From Big Medical Encyclopedia

ULTRAMICROSCOPE — opticheskpy the device for detection of the most fine particles (to 2 nanometers) in which an observed object is lit sideways. The particle which got to a light flux scatters light and is observed against the background of a dark field as a bright point.

For the first time this reception of observation of microparticles is described in 1740 by M. V. Lomonosov. At., in Krom light from an electric arch moved through a slot-hole opening perpendicular to an optical axis, is offered in 1902 avstr. scientists H. Siedentopf and R. Zhigmondi. In flowing At., designed in 1953 by the Soviet scientists B. V. Deryagin and G. Ya. Vlasenko, the flow of the studied liquid on a spaghetti goes towards to an axis of observation; at the same time the particle which is in current of liquid, crossing a zone of lighting, is registered visually or by means of photometric devices as bright flash. Later the design was offered, in a cut lenses of the lighter and an ultramicroscope are located mutually perpendicularly. An object (fluid or gel medium) is placed in the form of a drop directly on a lens of a lens. On the device U. differs from a usual biol. a microscope (see) hl. obr. on a way of lighting and a design of the lighter (condenser). For mikrobpol. and bacterial. researches widely use the bptsent-richesky condenser (kardiond-game-densor). The Bitsentrichesky condenser has two spherical deflecting walls (convex and concave), to-rye create the light flux which is not getting to a lens U.

For ultramicroscopy it is possible to use usual biol. microscopes with increase in X 400 — 600 on condition of creation of a dark field and strong side lighting by means of special condensers of a dark field (see. Dark field method).

At. does not allow to determine a form or structure of a particle by a diffraction spot (flash), but gives the chance to count quantity of particles, to see their movement and to judge their size (the geometrical sizes) on brightness of a diffraction spot against a dark background.

In connection with the invention of supermicroscopes (see the Submicroscopy) ultramicroscopes began to be applied less often, but as they are rather simple on the device and are cheap in operation, continue to use them in a number of branches of science (microbiology, bacteriology, etc.), for control of purity of free air, water, fluid and gel transparent mediums, and also for a research of colloid systems.

Bibliography: And p p e l t of. Introduction

to methods of microscopic examination, the lane with it., M., 1959; To about at z about in P. A. Bases of the analysis of disperse structure about! myshlenny pyly and the crushed materials, L., 1974. V. I. Belkevich.