Integrated 512x320 micro mirror array with novel lever-type piston-tip-tilt actuator

For large-scale integration of MEMS micro mirrors Fraunhofer IPMS has realized a novel actuator concept employing a kind of lever-mechanics to support both, a piston-tip-tilt capability as well as to expand deflection boundaries typically given by pull-in effects, e.g. by means of a push-pull operation. Therefore, within a novel approach, an arrangement of four torsional actuator plates is used to serve as levers, hinged to a common center plate as the base for the mirror on top. Deflecting all levers uniformly either towards or away from the center then causes an up and down or push-pull movement of the mirror, whereas any change to this uniform angular plate deflection introduces a torque and hence, a tilt to the mirror base. Such actuators have been integrated on active CMOS address circuitry forming arrays of 48µm, 512 x 320 micro mirrors, which have been fabricated and fully characterized for the first time. Therewith, push-pull and tip-tilt operation has been successfully demonstrated with up to ±1.8µm (3.6µm total) stroke and ±1.6° tilt.