This paper seeks to give a vivid description of a microscope as important laboratory equipment. According to Tim McCreigh, (2005, p. 35), this instrument was invented by Anton van Leeuwenhoek as an instrument which uses visible light and magnifying lenses to examine small objects which are not visible to the naked eye. This equipment has become useful equipment especially in the science world and it is used by students, researchers and medical practitioners. A microscope has different parts that contribute directly or indirectly to the magnification function.First is the body tube which is a cylindrical upper part with two or more eye piece lenses at the base to bring the image to focus for the eye which is placed on the upper part.
The eyepiece is fixed both at the top and the bottom of the body tube. The eyepieces can be replaced or interchanged depending on the degree of magnification that one seeks to achieve. The common magnification powers are 2x, 5x and 10x which represents the number of times the original object placed on the lens will be enlarged.Second is the objective lens which is cylindrical in shape and contains one or more lenses to collect light from the object sample to be viewed.
The objective lenses are screwed at the base of the microscope tube to form a movable circular nose piece. The movable part is helps in rotating the nose piece when selecting the required objective lens. A simple microscope uses objective lenses of magnification powers 4x, 5x, 10x, 20x, 40x, 80x and 100x but objective lenses of higher power can also be used. Third is the stage which is the platform on which the specimen to be viewed is placed.The stage has a hole in the centre through which light passes to illuminate the specimen.
On the stage, the specimen is mounted on rectangular glass plates known as slides to hold it in position. The microscope uses illumination source directed from below the stage. This light can be from a controllable source or daylight directed through a mirror mounted under the microscope stand. A condenser is a lens that serves to concentrate light from the illumination source that is in turn focused through the object and magnified by the objective lens.The other part is a diaphragm which is a thin opaque structure with an opening at its centre.
The role of the diaphragm is to stop the passage of light allowing only light that is passing through the aperture. All of these optical parts are attached to a rigid arm which in turn is attached to a robust U shaped foot to give the whole structure stability, a microscope should be held by the base as its optical parts are very sensitive to touch or dust.The arm is able to rotate at the joint with the foot to allow for the adjustment of the viewing position. The image is adjusted by fine adjustment knob and course adjustment knob to give a fine or rough image respectively. (Tim McCreigh, 2005, p.
36). Conclusion A microscope can is generally a device that gives an enlarged image of an object or substance that is too small or not visible with the unaided eye. Only one eye should be used to view the specimen.
