optical microscope

Last reviewed 01/2018

The light microscope is widely used to study the structure of cells. A light source at the base of the unit sends light rays up to a condenser lens. The lens focuses the light on a transparent and translucent plate just above it - the stage. Upon the stage is the tissue specimen that is being examined. It is cut until the thickness is only a matter of a few cell breadths.

The light passes through the specimen and is absorbed differentially across the surface of the cell; this produces contrast which is enhanced by the use of stains selective for individual components within the cell.

The light transmitted through the specimen passes up to an objective lens which diverges the rays, resulting in magnification. Finally, an ocular lens close to the eye magnifies a specific area of all the light that it receives.

The resolution of the light microscope is optimally about 0.3 micrometres.