US Patent 7274517 Micromirror array lens with focal length gradient

An optical system includes a refractive lens system and a micromirror array lens with angled positioning to improve light efficiency. The micromirror array lens is optically coupled to the refractive lens system, and has a focal length gradient. The micromirror array lens is configured to focus the light input refracted by the micromirror array lens onto a focal plane, the micromiror array lens is positioned at an acute angle with respect to the light input and the focal plane. The optical system may further include an infrared filter and/or an optical stop to block unwanted light. The advantages of the present invention include improved light efficiency, image quality, and/or focusing.