The Use of Optical Interference to Obtain Selective Energy Absorption

Abstract : Solar radiation offers a virtually inexhaustible source of energy. With foreseeable depletion of the earth's store of fossil fuel and the recognized need for auxiliary power for space vehicles, there is an increasing interest in efficient solar energy conversion. Except for very short missions, all space flights to date have been powered by direct photovoltaic quantum conversion of solar energy using silicon solar cells. Several other conversion systems are under investigation and some have been in varying degrees reduced to practice. Most of these systems, e.g. thermoelectric, thermionic and solar turbine, are dependent upon the thermodynamic conversion of energy from a source heated by absorption of solar irradiance. Fundamental to the effiency of these systems is a receiver having high absorption in the spectral range from about O.3 mu to l.5 mu, which includes about 90% of the solar energy, and low radiation loss over the range of operating temperatures.