Thomas Knieling

Quasistatic mirrors with large apertures

Excellent accuracy laser projection for high quality optical sensing and measurement tasks . Fraunhofer ISIT has developed 1D and 2D quasistatic scanning mirrors with piezoelectric AlN and AlScN based actuation.

© Fraunhofer ISIT / photocompany, Itzehoe
Gefertigte Spiegel mit 2 mm und 5 mm Aperturen

While commonly used piezoelectric materials like PZT show pronounced non-linear behavior like hysteresis, the non-ferroelectric nitride-based actuators ensure high linearity and large tilting angles. A special rose-leaf shaped actuator designs allows fast and powerful mirror actuation. Compared to electrostatic actuation, pull-in effect and limited actuation range are avoided by using a piezoelectric bimorph. Moreover, mirror plates with different sizes and optical coatings can be used on top of this actuation platform for flexible design and manufacturing of piezoelectric MEMS mirrors. Combined with our advanced multiple-wafer glass-frit bonding technique for hermetic sealing, high mechanical robustness and protection against particles and humidity are achieved. 


Technical specifications

Mirror apertures 2 mm, 5 mm, (10 mm)
Resonant frequencies  ~ 1200 Hz, ~ 250 Hz
Driving voltage (piezoelectric) Up to ~150 V
Field of view (@80V) 16°, 20°



Unique advantages and possibilities

  • Fast and robust AlN/AlScN-based quasistatic mirror actuation for ROI and arbitrary laser projection, e.g. for LIDAR applications in automotive and robotics
  • Various combinations of mirror apertures and frequencies, e.g. for far field laser scanning > 250 m
  • Highly linear mirror movement
  • Optical wafer level packaging with inert gas
  • HR (mirror) and AR (package) coatings for wavelength selection and stray light suppression

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