Abstract: The invention increases the efficiency of energy conversion processes by providing a system including a thermal radiation source, a reflective surface, and an energy collector such that a photon flux emitted by the thermal radiation source is substantially isotropically reflected by the reflective surface. The thermal radiation source can include additional elements for selecting the angle and wavelengths of the emitted radiation, and the reflective surface may comprise a diffuse reflective surface formed of ceramics, composites, plastics, or metals.