Ultramicroscope

Name:
Ultramicroscope
Detailed information:
A development of the compound optical microscope invented in 1903 by Zsigmondy and Siedentopf. Its essential feature is a strong light beam from an arc lamp, focused by passing through two lenses, which illuminates the specimen at right angles to the axis of observation. The presence of suspended colloidal particles as small as 5 microns is detectable because of the light-scattering effect of the particles as they move about in the suspension (Tyndall effect). Since the light reflected or scattered by the particles is the only light that enters the microscope, the particles appear as points of light against a dark background (dark-field illumination). There is no resolution of individual particle shape or size; the instrument shows only that particles are present. The ultramicroscope has been of great value in the study of colloidal suspensions, such as rubber latex, and of various biological phenomena; its usefulness has diminished since the advent of the electron microscope.See Tyndall Effect.