A deformable membrane mirror and a related method for its use, the mirror including a deformable membrane having a reflective front face and a back face, and further including electrodes located on both sides of the membrane, to provide a desired surface contour without imparting a concave bias to the membrane. The electrodes include a first set of electrodes spaced from the back face of the membrane, and at least one additional electrode spaced from the front face of the membrane.