Abstract
Optical systems typically use galvanometers (galvos) and scanners. Galvos move, quasi-statically, from one static position to another. Scanners move in an oscillatory fashion, typically at the device resonant frequency. MEMS devices, which have many advantages and are often used in optical systems, are typically high Q devices. Moving from one position to another for a galvo or one amplitude to another for scanners, can take many periods to settle following the ring down. During these transitions, the optical system is inactive. Here, we show how precisely timed pulses can be used (in an open loop manner) to begin or end scanner motion without ring up/ring down time. The size of pulse required is found to depend on the Q of the device, and relationships are derived. The pulse can also be separated into multiple pulse spaced one period apart if pulses of the necessary size are not possible due to constraints of the physical device. For finite Q scanners, the amplitude decreases after the initial pulse due to damping. This can be eliminated by applying an excitation at the frequency of the scanner. The necessary amplitude for this excitation is derived. Finally, by combining this open loop control algorithm with an open loop control algorithm for galvo motion the device can seamlessly move between scanner and galvo functioning. These control algorithms are demonstrated using computer simulations, analytical models and a commercially available MEMS mirror (Mirrorcle Technologies, A8L2.2).
Highlights
M EMS devices are playing a large and growing role in transducing the electronic domain into the mechanical [1]–[3]
We show how they can be combined with an open loop control algorithm for galvos described previously by Imboden et al which allows galvos to transition in less than a period as well [16]
The key to the approach we present here is to apply the rest of the pulse sequence at times that correspond to integer values of the device period, which for MEMS devices may be known to 1 ppm or better
Summary
M EMS devices are playing a large and growing role in transducing the electronic domain into the mechanical [1]–[3]. We discuss how they both can be operated with open loop control algorithms and achieve essentially ideal behavior These two types of operation, quasi-static and scanning, are widely used because they represent two stable states for a moderately high Q MEMS device, oscillating at resonance or being static [12], [13]. We show how they can be combined with an open loop control algorithm for galvos described previously by Imboden et al which allows galvos to transition in less than a period as well [16] Combining these algorithms allows MEMS devices to move seamlessly between scanner and galvo functioning creating complex responses. These algorithms are demonstrated here with computer simulations, analytical models, and experimentally
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
