Analysis of the response function for various possible bimorphtype deformable mirrors is presented by numerical calculation. Using this response function, sensitivity comparison of a five-layer bimorph with two- and three-layer structures is carried out. It is shown that the displacement of a bimorph deformable mirror surface reduces when the number of layers increases, and the displacement is closely related to the distance of the control layer from the median plane. The farther electrode contributes the larger deformation on the surface. Furthermore, for a fixed position of the control layer, the displacement is directly proportional to the loading voltage and inversely proportional to the square of the thickness of the PZT layer, and it increases about 1.4 times when the area of the electrode doubles. (c) 2007 Optical Society of America.