Interference of Spherical Wave of Thermal Radiation Emitted by a Film System

Abstract

We deal with the emission characteristics of thermal radiation by a surface film system which consists of a metal substrate and a semi-transparent film. First, a spectroscopic experiment is made on emitted thermal radiation of this film system. It is reconfirmed that thermal radiation emitted by this system shows clear interference phenomenon. This system is suggested to be prospective for a spectrally-functional surface which emits radiation in a spectral band region selectively. Next, in order to analyze the thermal radiation emission of the film system, we present a theoretical model of an electromagnetic theory for spherical wave, which is combined with the Planck theory of thermal radiation. Mechanism of interference of emitted thermal radiation wave is discussed on the basis of the model. It is suggested that thermal radiation waves emitted by plural number of dipoles of the metal substrate can be coherent to each other.