Design of ZnS antireflective microstructures for mid- and far-infrared applications

We present broadband antireflective microstructures (AMSs) for high-performance imaging systems in mid- and far-infrared wavelength ranges. Diffraction efficiencies of AMSs on ZnS substrates were calculated using a rigorous coupled wave analysis method. The results show the effect of height, period, and shape of AMSs on the reflection characteristics. We also discuss the optimum geometry of AMSs by considering fabrication tolerances.