High-speed automatic focusing system, imaging device and its method

The invention discloses an automatic focusing system, imaging apparatus and method thereof. The automatic focusing system comprises at least one micromirror array lens, an image sensor, and a signal processor. The micromirror array lens images an object and focuses the image on the image sensor. The image sensor receives the light and converts the photo energy of the light to electrical energy in the form of an electrical signal. The image sensor sends the electrical signal, which carries image data concerning the object, to the signal processor. The signal processor receives the electrical signal, compares the image quality of the image data to its focus criteria, and generates a control signal, which it sends to the micromirror array lens to adjust the focal length of the micromirror array lens. This interative process is continued until the quality of the image data meets the focus criteria, and the process is completed within the afterimage speed of the human eye.