is a photometry chart for the oled 1 on its own the diagram b in fig3 is a photometry chart obtained with the oled 1 and the lens 11 placed in front of it in accordance with the invention as can be seen the invention enables the photometric distribution to be optimized and thus the efficiency of the optical device 10 to be increased thus it is possible to reduce the area of the surface emitting light source 1 oled sources being costly and the cost increasing with the area of the surface emitting light source 1 it is important to optimize their use furthermore the homogeneity of the oled 1 is more guaranteed if its dimensions are small this is an additional argument for seeking to reduce its area in the example described the oled 1 is centered on the optical axis x and its dimensions are 20 mm wide and 12 mm high the plane convex lens 11 is focused on the center of the surface emitting light source 1 its entry face 12 is situated at a distance d of 17 mm from the surface emitting light source 1 diagrams a and b in fig4 shows iso candela curves for the surface emitting light source 1 on its own and for the surface emitting light source 1 associated with the lens 11 respectively that for the surface emitting light source 1 on its own case a in fig4 has symmetry of revolution as indicated the photometry charts to.