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Click Here For Best Selection Of High Quality Polarizing Microscope

Click Here For Best Selection Of High Quality Polarizing Microscope

In optical mineralogy, Convergent Light is usually obtained by passing the rays of polarized light through a strong condensing lens of petrographic polarizing microscope. This lens generally fits like a cap over the top of the polarizer. The condensing lens of the polarizing microscope can be brought very close to the lower surface of the section on the stage by means of a suitable adjustment. As described in optical mineralogy books, this

condensing lens sends a cone of light through the section being evaluated under the polarizing microscope. A series of optical phenomena called interference figures are produced between crossed nicols of petrographic polarizing microscopes.

 

            A minute bundle of parallel rays traverse each direction in which rays are sent. And these rays, when evaluated between crossed nicols extinguish and produce interference colors. It can be noticed more clearly under polarizing microscope that each direction yields a spot or picture in the field of view of the microscope. A picture or interference figure may be found from these spots when combined. This would depend also upon the structure of the section for all the directions traversed by the rays.

 

            As suggested in optical mineralogy, a high power objective lens of petrographic polarizing microscope must be used in doing the evaluation. It can be noticed that when the eyepiece of the microscope is removed, a small image of the interference figure will be found. In some petrographic polarizing light microscope, by retaining the eyepiece or by using an additional Bertrand Lens, a magnified image of the interference figure can be obtained.

 

            As a general rule in optical mineralogy, care must be taken to have strong illumination and the condensing lens of the polarizing microscope should be close up under the section in order to get good results. With the use of monochromatic light, the tests are best made. With the use of white light on the other hand, the effects are substantially the same. The only difference that noticeably occurs is that, the rings and curves are variously colored instead of being simply light and dark.

            It is also very important to note that interference figures are not found in isotropic minerals.



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Monday, April 28th, 2008 at 3:20 am
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Optical Mineralogy
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Click Here For Best Selection Of High Quality Polarizing Microscope