Improved vision by eye abberation 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 x 200 mirror elements across an active area of 9.8 x 8.0 mm 2. 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 x 40 µm 2 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 2ò§... 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 external 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.