Articles techniques et présentations

Beam steering and adaptive optics micromirror applications commonly demand optically flat surfaces with minimal mass. When reflective coatings (usually metallic Au or Al) are applied to micromirror surfaces in order to meet optical reflectivity requirements the resulting film stress (usually tensile) can be substantial. The mass of the mirror can be a limiting factor in the dynamic performance. This work provides a quantitative comparison of the design trades between curvature and mass among three different mass reduction etch patterns (hemispherical, square, and triangular) for a notional micromirror element. The results show the each approach can offer reduced mass and curvature values not attainable by micromirror plate thinning alone.