Microscope can simple be refer an instrument that facilitate the visualization of microorganism. Microorganism are those organism that we cannot see with our naked eyes. Microscope is one of the most exorbitant and fragile instrument use in the clinical laboratory. Due to it exorbitant and fragility, it is advisable that microscope should only be handle by a well-trained laboratory personnel. Microscope are of different type and size, understanding basic principle of one will pave way to have an idea of the basic principle of the other, because despite the different in microscope, they still have the same mechanism of operation. Of all type of microscope, bright field microscope is the most commonly used microscope, as such we are going to look at the working principle of bright field also known as light microscope.
Working principle of a microscope
Microscope work by magnifying the object under investigation. Magnification is simple mean to enlarge the size of an object, there are many glass design to carry out magnification process, and those glass are called magnifying glass. Microscope that is made up of magnifying glass is called simple microscope. Essentially the common type of microscope use in the medical laboratory are often called compound microscope. The reason it been called compound microscope is because the microscope is made up of two or more magnifying glass. In compound microscope, it make use of the combining power of two or more magnifying glass to yield magnification of object under investigation. The glass that help in carrying out magnification of an object under investigation is called objective lens. Compound microscope basically have two lens, they are; Objective lens ocular lens.
As we said earlier, objective lens help to magnify the image of the object under investigation, further magnification is carried out by ocular lens, which is now view with eye.
Ocular lens is also called eye lens, as the name imply, is the point where the magnifying image is views with eye. Ocular lens, is the lens where direct eye visualization passes through to view the image magnify by objective lens. An object to be observe with light microscope must be very minute so that light can pass through the object. The object absorb some light directed from thee light source, why some of the light pass through the object, and contrast can be produce as a result of variation of light absorption by the different part of the specimen. Conversely, compound microscope optical system did not unravel details contrast from unstained specimen, as such there is the need of contrast enhancement by staining.