Apparatus and method to angularly position micro-optical elements

摘要

A micro-opto-electro-mechanical transducer in which an optical element is angularly positioned by electrical field coupling. Movable electrodes of two orthogonally disposed, differential variable capacitors are coupled to the optical element constrained by structural means to angular displacement around two free-axes of rotation. Cooperating stationary capacitor electrodes with surface contoured regions facing the movable electrodes are affixed to the structural means. A thin dielectric layer of high permittivity material provides a region of fixed spacing between the capacitor electrodes. The surface contoured regions constrain the approach of the movable electrodes with angular displacement of the optical element. Both the open-loop gain and the equilibrium voltage-angle response of the transducer is largely independent of displacement. Electrostatic force feedback maintains the optical element at voltage programmed positions of static equilibrium over a wide angular range of tip and tilt. In simpler embodiments, the optical element is angularly positioned in one direction around one axis of rotation. A preferred method of control allows an electrode of each variable capacitor to be electrically grounded.