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Micro-Opto-Electro-Mechanical resonant micromirror featuring a 4 mm aperture for laser-based measurement is presented. The MOEMS-mirror is fabricated on an SOI-wafer with piezoelectric actuators based on aluminium nitride thin films and packaged in a vacuum for a high-efficiency operation. The design of the device features four symmetrical co-radial beam structures, where each beam structure incorporates discrete piezoelectric elements for actuation and sensing. The integrated sensing element provides an accurate and real-time feedback signal for the control system, as it is directly mechanically coupled to the source of movement. Symmetrical design allows the mirror to be excited in the desired mode by modifying the frequency and phase on each of the driving actuators. For the laser measurement applications driving the mirror opposite actuators in opposite polarity and perpendicular axis with different frequencies, creates up to a 40-degree field of view Lissajous scanning pattern. The amplitude of the resonance is strongly affected by the Duffing-type nonlinearity and the derivative of the amplitude vs. frequency curve is small, allowing relatively large changes of frequencies without affecting the amplitude. Phe presented digital control method allows adjustment of frequencies via a phase accumulator to control Lissajous pattern parameters: ratio, phase and amplitude. Due to the high efficiency of aluminium nitride actuators and high Q value, a direct low-voltage CMOS interface can be implemented between the digital control system and piezoelectric actuators. The high amplitude feedback signals allow straightforward conversion to the digital domain and enable monitoring of operation mode and phase.

Piezoelectrically actuated resonant micromirrors were designed to meet the light detection and ranging (LiDAR) system requirements. Key features were a 3-mm mirror aperture, a 40-deg field of view, and a 50-Hz refresh rate. The presented micromirror provides biaxial symmetrical beam steering with ±12.7 deg mechanical tilt angle, resulting in a 50-deg field of view with an adjustable Lissajous XY-scanning pattern for a forward-looking LiDAR system. The mirrors were fabricated using silicon on insulator wafers, and actuation was based on piezoelectric aluminium nitride thin film. The mirrors were vacuum packaged for high-quality factor resonator operation. The device design contained eight separate piezoelectric aluminium nitride elements arranged as differential pairs for each axis, where each actuator was equipped with a sensing element providing a mechanically coupled electrical feedback signal. The piezoelectric elements connected as actuators required only minimal power and were directly compatible with CMOS low-voltage logic, which eases integration to driving digital systems. The sense elements are used to monitor phase, amplitude, and frequency. A digital control system connected to each of these elements provides accurate frequency and phase control of independent orthogonal resonators, permitting control of the X and Y amplitudes and the refresh rate of the Lissajous pattern.