The use of the fine lens and the light source.
A light microscope uses focused light and lenses to magnify an object. Light microscopes come in several forms. (1) Simple light microscopes use a single lens to magnify an object and cannot reach high magnification just like a handheld lens whose highest clear magnification in the best conditions is 25x. (2) Compound light microscopes use two sets of lenses - an objective lens and an eye piece. This is the type of light microscope whose magnification power reaches between 1000x and 2000x.