Micromirrors are micrometer-scale mirrors that are widely used in many applications, mainly in optical-fiber telecommunications, optical scanners, and optical instrumentation. Micromirrors can be integrated within photonic chips, which can be seen as the miniaturized counterparts of the macroscopic optical benches. In optical communication, micromirrors are important building blocks for cross couplers, variable optical attenuators, and external cavity tunable lasers. In all those applications, the efficiency of coupling light in and out from these micromirrors is a key performance indicator governing the signal quality. In instrumentation, micromirrors are also important building blocks of optical interferometers and optical resonators. In these cases, the coupling efficiency is also a key performance indicator affecting the metrological properties.