B is a side view of a detail of the illumination system shown in FIG. 2A; [0025]FIG. 3A is a cross-sectional view of an alternative example of an illumination system in accordance with the invention; [0026]FIG. 3B is a side view of a detail of the illumination system shown in FIG. 3A; and [0027]FIG. 3C is a cross-sectional view of a further detail of FIG. 3A.