The invention relates to an assembly for illuminating objects with light of different wavelengths in microscopes, automatic microscopes and devices for fluorescent microscopy applications. Said assembly comprises LED light sources for illuminating the objects, which are positioned in the illumination beam path of the microscope or device. A receiving element (6; 13) that can be rotated about a rotational axis (5) is provided with respective fixing elements (7) for at least one LED (3; 3.1). The receiving device (6; 13) is situated in a housing (1) that can be placed on or positioned in the device housing (18). A drive unit (9) for the defined adjustment of the receiving device (6; 13) is provided in such a way that the LED (3; 3.1) can be positioned in front of a light emission opening of the housing (1) with the respective focal point wavelength that is required for measuring and/or observation purposes.
