MEMS actuator for in-plane movement of a mobile mass and optical module comprising the MEMS actuator

An apparatus, comprising:

• an optical module, comprising:
• a MEMS actuator comprising:
• a substrate;
• a mobile mass, the mobile mass being suspended over the substrate at a rest height measured along a first direction and extending in a plane of extension defining a second direction and a third directions perpendicular to the first direction;
• elastic elements arranged between the substrate and the mobile mass, the elastic elements having a first compliance parallel to the first direction and a second compliance parallel to the second direction, the first compliance being lesser than the second compliance;
• a plurality of piezoelectric actuation structures, wherein each piezoelectric actuation structure has a fixed portion that is fixed with respect to the substrate and a mobile portion configured to deform in a direction parallel to the first direction in response to an actuation voltage;
• and
• a plurality of movement-transformation structures, wherein each movement-transformation structure comprises:
• an elastic movement-conversion structure arranged between a respective one of the plurality of piezoelectric actuation structures and the mobile mass;
• each elastic movement-conversion structure being compliant in a direction parallel to a movement-transformation plane formed by the first and the second directions and having, in the movement-transformation plane, a first principal axis of inertia and a second principal axis of inertia;
• and
• wherein the first and second principal axes of inertia are transverse with respect to the first and second directions so that a deformation of each of the plurality of piezoelectric actuation structures in the movement-transformation plane causes a corresponding movement of the mobile mass along the second direction;
• a light source supported by the substrate of the MEMS actuator and configured to generate an initial light beam propagating towards the mobile mass;
• an optical detector supported by the substrate of the MEMS actuator and configured to detect an incoming light beam;
• an output optical element supported by the mobile mass and facing the light source, the output optical element configured to modify a direction of propagation of the initial light beam as a function of a relative position between the light source and the output optical element, thereby generating an output light beam;
• and
• an input optical element configured to focus the incoming light beam on the optical detector.