Abstract: A hollow-cylindrical ultrasonic actuator is disclosed a central axis, an inner peripheral surface facing the central axis and an outer peripheral surface facing away from the central axis and spaced apart from the inner peripheral surface, a closed inner contour curve, a closed outer contour curve, at least one electrode, and an electromechanical material provided between opposed electrodes. In a non-actuated state of the ultrasonic actuator, a curvature of the inner contour curve or of an outer contour curve includes at least three mutually spaced-apart local maximum points.

Abstract: The invention relates to an ultrasonic motor having a multilayer actuator in the form of a multilayer plate, having one or more friction elements or friction layers on its side surfaces and having an electrical exciter apparatus for the actuator. According to the invention, the multilayer plate has two intersecting, mirror-imaged asymmetrical generators for ultrasonic vibrations, to be precise in the form of layers of exciter electrodes and general electrodes which are alternately arranged with layers of piezoelectric ceramic, wherein a two-dimensional asymmetrical acoustic standing wave is generated in the multilayer actuator.

Abstract: An arrangement for a temperature-compensated multi-dimensional micropositioning of mutually position-defined optical components including a guide unit for housing the optical components and a plurality of piezo actors. The guide unit includes two spaced plates or rings. Also included is three equally spaced solid joints arranged or integrated between the rings or plates, and stack-type piezo actors secured in a neighbouring relationship with the solid joints in such a manner that actuation forces act on the rings or plates. Further, at least the surfaces of the rings or plates accommodating the optical components are coated with a material corresponding to that of the optical components, the guide unit and the optical components are made from materials with essentially the same temperature coefficients, and one stack-type piezo actor is arranged between two solid joints.