How to use a Microscope - Essay Example

How to use a Microscope Introduction A microscope is a biological instrument designed to give finer details of an objectthat an observer could not see using naked eyes or a hand lens. An object under observation is a specimen. There are several types of microscopes including the light microscope. This microscope is also called the optical microscope uses light to illuminate a specimen. It is the most common of all microscopes since schools commonly use it for academic demonstrations. The microscope uses compound lenses in magnifying objects under observation. Lenses in a light microscope refract light during observation to make the specimen underneath seem closer (Colgren and Svedberg, 1989, 17). An electron microscope is another example of a microscope. It is also called the scanning electron microscope or the compound and is more powerful than the light microscope. The electron microscope can magnify specimens up to a magnification of five hundred thousand times its original size. Its high revolving power makes it possible for the user to observe objects that are too small beyond the use of a light microscope. This power enables the microscope to separate objects that lie close to each other. The electron microscope does not use light to illuminate it instead uses the negatively charged electrical particles. The electrons form a beam that illuminates the specimens makes the microscope an important research tool in the biology discipline. Electron microscopes that are more powerful magnify specimens up to two million times the size of original objects (Hartley and Gregory, 1964, 33). Stereoscope microscope uses the binoculars that enable the observer to view specimens with larger sizes compared to those observed using both the light and electron microscope. A transmission electron microscope makes use of electrons that pass through the thin specimens during observation. This is different from the electron microspore that electrons scan the surface of the specimens during observation. Handling and care of the microscope I. An observer should always use both hands when handling a microscope. During this process, one hand should hold the base to provide support while the other holds the limbs. II. The observer should never place a microscope very close to the edge of the table or bench where observation is taking place. III. The person using the microscope should never touch the mirror and the lenses with hands whether with gloves or bear hands. IV. To clean dirty lenses, the observer should use a special lens tissue cleaning paper. Alternatively, an observer can use the common tissue paper moistened with ethanol (Hartley and Gregory, 1964, 111). V. To clean other parts of the microscope, the observer can use a tissue paper or a soft cloth. VI. Before the observer starts using a microscope, he should make sure that the low power objective lens click into position in line with the eyepiece. He should also do this after using the microscope. VII. The observer should not wet any part of the microscope. VIII. The observer must always clean and store the microscope at a safe place free from dust and moisture. Functions of parts of a microscope The limb or the arm supports the body tube and the stage. The base- It gives affirm and steady support to the entire microscope. The Body tube- it holds the eyepiece the revolving nosepiece in position for proper use of the microscope during observation. The coarse adjustment knob- The observer the coarse adjustment knob to raise or lower the body tube when the specimen is located at a longer distance to bring the image into clear focus. (Hartley and Gregory, 1964, 21). The fine adjustment knob- The observer uses the fine adjustment knob to raise or lower the body tube through smaller distances during observation to bring the image into a clearer and sharper focus. The diaphragm- This is an aperture regulating the amount of light passing through condenser to illuminate the specimen in a light microscope. Eye-piece- It contains a lens that adds to the magnification of the specimen under observation. The Objective lens- This part magnifies and brings the image of the specimen into focus. The mirror-It reflects light through the condenser to the specimen under review. The revolving nosepiece- It holds the objective lens in position. This enables the change from one objective lens to another (Stehli, 1970, 77). The condenser- This part concentrates light on the object to the stage. The stage- This the flat form where the observer places the specimen when it is on the slide. It has two clips that hold the slide in position. General procedure There are four general procedures that an observer follows when using any type of microscope. The observer must make sure that no backpacks and other useless items are on the aisles. The user must plug the microscope into the extension cords with each row of desks using the same cord (Colgren and Svedberg, 1989, 54). The third procedure requires the observer to store the microscope after wrapping the cord around the microscope. The observer should make sure the objective clicks into position. The user should carry the microscope with hands, one holding the base and the other the arm, or limb. Magnification Magnification is the number of times the specimen under observation is enlarged to reveal the details within its structure using the microscope. A microscope has three levels of magnification. Scanning is the first, there is the low, and the third is the high magnification power. The magnifications are on the objectives and the eyepiece of the microscope. To get the total magnification of an object, the observer multiplies the eyepiece lens magnification by the objective lens magnification. Example If the eyepiece lens has a magnification of five (X 5) for instance, and the lower power objective lens has a magnification of ten (X 10), then the total magnification is fifty- (50). This results from a multiplication five and ten. Magnification Ocular lens Total Magnification Scanning 5x 10x 50x Low Power 11x 10x 110x High Power 60x 10x 600x Focusing the specimen on a light microscope i. The user should always start by scanning the objective. There are observables in the setting and he should use the coarse adjustment knob to focus and increase the clarity. Images seen by this magnification are small however; the step comes first for clarity at higher magnifications. The observer cannot skip this step. The user should not use clips on stage to hold the slides at this level instead he should move the slides round to make sure that he sees the components of the image that appear(Stehli, 1970, 83). ii. The user should switch to the low power magnification after the first step. He uses the coarse adjustment knob for further focussing during this process. The steps are procedural and they must one another successively. iii. The third stage requires the user to switch to the high power. When the user is reviewing specimens with thick slides and those without covers, he should not use the high power objective lenses during observation. The user should only use the fine adjustment knob to focus specimens at this stage. If the specimen appears very dark or light during the review process, the user should adjust the diaphragm to get the colour he requires. The observer can see a line through the viewing field. If this happens, he should twist the eyepiece and in the process, the line should disappear. Using a compound microscope Using a compound microscope differs slightly with the process of using a light microscope because it is more powerful and uses more than one convex lens. The lenses appear on two opposite ends of the tube. When the user moves the top part of the body tube, the process raises or lowers the eyepiece. This magnifies the image and puts it into focus. The user of the compound microscope needs to inspect it before use. The head has various optical elements that include the nosepiece, the eyepiece tube, the objective lens, and the eyepiece (Stehli, 1970, 41). On a compound microscope, the number of lens can be up to a maximum of five. The arm of connects the head to the base of the microscope. The stage carries slides with specimens during observation and has the illuminator and the focusing knob. Preparation of slides Preparation of the slide entails placing the sample between two pieces of glass. The observer then places the slide at the centre of the stage surrounding the hole of the glass. This allows proper illumination of the specimen. To secure the specimen on stage, the user of the microscope must move the clips that are on stage to make sure they hold the specimen firmly. Focusing the image The user needs to look through the eyepiece during the review process to focus. He should adjust the source of light to get the right amount of light necessary for observation. Brighter illumination gives a better focus but the effect of the same on the user is important. The user should use the coarse adjustment knob in a reverse direction as he did earlier. This automatically moves the stage away from the lens. The process should be slow until the specimen comes into focus. Using the fine adjustment knob makes the focus of the image clearer. Magnification of the object using the compound microscope requires that the user should reposition the slide with the specimen for direct review. Trouble shooting The user of any microscope may encounter problems in the process of reviewing specimens. Some of these include the image appearing very dark. In this case, the user should adjust the diaphragm to make sure that the light is on. Brighter illumination makes the focus of the image clearer (Stehli, 1970, 113). The other problem is that the reviewer can see a spot in the viewing field even after several movements. This problem shows that the lenses are dirty and the observer should use the necessary cleaning paper to clean it thoroughly. When the observer does not see anything while using the high power magnification, it means that he skipped a stage during his shifting from one stage while focusing. Works Cited Colgren, John, & Marilyn Svedberg. How to Use a Microscope. London: United Learning, 1989. Hartley, Gregory. How to Use a Microscope. Garden City: Natural History Press, 1964. Print. Stehli, Georg. The Microscope and How to Use It. New York: Dover Publications, 1970. Print. Read More