Experimental Study on Coherence of Thermal Radiation of Thin Film Structures

The spectral, angular and polarization characteristics of thermal radiation from plane-parallel Si films are studied experimentally. Pronounced spectral and angular peaks demonstrate the presence of thermal radiation coherence. Two kinds of multilayer films are designed to obtain favourable radiant properties. The ZrO₂--Ge--ZnS film has a broad anti-reflection band in the wavelength range from 3.5μm to 8μm. The spectral and angular emissivities of the MgF₂--ZnS--Ge--Al film are tremendously enhanced compared with those of an uncoated aluminium film. This can be helpful to the design of elements that generate controlled thermal radiation.