A MEMs scanning device has a variable resonant frequency. In one
embodiment, the MEMs device includes a torsion arm that supports an
oscillatory body. In one embodiment, an array of removable masses are
placed on an exposed portion of the oscillatory body and selectively
removed to establish the resonant frequency. The material can be removed
by laser ablation, etching, or other processing approaches. In another
approach, a migratory material is placed on the torsion arm and
selectively stimulated to migrate into the torsion arm, thereby changing
the mechanical properties of the torsion arm. The changed mechanical
properties in turn changes the resonant frequency of the torsion arm. In
another approach, symmetrically distributed masses are removed or added
in response to a measured resonant frequency to tune the resonant
frequency to a desired resonant frequency. A display apparatus includes
the scanning device and the scanning device scans about two or more axes,
typically in a raster pattern. Various approaches to controlling the
frequency responses of the scanning device are described, including
active control of MEMs scanners and passive frequency tuning.