A light beam from, for example an optical fibre 11a, held by a waveguide support portion 1 is guided to an illuminated region 21a of a light-deflecting portion 2. A light beam 221 from one light-deflecting device 201 inside this region is reflected by a reflecting surface 31 and passed as a light beam 222 through a light-deflecting device 202 in another illuminated region 21b and arrives at an optical fibre 11b. A light beam 13b from the optical fibre 11b takes the reverse route to the foregoing route. In this way, various light-deflecting devices in one illuminated region are optically coupled to light-deflecting devices in other illuminated regions. Their intensities are made substantially equal. At least 3 waveguides eg. optical fibres 11 are used. N waveguides may be used with less than N<2>-N light deflecting devices e.g. diffraction gratings. <IMAGE>
