Optical system with an ultra-compact LED module and low geometric etendue, a unique light guide, and Fresnel lens with an optical texture that can obtain 10% more light than with a conventional lens. Its optics/source assembly has been specially developed to ensure a perfectly homogeneous colour mix regardless of the colour blend selected. This optical combination is ideal for use with a lens or a beam ovalizer filter that is particularly suited to this type of application. Using a single source transmitting lens eliminates the multiple shadows projected.