Anamorphic concentration of solar radiation beyond the one-dimensional thermodynamic limit

We propose and demonstrate a new scheme for anamorphic concentration of a big (40 cm x 40 cm) diffuse light source to achieve an extremely high concentration in one lateral direction at the expense of that in the other direction, to preserve the total (two-dimensional) optical brightness. Such anamorphic concentration is achieved by a combination of two conventional two-dimensional concentrators and a properly designed retroreflector array. Our experiments in search of a diffuse white-light source with properties comparable with those of solar radiation have yielded 28-fold improvement of the one-dimensional concentration ratio compared with those of conventional concentrators and 14-fold improvement compared with the one-dimensional thermodynamic limit. (C) 2000 Optical Society of America OCIS codes: 080.2740, 220.1770, 230.6080, 350.6050.