The field of microscopy involves the use of microscopes to view various forms of microscopic particles and organisms (Sengbusch, 2003). At a basic level, the microscope is what allows researchers to see and study microorganisms in detail; without the ability to enlarge and enhance organisms smaller than what the eye can see, we would not be able to examine them and their structures and would have to rely on indirect observation to make conjectures about the various microorganisms' physiological processes, behavior, and interaction with each other and with multi-celled organisms. Microscopes come in varying types, including the optical microscope (which utilizes focused light and which most people are familiar with) and the electron microscope (which utilizes electron beams). Optical microscopes are limited by their ability to display lighter objects, but staining techniques are often used to enhance the visibility of biological specimens and optical microscopes are still widely used. Because microscopes are integral to microbiology, and optical microscopes in particular are still common, it is important for a microbiologist to know how to handle and use an optical microscope properly.
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The microscope should be carried by supporting it with your dominant hand under the base and holding the arm securely with the other hand (Maxwell, 2010). After setting the microscope at the lab station and turning it on, wait 3-5 minutes for the lamp to adjust itself, and then lock the specimen using the locking mechanism on the upper surface of the microscope stage. After locking the specimen, one should use the X-Y adjustment (located on the lower right-hand side) until the slide is directly over the diaphragm of the microscope (the lens structure used to eliminate stray rays of light). The knobs on the side of the microscope adjust the two topmost lenses, called the ocular lenses, located inside the microscope eyepiece. One should adjust the coarse focus (the larger of the two knobs) until the specimen is in view. One should adjust the fine focus until the detail of the specimen can be seen clearly.
Further clarity can be achieved by adjusting the power objective lenses; the nosepiece of the power objective structure is located under the ocular lenses. Rotate the nosepiece and then readjust the fine focus until the image is clear again. In order to get the clearest image, one might also use oil with the 100x objective lens in a process called oil immersion. When performing oil immersion, one should first rotate the nosepiece toward the 100x objective lens until it is just outside the light path. One should then place one drop of oil on the slide and rotate the 100x objective lens into the light path. Then one should once again use the fine adjustment knob to bring the specimen into focus and should not return the power objective to a lower strength.
When finished using the microscope, one should make sure that the microscope is clean. The100x objective lens will need to be cleaned after every use, and the other ocular, objective, and condenser lenses will need to be cleaned if they have also had contact with oil. The lenses should be cleaned using lens cleaner and lens paper; other kinds of paper can damage the lens and should not be used. After tearing off about ¼ of a lens paper sheet, one should wet one corner of the torn-off piece of paper, wipe the lens with the moistened corner, and then quickly dry it with another corner of the piece. One should then repeat the process as necessary for all of the other lens groups. Lenses should be returned to their proper places, the stage should be moved back to the lowest position, the microscope should be set to the lowest power objective, and the cover should be placed back on the microscope before returning it to the cabinet.
With proper care, the microscope can continue to serve as an integral part of the biological research process.
- Maxwell, R. 2010, posting date. Introduction to Microscopy. Georgia State University Department of Biology.
- Sengbusch, P. V. 2003, posting date. Microscopy. Botanik Online. http://www.biologie.uni-hamburg.de/b-online/e03/03.htm
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