Periodical surface structuring of metals by laser interference metallurgy as a new fabrication method of textured solar selective absorbers

The direct processing of metallic surfaces by an unique technique known as laser interference metallurgy as a new fabrication method of textured solar selective absorbers was illustrated. The method is based on the formation of interference patterns which are produced when two or more coherent laser beams are overlapped on the surface of a material. Surface structuring of low thermal emittance metals brings the desired spectral selectivity in a simple and inexpensive manner without the difficulty of controlling thickness and composition of conventional coatings. The surface irregularities such as grooves and pores with dimensions comparable to the cut-off wavelength increase the solar absorptance and infrared emittance by multiple reflections. The spectral properties of the structured samples indicates that the larger the aspect ratio, the better is the solar absorptance.