Illumination system for light microscopes

Claim 1

In an illuminating optical system for illuminating an object in a microscope utilizing Kohler''s method comprising, a light source; a collector lens for forming the image of the light source; a plurality of interchangeable condenser lenses; each condenser lens being alternatively moved from an inoperative position in which the condenser lens is out of the optical axis into an operative position position in which a focal point of said moved condenser lens is located about at the point in which the image of the light source is formed, said object being illuminated by the light passing through one of a plurality of condenser lenses, which is in the operative position thereof; a plurality of interchangeable objective lenses; each objective lens being arranged in paired relation to each condenser lens and alternatively moved together with the paired condenser lens into an operative position for forming the image of the object, a plurality of interchangeable aperture stops; each aperture stop being arranged in paired relation to each condenser lens between the condenser lens and the collector lens and having an aperture opening corresponding to the magnification of the corresponding objective lens and being movable together with the corresponding objective and condenser lens pair, each aperture stop being located at the focal point of its corresponding condenser lens, a field stop being disposed at a conjugate point relative to the object between said collector lens and the aperture stop which is in the operative position thereof; an eyepiece for enlarging the image of the object; the improvement residing in that the ratio of the focal length of each objective lens to that of the paired condenser lens is equal.