ABSTRACT
For a long time, the light microscope was the only means to observe tissues and cells. But the light microscope has its limitations; it was not possible to obtain a magnification higher than 1000 and 2000, for the highest performing microscopes. The principle of the microscope is based upon the resolving power, still called resolution. Resolution is the smallest size of a detectable object, that is, the smallest distance between two points at which the two points can be separately observed. Under this distance, only one point is observed, one of them being hidden by the other.
