A system (50, 60, 70, 80, 90, 120) for disinfecting a surface comprising: an illuminator (40, 40A, 40B) including: a parabolic reflector as a reflective mirror; and a set of ultraviolet radiation sources located within a proximity of a focus point of the parabolic reflector, the set of ultraviolet radiation sources configured to generate ultraviolet radiation directed at the parabolic reflector; a reflective surface (54, 64, 74, 84, 124) located adjacent to the illuminator (40, 40A, 40B) to direct an ultraviolet radiation beam towards at least 50% of the reflective surface (54, 64, 74, 84, 124); wherein the reflective surface diffusively reflects at least 30% of the ultraviolet radiation; characterized by a set of optical elements (32, 66, 76A, 76B, 76C) located between the illuminator (40,40A, 40B) and the reflective surface (54, 64, 74, 84, 124), the set of optical elements (66, 76A, 76B, 76C) configured to direct the ultraviolet radiation beam towards at least 50% of the reflective surface (54, 64, 74, 84, 124); wherein the set of ultraviolet radiation sources are coupled by a diffusive waveguide structure located together with the ultraviolet radiation sources in the proximity of the focal point of the parabolic reflector, wherein the set of optical elements (32, 66, 76A, 76B, 76C) includes a first lens (66, 76A) and a second lens (66, 76B, 76C), wherein a focal length of each lens (66, 76A, 76B, 76C) is comparable to a diameter of the ultraviolet radiation beam, and wherein the second lens (66, 76B, 76C) is movable with respect to the first lens (66, 76A). an illuminator (40, 40A, 40B) including: a parabolic reflector as a reflective mirror; and a set of ultraviolet radiation sources located within a proximity of a focus point of the parabolic reflector, the set of ultraviolet radiation sources configured to generate ultraviolet radiation directed at the parabolic reflector; a parabolic reflector as a reflective mirror; and a set of ultraviolet radiation sources located within a proximity of a focus point of the parabolic reflector, the set of ultraviolet radiation sources configured to generate ultraviolet radiation directed at the parabolic reflector; a reflective surface (54, 64, 74, 84, 124) located adjacent to the illuminator (40, 40A, 40B) to direct an ultraviolet radiation beam towards at least 50% of the reflective surface (54, 64, 74, 84, 124); wherein the reflective surface diffusively reflects at least 30% of the ultraviolet radiation; characterized by a set of optical elements (32, 66, 76A, 76B, 76C) located between the illuminator (40,40A, 40B) and the reflective surface (54, 64, 74, 84, 124), the set of optical elements (66, 76A, 76B, 76C) configured to direct the ultraviolet radiation beam towards at least 50% of the reflective surface (54, 64, 74, 84, 124); wherein the set of ultraviolet radiation sources are coupled by a diffusive waveguide structure located together with the ultraviolet radiation sources in the proximity of the focal point of the parabolic reflector, wherein the set of optical elements (32, 66, 76A, 76B, 76C) includes a first lens (66, 76A) and a second lens (66, 76B, 76C), wherein a focal length of each lens (66, 76A, 76B, 76C) is comparable to a diameter of the ultraviolet radiation beam, and wherein the second lens (66, 76B, 76C) is movable with respect to the first lens (66, 76A).