microscopy principle.
The Simplest Polarizing Light Microscope
Microscope experts say that the polarizing light microscope that has a polarizer between the condenser and light source is the simplest of this kind of microscope. Usually, you’ll find this polarizer oriented in east and west transmission directions horizontally across the microscope’s façade.
If you are wondering how the specimen is illuminated in such simple lens system, the answer lies within the vibration direction of the plane polarized light.
Another simple polarizing light microscope you ought to know is one that not only has an east-west polarizer in the middle of the condenser and light source, but also has a north-south analyzer. This analyzer is positioned between the eyepiece and the lens’ back focal plane.
The advantage of this polarizing light microscope is that since the polarizer and the analyzer meets or crosses pathways no light will be seen if there is no specimen in the slide. However, if you will place a specimen you will see the extremity of the dim background and the intensity of the sample.
Applications of the Polarizing Light Microscope
This light microscope has been regarded as very important in viewing thick polished samples like rocks, whereas other kinds of microscopes like the standard electron microscope can only be used in examining specimens that are extremely thin, because the multiple electron scatterings and movements is prone to the destruction of the projected image’s contrast.
This is the reason why applications of polarizing light microscope entail rock and mineral identification and medical tests analysis. In medicine, polarizing light microscope is important to view the microscopic crystals found in our urine. Also, scientific researchers in biochemistry make use of polarizing light microscope.
Geology and mineralogy also benefits from this microscope since through the existence of polarizers geologists can identify asbestos and study the mineral components of meteorites and other rocks.
How can unpolarized light become polarized?
You may be wondering how about unpolarized light be useful in viewing polarizing light microscope and how this has been the principle of such polarizing microscopy. Well, unpolarized light can partially be polarized through the aid of smooth dielectric surface’s reflection,this can be done by using glass or highway plane.
It was proven in the 1800s, through E. L. Malus’s discovery. Malus peered through a portion of quartz the reflected light seen in the Luxembourg Palace’s windows. He noticed that as he turned the piece of quartz around the brightness of the light reflected in the windows mitigated and was even totally dimmed at some angles of the rotation.
Thus, unpolarized light can also be polarized through dichroism, a process of seeing different colors through fractional light absorption when viewed in different directions or differing polarization.
Moreover, light can also be polarized through birefringence. This manner of transforming unpolarized light to polarized light was first introduced by Shinya Inoue in his discovery in the 1950s that spindles of dividing cells were made of filaments and not of membranes like what Keith Porter insisted. This method based on Inoue’s sign of birefringence then became the springboard of the study of polarized light microscopes.
Perhaps you wonder how Inoue came up with the conclusion that the spindle apparatus is not made of membrane, well through the sign of birefringence he found out that there exist an arrangement of atoms and molecules.
Birefringent materials and polarizing light microscope have the capacity to generate two plane polarized light waves from unpolarized light. These materials contain an optic axis. Such is thought of the axis across the point wherein materials appeared to be arranged.
If you are asked what is a polarizing light microscope all you have to remember is that it is a complex optical device with a simple light principle that makes geology and medicine successful.
