Design, simulation and characterization of a MEMS optical scanner

This paper reports on the design, simulation and opto-electro-mechanical characterization of a microelectromechanical system (MEMS) scanner actuated by an out-of-plane ( vertical) electrothermal actuator that was fabricated using a single layer silicon-on-insulator (SOI) foundry process. The overall size of the scanner, including the micromirror and the actuator, is 2 mm x 1 mm. A maximum static mechanical tilting angle of 5 degrees is achieved at a dc driving voltage of 18 V and current of 23 mA, corresponding to a 10 degrees optical scan angle. The scanner can be operated from dc to low frequencies ( the 3 dB bandwidth is from 0 Hz to 80 Hz), which meets the requirement for certain practical opto-electronic systems such as optical coherence tomography (OCT) systems. The scanner has a maximum mechanical tilting angle of 8 degrees at its resonant frequency of 2.19 kHz, corresponding to a total of 16 degrees maximum optical scan angle. Simulations of static and dynamic performances of the scanner have been conducted using finite element method (FEM) software, resulting in outcomes similar to the experimental findings. A thermal response time of 60 ms is calculated numerically using heat flow theory, while a thermal response time of 55.6 ms was experimentally obtained by analysing the intensity distribution of the scanned patterns generated when using a square driving waveform to drive the scanner.