Abstract: Reflector having a composite reflectivity enhancing layer as reflecting surface layer on a reflector body where the said composite has a sandwich structure with an aluminum layer facing the reflector body, an outer layer, the HI-layer, with a refractive index n.sub.2 facing the radiation to be reflected, and an intermediate aluminum oxide layer, the LI-layer, with a refractive index n.sub.1 which is smaller than n.sub.2. The LI-layer is a transparent and pore-free barrier layer produced by anodic oxidation of the aluminum layer and having a dielectric constant .epsilon..sub.1 of 6 to 10.5 at 20.degree. C. and the optical layer thickness d.sub.opt.1 of the LI-layer and d.sub.opt.2 of the HI-layer are such thatd.sub.opt,i =d.sub.i.n.sub.i =l.sub.i..lambda./4.+-.10 nm, i=1, 2where d.sub.1 represents the thickness of the LI-layer in nm, d.sub.2 the thickness of the HI-layer in nm, .lambda. the average wave length in nm of the light striking the reflector surface and l.sub.1, l.sub.2, uneven natural numbers.