Abstract: A luminaire for providing wide-angle illumination has a housing with an open side and an arcuate reflector with a reflecting surface that defines a plane of substantial symmetry. This reflecting surface is mounted within the housing and arranged to orient the reflecting surface towards the open side and has first and second reflector portions that are substantially mirror images of each other in relation to the plane of symmetry. The reflecting portions define a focal axis that is normal to said plane of symmetry and formed of a plurality of a substantially elongate reflecting facet surfaces or a series of reflector strips each of which is substantially parallel to the focal axis, the arcuate reflector having asymmetrical cycloidal cross sections in planes substantially normal to the focal axis, and the reflector portions forming an indentation or cusp in the direction of the light source at the point where they meet along the plane of symmetry at least in the region of the focal axis.