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As described above, a thin preparation of well-shaped prismatic urea crystallites can be oriented either North-South or East-West by reference to the crosshairs in the eyepiece. The thin sections show the original quartz nuclei (Figure 9(a-c)) on which the buildup of carbonate mineral occurred. At the highest magnifications (60x and 100x), even minute errors in centration can lead to huge differences in specimen placement as the stage is rotated. The polarizing microscope is a specialized magnification instrument. In order to match the objective numerical aperture, the condenser aperture diaphragm must be adjusted while observing the objective rear focal plane. When the specimen long axis is oriented at a 45-degree angle to the polarizer axis, the maximum degree of brightness will be achieved, and the greatest degree of extinction will be observed when the two axes coincide. This Polaroid filter, or polarizer, blocks the vibrations in either the horizontal or vertical plane while permitting the passage of the remaining plane of light. 32 related questions found. Crocidolite displays blue colors, pleochroism, and murky brown polarization colors. polarizing microscope disadvantages . The Brce-Khler compensator enables precise measurements of exceedingly small retardation values found in weakly birefringent organic specimens and low-strain glasses. Although similar to the common brightfield microscope, the polarized light microscope contains additional components that are unique to instruments of this class. The crossed polarizer image (Figure 9(b)) reveals quartz grains in grays and whites and the calcium carbonate in the characteristic biscuit colored, high order whites. Softer materials can be prepared in a manner similar to biological samples using a microtome. First-order red and quarter wavelength plates are usually mounted in long rectangular frames that slide the plate through the compensator slot and into the optical pathway. The first step in diopter adjustment is to either line up the graded markings (Figure 10) on eyepieces equipped with such markings or turn the eye lenses clockwise to the shortest focal length position. It is the standard microscope that is used in Biology, Cellular Biology, and Microbiological Laboratory studies. Some polarizers are held into place with a detent that allows rotation in fixed increments of 45 degrees. If the diaphragm is not opened again after conoscopic observations, the field of view is restricted when the microscope is returned to orthoscopic viewing mode. One of the most common medical applications for polarized light microscopy is the identification of gout crystals (monosodium urate) with a first order retardation plate. One of these beams (labeled the ordinary ray) is refracted to a greater degree and impacts the cemented boundary at an angle that results in its total reflection out of the prism through the uppermost crystal face.