MEMS-Based Tunable Iris Diaphragm

A microelectromechanical system tunable iris for miniaturized optical systems with a continuous tuning range of 0.45 mm to 1.56 mm is reported. In the proposed design, totally eight blades are combined together to form an octagonal aperture. These blades are evenly arranged in two chips and suspended with T-shaped beam structures, which are specially designed to convert the translatory movement provided by the electrostatic comb drive actuators into in-plane rotation of the blades. When all the blades are simultaneously rotated clockwise or counterclockwise, the aperture size will be increased or decreased accordingly. From experimental results, blade rotation angles of 10° and 11° have been demonstrated in the clockwise and counterclockwise directions, respectively. Consequently, a continuous tuning range from 0.45 mm to 1.56 mm for the aperture diameter of the as-fabricated tunable iris diaphragm has been successfully achieved. At the same time, the response time on the order of milliseconds has also been observed with the current device.