Ein neuartiger Mikroaktor zur ein- und zweidimensionalen Ablenkung von Licht

A novel electrostatically driven silicon Micro Scanning Mirror for one and two dimensional deflection of light is presented. A special configuration of the driving electrodes allows the use of small electrode gaps without restricting the deflection of the plate geometrically. Two dimensional deflection is obtained by a gimbal mounting of the mirror plate. The modelling of the actuator is done by analytical and numerical calculations. For the fabrication of the actuators a CMOS compatible process has been developed. The mechanical elements are patterned in a 30 um thick layer of single crystal silicon. Using the ASE process 4 - 5 um wide trenches are etched into this layer with almost perpendicular sidewalls. In the case of the 2D-Scanner filled isolation trenches are used which allow to excite the two oscillations independently. 36 1D-variants have been designed and characterized. The scanning frequencies cover the range from 0.14 kHz up to 32 kHz. The mirror plates are quadratic with a side length between 0.5 mm and 3.0 mm. Synchronizing the driving voltage with the mechanical oscillation it is possible to achieve a stable oscillation. For large deflection angles a linear dependence of the deflection angle on the driving voltage has been observed. A mechanical deflection angle of up to +/-15° is achieved at a driving voltage of 20 V only, proving the high effectiveness of the driving principle. The performance of the 2D-scanner is demonstrated by three variants. Various Lissajous patterns with a frequency ratio between 1:1 and 13:1 have been generated. Investigations regarding the mechanical performance of the actuators have been carried out. The actuators have a shock resistance of more than 1000 g. Long run tests at a deflection angle of +/-15° mechanical with a duration of more than 10^9 have been performed. The characteristics of the devices did not change. Because of its performance the novel actuator is suitable to replace conventional scanners in a large variety of applications.



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