Ultramicroscope, special microscope used for studying colloidal particles (particles in solution or suspension) too small to be seen with a regular-light microscope. A high intensity light beam originates not from the bottom of the instrument as with an ordinary microscope, but from the side. As this beam passes through the solution or suspension, the colloidal particles scatter the light, producing tiny dots of light that then can be seen against a dark background. The ultramicroscope, however, cannot provide the viewer with any structural detail of the particles.
See also: Microscope.