An illumination system includes a light guide having an entrance face, an exit face and an aperture in which a light source can be arranged Various elements are arranged in the light guide to increase the angle of light beams incident in the light guide with respect to the optical axis of the system and to create a homogeneous illumination at the exit face of the light guide. With this arrangement, the length of a given light guide is reduced, making the illumination system smaller, lighter and more compact with even illumination and a high optical efficiency. The illumination system can be included in a display system.