Optical MEMS-based micromirror arrays for active light steering in smart windows

Different concepts for active windows for dynamic light regulation and vibrant climatization support in buildings are compared, followed by a MEMS concept using millions of micromirrors inside insulation or vacuum glazing to guide and control light by electrostatic mirror actuation. The concept enables energy saving, tailored personalized lighting, security, and smart personalized environments in buildings. The window transmission is controlled continuously, showing the eye a variable-tone pane. The amount, direction, and degree of steering of the guided light are tailored to winter, summer, and variable daytime requirements, protecting rooms and persons inside from sun-light while providing tailored natural daylight illumination. The concept is based on reflection, in contrast to existing concepts based on absorption. These micromirror arrays have been designed, fabricated, and characterized. Experimental results on electrostatic actuation voltages, extrapolated lifetime, power consumption, and heat impact regulation are presented. (c) 2018 The Japan Society of Applied Physics