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 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.