Illumination device for synthesizing light from an object at virtually infinite distance

An illumination device for synthesizing light from an object at virtually infinite distance comprises a primary light source configured to emit a primary light, a concentrator positioned downstream the primary light source and configured to reduce the divergence of the primary light, an emitting surface positioned downstream the concentrator, and an absorber made of light-absorbing material positioned upstream the emitting surface and configured to absorb light rays which cross the emitting surface in an upstream direction and which, in the absence of the absorber would not be directed toward the primary light source, wherein the primary light source, the concentrator, the emitting surface and the absorber are configured so that they produces from the primary light an output light that exits the emitting surface with a luminance profile which is spatially uniform across the emitting surface, and has a narrow peak in the polar-angle distribution around an output-light direction.