A scanning device includes a frame, having a central opening, and an array including a plurality of parallel mirrors contained within the central opening of the frame. Hinges respectively connect the mirrors to the frame and define respective, mutually-parallel axes of rotation of the mirrors relative to the frame. A main drive applies a driving force to the array so as to drive an oscillation of the mirrors about the hinges at a resonant frequency of the array. A sensor is configured to detect a discrepancy in a synchronization of the oscillation among the mirrors in the array, and an adjustment circuit applies a corrective signal to at least one of the mirrors in order to alleviate the detected discrepancy.