TRANSILLUMINATION DEVICE AND METHOD FOR LIGHT MICROSCOPES, AND A MICROSCOPE SYSTEM

An apparatus and method for transmitted light illumination for light microscopes having changing effective entrance pupil of an objective. The apparatus has a light source for emitting an illuminating light beam, wherein a beam path of the illuminating light between a diaphragm edge and a sample held by a holding device is free from adjustable beam focussing components. In order to adapt the beam path of the illuminating light to the effective entrance pupil of the objective, the diaphragm edge may be variably positioned in the direction of the optical axis, wherein a position of the diaphragm edge in the direction of the optical axis can be varied irrespectively of a position of the diaphragm edge transversely to the optical axis.