Measurements of a fabricated micro mirror using a lateral-effect position-sensitive photodiode

The characteristics of a fabricated micro mirror were determined using an optical measurement system. The system consisted of a helium-neon laser, a p-i-n lateral-effect photodiode, and other fundamental optical elements, For testing, we used a micro mirror array (1 x 4) in which each mirror was composed of a mirror plate, two torsional flexure hinges, two address electrodes, and two support posts. A mirror plate was designed to a size of 100 x 110 x 1.5 mu m(3) and the hinge size was 20 mu m long, 5 mu m wide, and 0.5 mu m thick. The micro mirror array was fabricated using micromachining technology and a lithography-galvanoformung-abformung-like process using nickel electroplating. The variation in the mirror's deflection angle with applied voltage was measured as a static characteristic. The downward threshold voltage of the 0.5-mu m thick hinge was 48 V, The step response time, as a dynamic characteristic, was 21.8 mu s when a 64-V step voltage higher than the downward threshold voltage was applied to an address electrode. The lifetime of the fabricated micro mirror was tested for both unidirectional and bidirectional operation.