GB866437A - Improvements in or relating to microscopes - Google Patents

Abstract

866,437. Microscope condensers. COOKE TROUGHTON & SIMMS Ltd., and PAYNE. B. O. Oct. 21,1957 [Oct. 19, 1956], No. 31931/56, Class 97(1) A condensing lens system for a microscope is capable of producing bright field illumination, phase contrast illumination, or dark ground illumination and includes a catoptric element, a first surface of which is disposable adjacent the microscope slide whilst one or more further surfaces is or are disposed adjacent a dioptric element, and means for relatively displacing said elements between a bright field and phase contrast illumination position in which light incident on the dioptric element is refracted so as to be incident on the catoptric element as a convergent cone which passes therethrough without reflection, and a dark ground illumination position in which an annular light beam incident on the dioptric element is refracted so as to be incident on the catoptric element as a hollow divergent cone which is internally reflected within the catoptric element to emerge therefrom as a hollow convergent cone of apical angle substantially greater than that of the first mentioned convergent cone. As shown, the catoptric element 1 comprises an annular reflecting surface 10 supporting a cover glass 9, a spherically curved reflecting surface 11 and a spherical surface 12, whereas the dioptric element 2 consists of lens components 3, 4 and 5. The element 2 is mounted in a sleeve 7 having an external rack 17 engaged by a pinion 18 on a spindle which is carried by and projects outside a sleeve 8 to which is clamped a bracket 14 supporting the element 1. Thus, by rotating pinion 18, element 1 can be moved axially relatively to the element 2 to the_ positions giving the desired kind of illumination. The sleeve 7 is connected to an arrangement 22 which includes a rotatable disc 23 having five apertures therein, in four of which are seated rings 37 carrying annular diaphragms of different dimensions. The rings are held in these apertures by resilient tongues provided on an aperture plate secured to the disc 23. A detent device is provided to define the positions in which a selected diaphragm or the unoccupied aperture in disc 23 will be disposed below the element 2.