Resonant micro-mirror oscillation amplitude measurement and all digital actuation

Abstract

The accurate measurement of oscillation amplitude in high frequency resonant micro-mirrors is critical for the correct operation in high precision applications. This paper proposes a novel technique for measuring the oscillation amplitude using a single photodiode placed in the path of the reflected laser beam. Furthermore, for the first time, a measurement-based comparison for different all-digital fractional-N dividers used for the fine adjustment of the mirror drive frequency is presented. It was found that the dithering method, typically used in instrumentation applications, can be successfully applied for the drive of high performance micro-mirrors whilst requiring minimal circuit complexity.