GB379228A - Improvements in devices for dark-field illumination of microscopic objects in incident light - Google Patents

Abstract

379,228. Microscopes. ZEISS, C., [Firm of], Carl-Zeiss-Strasse, Jena, Germany. Feb. 22, 1932, No. 5196. Convention date, March 3, 1931. [Class 97 (i).] A dark ground. illuminator to be attached to a microscope tube, and to be used in conjunction with a lateral source of light, consists of a reflector having one or more plane surfaces inclined to the axis of the objective and directing the rays into the viewing direction, and a reflecting system causing the rays to converge approximately to a point, the reflector and the reflecting system comprising a single constructional element encircling the objective. In Fig. 1 a housing 1 fitting round the objective 15 and attached thereto by a bayonet fastening, contains a right-angled prism 2, the silvered face 3 of which reflects light from a source 10 and directs it parallel to the axis of the objective, the light being received by a paraboloidal reflector 5 cemented to the prism 2, and thereby converged approximately to a point. The reflectors have a central aperture through which the objective passes. The housing 1 has a cylindrical extension 7 forming a mount for a lens 9 at the focus of which is the lamp 10 mounted in a cap 13 attached to the housing. In Fig. 3 the single prism of Fig. 1 is replaced by two prisms 21, 22 having reflecting surfaces 23, 24 which may receive light from separate sources. The housing 18 is attached to the objective by a screw 28 entering a groove 29 so that it can be rotated around the axis of the objective to vary the azimuth of the illumination. In another form the plane reflector consists of a prism of equilateral cross section with two reflecting surfaces each of which serves as a light-entrance face for the other.