Download our guide to achieve complete Koehler illumination. Aimed at helping scientists to get the best from their microscopes, it is one of the easiest (yet often overlooked) ways of seeing your preparation more clearly.
All too frequently, sophisticated and well-equippedmicroscopes fail to yield quality images because ofincorrect use of the light source. Illumination of a specimen should be bright, glare-free and evenly dispersed in the field of view. Koehler illumination provides bright, even illumination and is the method of choice for the majority of modern microscopes.
Koehler Illumination is a process that provides optimum contrast and resolution by focusing and centering the light path and spreading the light evenly over the field of view. To allow a microscope to be set up for Koehler, it must have two adjustable iris diaphragms: the aperture diaphragm at the substage condenser and the field diaphragm nearer to the lamp. The aperture iris diaphragm controls the angular aperture of the cone of light from the condenser, while the field iris diaphragm controls the area of the circle of light illuminating the specimen.
