Devices (100) comprise light sources (1) for producing light into directional ranges (70) and light blockers (10) for blocking the light in parts (71) of the directional ranges (70). The light blockers (10) have inner sides (11) and outer sides (12), and are made of materials having optical indices. Combinations of shapes of the outer sides (12) and the optical indices will reflect the light in the parts (71) of the directional ranges (70) at the outer sides (12), for example back to the light sources (1). The shapes of the outer sides (12) may be saw tooth shapes, the optical indices may be larger than 1.4, total reflection may take place for the light in the parts (71) of the directional ranges (70) when incoming at angles smaller than 40° with sides (14, 15) of saw teeth (13) of the saw tooth shapes. Shapes of the inner sides (11) may correspond with shapes of light output graphs of the light sources (1) in the parts (71) of the directional ranges (70).