Precision electrostatic actuation and positioning

An electrostatically-controllable actuator comprising:

• a stationary electrode;
• an actuation element separated from the stationary electrode by an actuation gap, the actuation element including a mechanically constrained actuation support region and a conducting actuation region connected to the actuation support region and free to be deflected through the actuation gap;
• and
• an auxiliary element separated from the actuation element by an auxiliary gap, the auxiliary element including a mechanically constrained auxiliary support region connected to the actuation element, and a deflection region connected to the auxiliary support region and free to be deflected through the auxiliary gap, the auxiliary gap being less than the actuation gap and being selected to produce controlled and stable displacement of the actuation region over a displacement range extending to a specified point in the actuation gap when an actuation voltage is applied between the actuation region and the stationary electrode.

An electrostatically-controllable diffraction grating comprising:

• a plurality of electrically isolated and stationary electrodes formed on a substrate;
• a plurality of actuation elements each suspended, by a corresponding mechanically constrained support region, over the substrate by a vertical actuation gap, each actuation element including a conducting actuation region connected to the corresponding actuation support region and free to be deflected through the actuation gap;
• and
• a plurality of mirror elements each including an optically reflecting upper surface and each vertically suspended over a corresponding actuation element by a mechanically constrained mirror support region connected to the corresponding actuation element and defining a vertical mirror gap, each mirror element including a mirror deflection region connected to the mirror support region and free to be deflected through the mirror gap, the mirror gap being less than the actuation gap and being selected to produce controlled and stable displacement of the actuation region through a displacement range to a specified point in the actuation gap when an actuation voltage is applied between the actuation region and a corresponding stationary electrode, for diffracting a beam of light incident on the grating as it is reflected from the upper surfaces of the mirror elements.