Improved vision by eye aberration correction using an active-matrix addressed micromirror array
For the correction of the human eye's higher order aberrations in vision science we developed a new micromirror device with an monolithically integrated active CMOS address matrix providing a fine segmented array of 240 × 200 mirror elements across an active area of 9.8 × 8.0 mm2. The micromirrors possess a piston-type architecture for a pure phase shifting capability and are fabricated by means of aluminum surface-micromachining. Using a basic pixel size of 40 × 40 m2 a mechanical stroke of at least 450 nm is obtained at address voltages below 30V, which is suitable for both active matrix addressing and a modulo 2 phase correction in the visible. Furthermore, an active CMOS address matrix similar to a DRAM was developed providing one switching transistor and one storage capacitor for each mirror cell. Those devices were fabricated within a special high voltage CMOS process providing a full analog address capability of up to 30V at an 8 bit resolution defined by the ext ernal driving board. Using interferometric surface profile and laser vibrometer measurements we will present latest experimental results of the mirrors' electromechanical properties. For the first time those micromirror devices now also have been implemented into an ophthalmic diagnosis system for the measurement and correction of the human eye's wave aberrations. Therefore, first results of the obtained aberration reduction as well as the impact on vision enhancement will be presented.