A display comprising an observer window, which in 3D and/or 2D representation mode of a 3D scene can be adapted to changing eye positions. Several observers can use the display simultaneously. The display includes a light modulation device having an actuatable diffraction unit and a controllable spatial light modulator, in which a 3D scene is coded in an actuatable manner, and a control unit. An observer window can be generated using coherent light beams on alternating eye positions. The diffraction unit includes at least electrodes and a controllable material into which a prism and/or lens function and/or scatter function can be written as a diffraction grating with a phase progression in an at least one-dimensionally controllable manner.