1. A three-dimensional imaging system comprising: a) a variable focal length MicroMirror Array Lens (MMAL), wherein the MMAL comprises a plurality of micromirrors, wherein motion of each micromirror has two rotational degrees of freedom and one translational degree of freedom, wherein each of the micromirrors in the MMAL is controlled to change the focal length of the MMAL; b) an imaging unit which captures images formed on the image plane by the MMAL; and c) an image processing unit which produces three-dimensional image data using the images captured by the imaging unit and the focal length information of the MMAL.